JP2003149587A - 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 1st, 2nd, and 3rd surfaces as optical surfaces; and the light which is made incident from the original picture through the 3rd surface B is reflected by the 1st surface A, reflected by the 2nd surface C, reflected by the 1st surface, reflected by the 3rd surface, transmitted through the 1st surface, and guided to the eye of the observer or the projected surface. The imaging optical system which guides light from a subject to an imaging surface is provided with 1st, 2nd, and 3rd surfaces as optical surfaces; and the light which is made incident from the subject through the 1st surface is reflected by the 3rd surface, reflected by the 1st surface, reflected by the 2nd surface, reflected by the 1st surface, transmitted by the 3rd surface, and guided to the imaging surface.

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. 12 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 is reflected by the half mirror 102, is incident on 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. 13 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 optical system type shown in FIG. 13 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 characteristics of the thin type of the type shown in FIG. 13, 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 that can achieve a wide display angle of view while using a small-sized display element, and a compact display optical system as a whole, and a compact image pickup optical system that can achieve a wide shooting angle of view. I am trying.

[0014]

In order to achieve the above object, in the first 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, the display surface is an optical surface. The first, second and third surfaces are provided, and the light transmitted from the original image through the third surface and incident is reflected by the first surface, reflected by the second surface, and reflected by the first surface. , Is reflected by the third surface and transmitted through the first surface to be guided to the observer's eye or the projection surface.

That is, by making the light substantially reciprocate between the first, second, and third surfaces to fold the optical path, a compact optical system configuration can be achieved with respect to the optical path length.

Further, by providing the first and third surfaces with a transmission function and a reflection 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 (real image) of the light in the display optical system (for example, a transparent body). That is, by adopting an intermediate imaging type that enlarges and displays a small intermediate image of the original image, the degree of freedom in optical design is increased and the original image can be displayed on a large screen.

By decentering the optical surface constituting the display optical system with respect to the light rays reflected by the surface,
It is possible to further reduce the thickness, and by providing the optical surface with a curvature, it is possible to remove an unnecessary surface in the display optical system and achieve size reduction. Furthermore, by making the optical surface a rotationally asymmetrical surface (free-form surface), various aberrations can be corrected well, and if multiple rotationally asymmetrical surfaces (free-form surface) are adopted, the aspect ratio of the original image and the aspect ratio of the display image can be It is possible to make them close to each other, and it is possible to obtain a high-quality display image.

The 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).

In the second invention of the present application, in the image pickup optical system for guiding the light from the subject to the image pickup surface, the first, second and third surfaces, which are optical surfaces, are provided, and the first surface is set from the subject. The light transmitted and incident is reflected by the third surface, reflected by the first surface, reflected by the second surface, reflected by the first surface, transmitted through the third surface, and transmitted through the imaging surface. I am trying to lead to.

That is, the light is substantially reciprocated between the first, second and third surfaces to substantially overlap the optical paths,
It is possible to achieve a compact optical system with respect to the optical path length.

Further, by providing the first and third surfaces with the transmissive action and the reflective action, 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 imaging type that reduces the intermediate image of the subject and guides it to the imaging surface, the degree of freedom in optical design increases, and it is possible to sufficiently reduce the subject image with a wide angle of view and guide it to the imaging surface. Become.

Further, by decentering the optical surface constituting the image pickup optical system with respect to the reflected light, it is possible to achieve further reduction in thickness, and since the optical surface has a curvature, it is unnecessary in the image pickup optical system. It becomes possible to reduce the size by removing the surface. Furthermore, by making the optical surface a rotationally asymmetric surface (free-form surface), various aberrations can be corrected well, and if multiple rotationally asymmetric surfaces (free-form surface) are adopted, the aspect ratio of the subject and the aspect ratio of the captured image can be It is possible to make them close to each other, and it is possible to obtain a high-quality photographed image.

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,
It is possible to reduce the light amount loss by totally reflecting the light on any one of the optical surfaces.

Further, 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, it is incident on the folded reflection surface. The angle θ formed by the light ray and the reflected light ray preferably satisfies | θ | <30 ° (1). If this condition is not satisfied, the optical system becomes large.

In the above optical system, the reflection angle with respect to the normal line at the hit point of the central angle-of-view chief ray that first enters the first surface and the reflection angle on the second surface that is incident on the first surface again. It is preferable that the angle of reflection of the central view angle principal ray with respect to the normal line at the hit point has the opposite sign. That is, the light reflected by the first surface is reflected by the second surface so as to return to the first light reflection area side (reflection area, near the reflection area, or near the reflection area) of the first surface. Effectively overlap the optical paths,
The long optical path length can be accommodated in a small optical system.

[0029]

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 and the xz section is the sagittal section. 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, it is a ray from the image center of the display element to the center of the exit pupil of the display optical system, and in the imaging optical system, it passes through the center of the entrance pupil of the imaging 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.

FIG. 2 shows the configuration of the entire display optical system when the first optical system 1 shown in FIG. 1 is used in an image display device. In the first optical system 1, the above three optical surfaces A, B and C are formed on a transparent body (hereinafter also referred to as the first optical element 1) whose inside is filled with an optical medium such as glass or plastic. Has been done.

Surfaces A and B on the transparent body both serve as transmissive and reflective surfaces acting as a transmissive surface and a reflective surface, and surface C is a reflective surface.

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

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 first light reflection region of 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 the light emitted from the image display element 3, a central angle-of-view chief ray that emerges from the center of the display surface of the image display element 3 and reaches the center of the exit pupil S is shown.

In this embodiment, the observer can place an eye near the position of the exit pupil S to visually recognize an enlarged image of the image displayed on the image display element 3.

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. Reflecting light in a substantially reverse direction from the outward path to the return path to form such a round-trip optical path is called return reflection, and a reflection surface (here, surface C) having this return reflection function is a return reflection surface. Call.

By thus providing the surface C with a function as a reflection reflection surface and forming a reciprocal optical path in the first optical element 1, the optical path is folded back so as to overlap, and the long optical path is reduced to the first small 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 round-trip optical path due to the reflection on the final reflecting surface B, and the image display element 3
It is guided to the exit pupil S without 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 reaching both ends of the exit pupil intersect in the first optical element 1, and an intermediate image of the image displayed on the image display element 3 is formed. First optical element 1
By forming an intermediate image in the inside, a compact structure can be obtained even if the power of the second optical system 2 is weakened, and the occurrence of extra aberrations in the second optical system 2 is suppressed, and the second optical system 2 is suppressed. The complication of 2 can be prevented.

In FIG. 4, the intermediate image is formed between the reflection on the C surface and the reflection on the A surface. However, the intermediate image formation 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 portion of the first optical system 1 and the other portion. The optical system 2 of 2 corresponds to a relay optical system.

In this embodiment, the surface B when acting as the final reflecting surface is the surface A when acting as the exit surface.
On the other hand, it is a concave mirror having very strong optical power and bears the main power of the eyepiece optical system part. 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 image formation or aberration correction, the number of optical surfaces required for the entire optical system can be reduced, and the effect of reducing manufacturing costs 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.

Further, the surfaces A and B of the first optical system 1 are surfaces which are inclined with respect to the reflected light rays when the effective light rays 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 B-side reflection → the A-side exit optical path is folded together.

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.

Since the surface B is a curved surface having a stronger power than that of the surface A, it is preferable to suppress the occurrence of decentering aberration by making the surface B rotationally asymmetric.

More preferably, by making all three surfaces A, B, and C constituting the first optical system 1 rotationally asymmetrical, 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, the reflection on the surface A is defined as total internal reflection in the first optical element 1 on both the forward and backward paths, and the light flux finally reflected on the surface B is incident on the surface A at an angle equal to or less than the critical angle. It is preferable to emit the light with less loss of light amount. If the reflected light flux is totally reflected at least in the area where the reflected light flux and the outgoing light flux are shared on the surface A, the degree of freedom in design is increased to the same degree as in the case where all the reflected light flux is totally reflected. The brightness of 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 total length of the first optical system 1 is suppressed to be short, and a very compact display optical system is provided. You can configure the system.

In this embodiment, the surface A and the surface B are both
Although a semi-transmissive reflective film may be formed in the same manner as in, the reflection on the surface A is the reflection between the optical material such as glass forming the transparent body and the air, so that the light incident on the surface A is If the light enters at a large angle with respect to the normal, total reflection occurs, and the reflectance becomes almost 100%. On the other hand, if the incident angle at the time of passing through the surface A is set small, the reflectance is usually about 4%. Therefore, the light utilization efficiency can be improved.

(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 a first optical system (first optical element) similar to that shown in FIG. 1, 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 this embodiment, the surface A (first surface) of the first optical element 1 acts as an incident surface and a reflection surface for 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
Is transmitted through the surface A to the optical element 1 of, and reflected by the surface B,
It is reflected on the surface A and guided to the surface C. Then, the light is reflected back on the surface C and returned to the first light reflection area on the surface A,
The light is 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, the light from the desired subject forms an image on the image pickup surface of the image pickup device 4,
As a result, an image of the subject 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, the degree of freedom of the photographing angle of view is improved with respect to the size of the image pickup element 4 and a wide angle of view can be achieved. Along with this, the optical path length becomes longer. By forming a reciprocating optical path in the first optical element 1, the overall length of the first optical system 1 is kept short, and a very compact imaging optical system is realized.

In the first and second embodiments described above, the central angle-of-view principal ray (in the display optical system, it is a light 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.
It differs from the first embodiment in that the central view angle principal ray reflected by is reflected back at an angle θ on the surface C and is reflected again at a position higher than the previous reflection point on the surface A. Also, FIG.
In the first optical system 1 ″ of No. 1, the central angle-of-view chief ray reflected on the surface A is reflected back at the surface C at an angle θ, and is reflected again at a position lower than the previous reflection point on the surface A. The point is
Different from the embodiment.

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 as shown in the second embodiment. You can

Numerical examples of the above embodiments will be described below.

[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 (first 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.

Reference numeral 2 denotes a second optical system, 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 the present numerical example, the optical surfaces from S2 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 in which the observer's visual axis direction is the z axis, the direction perpendicular to the z axis in the paper is the y axis, and the direction perpendicular to the paper is 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 a 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.

[0082]

[Equation 1]

The numerical values next to FFS in the TYP column correspond to the aspherical surface coefficients k and ci (i = 2, 3, 4 ...) whose surface shape is shown at the bottom of the table. It shows that the shape is rotationally asymmetric. The value of the term of coefficient ci not shown in the table is 0.

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 on 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.

Further, 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.

[0086]

[Table 1]

As can be seen from Table 1, the light from the image display surface SI is incident on the transparent body (optical element) which constitutes the second optical system 2 from 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 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 object point at the infinity in the negative direction of the z-axis passes through the diaphragm S1 and is guided to the first optical system 1. Then, the light incident on the first optical element 1 from S2 (Surface A) is reflected by S3 (Surface B), reflected by S4 (Surface A), and reflected back by S5 (Surface C) and S6 (Surface). Surface A)
After being reflected by, the first optical element 1 is emitted from S7 (Surface B) and guided to the second optical system 2. Then, the light guided to the second optical system 2 is incident on the optical element from S8 and S9
And then exit S10 to form an image on the imaging surface SI.

The reflection at S4 and S6 is total internal reflection in both cases.

[Numerical Embodiment 2] FIG. 9 shows a numerical embodiment 2.
It is an optical sectional view of FIG. In addition, Table 2 shows optical data.

In the second numerical example, the second optical system 2 is
It is composed of two optical elements 21 and 22 each having two surfaces, and one surface of the optical element 21 is joined to the transparent body of the first optical system 1. This joint surface is referred to as S7.

Light from the image display surface SI passes through S10, S9 and S8 of the second optical system 2 and enters the transparent body from the joint surface S7 (surface B) between the optical element 21 and the transparent body. Then, the back surface is reflected at S6 (Surface A), the back surface is reflected at S5 (Surface C) and folded, and the back surface is reflected at S4 (Surface A) and S3.
The back surface is reflected by (Surface B), the transparent body is emitted from S2, and is guided to the exit pupil S1 (S) of the optical system.

The reflections at S4 and S6 are total internal reflection.

[0095]

[Table 2]

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 numerical example 1 is obtained.

The numerical example 2 can also be used in an image pickup optical system as in the numerical example 1.

[Numerical Embodiment 3] FIG. 10 shows a numerical embodiment 3.
It is an optical sectional view of FIG. In addition, Table 3 shows optical data.

In this numerical example, the second optical system 2 has a 3
It is composed of a prism-shaped transparent body (optical element) having two optical surfaces S8, S9 and S10 on the same medium.

The light from the image display surface SI passes through S10, S9 and S8 of the second optical system 2 toward the transparent body (first optical element) of the first optical system 1 and is directed to the surface S7 (surface). B) enters the transparent body. Then, the back surface is reflected at S6 (Surface A),
The back surface is reflected at S5 (Side C) and folded back, and S4 (Side A)
Is reflected on the back surface, S3 (surface B) is reflected on the back surface, the first optical element 1 is emitted from S2, and the exit pupil S1 (S) of the optical system is emitted.
Be led to.

[0101]

[Table 3]

In this numerical example, some of the light beams reflected on the surface S6 do not satisfy the condition of total reflection.
As shown in the figure, a reflection film is formed on a part of the surface so that the back surface is reflected.

At this time, the reflection film is formed so as not to cover the area of the surface S2 through which the light flux emitted. The reflective film is made of metal or dielectric.

In the reflection film forming area near the area through which the emitted light beam passes, if the film structure is such that the reflectance gradually decreases as it approaches the area through which the emitted light beam passes, the reflection film forming portion and the non-formation portion are formed. It is preferable because the boundary with is hard to be observed.

In this numerical example, if a numerical value having a dimension of length is considered as mm, a display optical system having substantially the same specifications as the numerical example 1 is obtained.

The numerical example 3 can also be used in the image pickup optical system as in the numerical example 1.

[Numerical Embodiment 4] FIG. 11 shows a numerical embodiment 4.
It is an optical sectional view of FIG. Further, Table 4 shows optical data.

In this numerical example, S9 and S11 of the second optical system 2 are the same surface provided with the semi-transmissive reflective film. The second optical system 2 has three optical surfaces S8, S9 (S11
Surface), and a prism-shaped transparent body (optical element) having S10 on the same medium.

The optical surfaces from S1 to S11 are all rotationally asymmetrical surfaces and have a plane symmetric shape having the paper surface (yz section) as the only symmetric surface.

The light from the image display surface SI enters the optical element of the second optical system 2 through the half mirror surface S11 and S1
The light is reflected on the back surface at 0, reflected on the half mirror surface S9, and emitted from S8 toward the first optical element 1. The light directed to the first optical element 1 enters the first optical element 1 from the surface S7 (surface B), is reflected on the back surface at S6 (surface A), and is S5 (surface C).
Is reflected and folded back at S4 (Surface A), reflected at S3 (Surface B), reflected at S3 (Surface B), and emitted from the first optical element 1 from S2 to the exit pupil S1 (S) of the optical system. Be guided.

The reflections at S4 and S6 are total internal reflection.

[0112]

[Table 4]

Numerical Example 4 is a display optical system having substantially the same specifications as Numerical Example 1 when the numerical value having the dimension of length is considered as mm.

The numerical example 4 can also be used for an image pickup optical system as in the numerical example 1.

Although the display optical system has been described in the embodiments other than the second embodiment, in the embodiments other than this, an image pickup device such as a CCD is arranged at the position of the image display device 3 and the exit pupil S is adjusted. The subject light from the outside captured from the position can be used as an image pickup 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 (the reflected light exists in the counterclockwise direction in the paper surface with respect to the surface normal). Case), 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 with respect to the surface normal). There is.

By taking such an optical path, the first
Since the light beam substantially reciprocates between the first surface and the second surface, the space in the first optical system can be effectively used to realize a small optical system having a long optical path length.

In each of the embodiments described above, the first
The optical system of No. 1 has been described as being composed of a transparent body having three optical surfaces A, B and C. However, in the present invention, any or all of the above three optical surfaces are composed of mirror members. It can also be applied when

[0120]

As described above, according to the first invention of the present application, the light path is made to substantially reciprocate between the first, second and third surfaces so that the light path is folded back. However, a small optical system can be realized. Therefore, it is possible to achieve a wide display angle of view while using a small original image, and it is possible to realize a small display optical system as a whole.

Further, since the first and third surfaces have the transmitting and reflecting functions, 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 optical design is increased and the original image can be displayed on a large screen.

According to the second invention of the present application, since the light path is folded back by causing the light to substantially reciprocate between the first, second and third surfaces, the optical system is small in size. A long optical path can be secured. For this reason, it is possible to achieve a wide shooting angle of view while being compact.

Further, since the first and third surfaces have the transmitting and reflecting functions, the number of optical surfaces can be reduced, and the image pickup optical system can be further downsized.

If the light is formed into an intermediate image in the image pickup optical system, the degree of freedom in optical design 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 can be reduced. Even if the length is considerably long, the image pickup optical system can be made compact.

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 of the present invention.

FIG. 9 is a sectional view of an optical system according to Numerical Example 2 of the present invention.

FIG. 10 is a sectional view of an optical system according to Numerical Example 3 of the present invention.

FIG. 11 is a sectional view of an optical system according to Numerical Example 4 of the present invention.

FIG. 12 is a block diagram of a conventional display optical system.

FIG. 13 is a configuration diagram of a conventional display optical system.

[Explanation of symbols]

1,1 ', 1 "First optical system 2 Second optical system 3 image display device 4 image sensor

─────────────────────────────────────────────────── ───

[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]

11. The image pickup apparatus characterized by including an imaging optical system according to claim 10.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0084

[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 Nd at that surface. It shows that the light is reflected. When the medium is an air layer, only the refractive index Nd is shown as 1.000 and the Abbe number νd is omitted.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 5/225 H04N 5/225 D (72) Inventor Tomomi Matsunaga 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Akinari Takagi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Hideki Morishima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. In-house F-term (reference) 2H087 KA02 KA06 KA07 KA23 LA01 LA11 RA06 RA12 RA13 RA44 RA45 TA01 TA02 TA05 TA06 2H101 FF00 5C022 AA00 AC54 AC78

Claims (18)

[Claims] 1. 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 having first, second and third surfaces which are optical surfaces. Light incident on the first surface is reflected by the first surface, is reflected by the second surface, is reflected by the first surface, is reflected by the third surface, and is reflected by the first surface. A display optical system, which transmits light through the surface of the above and guides it to an observer's eye or a projection surface. 2. The display optical system according to claim 1, wherein light forms an intermediate image in the display optical system. 3. The display optical system according to claim 2, 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. 4. The display optical system according to claim 1, wherein at least one of the first to third surfaces is decentered with respect to a light ray reflected by the surface. 5. The display optical system according to claim 1, wherein at least one of the first to third surfaces has a curvature. 6. The at least one of the first to third surfaces is a rotationally asymmetric surface.
The display optical system described in 1. 7. The display optical system is configured by using a transparent body whose inside is filled with an optical medium, wherein light is totally reflected by any optical surface formed on the transparent body. The display optical system according to claim 1, wherein the display optical system is a display optical system. 8. The angle θ formed by a central angle-of-view principal ray incident on the second surface and a reflected ray thereof satisfies the condition of | θ | <30 °. Display optics. 9. An image display device comprising the display optical system according to claim 1. Description: 10. An imaging optical system for guiding light from an object to an imaging surface, comprising: first, second, and third surfaces that are optical surfaces, and transmitting the first surface from the object. The incident light is reflected by the third surface, reflected by the first surface, reflected by the second surface, reflected by the first surface, and transmitted through the third surface. An image pickup optical system characterized by being guided to an image pickup surface. 11. The image pickup optical system according to claim 10, wherein light forms an intermediate image in the image pickup optical system. 12. The imaging optical system according to claim 11, wherein a transparent body whose inside is filled with an optical medium is used to form an intermediate image of light in the transparent body. Imaging optics. 13. The image pickup optical system according to claim 10, wherein at least one of the first to third surfaces is decentered with respect to a light ray reflected by the surface. 14. The imaging optical system according to claim 10, wherein at least one of the first to third surfaces has a curvature. 15. The imaging optical system according to claim 10, wherein at least one of the first to third surfaces is a rotationally asymmetric surface. 16. The imaging optical system is configured by using a transparent body whose inside is filled with an optical medium, wherein light is totally reflected by any optical surface formed on the transparent body. The imaging optical system according to claim 10, which is characterized in that. 17. The imaging optics according to claim 10, wherein an angle θ formed by the chief ray incident on the second surface and its reflected chief ray satisfies the condition | θ | <30 °. system. 18. An image pickup apparatus comprising the image pickup optical system according to claim 10.