JP2003149590A - Display optical system, image display unit, and optical system and device for imaging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a display optical system and an imaging optical system have a wide angle of view by increasing the power of the optical system to constitute the display optical system or imaging optical system by using a small-sized image display element. SOLUTION: The display optical system which guides light from an original picture 3 to the eye of an observer or a projected surface is provided with a 1st surface A which has at least reflecting operation, a 2nd surface C which reflects a light beam reflected by the 1st surface to return it to the 1st surface, and a 3rd surface which transmits light traveling from the original picture to the 1st surface and reflects the light returned from the 2nd surface to the 1st surface and then reflected to guide the light to the eye of the observer or the projected surface. Then a center view angle main light beam which is made incident on the 1st surface again is reflected to the opposite side from the last time about the normal of a surface at its hit point to travel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display optical system suitable for an image display device such as a head mounted display or a projector for enlarging and displaying an original image displayed on an image display device or the like, and an imaging optical system suitable for the image pickup device. It is a thing.

[0002]

2. Description of the Related Art A head-mounted image display device (head-mounted display) which uses an image display device such as a CRT or LCD and enlarges an image displayed on the display device through an optical system is well known. Has been.

In the image display device such as the head mounted display, since these devices are mounted on the head, it is particularly required to reduce the size and weight of the entire device. Further, in consideration of weight balance, appearance and the like, it is preferable that the thickness is thin in the visual axis direction of the observer. Further, in order to give a powerful effect to the displayed enlarged image, a magnified image as large as possible is desired.

FIG. 19 shows an image display device using a conventional coaxial concave mirror. In the device, the display element 101
The light flux from the image displayed on the half mirror 102 is reflected by the half mirror 102 to enter the concave mirror 103, and the light flux reflected by the concave mirror 103 is guided to the eye E of the observer through the half mirror 102. The image displayed on the display element 101 is formed as a virtual image enlarged by the concave mirror 103. Thereby, the observer can observe the enlarged virtual image of the image displayed on the display element 101.

Further, for example, JP-A-7-333551, JP-A-8-50256, and JP-A-8-1603.
No. 40 and Japanese Patent Laid-Open No. 8-179238, an LCD as an image display element for displaying an image is disclosed.
There has been proposed an image display device that uses a (liquid crystal) and a thin prism as an observation optical system to reduce the thickness of the entire device.

FIG. 20 shows an image display device proposed in Japanese Patent Laid-Open No. 7-333551. In this device, the light emitted from the LCD 111 is incident on the incident surface 113 of the small decentering prism 112. Then, the total reflection surface 1 having a curvature formed on the prism 112.
The light flux is folded between the reflecting surface 115 and the reflecting surface 115, and then emitted from the eccentric prism 112 from the surface 114 and guided to the eye E of the observer. This enables the display device (LCD)
A virtual image of the image displayed on 111 is formed, and an observer observes this virtual image.

The reflecting surface 115 of the decentering prism 112 is composed of a decentered free-form surface composed of a decentered non-rotationally symmetric surface (a surface having a different optical power depending on the azimuth angle, a so-called free-form surface).

The type of optical system shown in FIG. 20 is characterized in that it is easier to make the entire apparatus thinner and to widen the field of view of the observation field as compared with the type using the conventional coaxial concave mirror shown in FIG. Have

[0009]

In recent years, LCDs, which are display elements for displaying images, have been made finer, and LCDs having the same number of pixels as the conventional ones but smaller in size than the conventional ones.
Etc. have been developed. Using such a downsized image display element is advantageous for downsizing the device,
In order to achieve the same angle of view as the conventional one, it is necessary to increase the magnification of the optical system.

In view of such a situation, Japanese Patent Laid-Open No. 10-1
Japanese Patent Laid-Open No. 53748 proposes an optical system in which a decentered prism and a relay lens system are combined and an intermediate image is once formed by the relay lens system and then an image displayed on a display element is guided to an observer. As a result, while having the characteristic of the thin type of the type shown in FIG. 20, the magnification is further improved and the angle of view is widened with respect to the LCD size.

Further, in order to further improve the optical performance as compared with the optical system proposed in Japanese Patent Laid-Open No. 10-153748, the internal reflection surface of the decentering prism is increased so that the intermediate image is formed only by the decentering prism. A type in which a second decentering prism is provided in the first decentering prism optical system, and the like in which the image is formed and the image is guided to an observer are disclosed in JP-A-2000-06.
6106, Japanese Patent Laid-Open No. 2000-105338,
JP 2000-131614 A, JP 2000-1
It is proposed in Japanese Patent Laid-Open No. 99853, Japanese Patent Laid-Open No. 2000-227554, Japanese Patent Laid-Open No. 2000-231060, and the like.

Generally, an optical system of the type that temporarily forms an intermediate image has a problem that the optical path length becomes long and the size of the apparatus becomes large. And using a dual-purpose surface that fulfills the reflection function,
We are aiming for miniaturization by devising ways such as intersecting the optical paths.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a display optical system which can achieve a wide display angle of view while using a small display element, and a small display optical system as a whole, and an imaging optical system which is small and can achieve a wide imaging angle of view. I am trying.

[0014]

In order to achieve the above object, the first invention of the present application has at least a reflecting action in a display optical system for guiding light from an original image to an observer's eye or a projection surface. The first surface, the second surface that reflects the light rays reflected by the first surface back toward the first surface, and the light that goes from the original image to the first surface, and the second surface From the center surface angle chief ray re-incident on the first surface. The normal of the surface on that hit point is reflected on the side opposite to the previous time and proceeds.

Further, in the second invention of the present application, in the display optical system for guiding the light from the original image to the observer's eye or the projection surface,
A first optical system having at least first, second and third surfaces, at least second and third surfaces being curved surfaces,
The light passes through the third surface, enters the first optical system, is reflected at least once each by the first and second surfaces in the first optical system, and is reflected by the first and second surfaces. 3rd reflection from 3 times or more
After returning to the surface, the light is reflected by the third surface, transmitted through the first surface, and emitted from the first optical system.

In these inventions, the light is substantially reciprocated between the first, second and third surfaces to substantially overlap the optical paths, so that a long optical path can be secured even with a small optical system. ing. Therefore, it is possible to achieve a wide display angle of view while using a small original image (an image displayed on the image display element or the like), and it is possible to realize a small display optical system as a whole.

Further, the light reflected by the first surface a plurality of times is
First, the light is directed in a direction different from that of the light incident on the first surface.
By providing this surface, it is possible to prevent this light from interfering with the light that first enters the first surface.

Further, by providing the third surface with a transmitting function and a reflecting function, the number of optical surfaces can be reduced, and the size can be further reduced.

Incidentally, it is preferable to form an intermediate image of light in the display optical system (for example, a transparent body). That is, by adopting an intermediate image-forming type in which the intermediate image-forming surface of a small original image is enlarged and displayed, the degree of freedom in layout is increased, the original image can be displayed on a large screen, and the optical path length is considerably long. However, the display optical system can be made compact.

Further, by making the optical surface constituting this display optical system eccentric with respect to the light beam, it is possible to achieve further thinning, and by giving the optical surface a curvature, unnecessary surfaces in the display optical system can be obtained. It is possible to eliminate the above and reduce the size. Furthermore, by making the optical surface a rotationally asymmetric surface (free-form surface), various aberrations can be corrected well,
By adopting a plurality of free curved surfaces, the aspect ratio of the original image and the aspect ratio of the display image can be made close to each other, and a high quality display image can be obtained.

This display optical system is a projection type image display device for enlarging and projecting an image on a projection surface such as a head mounted display (HMD) or a screen for an observer to wear on the head to observe the image. It is suitable for image display devices such as (projectors).

According to the third aspect of the present invention, in the image pickup optical system for guiding the light from the subject to the image pickup surface, at least the first surface having a reflecting action and the light beam reflected by the first surface are again reflected by the first surface. And a second surface that reflects toward the first surface, and the light from the subject that is reflected toward the first surface, and the light that is reflected from the second surface back to the first surface and reflected again is on the imaging surface side. It has a third surface that is transmitted to the first surface, and the central angle-of-view chief ray that re-enters the first surface is reflected and travels on the opposite side to the normal of the surface on the hit point. .

Further, in the fourth invention of the present application, in the image pickup optical system for guiding the light from the object to the image pickup surface, there is provided a first optical system having at least first, second and third surfaces, and at least the first optical system. The second and third surfaces are curved surfaces, light passes through the first surface and enters the first optical system, and at least one of the first, second and third surfaces in the first optical system. The light is reflected once, reflected three times or more in total on the first and second surfaces, returned to the third surface, transmitted through the third surface, and emitted from the first optical system.

In these third and fourth inventions, the first,
By making the light substantially reciprocate between the second and third surfaces to substantially overlap the optical paths, it is possible to secure a long optical path length even though it is a small optical system. For this reason, it is possible to achieve a wide image angle of view while being compact.

Further, by providing the third surface with the transmitting function and the reflecting function, the number of optical surfaces can be reduced, and the size can be further reduced.

Incidentally, it is preferable to form an intermediate image of light in the image pickup optical system (for example, a transparent body). That is, by adopting an intermediate image formation type in which the intermediate image formation surface of the subject is reduced and guided to the image pickup surface, the degree of freedom in layout is increased, and it is possible to sufficiently reduce the object image having a wide angle of view and lead it to the image pickup surface. In addition, the image pickup optical system can be made compact even if the optical path length is considerably lengthened.

Further, by decentering the optical surface constituting the image pickup optical system with respect to the light beam, it is possible to further reduce the thickness, and by giving the optical surface a curvature, an unnecessary surface in the image pickup optical system. It is possible to eliminate the above and reduce the size. Furthermore, by making the optical surface a rotationally asymmetric surface (free-form surface), various aberrations can be corrected well,
By adopting a plurality of free curved surfaces, the aspect ratio of the subject and the aspect ratio of the captured image can be made close to each other, and a high quality captured image can be obtained.

The image pickup optical system is suitable for an image pickup apparatus such as a digital still camera or a video camera.

In the first and second inventions, an optical surface is formed on a transparent body whose inside is filled with an optical medium,
By causing the light to be totally internally reflected by one of the optical surfaces, it is possible to reduce the light amount loss even with a long optical path length.

In each of the display optical system and the image pickup optical system, it is preferable that the surface that reflects and returns light is a curved surface. If the folding reflection surface is a flat surface, the directions of the light rays of the peripheral image cannot be individually controlled at the time of reflection, so that the optical system becomes large. If the folding reflection surface is a rotationally asymmetric surface, the light ray direction of the peripheral image can be freely controlled, and therefore the size can be further reduced as compared with the case of a curved surface.

Here, the return reflection surface is a surface only for the reflection action, and it is desirable to reduce the light amount loss as much as possible by applying a metal mirror coating that reflects almost 100% of the light.

In the first and second inventions, when the central angle-of-view chief ray reflected by the first surface is reflected back at the second surface at an angle θ, the light is incident on the returning reflection surface. The angle θ formed by the central ray of principal angle of view and the principal ray of reflected central angle of view preferably satisfies | θ | <30 ° (1). If this condition is not satisfied, the optical system becomes large.

When the display optical system of the present invention is used as a head mounted display (HMD), it is preferable to provide an independent original image (image display element) and a display optical system for the left and right eyes.

That is, by having two original images (the same one) and two display optical systems (the same one) matching them, it is possible to divide the light into the left and right display optical systems by one original image. A bright display image can be obtained.

Further, in the display optical system of the present invention, it is preferable that the local meridional section, which is an eccentric section for both the left eye and the right eye, is arranged in the vertical direction of the human face (folding the light beam up and down).

Usually, the enlarged display image has a wide angle of view in the left-right direction of the human and a narrow angle of view in the up-down direction (right / left 4: up / down 3 or 16: 9 ratio), so that it is an eccentric section and eccentric aberration occurs. It is preferable to set the local generatrix cross section having a large angle at the top and bottom with a small angle of view because the occurrence of eccentric aberration in the enlarged display image can be reduced.

The above optical system, in other words, the first optical system
Angle with respect to the normal to the hit point of the central angle of view chief ray that first entered the surface of, and the normal to the hit point of the central angle of view chief ray that is reflected by the second surface and re-enters the first surface The reflection angle with respect to is the opposite sign. That is, the light reflected from the first surface
The surface of the first surface reflects the light so that it returns to the first light reflection area side (reflection area, near the reflection area, or near the reflection area), thereby effectively overlapping the light paths and reducing the long light path length. It is designed to be housed in the optical system of.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION Before describing the embodiments of the present invention, the definitions of the busbar section, the sagittal section, the local busbar section, and the local sagittal section used in this embodiment will be described.

In the definition of the conventional system that does not correspond to the eccentric system, when the z axis is the optical axis in each surface vertex coordinate system, the yz section is the conventional meridional section (meridional section), and the xz section is the sagittal section (sagittal). Cross section).

Since the optical system of this embodiment is a decentered system,
Local busbar cross section and local sagittal cross section corresponding to the eccentric system are newly defined.

Central view angle principal ray (in the display optical system, this is a ray from the image center of the display element to the exit pupil center of the display optical system, and in the image pickup optical system, it passes through the entrance pupil center of the image pickup optical system. The ray that reaches the center of the image) and the hit points of each surface are the local meridional section that includes the incident light and the exit light of the central angle of view principal ray, and each of them is perpendicular to the local meridional section that includes the hit point. A plane parallel to the sagittal section (normal sagittal section) of the surface vertex coordinate system is defined as a local sagittal section.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
An optical system (hereinafter referred to as a first optical system) that is an embodiment is shown. The first optical system 1 is configured to have three optical surfaces, and the surface A (first surface) and the surface B (third surface) are both transmissive and reflective. It is a reflective / combined surface, and the surface C (second surface) is a reflective surface.

On the surface C, a reflection film having a reflectance of about 100% is formed by metal deposition or the like, and the surfaces A and B are formed.
A semi-transmissive reflective film is formed on the substrate by metal vapor deposition or dielectric vapor deposition.

FIG. 2 shows the first optical system 1 shown in FIG.
Shows a configuration of the entire display optical system when it is used in an image display device by configuring a transparent body (hereinafter, also referred to as the first optical element 1) whose inside is filled with an optical medium.

In the figure, 2 is a second optical system, and 3 is an image display element (LCD or the like) for displaying an image. In the present embodiment, the surface B functions as an incident surface and a reflection surface of light from the image display element 3, the surface A functions as a reflection surface and an emission surface, and the surface C functions as a reflection surface.

The light modulated by the image display element 3 is guided to the first optical element 1 via the second optical system 2. The light that has entered the first optical element 1 from the surface B is reflected by the surface A, is then reflected in a substantially opposite direction by the surface C, and is guided to the surface A again. Then, after being reflected by the surface A, it is reflected by the surface B and exits the first optical element 1 from the surface A and reaches the exit pupil S.

In this figure, as an example of light emitted from the image display element 3, a central angle-of-view chief ray that exits the center of the display surface of the image display element 3 and reaches the center of the exit pupil S is shown.

In the present embodiment, the observer puts his eyes near the position of the exit pupil S, so that an enlarged image of the image displayed on the image display element 3 can be visually recognized.

In the first optical element 1, the light is
Surface B (transmission) → surface A (reflection) → surface C (return reflection) →
Surface A (re-reflection) → surface B (reflection) (→ surface A (transmission)) are passed through each surface in this order, and the optical path up to that point is returned to the final reflection surface B at the boundary of the return reflection at surface C. Follow in reverse.

Here, the surface B → the surface A → the surface C is referred to as a forward path, and the optical path of the surface C → the surface A → the surface B is referred to as a return path, and the forward path and the return path are collectively referred to as a round trip optical path.

In particular, the re-reflection on the surface A is performed so that the central angle-of-view principal ray is reflected on the side opposite to the first normal reflection on the surface A with respect to the normal of the surface on the hit point. It forms a round-trip optical path.

By thus providing the surface C with a function as a return reflection surface and forming a reciprocating optical path in the first optical element 1, the optical paths are almost overlapped and the long optical path is small in size.
Can be accommodated in the optical element 1. As a result, the entire display optical system is downsized.

The light rays from the image display element 3 pass through the reciprocating optical path due to the reflection on the final reflecting surface B, and the image display element 3
It is guided to the eyeball side instead of going to the side.

Further, as shown by the dotted line in FIG. 3, the light (maximum field angle chief ray) that exits the edge of the image display surface of the image display element 3 and reaches the center of the exit pupil S is the center field angle principal ray. Like the rays,
The light is guided to the first optical element 1 via the second optical system 2, passes through the B-side incident → A-side reflected → C-side folded reflection → A-side reflected → B-side reflected → A-side exit, and exit pupil S Be led to the center of.

Further, as shown by the chain line in FIG. 4, the rays of light that emerge from the center of the image display surface of the image display element 3 and reach both ends of the exit pupil S are the same as the central angle of view chief ray. It is guided to the first optical element 1 via the optical system 2 of No. 2 and passes through the B-side entrance → A-side reflection → C-side reflected reflection → A-side reflection → B-side reflection → A-side exit in the order of exit pupil S. Guided to both ends.

At this time, light rays from both ends intersect in the first optical system 1 to form an intermediate image of the image displayed on the image display element 3. By forming an intermediate image in the first optical element 1, a compact structure can be obtained even if the power of the second optical system 2 is weakened.
It is possible to suppress the occurrence of extra aberrations in 1) and to prevent the second optical system 2 from becoming complicated.

In FIG. 4, an intermediate image is formed between the reflection on the C surface and the reflection on the A surface, but the intermediate image forming position does not necessarily have to be at this position, and the first optical element 1 It may be formed inside.

Further, in order to facilitate the aberration correction of the so-called eyepiece optical system portion which guides the intermediate image to the exit pupil S as substantially parallel light, the intermediate image forming surface has a field curvature and astigmatism in the eyepiece optical system portion. It may be formed so as to be appropriately curved or have an astigmatic difference according to the situation in which.

In FIG. 4, the surface B, which is the final reflecting surface, and the portion of the surface A, which acts as the exit surface, correspond to the eyepiece optical system portion, and the other portions of the first optical system 1 and the other portions. The optical system 2 of 2 corresponds to a relay optical system.

In the present embodiment, the surface B, which acts as the final reflecting surface, is a concave mirror having a very strong optical power (1 / focal length) and bears the main power of the eyepiece optical system portion. ing. Therefore, eccentric aberration is largely generated on the concave mirror surface B, and it is difficult to completely correct the aberration only with the surfaces A and B as the eyepiece optical system, and the relay optical system portion cancels the aberration in the eyepiece optical system. By forming an intermediate image so that an intermediate image plane of such a shape is formed, it is possible to improve the image quality in the final image observation.

In the configuration described above, it is preferable that the first optical system 1 has at least two surfaces including the surface B which are curved surfaces. By reducing the number of surfaces that do not contribute to light collection, divergence, or aberration correction, the number of optical surfaces required for the entire optical system can be reduced, and the effect of manufacturing cost reduction can be expected. More preferably, the surfaces A, B, and C are each formed by a curved surface, so that the effect of further reducing the manufacturing cost can be obtained.

The surfaces A and B of the first optical system 1 are surfaces that are inclined with respect to the reflected light rays when the effective light rays that are finally guided to the exit pupil S are reflected by the respective surfaces, and are reflected back. To the C surface, which is the surface, that is, B surface incidence → A surface reflection →
Optical path of C surface and return path after C surface C surface → A surface reflection →
The first optical system 1 has a thin structure in which the optical path from the B-side reflection to the A-side exit is substantially overlapped.

That is, preferably, both the surface A and the surface B are curved surfaces decentered with respect to the effective light beam, and decentering aberration occurs. Therefore, it is desirable to use a rotationally asymmetric surface (so-called free-form surface) as at least one surface of the first optical system 1 to suppress the occurrence of decentration aberrations as much as possible.

Especially, since the surface B is a curved surface having a strong power,
It is preferable that the surface B has a rotationally asymmetric shape to suppress the occurrence of decentering aberration.

More preferably, all of the three surfaces A, B, and C constituting the first optical system 1 have a rotationally asymmetric shape, so that the degree of freedom of decentering aberration correction is increased and an image with good image quality is obtained. Can be displayed. At this time, if each rotationally asymmetric surface has a plane-symmetrical shape in the direction perpendicular to the paper surface with the cross-section of the paper being the only plane of symmetry, processing and manufacturing can be facilitated as compared to the case where there is no symmetry. ,preferable.

Further, it is preferable that the reflection on the surface A is the total internal reflection within the first optical element 1 since the light quantity loss is reduced. At least in a region where the reflected light flux and the outgoing light flux are shared on the surface A, if the reflected light flux is totally internally reflected, the degree of freedom in design is increased as compared with the case where all the reflected light fluxes are totally internally reflected. The same level of brightness can be secured.

By configuring the optical system as described above, it is possible to provide an image display device that displays an image displayed on the image display element 3 as a magnified image with good optical performance.

Further, by performing the intermediate image formation once in the first optical element 1, the degree of freedom in setting the display angle of view with respect to the display size of the image display element 3 is improved to widen the angle of view (high magnification display). ) Is made possible, and the optical path length is increased accordingly. By forming a reciprocal optical path in the first optical element 1, the first optical system is configured such that the reciprocal optical paths having a long optical path are substantially overlapped. It is possible to configure a very compact display optical system by suppressing the total length of 1 to be short.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention.
1 illustrates an imaging optical system that is an embodiment. In the figure, 1 is FIG.
First optical system (first optical element) similar to that shown in FIG.
2 is a second optical system, and 4 is an image sensor.

S is the first optical system 1 and the second optical system 2.
Is an entrance pupil of the image pickup optical system, and a diaphragm is placed at this position to prevent unwanted light from entering.

In the present embodiment, the surface A (first surface) of the first optical element 1 acts as an incident surface and a reflection surface of light from the subject, and the surface B (third surface) is a reflection surface. It acts as an exit surface, and the surface C (second surface) acts only as a reflecting surface.

The light from the subject that has passed through the diaphragm S is
The light enters the optical element 1 from the surface A, is reflected by the surface B, is reflected by the surface A, and is guided to the surface C. Then, the light is reflected back on the surface C, returned to the surface A, re-reflected on the surface A, transmitted through the surface B, and emitted from the first optical element 1. Here, the surface A and the surface B are eccentric with respect to the reflected light flux on each surface.

The light emitted from the first optical element 1 passes through the second optical system 2 and reaches the image pickup element 4. At this time, a desired light from the outside world (subject) is imaged on the imaging surface of the imaging device 4, whereby an outside world image can be taken.

By configuring the image pickup optical system as described above, it is possible to provide an image pickup apparatus which forms an image of a subject on the image pickup element 4 with good optical performance.

Further, by forming an intermediate image once in the first optical element 1, it is possible to increase the degree of freedom of the photographing angle of view with respect to the size of the image pickup element 4 and widen the angle of view. Along with this, the optical path length becomes longer. By forming a reciprocating optical path in the first optical element 1, the optical paths are almost overlapped, and the total length of the first optical system 1 is suppressed to be short, thereby realizing a very compact imaging optical system. is doing.

In the first and second embodiments described above, the central view angle principal ray (in the display optical system, a ray from the center of the display surface of the image display element to the center of the exit pupil S, and in the image pickup optical system, Although the reflected reflection on the surface C of a light beam that passes through the center of the entrance pupil and reaches the center of the image pickup surface of the image pickup element is substantially vertical reflection, the optical system of the present invention is not limited to this configuration. .

(Third Embodiment) FIGS. 6 and 7 show the configuration of a display optical system which is a third embodiment using a first optical system different from the first embodiment. In the first optical systems 1 ′ and 1 ″ shown in these figures, the optical path of the central angle-of-view chief ray is different from that of the first embodiment.

In both FIGS. 6 and 7, the first embodiment of the first embodiment is that an optical path of B-side incidence → A-side reflection → C-side folded reflection → A-side reflection → B-side reflection → A-side emission is formed. The optical system 1 is the same as the optical system 1.

However, in the first optical system 1'of FIG.
The central angle-of-view chief ray reflected at is reflected back at surface C at an angle θ, and is re-reflected at a position higher than the previous reflection point on surface A (however, the area near the first light reflection area). This is different from the first embodiment. Further, in the first optical system 1 ″ of FIG. 7, the central angle-of-view chief ray reflected by the surface A is reflected back at the surface C at an angle θ, and is located at a position lower than the previous reflection point on the surface A. (However, it is different from the first embodiment in that it is re-reflected in a region near the first light reflection region).

As described above, the light may be incident and reflected at a predetermined angle θ before and after the return reflection surface C. However, it is preferable that the angle θ satisfies | θ | <30 °.

If this condition is not satisfied, the first optical system becomes large and it becomes difficult to make the entire display optical system small, which is not preferable.

Although the display optical system having the first optical system has been described in the present embodiment, the same concept as in the present embodiment can be applied to the image pickup optical system shown in the second embodiment. You can

[Numerical Example 1] FIG. 8 shows an optical path sectional view of a numerical example of the first embodiment shown in FIG.
In the figure, 1 is a first optical system that constitutes a display optical system,
It is composed of a prism-shaped transparent body (optical element) having three optical surfaces. S2, S4, S6 are the same surface, S3, S7 are the same surface, and these two surfaces and S5 respectively correspond to the surfaces A, B, C described in the fourth embodiment.

Reference numeral 2 is a second optical system, and here, S8,
The transparent body is made of the same medium and has three surfaces S9 and S10. SI is an image display surface, and S1 is an exit pupil S of the display optical system.

In this numerical example, the optical surfaces from S1 to S10 are rotationally asymmetrical surfaces and have a plane symmetric shape having the paper surface (yz section) as the only symmetric surface.

Note that x, y, and z in the figure are coordinate system definitions with the observer's visual axis direction as the z axis, the direction perpendicular to the z axis in the paper plane as the y axis, and the direction perpendicular to the paper plane as the x axis. Is.

Table 1 shows the optical data of Numerical Example 1. The leftmost item SURF in the optical data in Table 1 indicates the surface number. Also, X, Y, Z and A are the first
The center of the surface S1 is the origin (0, 0, 0), and the position of the surface apex of each surface (x, y, in the coordinate system in which the y-axis and the z-axis shown in the figure and the x-axis in the depth direction of the paper are taken). z) and the rotation angle a (unit: degree) about the x-axis with the counterclockwise direction as the positive direction on the drawing.

R is the radius of curvature. The term TYP represents the type of surface shape, SPH is a spherical surface, and FFS is a rotationally asymmetric surface according to the following equation.

[0089]

[Equation 1]

The numerical value next to FFS in the TYP column indicates that the shape of the surface is a rotationally asymmetric shape corresponding to the aspherical coefficients k and ci described at the bottom of the table. .

Nd and νd (however, denoted as vd in the table) respectively indicate the refractive index and the Abbe number at the d-line wavelength of the medium after that surface, and the change in the sign of the refractive index N at that surface. It shows that the light is reflected. When the medium is an air layer, only the refractive index Nd is displayed as 1.000,
Abbe number νd is omitted.

The absolute value of the angle θ formed by the incident ray and the reflected ray of the central angle-of-view principal ray on the folding reflection surface is | θ |
It has been described as. The items in the above table are the same in the following numerical examples.

[0093]

[Table 1]

As can be seen from Table 1, the light from the image display surface SI is made incident on the optical element which is a transparent body constituting the second optical system 2 at S10, is reflected on the back surface at S9, and is emitted from S8. Heading to the first optical element 1. The light directed to the first optical element 1 enters the transparent body of the first optical element 1 from S7 (Surface B), is back-reflected at S6 (Surface A), and is back-reflected at S5 (Surface C). It is then folded back, reflected on the back surface at S4 (Surface A), reflected on the back surface at S3 (Surface B), exits the first optical element 1 from S2, and is guided to the exit pupil S1 (S).

Assuming that the numerical value having the dimension of length in this numerical example is mm, the exit pupil diameter is φ6 mm, the image display size is about 10 mm × 7.5 mm, and the horizontal is about 50 mm.
The display optical system displays an image at an infinity in the positive direction of the z-axis at an angle of view of 90 ° and a vertical angle of 39 °.

The optical system of this numerical example may be used as an image pickup optical system. In this case, the light from the object point at the infinite distance in the negative direction of the z-axis passes through the diaphragm S1 and is guided to the first optical element 1. Then, from S2 (Surface A) to the first optical element 1
The light incident on S3 (Surface B) is reflected by S3 (Surface A).
After being reflected by, reflected back at S5 (surface C), reflected at S6 (surface A), emitted from S7 (surface B) and guided to the second optical system 2. Then, the light guided to the second optical system 2 enters the transparent body from S8, is reflected in S9, and is reflected in S10.
Is emitted to form an image on the imaging surface SI.

(Fourth Embodiment) FIG. 9 shows a fourth embodiment of the present invention.
1 illustrates a configuration of a display optical system that is an embodiment. In addition,
In this embodiment, points different from the first embodiment will be mainly described. In the present embodiment, the first optical system 21 has a total of four optical surfaces including an optical element similar to a transparent body having three optical surfaces and a reflecting surface C separately provided. It is configured.

Of the three optical surfaces A, B, and D on the optical element, surfaces A and B are both transmission / reflection surfaces that act as transmission and reflection surfaces, surface D is a transmission surface, and surface C is a reflection surface. is there.

A reflective film having a reflectance of about 100% is formed on the surface C by metal vapor deposition or the like, and a semi-transmissive reflective film is formed on the surface B by vapor deposition of a metal or a dielectric.

The light modulated by the image display element 3 is guided to the optical element of the first optical system 21 via the second optical system 2. Light enters the optical element of the first optical system 21 from the surface B, is reflected by the surface A, and is transmitted through the surface D. The light transmitted through the surface D enters the surface C and is reflected so as to return in a direction substantially opposite to the incident direction. Thereby, the light is again transmitted through the surface D and guided to the surface A, re-reflected by the surface A and reflected by the surface B, and then transmitted through the surface A and emitted from the optical element of the first optical system 1. , Reaches the exit pupil S.

Also in the present embodiment, when the observer puts his eyes near the position of the exit pupil S, it becomes possible to visually recognize a magnified image of the image displayed on the image display element 3.

In the present embodiment, the first optical system 21
In, the light passes through each surface in the order of B → A → D → C → D → A → B (→ A), and follows the optical path up to that point with the reflection at the surface C as a boundary.

The first optical system 21 is the optical path of B → A → D → C → D → A → B, which follows the previous path in reverse with the surface C interposed.
By forming a round-trip optical path inside, the optical paths are almost overlapped,
The size of the first optical system 21 is reduced with respect to the optical path length by effectively utilizing the inside of the first optical system 21. As a result, the entire display optical system can be downsized.

In the present embodiment, the surface D is used as a transmission surface, and the first optical system 21 has four optical surfaces, and the first optical system 21 has four optical surfaces.
The number is one more than that in the embodiment. As a result, the degree of freedom in optical design is increased, and aberration correction can be performed better.

In particular, as compared with the first embodiment, the transmissive surface between the transparent body and the air is increased, and the degree of freedom for correcting chromatic aberration is increased.

[Numerical Example 2] FIG. 10 is an optical sectional view showing a numerical example of the fourth embodiment. 20 in the figure
Is a display optical system, and 21 is a first optical system having three optical surfaces.
A transparent body (first optical element) constituting the optical system of No. 22 and a reflection mirror member 22.

S2, S4 and S8 are the same surface, S3 and S9 are the same surface, and S5 and S7 are the same surface, which correspond to the surfaces A, B and D described in the fifth embodiment. Also, S6
Corresponds to the surface C.

Reference numeral 30 in the drawing denotes a second optical system,
It is composed of the surfaces S9 to S12. In the present numerical example, one surface of the transparent body (first optical system 21) and one surface of the transparent body (optical element) forming the second optical system 30 are bonded to each other, and the bonding surface is It is S9.

These first and second optical systems 21, 30
In the present numerical example, all the surfaces that form (1) are rotationally asymmetrical surfaces, and have a plane symmetric shape having the paper surface (yz cross section) as the only symmetric surface. The optical data of this example is shown in Table 2.
Shown in.

[0110]

[Table 2]

As can be seen from Table 2, the light from the image display surface SI enters the first optical system 21 from S9 (surface B) through S12, S11 and S10 and is reflected by S8 (surface A). Then, the transparent body of the first optical system 21 is emitted while refracting at S7 (plane D). The emitted light is reflected by S6 (Surface C), enters the transparent body again from S5 (Surface D), is reflected by S4 (Surface A), is reflected by S3 (Surface B), and is S2 (Surface A). From which a transparent body is emitted and is guided to the exit pupil S1 (S).

Assuming that the numerical value having the dimension of the length in this numerical example is mm, the exit pupil diameter is φ6 mm, the image display size is about 10 mm × 7.5 mm, and the horizontal is about 50 mm.
The display optical system displays an image at an infinity in the positive direction of the z-axis at an angle of view of 90 ° and a vertical angle of 39 °.

The optical system of this numerical example may be used as an image pickup optical system. In this case, the light from the subject at infinity in the negative direction of the z-axis passes through the diaphragm S1, enters the transparent body of the first optical system 21 from S2, is reflected by S3 and S4, and is reflected by S5.
Eject a transparent body from. Then, the light is reflected in S6, again enters the transparent body from S7, is reflected in S8, and is emitted from the transparent body in S9. The light emitted from the transparent body is the second optical system 30.
To the imaging surface SI via S10, S11, S12.
An external (subject) image is formed on top.

(Fifth Embodiment) FIG. 11 shows a display optical system according to a fifth embodiment of the present invention. The present embodiment differs from the first to fourth embodiments in that the number of reflections in the first optical system 31 is 6 and the number of reflections in the first optical system is 4.

In the first optical system 31, of the three optical surfaces A, B and C formed on the transparent body (hereinafter also referred to as the first optical element 31), the surfaces A and B are both transparent surfaces. A surface that also serves as a transmissive and reflective surface that acts as a reflective surface, and a surface C is a reflective surface. On the surface C, a reflective film having a reflectance of about 100% is formed by metal vapor deposition or the like, and on the surface B, a semi-transmissive reflective film is formed by vapor deposition of metal or dielectric. Part of the surface A (upper part) is approximately 1 by metal deposition or the like.
A reflective film having a reflectance of 00% is formed.

The light modulated by the image display element 3 is guided to the first optical element 31 via the second optical system 2.
The light enters the first optical element 31 from the surface B, is reflected by the surface A for the first time, and is guided to the surface C. The light reflected by the surface C for the second time is guided to the upper part of the surface A and reflected for the third time.
The third reflection on the surface A is such that the incident light is returned in a direction substantially opposite to the incident direction, and the light is again reflected on the surface C.
Are reflected back to the surface C, are reflected by the surface C for the fourth time, and are again guided to the surface A, and are reflected for the fifth time, and are guided to the surface B. And side B
After the sixth reflection at, the light passes through the surface A, exits the first optical element 31, and reaches the exit pupil S.

Also in this embodiment, the observer can view the enlarged image of the image displayed on the image display element 3 by placing the eyes near the position of the exit pupil S.

In this embodiment, in the first optical element 31, the light is surface B (transmission) → surface A (first reflection) → surface C.
(Second reflection) → Surface A (Third reflection (return reflection))
→ surface C (fourth reflection (rereflection)) → surface A (fifth reflection (rereflection)) → surface B (sixth reflection (reflection)) (→ surface A
After passing through each surface in the order of (transmission), the optical path up to that point is traced in reverse until the final reflection surface B is reached by the return reflection on the surface A.

A back-and-forth optical path is formed in the first optical element 31 in the order of the surface B, the surface A, the surface B, the surface A, the surface C, the surface A, the surface C, the surface A, and the surface B. Thus, the optical paths can be substantially overlapped with each other, and the space in the first optical element 31 can be effectively used to reduce the size of the first optical system 31 with respect to the optical path length. As a result, the entire display optical system can be downsized.

According to the present embodiment, the optical path length can be made longer than that of each of the above-mentioned embodiments, which is advantageous in the case of increasing the display enlargement ratio.

As shown by the dotted line in FIG. 12, the light (maximum field angle chief ray) that exits the edge of the image display surface of the image display element 3 and reaches the center of the exit pupil S is the second optical system 2. Plane B incident on the first optical element 31 → face A reflection → face C reflection → face A return reflection → face C re-reflection → face A re-reflection → face B reflection →
It is guided to the center of the exit pupil S by following the same path as the exit of the surface A and the central angle of view chief ray.

Further, as shown by the dotted line in FIG. 13, a ray of light that has exited from the center of the image display surface of the image display element 3 and reaches both ends of the exit pupil S also passes through the second optical system 2 and becomes a first ray. Surface B incidence → surface A reflection → surface C reflection → surface A reflection reflection → surface C re-reflection → surface A re-reflection → surface B reflection → surface A exit and the same path as the central field angle chief ray with respect to the optical system 31. Follow

At this time, light rays from both ends of the image display surface intersect in the first optical element 31, and an intermediate image forming surface of the image displayed on the image display element 3 is formed. By thus forming the intermediate image in the first optical element 31, a compact structure can be obtained even if the power of the second optical system 2 is weakened, and an extra aberration in the second optical system 2 is generated. It is possible to suppress the occurrence and to prevent the second optical system 2 from becoming complicated.

In the present embodiment, the intermediate image is formed during the re-reflection of the C surface → the re-reflection of the A surface, but the intermediate image plane need not necessarily be located at this position. Further, in order to facilitate the aberration correction of the so-called eyepiece optical system portion that guides the intermediate image formation surface to the exit pupil S as substantially parallel light, the intermediate image causes field curvature and astigmatism in the eyepiece optical system portion. It is preferable that the image is formed so as to be appropriately curved or have an astigmatic difference according to the situation.

In the present embodiment, the surface B which is the final reflection surface, the re-reflection surface on the surface A, and the portion acting as the exit surface correspond to the eyepiece optical system portion, and the first optical system 3
The other part in 1 and the second optical system 2 correspond to the relay optical system.

The surface B when acting as the final reflecting surface is
It is a concave mirror having a very strong optical power (1 / focal length), and bears the main power of the eyepiece optical system part. Therefore, the occurrence of decentration aberration is large on the concave mirror surface B,
It is difficult to completely correct aberrations only with the surfaces A and B as the eyepiece optical system, and the relay optical system portion should form an intermediate image forming surface in a shape that cancels the aberration in the eyepiece optical system. Thus, it becomes possible to improve the image quality in the final image observation.

In the above-described embodiment, by making at least the surfaces B and C of the first optical system 31 curved surfaces, the surfaces that do not contribute to the light collection, divergence, or aberration correction are reduced, and the surfaces required for the optical system are reduced. The number can be reduced. Further, by forming each of the surfaces A, B, and C with a curved surface, it is possible to provide an optical element in which a surface that does not contribute to light collection or divergence or aberration correction is further omitted, and a cost reduction effect can be expected.

The surfaces B and C and the surface A of the first optical system 31 are
A part (lower part) of the area is formed by a surface inclined with respect to an arbitrary ray forming the reflected light flux when the effective light flux guided to the exit pupil S is reflected by each surface, and
Surface incidence → A surface reflection → C surface reflection → A surface reflection and back reflection →
An optical path of C surface re-reflection → A surface re-reflection → B surface reflection → A surface emission is formed.

That is, a part of the surfaces B and C and the surface A (lower part)
The area of is an eccentric reflection curved surface decentered with respect to an arbitrary ray forming the reflected light flux, and eccentric aberration occurs here.
Therefore, by using a rotationally asymmetric surface (so-called free-form surface) for at least one surface of the first optical element 31,
It is desirable to suppress the occurrence of decentration aberrations as much as possible.

In particular, since the surface B is a curved surface having a strong power, it is preferable to make the surface B rotationally asymmetrical to suppress the occurrence of decentration aberrations.

More preferably, by making all three surfaces A, B and C forming the first optical system 31 rotationally asymmetrical, the degree of freedom of decentering aberration correction is increased and an image of good quality is obtained. Can be displayed. At this time, if each rotationally asymmetric surface has a plane-symmetrical shape in the direction perpendicular to the paper surface with the cross-section of the paper being the only plane of symmetry, processing and manufacturing can be facilitated as compared to the case where there is no symmetry. ,preferable.

Of the three reflections on the surface A, the third reflection (return reflection) in the first optical element 31 is
It is performed on the portion where a reflection film having a reflectance close to 100% is formed on the upper portion of the surface A by metal deposition or the like, and the other first reflection and the fifth reflection are performed on the lower portion of the surface A and are incident. Since the angle formed by the light and the normal to the surface A is large, reflection is caused by total internal reflection.

Regarding reflections other than the return reflection on the surface A,
When the reflection on the surface A is the total internal reflection within the first optical element 31, the loss of the light amount is reduced, which is preferable. If the reflected light flux is totally internally reflected at least in the area where the reflected light flux on the surface A and the emitted light flux are shared (the lower part of the surface A), all the reflected light flux other than the return reflection on the surface A is totally internally reflected. It is possible to secure the same brightness while increasing the degree of freedom in design as compared with the case of.

By configuring the display optical system as described above, it is possible to realize a display optical system that displays an image displayed on the image display element 3 as a magnified image with good optical performance. In addition, by forming an image once in the display optical system,
The degree of freedom of the display angle of view with respect to the display size of the image display element 3 is improved to allow a wider angle of view (high magnification presentation), and a long optical path length is provided in the first optical element 31 so that a round trip optical path is formed. By forming them, the first optical system 31 can be overlapped and the overall length of the first optical system 31 can be kept short, and a very compact display optical system can be constructed.

In the embodiment described above, the central ray at the central angle of view (in the display optical system, this is the light beam from the center of the display surface of the display element to the center of the exit pupil S, and in the image pickup optical system, the image is taken through the center of the entrance pupil. Although the reflected reflection on the surface A (which is a light ray reaching the center of the image pickup surface of the device) is substantially vertical reflection, the optical system of the present invention is not limited to this configuration.

(Sixth Embodiment) FIGS. 14 and 15 show the structure of a display optical system of a sixth embodiment using a first optical system different from that of the fifth embodiment. In the first optical systems 31 'and 31 "shown in these figures, the optical path of the central angle-of-view chief ray is different from that of the sixth embodiment.

In both FIGS. 14 and 15, an optical path of incidence of surface B → reflection of surface A → reflection of surface C → reflection of surface A → reflection of surface A → reflection of surface C → reflection of surface A → reflection of surface B → reflection of surface A is formed. The difference is similar to the fifth embodiment.

However, in the first optical system 31 'shown in FIG. 14, the central angle-of-view chief ray reflected on the surface C is reflected back at the surface A at an angle θ and is reflected from the reflection point ahead of the surface C. Is different from the fifth embodiment in that it is re-reflected at a higher position (a region near the first light reflection region).

In the first optical system 31 ″ shown in FIG. 15, the central angle-of-view chief ray reflected by the surface C is reflected back at the surface A at an angle θ, and is reflected from the first reflection point of the surface C. Is different from the fifth embodiment in that it is re-reflected at a lower position (a region near the first light reflection region).

As described above, the light may enter and reflect at a predetermined angle θ before and after the folding reflection surface A. However, the angle θ preferably satisfies | θ | <30 ° (1).

If this condition is not satisfied, the first optical system 3
1 ′ and 31 ″ become large and it is difficult to make the entire display optical system small, which is not preferable.

[Numerical Example 3] FIG. 16 shows an optical sectional view of a numerical example of the display optical system of the fifth embodiment shown in FIG.

In the figure, reference numeral 31 denotes a transparent body (first optical element) which constitutes the first optical system of the display optical system. S2, S
4, S6, S8 are the same surface, S3, S9 are the same surface, S5
S7 is the same surface, and these three surfaces correspond to the surfaces A, B, and C of the sixth embodiment, respectively. Reference numeral 2 denotes a second optical system, which is configured as a convex lens composed of S10 and S11 surfaces. Further, a reflective film is formed on the return reflection surface A (S6) and the surface C.

In this numerical example, S2, S4, S
The optical surfaces of S6, S8 are flat surfaces, and S3, S5, S7, S
All the optical surfaces from 9 to S11 are rotationally asymmetrical surfaces. These three surfaces have a plane symmetric shape having a paper surface (yz section) as the only symmetric surface. Table 3 shows optical data of this numerical example, and Table 4 shows local data for the central ray at the central angle of view.

[0145]

[Table 3]

[0146]

[Table 4]

As can be seen from Table 3, the light from the image display surface SI enters the convex lens of the second optical system 2 from S11, exits from S10, and goes to the first optical system 31. The light traveling toward the first optical system (first optical element) 31 is S
The light enters the first optical element 31 from 9 (face B), is reflected by S8 (face A), is reflected by S7 (face C), and then is reflected by S6 (face A).
-Reflect on the folded reflection surface), reflect on S5 (surface C) and reflect on S4 (surface A). Then, the light is reflected by S3 (surface B), exits the first optical element 31 from S2, and exit pupil S1
Guided by (S).

Assuming that the numerical value having the dimension of the length in this numerical example is mm, the exit pupil diameter is φ10 mm,
Image display size 10mm x 7.5mm and horizontal angle of view 5
This is a display optical system that displays an image at 0 ° in the infinity direction in the positive direction of the z axis.

The optical system of this numerical example may be used as an image pickup optical system. In this case, the light from the object point at the infinite distance in the negative direction of the z-axis passes through the diaphragm S1, is guided to the transparent body of the first optical system 31, and is incident on the transparent body from S2 (plane A) to S.
The light is reflected by 3 (surface B), S4 (surface A), S5 (surface C), and S6 (surface A-return reflection surface). Further, the light is reflected by S7 (Surface B), reflected by S8 (Surface A), emitted from the transparent body from S9 (Surface B), and guided to the convex lens of the second optical system 2. The light flux guided to the convex lens is
The light enters the convex lens from S10, exits from S11, and forms an image on the imaging surface SI.

Since the light reflected by S6 (Surface A-returning reflection surface) does not cause total internal reflection, at least S
It is advisable to form a reflective film on the part where the light is reflected at 6. However, a reflection film is not formed in the emission range of the light emitted from the surface A of the transparent body of the first optical system 31 (the range of S2 in this numerical example), and the light emitted from S2 is blocked. It is better not to become.

Of the light reflected by S4 and S8, the surface A
Since the light flux reflected in the emission range of the light emitted from is totally internally reflected, the loss of the light amount is small. Further, the light reflected by the surface C (S5 and S7 in this numerical example) does not cause total internal reflection, so it is preferable to form a reflective film on the surface C.

(Seventh Embodiment) FIG. 17 shows the arrangement of a display optical system according to the seventh embodiment of the present invention. In this embodiment, points different from the fifth embodiment will be mainly described.

In this embodiment, the surface A of the transparent body (optical element) forming the first optical system 51 is used as a transmission surface, and the reflection surface D disposed behind the surface A outside the optical element is folded back. It is different from the fifth embodiment in that it is used as a reflecting surface.

In the present embodiment, of the optical surfaces A, B and C on the optical element, both surfaces A and B are transmission / reflection surfaces which act as a transmission surface and a reflection surface, and a surface C is a reflection surface and a surface D.
Is a reflective surface.

The surfaces C and D are approximately 1 by metal vapor deposition or the like.
A reflective film having a reflectance of 00% is formed, and a semi-transmissive reflective film formed by vapor deposition of a metal or a dielectric is formed on the surface B.

The light modulated by the image display element 3 is guided to the first optical element 51 via the second optical system 2.
The light enters the first optical element 51 from the surface B, is reflected by the surface A, and is guided to the surface C. The light reflected on the surface C is guided to the upper part of the surface A, transmitted therethrough, and is incident on the surface D. On the surface D, the incident light is reflected so as to return in a direction substantially opposite to the incident direction. Then, the light passes through the surface A, enters the transparent body again, is reflected by the surface C, and is returned to the surface A. Then, after being reflected again on the surface A and reflected on the surface B, the light passes through the surface A, exits from the first optical element 1, and reaches the exit pupil S.

Also in this embodiment, the observer can view the enlarged image of the image displayed on the image display element 3 by placing the eyes near the position of the exit pupil S.

In this embodiment, the first optical element 5
In 1, light is B → A → C → A → D → A → C → A → B
After passing through each surface in the order of (→ A), the optical path up to that point is traced in reverse with the reflection on the surface D as a boundary. By forming a reciprocal optical path B → A → C → A → D → A → C → A → B in the first optical element 51, which reverses the normal path across the surface D,
The size of the first optical system 51 can be reduced with respect to the optical path length by making the optical paths substantially overlap and effectively utilizing the inside of the first optical element 51. As a result, the entire display optical system can be downsized.

In the present embodiment, by using the surface A as the transmitting surface, the number of optical surfaces forming the first optical system 51 is four, which is one more than that of the sixth embodiment. The degree of freedom in the optical design is increased, and the aberration is corrected more favorably.

In particular, as compared with the sixth embodiment, the transmission surface between the transparent body and the air is increased, and the degree of freedom for correcting chromatic aberration is increased.

[Numerical Example 4] FIG. 18 shows an optical sectional view of a numerical example of the display optical system according to the seventh embodiment. In the figure, 50 denotes a display optical system, and 51 denotes a first optical system including a transparent body (optical element) 51a having at least three surfaces and a reflection mirror member 51b. S2
S4, S6, S8 and S10 are the same surface, S3 and S11 are the same surface, and S5 and S9 are the same surface and correspond to the surfaces A, B and C described in the eighth embodiment. 3 in the figure
Reference numeral 0 is a second optical system, which is composed of S12 and S13.

The light from the image display surface SI is S13, S1.
2 enters the optical element 51a of the first optical system 51 from S11 (Surface B), is reflected by S10 (Surface A), and is reflected by S9.
The light is emitted from the optical element 51a while being reflected by (Surface C) and refracted by S8 (Surface A). The emitted light is reflected by S7 (reflection surface of the reflection mirror member 51b), enters the optical element 51a again from S6 (surface A), is reflected by S5 (surface C), and is reflected by S4 (surface A), The light is reflected by S3 (surface B), exits the optical element 51a from S2 (surface A), and is guided to the exit pupil S1 (S).

In this numerical example, if a numerical value having a dimension of length is considered as mm, a display optical system having specifications substantially equivalent to those of the first embodiment is obtained.

Although the display optical system has been described in the embodiments other than the second embodiment, an image pickup device such as a CCD is arranged at the position of the image display device 3 in this embodiment.
The subject light from the outside captured from the position of the exit pupil S can be used as an imaging optical system by forming an image through the reverse optical path described in each embodiment.

Further, in all the embodiments described above, when an arbitrary ray of the light flux passing through the first optical system is traced, the ray is first (1) on the first surface.
An optical path is set for the second reflection and the second reflection with one reflection angle as a reference and the other reflection angle with the opposite sign.

Specifically, for example, in the paper surface of FIG. 1, the reflection angle in the first reflection (A-plane reflection) is a positive sign (when the reflected light exists in the counterclockwise direction in the paper surface of the normal line). If so, the optical path is such that the reflection angle in the second reflection (A-side re-reflection) has a negative sign (when the reflected light exists in the clockwise direction on the paper surface of the normal line).

By taking such an optical path, the first
Since the light flux substantially reciprocates between the first surface and the second surface, it is possible to effectively utilize the space in the first optical system to earn an optical path length. Moreover, a small optical system can be realized even if the optical path length is long.

[0168]

As described above, according to the first and second aspects of the present invention, the light is substantially reciprocated between the first, second and third surfaces so that the optical paths are substantially overlapped. Since it has a small optical system, a long optical path can be secured. Therefore, a wide display angle of view can be achieved while using a small original image, and a small display optical system as a whole can be realized.

Further, since the third surface has the transmitting function and the reflecting function, the number of optical surfaces can be reduced, and the display optical system can be further downsized.

If the light is formed into an intermediate image in the display optical system, the degree of freedom in layout is increased, the original image can be displayed on a large screen, and the display optical system can be displayed even if the optical path length is considerably lengthened. Can be made small.

According to the third and fourth aspects of the present application,
Since the light is substantially reciprocated between the first, second, and third surfaces to substantially overlap the optical paths, it is possible to secure a long optical path even with a small optical system. For this reason, it is possible to achieve a wide image angle of view while being compact.

Further, since the third surface has the transmitting function and the reflecting function, the number of optical surfaces can be reduced, and the image pickup optical system can be further downsized.

If light is formed as an intermediate image in the image pickup optical system, the degree of freedom in layout is increased, a subject image having a wide angle of view can be sufficiently reduced and guided to the image pickup surface, and the optical path length can be increased. The imaging optical system can be made compact even when the length is considerably long.

In the first and second inventions,
If the formula (1) is satisfied, it is possible to prevent the optical system from becoming large.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first optical system used in a display optical system that is a first embodiment of the present invention.

FIG. 2 is a configuration diagram of the display optical system.

FIG. 3 is a configuration diagram of the display optical system.

FIG. 4 is a configuration diagram of the display optical system.

FIG. 5 is a configuration diagram of an image pickup optical system that is a second embodiment of the present invention.

FIG. 6 is a display optical system (1) which is a third embodiment of the present invention.
Configuration diagram of.

FIG. 7 is a display optical system (2) which is a third embodiment of the present invention.
Configuration diagram of.

FIG. 8 is a sectional view of an optical system according to Numerical Example 1 (implementation form of the first embodiment) of the present invention.

FIG. 9 is a configuration diagram of a display optical system that is a fourth embodiment of the present invention.

FIG. 10 is a sectional view of an optical system according to Numerical Example 2 (implementation example of the fourth embodiment) of the present invention.

FIG. 11 is a configuration diagram of a display optical system that is a fifth embodiment of the present invention.

FIG. 12 is a configuration diagram of a display optical system according to the fifth embodiment.

FIG. 13 is a configuration diagram of a display optical system of the fifth embodiment.

FIG. 14 is a configuration diagram of a display optical system (1) which is a sixth embodiment of the present invention.

FIG. 15 is a configuration diagram of a display optical system (2) which is a sixth embodiment of the present invention.

FIG. 16 is a sectional view of an optical system according to Numerical Example 3 (implementation example of the sixth embodiment) of the present invention.

FIG. 17 is a configuration diagram of a display optical system that is a seventh embodiment of the present invention.

FIG. 18 is a sectional view of an optical system according to Numerical Example 4 (embodiment of the seventh embodiment) of the present invention.

FIG. 19 is a block diagram of a conventional display optical system.

FIG. 20 is a configuration diagram of a conventional display optical system.

[Explanation of symbols]

1, 1 ', 1 ", 11, 11', 11", 21, 31,
31 ', 31 ", 51 1st optical system 2 2nd optical system 3 Image display device 4 Imaging device

[Procedure amendment]

[Submission date] December 19, 2002 (2002.12.
19)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

15. An imaging apparatus comprising the imaging optical system according to claim 13 or 14.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

FIG. 20 shows an image display device proposed in Japanese Patent Laid-Open No. 7-333551. In this device, the light emitted from the LCD 111 is incident on the incident surface 113 of the small decentering prism 112. Then, the light flux is folded between the total reflection surface 114 and the reflection surface 115 having the curvature formed on the decentering prism 112, and then the light flux is emitted from the surface 114 from the decentering prism 112 and guided to the eye E of the observer. As a result, the display element (LC
D) A virtual image of the image displayed on 111 is formed, and an observer observes this virtual image.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0083

[Correction method] Change

[Correction content]

[Numerical Example 1] FIG. 8 shows an optical path sectional view of a numerical example of the first embodiment shown in FIG.
In the figure, 1 is a first optical system that constitutes a display optical system,
It is composed of a prism-shaped transparent body (optical element) having three optical surfaces. S2, S4 and S6 are the same surface, S3 and S7 are the same surface, and these two surfaces and S5 respectively correspond to the surfaces A, B and C described in the first embodiment.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0088

[Correction method] Change

[Correction content]

R is the radius of curvature. TYP term (numerical value
In the second embodiment, the FFS term) represents the type of surface shape, and SPH
Is a spherical surface, and FFS (a numerical value in Numerical Example 2) is a rotationally asymmetric surface according to the following equation.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0090

[Correction method] Change

[Correction content]

Numerical value next to FFS in the TYP column
(In Numerical Example 2, the number written in the FFS column) is
It shows that the shape of the surface is a rotationally asymmetric shape corresponding to the aspherical coefficients k and ci described in the lower part of the table.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0091

[Correction method] Change

[Correction content]

Nd and νd (however, indicated as vd in the table) respectively indicate the refractive index and the Abbe number at the d-line wavelength of the medium after that surface, and the change in the sign of the refractive index N d is the surface. Indicates that the light is reflected at. When the medium is an air layer, only the refractive index Nd is shown as 1.000 and the Abbe number νd is omitted.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0100

[Correction method] Change

[Correction content]

The light modulated by the image display element 3 is guided to the optical element of the first optical system 21 via the second optical system 2. Light enters the optical element of the first optical system 21 from the surface B, is reflected by the surface A, and is transmitted through the surface D. The light transmitted through the surface D enters the surface C and is reflected so as to return in a direction substantially opposite to the incident direction. Thereby, the light is again transmitted through the surface D and guided to the surface A, re-reflected by the surface A and reflected by the surface B, and then transmitted through the surface A and emitted from the optical element of the first optical system 21. , Reaches the exit pupil S.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0143

[Correction method] Change

[Correction content]

In the figure, reference numeral 31 denotes a transparent body (first optical element) which constitutes the first optical system of the display optical system. S2, S
4, S6, S8 are the same surface, S3, S9 are the same surface, S5
S7 is the same surface, and these three surfaces correspond to the surfaces A, B, and C of the fifth embodiment, respectively. Reference numeral 2 denotes a second optical system, which is configured as a convex lens composed of S10 and S11 surfaces. Further, a reflective film is formed on the return reflection surface A (S6) and the surface C.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] 0156

[Correction method] Change

[Correction content]

The light modulated by the image display element 3 is guided to the first optical element 51 via the second optical system 2.
The light enters the first optical element 51 from the surface B, is reflected by the surface A, and is guided to the surface C. The light reflected on the surface C is guided to the upper part of the surface A, transmitted therethrough, and is incident on the surface D. On the surface D, the incident light is reflected so as to return in a direction substantially opposite to the incident direction. Then, the light passes through the surface A, enters the transparent body again, is reflected by the surface C, and is returned to the surface A. Then, after being reflected again on the surface A and reflected on the surface B, the light passes through the surface A, exits from the first optical element 51 , and reaches the exit pupil S.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0161

[Correction method] Change

[Correction content]

[Numerical Example 4] FIG. 18 shows an optical sectional view of a numerical example of the display optical system according to the seventh embodiment. In the figure, 50 denotes a display optical system, and 51 denotes a first optical system including a transparent body (optical element) 51a having at least three surfaces and a reflection mirror member 51b. S2
S4, S6, S8, and S10 are the same surface, S3 and S11 are the same surface, and S5 and S9 are the same surface, which correspond to the surfaces A, B, and C described in the seventh embodiment. 3 in the figure
Reference numeral 0 is a second optical system, which is composed of S12 and S13.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Name of item to be corrected] 0166

[Correction method] Change

[Correction content]

Specifically, for example, in the paper surface of FIG. 2 , the reflection angle in the first reflection (A-plane reflection) is a positive sign (when the reflected light is in the counterclockwise direction in the paper surface of the normal line). If so, the optical path is such that the reflection angle in the second reflection (A-side re-reflection) has a negative sign (when the reflected light exists in the clockwise direction on the paper surface of the normal line).

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0167

[Correction method] Change

[Correction content]

By taking such an optical path, the first
Since the light beam substantially reciprocates between the first surface and the second surface, it is possible to effectively utilize the space in the first optical system and obtain the optical path length. Moreover, a small optical system can be realized even if the optical path length is long.

[Procedure Amendment 13]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

[Procedure Amendment 14]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

[Procedure Amendment 15]

[Document name to be corrected] Drawing

[Correction target item name] Figure 9

[Correction method] Change

[Correction content]

[Figure 9]

[Procedure Amendment 16]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 11

[Correction method] Change

[Correction content]

FIG. 11

[Procedure Amendment 17]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 12

[Correction method] Change

[Correction content]

[Fig. 12]

[Procedure 18]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 13

[Correction method] Change

[Correction content]

[Fig. 13]

[Procedure Amendment 19]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 14

[Correction method] Change

[Correction content]

FIG. 14

[Procedure amendment 20]

[Document name to be corrected] Drawing

[Correction target item name] Figure 15

[Correction method] Change

[Correction content]

FIG. 15

[Procedure correction 21]

[Document name to be corrected] Drawing

[Correction target item name] Fig. 16

[Correction method] Change

[Correction content]

FIG. 16

[Procedure correction 22]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 17

[Correction method] Change

[Correction content]

FIG. 17

[Procedure amendment 23]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 18

[Correction method] Change

[Correction content]

FIG. 18

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 5/72 H04N 5/72 C 5/74 5/74 A (72) Inventor Tomomi Matsunaga Ota Ward, Tokyo 3-30-2 Shimomaruko Canon Inc. (72) Inventor Kazutaka Inoguchi 3-30-2 Shimomaruko Ota-ku, Tokyo Incorporated Canon Inc. (72) Akinari Takagi 3 Shimomaruko Ota-ku, Tokyo C-No. 30-2 Canon Inc. F-term (reference) 2H042 CA01 CA12 CA14 2H087 KA06 KA07 RA41 RA45 TA01 TA03 TA04 5C022 AA11 AA13 AC03 AC09 AC42 AC54 AC78 5C058 AA06 BA31 DA11 EA12

Claims (24)

[Claims] 1. A display optical system for guiding light from an original image to an observer's eye or a projection surface, wherein a first surface having at least a reflecting action and a light beam reflected by the first surface are re-described. The second surface that reflects toward the first surface and the light that travels from the original image to the first surface are transmitted, and the light that is returned from the second surface to the first surface and reflected again is A third surface that has a third surface that reflects and guides to the observer's eye or the projection surface, and the central angle-of-view chief ray that re-enters the first surface is with respect to the normal line of the surface on the hit point, A display optical system characterized by reflecting on the side opposite to the previous time and proceeding. 2. A display optical system for guiding light from an original image to an eye of an observer or a projection surface, the display optical system including at least a first optical system having first, second and third surfaces, The second and third surfaces are curved surfaces, light passes through the third surface and enters the first optical system, and the light is transmitted through the first optical system to the first and second surfaces. At least once each, and then reflected on the first and second surfaces a total of three times or more, returned to the third surface, reflected on the third surface, and transmitted through the first surface. A display optical system, which emits light from the first optical system. 3. The display optical system according to claim 1, wherein light forms an intermediate image in the display optical system. 4. The display optical system according to claim 3, wherein a transparent body whose inside is filled with an optical medium is used, and light forms an intermediate image in the transparent body. Display optics. 5. The display optical system according to claim 1, wherein at least one of the first to third surfaces is decentered with respect to an incident light beam. 6. The display optical system according to claim 1, wherein at least one of the first to third surfaces has a curvature. 7. The surface according to claim 1, wherein at least one of the first to third surfaces is a rotationally asymmetric surface.
Or the display optical system described in 2. 8. The display optical system according to claim 1, wherein the first to third surfaces are formed on a transparent body whose inside is filled with an optical medium. 9. The first and third surfaces are formed on a transparent body whose inside is filled with an optical medium, and the second and third surfaces are formed.
3. The display optical system according to claim 1 or 2, wherein the surface is formed of a reflecting member. 10. The light is totally internally reflected by any one of the optical surfaces formed on the transparent body.
Or the display optical system according to item 9. 11. The angle θ formed by the central angle-of-view chief ray incident on the second surface and its reflected central angle-of-view chief ray satisfies the condition of | θ | <30 °. The display optical system according to 1 or 2. 12. An image display device comprising the display optical system according to claim 1. 13. An imaging optical system for guiding light from a subject to an imaging surface, the first surface having at least a reflecting action, and the light beam reflected by the first surface directed to the first surface again. And a second surface that reflects the light from the subject toward the first surface, and the light that is returned from the second surface to the first surface and then reflected again to the imaging surface side. A third surface to be transmitted, and the central angle-of-view chief ray re-incident on the first surface is reflected and travels to the opposite side to the normal of the surface on the hit point. Imaging optical system characterized by. 14. An imaging optical system for guiding light from a subject to an imaging surface, comprising: a first optical system having at least first, second and third surfaces, and at least the second and third surfaces. Is a curved surface, light passes through the first surface, enters the first optical system, and is reflected at least once by the first, second, and third surfaces in the first optical system. Then, the imaging is performed by reflecting the light on the first and second surfaces three times or more in total, returning to the third surface, transmitting through the third surface, and exiting from the first optical system. Optical system. 15. The image pickup optical system according to claim 13, wherein light forms an intermediate image in the image pickup optical system. 16. The display optical system according to claim 15, wherein a transparent body whose inside is filled with an optical medium is used, and light is intermediately imaged in the transparent body. Imaging optics. 17. The imaging optical system according to claim 13, wherein at least one of the first surface and the second surface is decentered with respect to an incident light ray. 18. The image pickup optical system according to claim 13, wherein at least one of the first surface and the second surface has a curvature. 19. The image pickup optical system according to claim 13, wherein at least one of the first surface and the second surface is a rotationally asymmetric surface. 20. The imaging optical system according to claim 13, wherein the first to third surfaces are formed on a transparent body whose inside is filled with an optical medium. 21. The first and third surfaces are formed on a transparent body whose inside is filled with an optical medium, and the second surface is composed of a reflecting member. The imaging optical system according to claim 13 or 14. 22. Light is totally internally reflected on any one of optical surfaces formed on the transparent body.
The imaging optical system according to 0 or 21. 23. The angle θ formed by the central angle-of-view chief ray incident on the second surface and its reflected central angle-of-view chief ray satisfies the condition of | θ | <30 °. 13 or 14
The image pickup optical system described in 1. 24. An image pickup apparatus comprising the image pickup optical system according to any one of claims 13 to 23.