JP2003004910A - Optical element and optical device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element suitable for a portable display device in which a preferable enlarged image can be obtained although the element is small-sized and inexpensive with little power consumption. SOLUTION: The projection type optical device is composed of a display element 3 to display a video or its intermediate video, a relay optical system 31 to project the video displayed on the display element or the intermediate video, and an eyepiece optical system 32 having a converging function to converge the flux from the relay optical system 31 to the eyes of an observer. The eyepiece optical system 32 has at least one free curved face 21 and at least one Fresnel reflective face 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element and an optical device using the same, and more particularly to a display device having a free-form surface and a Fresnel reflecting surface in an eyepiece optical system with little distortion and various aberrations, which can be carried around. The present invention relates to an optical element used for a small display device.

[0002]

2. Description of the Related Art As a small display device, a direct-view type liquid crystal display device has been widely used as a mobile phone or a mobile terminal. However, in order to display a high-definition display having a large number of pixels and a moving image, it is necessary to use an active matrix liquid crystal which has a high display speed and is expensive, and there is a problem that the display device becomes expensive. In addition, it consumes a large amount of power, requires a battery having a large capacity to display for a long time, and requires a large and heavy battery. Furthermore, there was a concern that the displayed contents would be seen by people around them.

On the other hand, as an enlarged display by an optical system using a small-sized display element, Japanese Patent Laid-Open No. 102527/1988 has been proposed.
And JP-A-5-303054 by the present applicant. These enlarge and display a display device as a virtual image using a concave mirror. In particular, the latter obtains a projected image with less aberration by using a non-rotationally symmetric reflecting surface. However, a relatively large size is required for the display element, a particularly small display element cannot be used as compared with a direct-view type display device, and the original purpose cannot be achieved.

Next, JP-A-5-3030 by the present inventor
No. 55, Japanese Patent Application Laid-Open No. 2000-221440 proposes a method of projecting an image of a display device once in the air and further magnifying and displaying the image by a concave mirror. Examples of the apparatus include those disclosed in JP-A-7-270781 and JP-A-9-139901.

US Pat. No. 5,274,406 discloses a free-form surface having an eccentric arrangement for correcting image distortion and defocus when an image is projected on a screen using a projection lens having an eccentric arrangement. Also, it has been proposed to use a reflective surface composed of the Fresnel surface.

Further, US Pat. No. 4,006,971 discloses a Fresnel reflecting surface or a Fresnel refracting surface used in a finder system of a camera, in which an astigmatism and a coma are formed by forming the Fresnel surface as an elliptical surface. A correction for aberration has been proposed.

Further, in Japanese Unexamined Patent Publication No. 7-104209, a mirror constituting an eyepiece optical system of a head-mounted display device has a rotationally asymmetric power, and the mirror of the eyepiece optical system is a collection of minute mirrors. Those composed of the body have been proposed.

[0008]

In the conventional type in which the display element is directly magnified by a concave mirror or the like, a large display element has to be used as a display element, and a small display device cannot be constructed. Further, in the case of the method of projecting the image of the display element once in the air, a small display element can be used, and it is an optical system capable of observing a large screen display at low cost. The exit pupil position of the system is short, and it is necessary to dispose the eyepiece optical system immediately in front of the head, and when observing while holding it in the hand, it was not possible to observe the entire screen.

Further, when a reflective type eyepiece optical system is used, the optical path can be folded back, and the apparatus can be miniaturized such that it can be folded when not in use, but the amount of eccentric aberration of the pupil is generated. However, there is a problem that it becomes difficult to observe an image on the entire surface of the screen.

The present invention has been made in view of such problems of the prior art, and an object thereof is to provide a portable display device which can obtain a good magnified image while being small in size, low in power consumption, and inexpensive. It is to provide a suitable optical element.

[0011]

The optical element of the present invention which achieves the above object is an optical element having at least two optical action surfaces, one of which is a rotationally asymmetric surface. Another optical working surface is a Fresnel surface.

An image enlarging optical device can be constructed by using such an optical element.

An image display device can be constructed by using such an optical element having a positive power and using it together with a relay optical system for enlarging an image.

Further, according to the present invention, a display element for displaying an image or an intermediate image thereof, a relay optical system for projecting the image or the intermediate image displayed on the display element, and a light flux from the relay optical system for an observer. A projection-type optical device comprising an eyepiece optical system having a converging action that converges toward an eyeball, the eyepiece optical system having at least one free-form surface and at least one Fresnel reflecting surface. Is included.

Hereinafter, the reason why the above structure is adopted in the present invention and the operation thereof will be described.

The projection type optical apparatus of the present invention observes a display element or an intermediate image thereof for displaying an image, a relay optical system for projecting the image or the intermediate image displayed on the display element, and a light beam from the relay optical system. And an eyepiece optical system having a converging action that converges toward the human eyeball, and a decentered prism optical system is used as the relay optical system.

Since small display elements have high productivity,
It is possible to obtain a high-pixel display element at low cost.
It is desirable to use a display element having a diagonal length of a display image of 1 inch or less, and more preferably to use a display element having a diagonal length of 0.5 inch or less, which is advantageous when an inexpensive display device is constructed.

When such a small display element is used, the enlargement magnification is insufficient only by enlarging the display image with an optical system such as a magnifying glass, and the image should be observed as a sufficiently large image. I can't. Therefore, the image of the display element is once enlarged and projected by the relay optical system, the image (intermediate image) projected by the relay optical system is further enlarged by the eyepiece optical system, and at the same time, the light flux from the relay optical system is converged on the observer's eye. It is important that the eyepiece optical system has the function of

The optical element of the present invention can be used as an image magnifying optical device such as a magnifying glass, but is also used as an eyepiece optical system for use with such a relay optical system.

By using a decentered prism optical system as a relay optical system for enlarging and projecting a small display element in the vicinity of the eyepiece optical system, a small relay optical system can be constructed.

That is, as a relay optical system, an incident surface formed of a medium having a refractive index (n) larger than 1 (n> 1), and a luminous flux emitted from a display element entering the prism, and the luminous flux At least one reflecting surface that reflects inside the prism and an exit surface that emits the light beam to the outside of the prism, and at least one reflecting surface includes one or more decentering prisms having a curved surface shape that gives power to the light beam. It is desirable to use the decentered prism optical system.

A refractive optical element such as a lens can be given power only by providing a curvature at its boundary surface. Therefore, when light rays are refracted at the boundary surface of the lens, chromatic aberration is unavoidable due to the chromatic dispersion characteristic of the refractive optical element. As a result, another refractive optical element is generally added for the purpose of correcting chromatic aberration.

On the other hand, a reflective optical element such as a mirror or prism does not cause chromatic aberration in principle even if its reflecting surface has power, and another optical element is provided only for the purpose of correcting chromatic aberration. No need to add. Therefore, the optical system using the reflective optical element can reduce the number of constituent optical elements from the viewpoint of chromatic aberration correction, as compared with the optical system using the refractive optical element.

At the same time, in the reflection optical system using the reflection optical element, since the optical path is folded, it is possible to make the optical system itself smaller than the refraction optical system.

Further, since the reflecting surface has a higher sensitivity to decentering error than the refracting surface, high precision is required for assembly and adjustment.
However, among the reflective optical elements, since the relative positional relationship of the respective surfaces of the prism is fixed, it is sufficient to control the eccentricity of the prism alone, and unnecessary assembly accuracy and adjustment man-hours are unnecessary.

Further, the prism has an entrance surface, an exit surface, and a reflecting surface which are refracting surfaces, and has a greater degree of freedom in aberration correction than a mirror having only a reflecting surface. In particular, by reflecting most of the desired power on the reflecting surface and reducing the power of the entrance surface and the exit surface, which are refracting surfaces, while maintaining a large degree of freedom in aberration correction compared to a mirror, the It is possible to make the occurrence of chromatic aberration much smaller than that of such a refracting optical element. Further, since the inside of the prism is filled with a transparent material having a higher refractive index than that of air, the optical path length can be made longer than that of air, and the optical system of the optical system can be used rather than a lens or mirror arranged in the air. It can be made thinner and smaller.

Further, the projection optical system is required to have good image forming performance not only in the central performance but also in the periphery. In the case of a general coaxial optical system, the sign of the ray height of an off-axis ray is reversed before and after the stop, so that the symmetry of the optical element with respect to the stop is broken and the off-axis aberration is deteriorated. Therefore, it is general to arrange the refracting surfaces with the diaphragm interposed therebetween to sufficiently satisfy the symmetry with respect to the diaphragm and correct the off-axis aberration.

Therefore, according to the present invention, the incident surface on which the light beam emitted from the display element is made incident on the prism, and the at least one reflecting surface for reflecting the light beam on the prism,
An exit surface for emitting the light beam to the outside of the prism, and at least one reflecting surface has a curved surface shape that gives power to the light beam, and the curved surface shape is a rotationally asymmetric surface shape that corrects aberrations caused by decentering. By correcting the eccentric aberration using the prism member configured as described above, it becomes possible to satisfactorily correct not only the center but also the off-axis aberration.

Further, the light flux forming the primary image projected by such a relay optical system forms a primary image while diverging from the relay optical system. The eyepiece optical system is required to have a converging function for efficiently converging this divergent light beam to the observer's eye. When the eyepiece optical system does not have this converging action, the light flux forming the primary image reaches the observer's eye while diverging, so that the light flux entering the eyeball and recognized as an image exits the display element. Only a very dark image can be observed because it becomes a very small part of the light flux.

Therefore, in the present invention, it is important that the optical element used in the eyepiece optical system or the like has a converging action. Therefore, if the optical element has a geometrical shape such as a spherical surface, a protrusion corresponding to a spherical deficiency will occur. Cannot be miniaturized. Therefore, it is important to have a Fresnel surface as a surface that bears the converging action of the optical element. Further, in order to make the device compact, it is necessary to bend the optical path, and it is important to dispose the Fresnel surface eccentrically. But,
By eccentrically arranging the surface having the converging function, decentering aberration occurs, and it becomes difficult to observe a uniform image on the entire screen. In order to cancel such eccentric aberration, it is desirable to form the Fresnel surface by a rotationally asymmetric free-form surface or the like, but it is very difficult to manufacture a rotationally asymmetric Fresnel surface. Therefore, the optical element used for the eyepiece optical system has a converging action, a small amount of eccentric aberration is generated, and a rotationally symmetric Fresnel surface that is easy to manufacture and a free-form surface that corrects eccentric aberration. It is important to have separate asymmetric surfaces. With this configuration, the light rays that have emitted from the display element and have passed through the relay optical system are effectively gathered at the observer's eyeball, and at the same time, display with good illumination efficiency can be obtained, and at the same time, the contents displayed to the neighbors even in the train etc. You will not have to worry about being peeked at.

The free-form surface is, for example, US Pat. No. 6,124,989 (JP 2000-66105 A).
(A) is a free-form surface, and the Z axis of the definition expression is the axis of the free-form surface.

Here, the Fresnel surface used in the present invention will be described. The Fresnel surface is obtained by cutting the basic curved surface into thin ring-shaped small surfaces, and arranging a large number of the divided ring-shaped small surfaces in the shape of an orbicular zone. The Fresnel surface used in the present invention has the basic curved surface rotationally symmetrical. It has a flat surface shape, and its schematic view is shown in FIG. FIG. 13A is a perspective view of the Fresnel surface 60 used in the present invention, and FIG. 13B is a vertical cross-sectional view including the center thereof. In the illustrated example, in order to realize the rotationally symmetric Fresnel surface 60, the Fresnel pitch is formed into a rotationally symmetric spherical surface to realize the rotationally symmetric Fresnel surface. Then, by making this Fresnel surface 60 a refraction surface, it becomes a Fresnel transmission surface,
By using the Fresnel surface 60 as a reflecting surface, it becomes a Fresnel reflecting surface. The Fresnel surface 60 may be a Fresnel transmissive surface, and another optical surface close to the Fresnel transmissive surface may be a reflective surface to form a Fresnel reflective surface.

Now, in the optical element of the present invention, FIG.
As shown in a schematic cross section in (a), a rotationally symmetric Fresnel surface is used as a Fresnel transmission surface 61, and a medium having a refractive index (n) larger than 1 (n> 1) is sandwiched between the incident side and the exit side. The surface (optical action surface) of the optical element is a transmission surface 62 having a rotationally asymmetrical shape such as a free-form surface.
It can be set to 3, or as shown in FIG.
A rotationally symmetric Fresnel surface is used as a Fresnel transmission surface 61, and a surface on the exit side (optical action surface) of a medium having a refractive index (n) larger than 1 (n> 1) is rotationally asymmetrical such as a free-form surface. The reflecting surface 64 can be a rear-view mirror type optical element 65, and as shown in FIG. 12C, a medium having a refractive index (n) larger than 1 (n> 1) can be freely sandwiched. It is also possible to use a rear surface mirror type optical element 67 in which the exit side surface (optical action surface) of the rotationally asymmetrical transmission surface 62 such as a curved surface is a rotationally symmetric Fresnel reflection surface 66.

In the present invention, the optical element as described above is used as an eyepiece optical system having a converging action, and a relay optical system for projecting an image or an intermediate image displayed on the display element, and the relay optical system It is possible to configure the projection type optical device by converging the light flux of (3) toward the eyeball of the observer by the eyepiece optical system. Such a configuration
Although it is similar to the case of Japanese Patent Application Laid-Open No. 2000-221440, that of Japanese Patent Application Laid-Open No. 2000-221440 was invented with the idea of mounting on the observer's head for observation, and can be easily used in a crowded train. It is unsuitable for use in a pocket when you take it out of your pocket.

Accordingly, in the present invention, the focal length of the eyepiece optical system is optimized so that the exit pupil of the eyepiece optical system is changed from the eyepiece optical system so that the entire screen can be observed even at a position where the display element is separated from the eye by 50 mm or more. It is important to separate them by 80 mm or more. That is, when EXPe is the axial distance between the exit pupil position of the eyepiece optical system and the exit pupil side surface of the eyepiece optical system, it is preferable that the conditional expression of 80 mm <EXPe <1000 mm (1) is satisfied. . If the lower limit of 80 mm of the above conditional expression is exceeded, the entire screen cannot be observed unless the eyes are brought close to the device for observation.
It becomes hard to see. Also, when operating the operation buttons or switches arranged on the device, if the lower limit is exceeded,
The distance between the device and the observer's face becomes too short, making it impossible to carry a finger between the device and the face for operation. If the upper limit of 1000 mm is exceeded, on the contrary, the distance becomes too large, and the screen becomes small so that a detailed image cannot be observed, and at the same time, it becomes unreachable for the operation and cannot be operated.

More preferably, it is important to satisfy the condition of 100 mm <EXPe <1000 mm (1-1). The lower limit of 10
When the distance exceeds 0 mm, the observer operates the operation buttons and the like arranged on the display element instead of the display screen, so that the hands cannot be put between the display element and the observer's face, and the operator operates while viewing the screen. I will not be able to.

More preferably, it is important to satisfy the condition of 300 mm <EXPe <1000 mm (1-2). The lower limit of 30
If the distance exceeds 0 mm, the display element is close to the clear vision, so that it is too close to be seen when operating the operation buttons or the like, and the display becomes invisible.

Now, the powers of the decentered optical system and the optical surface will be defined. When the optical axis direction is the Z-axis direction, the decentering direction of the decentered optical system and the optical surface is the Y-axis direction, and the direction orthogonal to them is the X-axis direction, two in the YZ plane and the XZ plane are defined. With respect to light rays in one direction, parallel rays separated from the axial principal ray by a minute distance are made incident on the decentered optical system and the optical surface, and powers Px and Py are defined in the same manner as in paragraph [0049] of JP-A No. 11-194267. The focal length F
It is defined as x and Fy.

When the power of the eyepiece optical system is Px3 and Py3 and the power of the relay optical system is PPx and PPy, 0 <| Px3 / PPx | <2 (2) 0 <| Py3 / PPy | <2 It is important that at least one of the conditions (3) is satisfied.

This conditional expression expresses the ratio of the powers of the eyepiece optical system and the relay optical system. When the lower limit of 0 is exceeded, the power of the eyepiece optical system becomes too small (weak), and the eyepiece optical system has a size that is easy to see. Since the display device does not have an observation angle of view, the displayed image is too small to observe a fine display. Further, when the upper limit of 2 is exceeded, the power of the relay optical system becomes too small (weak), a small display element cannot be used, the device becomes large, and at the same time the power consumption becomes large, which is expensive. Become.

More preferably, 0.01 <| Px3 / PPx | <0.7 (2-1) 0.01 <| Py3 / PPy | <0.7 (3-1) It is important to meet at least one of the conditions. These conditional expressions are similar to the above conditional expressions, but if the respective upper limits of 0.7 are exceeded, it becomes important in the case of constructing a display device in which the size of the eyepiece optical system is B5 size or less. It will not fit in the B5 size, and will not be a portable notebook size.

More preferably, 0.01 <| Px3 / PPx | <0.4 (2-2) 0.01 <| Py3 / PPy | <0.4 (3-2) It is important to meet at least one of the conditions. These conditional expressions are similar to the above conditional expressions. However, when the respective upper limits of 0.4 are exceeded, it becomes important when constructing a display device in which the size of the eyepiece optical system is B6 size or less. It will not fit in B6 size, and it will not be a display device that fits in a pocket.

When the power in the X direction of the entire projection optical system of the projection display apparatus of the present invention is Px and the power in the Y direction is Py, 0.5 <Px / Py <1.8 (4) It is important to satisfy the following conditional expression. This condition is X
If the lower limit of 0.5 is exceeded, the power in the Y direction becomes too large with respect to the X direction, and the image size in the Y direction becomes smaller than that in the X direction. Too much. On the contrary, when the upper limit of 1.8 in the above conditional expression is exceeded, X
The power in the Y direction becomes too small with respect to the direction, and the size of the image in the Y direction becomes too large compared to that in the X direction.

More preferably, it is necessary to satisfy the condition of 0.7 <Px / Py <1.7 (4-1). The meanings of the lower limit and the upper limit of this condition are the same as above.

More preferably, it is necessary to satisfy the condition of 0.8 <Px / Py <1.6 (4-2). The meanings of the lower limit and the upper limit of this condition are the same as above.

Next, the power in the X direction of the entire projection optical system of the projection type optical device of the present invention is Px, and the power in the Y direction is Py.
When the power of the eyepiece optical system arranged in front of the observer's eye is Px3 and Py3, 0.01 <| Px3 / Px | <1.0 (5) 0.01 <| Py3 / Py It is important that at least one of the conditions | <1.0 (6) is satisfied. These conditions regulate the power of the eyepiece optical system and the power arrangement of the relay optical system. If the lower limit of 0.01 is exceeded, the power of the eyepiece optical system becomes too small, and the projection of the relay optical system becomes too small. Unless the magnification is increased, a wide observation image cannot be presented. However, increasing the projection magnification of the relay optical system increases the distance between the object images of the relay optical system, making it difficult to reduce the size of the optical system. Further, when the upper limit of 1.0 is exceeded, the power of the eyepiece optical system becomes too strong this time, and a large amount of eccentric aberration occurs due to the eccentrically arranged eyepiece optical system, which makes it impossible to correct by the relay optical system. Become.

More preferably, 0.2 <| PX3 / Px | <0.7 (5-1) 0.2 <| PY3 / Py | <0.7 (6-1) It is important to meet at least one of the conditions. The meanings of the lower and upper limits of these conditions are the same as above.

Next, the power in the X direction of the entire projection optical system of the projection type optical device of the present invention is Px, and the power in the Y direction is Py.
When the power of the relay optical system is PPx and PPy, 0.5 <| PPx / Px | <10.0 (7) 0.5 <| PPy / Py | <10.0 It is important to satisfy at least one of the conditions (8). These conditions define the power arrangement of the relay optical system having the function of the projection optical system. If the lower limit of 0.5 is exceeded, the power of the relay optical system becomes too small and The focal length becomes too large, and it becomes difficult to make the optical system compact. Also, the upper limit of 1
When 0.0 is exceeded, the focal length of the relay optical system becomes too short this time, and it becomes impossible for the relay optical system to correct the eccentric aberration due to the eccentrically arranged eyepiece optical system.

More preferably, 1.0 <| PPx / Px | <8.0 ... (7-1) 1.0 <| PPy / Py | <8.0 (8-1) It is important to meet at least one of the conditions. The meanings of the lower and upper limits of these conditions are the same as above.

The data of the following Examples 1 to 4 relating to the above conditional expressions (1) to (8) of the present invention are shown below. ─────────────────────────── Example 1 2 3 4 ───────────────── ────────── EXPe 300 300 300 300 Px / Py 0.980 1.565 0.981 1.526 ｜ Px3 / Px ｜ 0.516 0.373 0.413 0.614 ｜ Py3 / Py ｜ 0.279 0.520 0.267 0.571 ｜ PPx / Px ｜ 2.983 1.948 3.622 2.399 ｜ PPy / Py ｜ 2.817 2.905 2.294 2.868 ｜ Px3 / PPx ｜ 0.173 0.192 0.114 0.256 ｜ Py3 / PPy ｜ 0.099 0.179 0.116 0.199 ──────────────────────── ───.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a projection display device which is a projection type optical device of the present invention will be described below.

Before describing specific numerical examples 1 to 4, examples of usage of the projection display apparatus of the present invention will be described.

In the first mode of use of the present invention, as shown in FIG. 1, the eyepiece optical system 32 is composed of at least an optical element 34 having a reflecting action. This optical element 34
Is an optical element in the form of FIG. 12 (b) or (c).
In the case of FIG. 1, it is desirable that the operation button 33 is arranged on the main body 30 of the display device before the relay optical system 31 when viewed from the observer side. With this arrangement, it is possible to avoid the problem of blocking the image each time the button is operated without blocking the optical path with the hand of operating the operation button 33. Further, the relay optical system 31 is arranged in front of the eyepiece optical system 32, so that the eyepiece optical system 3
It is possible to observe the image reflected by 2 without difficulty. In FIG. 1, the eyeball position of the observer is indicated by E.
Although the image display element is arranged on the main body 30 side of the relay optical system 31, the illustration is omitted.

Further, in the case of FIG. 1, the eyepiece optical system 32 is
By using a mechanism that opens and closes from the main body 30, it becomes possible to store it in a pocket when carrying it. In addition, at this time, if the function of cutting off the power supply is added, the power saving effect is high.

Furthermore, by opening and closing the observer side from the main body 30 to open and close, the optical surface of the eyepiece optical system 32 is not exposed on the surface during storage, and the optical surface of the optical system is dirty. Is less likely to adhere, which is more preferable.

As shown in FIG. 2, the second mode of use of the present invention is to construct the eyepiece optical system 32 with at least an optical element 35 having a transmitting action. This optical element 35
Is an optical element in the form of FIG. In the case of FIG. 2, it is desirable that the operation button 33 is arranged on the main body 30 of the display device before the eyepiece optical system 32 when viewed from the observer side. With this arrangement, it is possible to avoid the problem of blocking the image each time the button is operated without blocking the optical path with the hand of operating the operation button 33. Further, by disposing the eyepiece optical system 32 in front of the relay optical system 31, it is possible to observe the image without difficulty.

In the case of this embodiment, the eyepiece optical system 3
It is preferable to store 2 by tilting it to the relay optical system 31 side. As a result, the role of the cover that protects the relay optical system 31 can be substituted by the surface of the eyepiece optical system 32.

Further, in both of the usage patterns of FIG. 1 and FIG. 2, a reflecting mirror 36 (FIG. 2) is arranged between the relay optical system 31 and the eyepiece optical system 32, and the optical path is bent so that the relay optical system is bent. It is possible to shorten the distance from 31 to the eyepiece optical system 32. More preferably, by providing the reflecting mirror 36 with power, the eyepiece optical system 3
It is possible to disperse the power of 2 and display a larger screen image clearly.

Further, by housing the reflecting mirror 36 under the eyepiece optical system 32, it is possible to prevent the optical element from being exposed and improve the dustproof property.

Next, the eyepiece optical system will be described. Although the eyepiece optical system is treated as a surface having no diffusivity in the numerical examples described later, it is more preferable that it has a certain degree of diffusivity. The reason will be described below.

Eyepiece optical system 32 disposed near the projected image
As shown in FIG. 3, it is important that the light rays are less scattered and the light rays are selectively converged in the direction of the observer. As shown in FIG. 4, the eyepiece optical system 32 having a large scattering property is generally preferable because unevenness in illuminance from the viewing position is unlikely to occur, but in the portable display device of the present invention, When the incident light 51 is scattered, the number of light rays reaching the eyeball of the observer is reduced and the illumination light is wasted. Furthermore, if the brightness of the lighting is increased in order to compensate for the brightness of the display screen that is unnecessarily scattered and becomes dark, power consumption increases,
The usage time becomes extremely short, and a large and heavy battery will be attached to a small display device. In order to avoid this problem, it is important to use a screen having a low scattering property as the eyepiece optical system 32 in the present invention, as shown in FIG. 3 and 4, the eyepiece optical system 32 is shown as an optical element having a reflecting action, but of course, FIG.
The same applies when an optical element having a transmissive action such as 2 (a) is used.

Also, when observing in a train or the like, a screen with low diffusivity is preferable, and a screen with low diffusivity is preferable from the viewpoint of readability to prevent others from seeing the display contents. The content displayed is visible to the person who sits down. .

More preferably, the diffusiveness of the screen surface is the angle formed by the normal to the optical surface of the eyepiece optical system 32 with respect to the intensity in the direction of regular specular reflection. It is preferable that the diffused light intensity in the direction of 20 ° is 50% or less from the viewpoint of effective use of light.
More preferably, the one having a low scattering property, which has a diffusion intensity of 50% or less in the direction of an angle of 10 ° with the surface normal, is more preferable.

More preferably, as shown in FIG. 5, the scattering range 53 of the eyepiece optical system 32 is preferably larger than the vertical direction with respect to the horizontal direction corresponding to both eyes of the observer. When the scattering range 53 is large in the horizontal direction with respect to the vertical direction, the light flux from the relay optical system 31 can be effectively guided to both eyes of the observer, and it is possible to observe with both eyes.

Further, as shown in FIG. 6, the eyepiece optical system 32
Diffractive optical element (DOE) and hologram optical element (HO
E) is added and the number of rays emitted from the relay optical system 31 is 2
By splitting into two and moving towards both eyes of the observer,
A more efficient diffusion range 53 can be obtained. The same effect can be obtained by using a prism sheet formed by arranging one-dimensional micro prisms having an obtuse angle.

By the way, in the present invention, the display position of the virtual image observed by the observer's eye is constructed so as to be presented in the vicinity of the eyepiece optical system 32, but it is presented further to the observer side than the surface of the eyepiece optical system 32. By doing so, it becomes possible to give a further sense of reality to the displayed image. In addition, when the surface of the eyepiece optical system 32 has the above-mentioned diffusivity, it is possible to observe a clear image by matching the virtual image position with the surface of the eyepiece optical system 32 having the diffusive property. Become. Also, especially for images with a small number of display pixels,
By intentionally shifting the minute distance display image position and the surface having diffusivity, it is possible to obtain a smooth image by the low-pass filter effect.

Further, as in the numerical example described later, the eyepiece optical system 32 may be set to 40 cm from the observer, but the image may be presented 1 m away. Can be set arbitrarily.

More preferably, by providing a mechanism for moving the display element in the optical axis direction, the position of the real image projected by the relay optical system 31 is moved, and the position of the virtual image formed by the eyepiece optical system 32 is infinite. It is desirable to be able to move from a distance to the vicinity of the eyepiece optical system 32. With this mechanism, it is possible to adjust the virtual image position to a position desired by the observer, and it is possible to select an image position that is easily seen by people with myopia, hyperopia, and presbyopia.

Since the optical element forming the eyepiece optical system 32 of the present invention is constructed by using a rotationally asymmetric surface,
In particular, the object center is ejected, passes through the observer's iris center,
In the case of a decentered optical system in which an axial chief ray reaching the center of the fundus decenters and enters the eyepiece optical system 32, the eyepiece optical system 32
By forming a rotationally asymmetric surface, it is possible to correct trapezoidal distortion of the image caused by decentering and decentering aberration such as inclination of the image plane. When the relay optical system 31 is composed of a decentered prism optical system, the relay optical system 3
This makes it possible to share the correction of eccentric aberration with No. 1 and is more preferable.

Next, the relay optical system 31 will be described. As the relay optical system 31 according to the present invention, various decentering prism optical systems having a number of internal reflections of 1 or more, which have been already proposed by the present inventors, or a decentering prism optical system including a plurality of decentering prisms can be used. Among them, as a representative example, like the decentered prisms of Examples 1 to 4, two reflecting surfaces are provided, which are composed of an entrance surface, a first reflecting surface, a second reflecting surface and an exit surface. It is possible to use an optical path in which the optical path that connects the first reflection surface and the first reflection surface intersects the optical path that connects the second reflection surface and the exit surface in the prism.

The decentering prism having such a shape has a high degree of freedom in aberration correction, and produces less aberration. further,
Since the arrangement of the two reflecting surfaces is highly symmetrical, the aberrations generated by these two reflecting surfaces are corrected by the two reflecting surfaces,
Less aberration. In addition, because the optical path forms a crossing optical path within the prism, the optical path can be made longer than a prism with a structure that simply folds the optical path, and the prism can be made smaller for the length of the optical path. can do.

Further, as shown in FIG. 19A, the first surface 11 facing the display element 3 and the eyepiece optical system 32 (see FIG. 14).
Etc.) and a third surface 13 facing each other,
The light ray from the display element 3 refracted on the surface 11 and incident on the prism is totally reflected on the second surface 12, the reflected light is reflected on the third surface 13, and the reflected light is in turn the first surface 11 The light is totally reflected by the second surface 12, and this reflected light is refracted by the second surface 12 and then exits the prism. The first surface 11 serves as the incident surface and the third reflecting surface, and the second surface 12 serves as the first reflecting surface. It also serves as the exit surface,
The decentered prism 10 in which the light ray makes one revolution in the prism may be used. Since the decentering prism 10 has three reflecting surfaces, it is possible to disperse power on the reflecting surfaces three times, and it is possible to reduce the occurrence of aberration. Further, because the optical paths intersect within the prism, the optical path length can be made longer than that of a prism having a structure in which the optical paths are simply folded.

As shown in FIG. 19B, the first surface 11 facing the display element 3, the second surface 12 facing the eyepiece optical system 32, and the third surface 13 are composed of the first surface 11. The light beam from the display element 3 refracted at 11 and incident on the prism is
The light is totally reflected by the surface 12, and the reflected light is reflected by the third surface 13,
The reflected light is then refracted by the second surface 12 and emitted to the outside of the prism, and the decentered prism 10 in which the second surface 12 also serves as the first reflecting surface and the emitting surface may be used. This decentering prism 10 which also serves as a first reflecting surface and an exiting surface is designed so that the first reflecting surface largely bends the light beam, and the second reflecting surface reflects the light ray to the exiting surface at a small bending angle. It is possible to reduce the thickness of the optical system in the outgoing light ray direction.

As shown in FIG. 19C, the first surface 11 facing the display element 3, the second surface 12 facing the eyepiece optical system 32, and the third surface 13 are composed of the first surface 11. The light beam from the display element 3 refracted at 11 and incident on the prism is
The light reflected by the surface 13 is totally reflected by the first surface 11 this time, and the reflected light is refracted by the second surface 12 and emitted outside the prism. The decentering prism 10 that also serves as two reflecting surfaces may be used. This decentered prism 10 which also serves as a second reflecting surface and an incident surface,
Since the light ray is largely bent at the second reflecting surface and the first reflecting surface reflects the light ray to the second reflecting surface at a small bending angle, it is possible to reduce the thickness of the prism optical system in the incident light ray direction. It is a thing.

In the projection display device of the present invention, when the eyepiece optical system 32 can be opened and closed from the main body 30, as shown in FIG. 7, when the eyepiece optical system 32 is closed without being opened, the wall surface 54 It can also be used as a projector for projecting images on the screen. In this case, a mechanism for moving the display element to align the position of the projected image with the wall surface 54 is required. If the brightness of the projection display device is insufficient,
As shown in FIG. 8B, an external light source device 38 can be attached to, for example, the lower surface of the main body 30, and a built-in light source 37 for observation through the normal eyepiece optical system 32 of FIG. 8A. It is also possible to move the display element 3 from the use position to the outside of the use position as indicated by an arrow in the figure so that the display element 3 can be illuminated from the back surface with the illumination light from the external light source 39 in the external light source device. In the case of FIG. 8B, the display element 3 can be moved in the arrow direction so as to be close to the decentered prism 10 forming the relay optical system 31 and focus adjustment can be performed.

Further, as shown in FIG. 9, two relay optical systems 31L and 32R are used, the left and right display elements are arranged corresponding to the relay optical systems 31R and 32L, and the eyepiece optical system 32 is moved to the left and right. In common, by displaying a binocular parallax image on each display element, the optical paths from the left and right display elements are separated for the left and right eyes, and an image with parallax can be observed for the left and right eyes of the observer. The configuration enables binocular stereoscopic viewing, and a projection display device capable of observing a stereoscopic image without special glasses can be provided.

Further, the projection display device of the present invention is not limited to the above-mentioned portable type of use, but can be configured as a handheld viewer type as shown in FIG. Also, FIG.
The configuration shown in FIG. 1 is also possible. In this configuration, the support member 42 of the relay optical system 31 also serves as the protective cover of the eyepiece optical system 32, thereby improving the dustproof property during carrying. It becomes possible.

Numerical Examples 1 to 4 of the optical system used in the projection display apparatus of the present invention will be described below.

Although the constituent parameters of Examples 1 to 4 will be described later, the coordinate system is the backward ray tracing from the position of the exit pupil 1 (observer's pupil) toward the display element 3, and as shown in FIG. 2 is defined as a ray that passes through the center of the exit pupil 1 of the optical system vertically and reaches the center of the display element 3. Then, in the backward ray tracing, the center of the exit pupil 1 is the origin of the decentered optical surface of the decentered optical system, the direction along the axial chief ray 2 is the Z-axis direction, and the optical path from the exit pupil 1 to the eyepiece optical system 32 of the optical system. The direction toward the surface 21 of the element 20 facing the exit pupil 1 is defined as the Z-axis positive direction,
The plane of the drawing is taken as the YZ plane, the origin is orthogonal to the YZ plane, and the direction from the front to the back of the paper is the positive direction of the X axis.
The Y-axis is the axis that constitutes the right-handed orthogonal coordinate system with the Z-axis.

For the eccentric surface, the amount of eccentricity from the center of the origin of the optical system to the top of the surface (X axis direction, Y axis direction, Z
Axial directions are X, Y, and Z, respectively, and the X-axis of the center axis of the surface (for free-form surfaces, the Z-axis of equation (a) above, and for aspherical surfaces, Z-axis of equation (b) below). , Y-axis, and Z-axis tilt angles (α, β, γ (°))
And are given. In that case, positive α and β mean counterclockwise rotation with respect to the positive directions of the respective axes, and positive γ means clockwise rotation with respect to the positive direction of the Z-axis. In addition, how to rotate α, β, γ of the central axis of the surface is determined by the central axis of the surface and its XYZ.
The Cartesian coordinate system is first rotated α counterclockwise around the X axis, and then the center axis of the rotated surface is set to Y in the new coordinate system.
The coordinate system rotated by 1 counterclockwise around the axis and also rotated by 1 degree is rotated counterclockwise by β around the Y axis, and then the center axis of the surface rotated by 2 degrees is changed to a new coordinate system. In this case, γ rotation is performed in the clockwise direction around the Z axis of the various coordinate systems.

The shape of the surface of the free-form surface used in the present invention is, for example, the free-form surface defined by the equation (a) of US Pat. No. 6,124,989 (JP 2000-66105 A), The Z-axis of the defining equation becomes the axis of the free-form surface.

The aspherical surface is a rotationally symmetric aspherical surface given by the following defining equation.

Z = (y ² / R) / [1+ {1- (1 + K) y ² / R ² } ^1/2 ] + Ay ⁴ + By ⁶ + Cy ⁸ + Dy ¹⁰ + ... (b) However, Z Is an optical axis (axial principal ray) with the traveling direction of light being positive, and y is a direction perpendicular to the optical axis. Here, R is a paraxial radius of curvature, K is a conical constant, and A, B, C, D, ... Are aspherical coefficients of 4th order, 6th order, 8th order, and 10th order, respectively.
The Z axis of this defining equation is the axis of the rotationally symmetric aspherical surface.

The term relating to the free-form surface and aspherical surface for which no data is described is 0. For the refractive index,
Those for the d-line (wavelength 587.56 nm) are shown. The unit of length is mm.

In Example 1 described below, the eyepiece optical system 32 is arranged with an inclination of 20 ° with respect to the visual axis (corresponding to the axial chief ray 2 passing through the center of the exit pupil 1). , Viewing angle of view 13 ° horizontal, vertical 10 °, pupil system φ15 mm, the distance from the exit pupil 1 at the observer's eyeball position to the image is 30
cm, and the display element 3 of 4.8 × 3.2 mm is used.

In the second embodiment, the eyepiece optical system 32 is arranged at an angle of 20 ° with respect to the visual axis, and the observation angle of view is horizontal 13 °, vertical 10 °, the pupil system φ15 mm, and the observer's eyeball position. The distance from the exit pupil 1 to the image is 30 cm, and the display element 3 of 8.9 × 6.7 mm is used.

In the third embodiment, the eyepiece optical system is arranged without inclination with respect to the visual axis, and the observation angle of view horizontal 13
°, vertical 10 °, pupil system φ15 mm, the distance from the exit pupil 1 at the observer's eyeball position to the image is 30 cm,
The display element 3 having a size of 4.8 × 3.2 mm is used.

In the fourth embodiment, the eyepiece optical system is arranged without inclination with respect to the visual axis, and the observation angle of view horizontal 13
°, vertical 10 °, pupil system φ15 mm, the distance from the exit pupil 1 at the observer's eyeball position to the image is 30 cm,
The display element 3 of 8.9 × 6.7 mm is used.

The following examples are designed on the assumption that the eyepiece optical system 32 does not have the diffusivity, and the diffusivity is a desired diffusivity, and the diffusive element can be used.

The configuration of the optical system of each example will be described.

An optical path diagram of the entire optical system of Example 1 is shown in FIG.
FIG. 15 shows an enlarged optical path diagram in which the optical path leading to the exit pupil is omitted. The optical system of the second embodiment is similar to that of the first embodiment, and is not shown. In addition, FIG. 1 shows an optical path diagram of the entire optical system of Example 3.
FIG. 6 shows an enlarged optical path diagram in which the optical path leading to the exit pupil is omitted. The optical system of the fourth embodiment is the same as that of the third embodiment, and is not shown.

In each of the optical systems of Examples 1 to 4, in the eyepiece optical system 32 facing the exit pupil 1, the entrance side surface 21 is a transparent surface which is a free-form surface, and the back side surface 22 is a Fresnel reflection surface. The relay optical system 31 facing the display element 3 is composed of the decentered prism 10. The decentering prism 10 of these examples includes a first decentering prism facing the display element 3.
The light beam from the display element 3 which is composed of the surface 11, the second surface 12 facing the optical element 20, the third surface 13, and the fourth surface 14 and which is refracted by the first surface 11 and enters the prism is , Third
The light is reflected by the surface 13, the reflected light is reflected by the fourth surface 14, and the reflected light is refracted by the second surface 12 and emitted outside the prism.
The image of the display element 3 is formed near the surface 21 on the front surface side of the optical element 20, and the optical path connecting the first surface 11 and the third surface 13 connects the fourth surface 14 and the second surface 12. The light path intersects the prism, and the light beam makes one rotation in the decentering prism 10.

In Examples 1 to 4, the incident side surface 21 of the optical element 20 and the first surface 11 to the third surface of the decentering prism 10 were used.
The surface 14 is composed of a free-form surface, and the Fresnel reflection surface 22 of the optical element 20 is composed of a rotationally symmetric aspherical surface.

Numerical data of each example are shown below. In the table below, "FFS" is a free-form surface, "ASS" is an aspherical surface, "RE" is a reflecting surface, and "FR" is a Fresnel reflecting surface. Show.

Example 1 Surface Number Curvature Radius Surface Spacing Eccentricity Refractive Index Abbe Number Object Surface ∞ Eccentricity (1) 1 ∞ (pupil) 2 FFS Eccentricity (2) 1.5254 56.2 3 ASS (FR) Eccentricity (3) 1.5254 56.2 4 FFS Eccentricity (2) 5 FFS Eccentricity (4) 1.5254 56.2 6 FFS (RE) Eccentricity (5) 1.5254 56.2 7 FFS (RE) Eccentricity (6) 1.5254 56.2 8 FFS Eccentricity (7) Image plane ∞ Eccentricity (8) ASS R- 188.64 K 0.0000 A 7.0 180 × 10 ^-8 B -1.5051 × 10 ^-11 FFS C ₄ 1.0224 × 10 ^-4 C ₆ -1.0000 × 10 ^-3 C ₈ -1.1547 × 10 ^-5 C ₁₀ -1.2651 × 10 ^-5 C ₁₁ -1.2735 x 10 ^-7 C ₁₃ -2.1182 x 10 ^-7 FFS C ₄ 7.1420 x 10 ^-2 C ₆ 1.3086 x 10 ^-2 C ₈ -2.1790 x 10 ^-3 C ₁₀ -2.5270 x 10 ^-3 FFS C ₄ 9.1531 x 10 ^-3 C ₆ -2.7747 x 10 ^-3 C ₈ -5.3039 x 10 ^-4 C ₁₀ -9.5628 x 10 ^-4 FFS C ₄ -1.7688 x 10 ^-2 C ₆ -1.9386 x 10 ^-2 C ₈ -3.5040 x 10 ^-5 C ₁₀ -3.7 180 x 10 ^-4 FFS C ₄ -7.6339 x 10 ^-3 C ₆ 3.9 196 x 10 ^-2 C ₈ 3.6 107 x 10 ^-3 Eccentricity (1) X 0.00 Y 0.00 Z 30 0.00 α 20.00 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y 0.00 Z 300.00 α 20.00 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y 0.00 Z 302.00 α 20.00 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y -51.27 Z 238.90 α 42.65 β 0.00 γ 0.00 Eccentricity (5) X 0.00 Y -60.40 Z 230.60 α 67.90 β 0.00 γ 0.00 Eccentricity (6) X 0.00 Y -52.13 Z 230.05 α 118.02 β 0.00 γ 0.00 Eccentricity (7) X 0.00 Y -59.55 Z 239.62 α 136.89 β 0.00 γ 0.00 Eccentricity (8) X 0.00 Y -61.14 Z 241.90 α 135.48 β 0.00 γ 0.00.

Example 2 Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object plane ∞ Eccentricity (1) 1 ∞ (pupil) 2 FFS Eccentricity (2) 1.5254 56.2 3 ASS (FR) Eccentricity (3) 1.5254 56.2 4 FFS Eccentricity (2) 5 FFS Eccentricity (4) 1.5254 56.2 6 FFS (RE) Eccentricity (5) 1.5254 56.2 7 FFS (RE) Eccentricity (6) 1.5254 56.2 8 FFS Eccentricity (7) Image plane ∞ Eccentricity (8) ASS R- 185.29 K 0.0000 A 5.7336 × 10 ^-8 B -2.6176 × 10 ^-11 FFS C ₄ 1.5340 × 10 ^-3 C ₆ -1.0000 × 10 ^-3 C ₈ -1.1347 × 10 ^-5 C ₁₀ -1.9015 × 10 ^-5 C ₁₁ -7.0896 x 10 ^-7 C ₁₃ -5.8244 x 10 ^-7 FFS C ₄ 5.6990 x 10 ^-3 C ₆ -1.8913 x 10 ^-2 C ₈ 2.5368 x 10 ^-5 C ₁₀ -1.1589 x 10 ^-3 FFS C ₄ 5.9 656 x _{^{10 -3 C 6 -1.3076 × 10 -3}} C 8 -1.8411 × 10 -4 C 10 -6.9564 × 10 -4 FFS C 4 -1.4038 × 10 -2 C 6 -1.3977 × 10 -2 C 8 6.8437 × 10 - ⁶ C ₁₀ -4.5868 x 10 ^-4 FFS C ₄ -2.0085 x 10 ^-2 C ₆ 2.2 18 1 x 10 ^-2 C ₈ 3.2550 x 10 ^-3 Eccentricity (1) X 0.00 Y 0.00 Z 30 0.00 α 20.00 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y 0.00 Z 300.00 α 20.00 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y 0.00 Z 302.00 α 20.00 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y -49.30 Z 241.25 α 49.42 β 0.00 γ 0.00 Eccentricity (5) X 0.00 Y -59.07 Z 232.45 α 66.43 β 0.00 γ 0.00 Eccentricity (6) X 0.00 Y -49.50 Z 232.41 α 115.41 β 0.00 γ 0.00 Eccentricity (7) X 0.00 Y -56.81 Z 241.31 α 145.25 β 0.00 γ 0.00 Eccentricity (8) X 0.00 Y -59.15 Z 243.92 α 130.13 β 0.00 γ 0.00.

Example 3 Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object plane ∞ Eccentricity (1) 1 ∞ (pupil) 2 FFS Eccentricity (2) 1.5254 56.2 3 ASS (FR) Eccentricity (3) 1.5254 56.2 4 FFS Eccentricity (2) 5 FFS Eccentricity (4) 1.5254 56.2 6 FFS (RE) Eccentricity (5) 1.5254 56.2 7 FFS (RE) Eccentricity (6) 1.5254 56.2 8 FFS Eccentricity (7) Image plane ∞ Eccentricity (8) ASS R- 198.64 K 0.0000 A 3.8493 × 10 ^-8 B -1.9988 × 10 ^-12 C 4.5703 × 10 ^-17 FFS C ₄ 7.9 248 × 10 ^-4 C ₆ -1.0000 × 10 ^-3 C ₈ -2.2430 × 10 ^-5 C ₁₀ -1.3969 _{^{× 10 -5 C 11 -1.2766 × 10}} -7 C 13 -6.2969 × 10 -8 FFS C 4 1.0666 × 10 -1 C 6 2.7159 × 10 -3 C 8 -4.2718 × 10 -3 C 10 -2.6681 × 10 - ³ FFS C ₄ 4.0 925 × 10 ^-3 C ₆ -2.7051 × 10 ^-2 C ₈ -1.4928 × 10 ^-3 C ₁₀ -2.5227 × 10 ^-3 FFS C ₄ -1.8975 × 10 ^-2 C ₆ -2.4710 × 10 ^-2 C ₈ -2.1176 × 10 ^-4 C ₁₀ -5.3 840 × 10 ^-4 FFS C ₄ -4.3444 × 10 ^-3 C ₆ 5.2174 × 10 ^-2 C ₈ 5.4289 × 10 ^-3 Eccentricity (1) X 0 .00 Y 0.00 Z 300.00 α 0.00 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y 0.00 Z 300.00 α 0.00 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y -40.76 Z 302.00 α 0.00 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y -48.58 Z 242.10 α 23.44 β 0.00 γ 0.00 Eccentricity (5) X 0.00 Y -51.25 Z 230.29 α 64.58 β 0.00 γ 0.00 Eccentricity (6) X 0.00 Y -41.85 Z 229.52 α 111.29 β 0.00 γ 0.00 Eccentricity (7) X 0.00 Y -53.14 Z 238.31 α 125.92 β 0.00 γ 0.00 Eccentricity (8) X 0.00 Y -55.60 Z 240.30 α 113.36 β 0.00 γ 0.00.

Example 4 Surface Number Curvature Radius Surface Spacing Eccentricity Refractive Index Abbe Number Object Surface ∞ Eccentricity (1) 1 ∞ (pupil) 2 FFS Eccentricity (2) 1.5254 56.2 3 ASS (FR) Eccentricity (3) 1.5254 56.2 4 FFS Eccentricity (2) 5 FFS Eccentricity (4) 1.5254 56.2 6 FFS (RE) Eccentricity (5) 1.5254 56.2 7 FFS (RE) Eccentricity (6) 1.5254 56.2 8 FFS Eccentricity (7) Image plane ∞ Eccentricity (8) ASS R- 196.82 K 0.0000 A 2.6342 × 10 ^-8 B -1.6186 × 10 ^-12 C -3.2724 × 10 ^-17 FFS C ₄ 1.5642 × 10 ^-3 C ₆ -1.0000 × 10 ^-3 C ₈ -2.4798 × 10 ^-5 C _10- 2.4 250 x 10 ^-5 C ₁₁ -4.9 650 x 10 ^-7 C ₁₃ -1.8 137 x 10 ^-7 FFS C ₄ 2.1255 x 10 ^-2 C ₆ 1.4745 x 10 ^-2 C ₈ -5.2688 x 10 ^-4 C ₁₀ -1.6479 x 10 _{^{-3 FFS C 4 4.4105 × 10 -3}} C 6 -6.0916 × 10 -3 C 8 -3.9903 × 10 -4 C 10 -9.9558 × 10 -4 FFS C 4 -1.4591 × 10 -2 C 6 -1.4933 × 10 - ² C ₈ -7.9728 x 10 ^-5 C ₁₀ -5.7 116 x 10 ^-4 FFS C ₄ -1.5065 x 10 ^-2 C ₆ 1.8124 x 10 ^-2 C ₈ 6.5 882 x 10 ^-3 Eccentricity (1) X 0.00 Y 0.00 Z 300.00 α 0.00 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y 0.00 Z 300.00 α 0.00 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y -36.61 Z 302.00 α 0.00 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y -48.40 Z 242.32 α 21.16 β 0.00 γ 0.00 Eccentricity (5) X 0.00 Y -46.78 Z 228.66 α 56.24 β 0.00 γ 0.00 Eccentricity (6) X 0.00 Y -36.18 Z 230.28 α 100.98 β 0.00 γ 0.00 Eccentricity (7) X 0.00 Y -47.50 Z 237.00 α 128.66 β 0.00 γ 0.00 Eccentricity (8) X 0.00 Y -50.98 Z 238.73 α 110.52 β 0.00 γ 0.00.

FIG. 18 shows the lateral aberration of Example 1 above. In this lateral aberration diagram, the numbers shown in parentheses represent (horizontal angle of view, vertical angle of view) and the lateral aberration at that angle of view.

As the decentered prism optical system used in the relay optical system of the projection display apparatus of the present invention, the type used in Examples 1 to 4 and the type having the number of internal reflections 2 to 3 shown in FIG. The present invention is not limited to the above prism, and an optical system including another type of decentered prism alone or a combination of these decentered prisms can be used.

The above-described optical element of the present invention and an optical device using the same can be constructed as follows, for example.

[1] In an optical element having at least two optical action surfaces, one of the optical action surfaces is a rotationally asymmetric surface, and the other optical action surface is a Fresnel surface. And optical element.

[2] The optical element as described in the above item 1, wherein the Fresnel surface is a rotationally symmetric Fresnel surface.

[3] The above-mentioned at least two optical action surfaces have at least a transmission action.
Alternatively, the optical element according to the item 2.

[4] The optical element according to the above 1 or 2, wherein one of the at least two optical action surfaces has at least a reflection action.

[5] Of the at least two optically active surfaces, the surface having the transmissive effect is constituted by a rotationally asymmetric surface,
5. The optical element according to any one of 1 to 4 above, wherein the surface having a reflecting action is a Fresnel surface.

[6] Among the at least two optically active surfaces, the surface having a transmissive effect is a Fresnel surface and the surface having a reflective effect is a rotationally asymmetric surface. The optical element according to any one of 1.

[7] An image enlarging optical device using the optical element described in any one of 1 to 6 above.

[8] An image display device characterized in that the optical element described in any one of the above items 1 to 6 has a positive power and is used together with a relay optical system for enlarging an image.

[0110]

[9] A display element for displaying an image or an intermediate image thereof, a relay optical system for projecting the image or the intermediate image displayed on the display element, and a light flux from the relay optical system is converged toward an eyeball of an observer. A projection-type optical device comprising an eyepiece optical system having a converging action, wherein the eyepiece optical system has at least one free-form surface and at least one Fresnel reflecting surface.

[10] When EXPe is the axial distance between the exit pupil position of the eyepiece optical system and the exit pupil side surface of the eyepiece optical system, the conditional expression is 80 mm <EXPe <1000 mm (1) 10. The projection type optical device described in 9 above, characterized in that

[11] The decentering direction of the entire optical system is the Y direction,
When the direction orthogonal to them is the X direction, the powers of the eyepiece optical system in the X and Y directions are Px3 and Py, respectively.
3. The power of the relay optical system in the X and Y directions is PP
When x and PPy, 0 <| Px3 / PPx | <2 ... (2) 0 <| Py3 / PPy | <2 ... (3) At least one of the conditions is satisfied. 11. The projection optical device according to 9 or 10 above.

[12] Let the decentering direction of all optical systems be the Y direction,
When the direction orthogonal to them is the X direction, the power in the X direction of the entire projection optical system is Px, and the power in the Y direction is Py, 0.5 <Px / Py <1.8 ( 4) The projection optical apparatus according to any one of 9 to 11 above, wherein at least one of the following conditions is satisfied.

[13] The decentering direction of all optical systems is the Y direction,
When the direction orthogonal to them is the X direction, the power in the X direction of the entire projection optical system is Px, the power in the Y direction is Py, and the powers in the X and Y directions of the eyepiece optical system are Px3 and Py3, respectively. , 0.01 <| Px3 / Px | <1.0 (5) 0.01 <| Py3 / Py | <1.0 (6) At least one of the conditions 13. The projection type optical device according to any one of 9 to 12 above, wherein

[14] The decentering direction of the entire optical system is the Y direction,
When the direction orthogonal to them is the X direction, the power in the X direction of the entire projection optical system is Px, the power in the Y direction is Py, and the powers in the X and Y directions of the relay optical system are PP.
When x and PPy, at least any one of the following conditions: 0.5 <| PPx / Px | <10.0 (7) 0.5 <| PPy / Py | <10.0 (8) 14. The projection optical apparatus according to any one of 9 to 13 above, characterized in that either one of the above is satisfied.

[15] The relay optical system is formed of a medium having a refractive index (n) larger than 1 (n> 1), and an incident surface on which the light flux emitted from the display element is incident into the prism, An eccentric prism having at least one reflecting surface that reflects the light flux inside the prism and an exit surface that emits the light flux outside the prism, and the at least one reflecting surface has a curved surface shape that gives power to the light flux, or 14. The projection optical apparatus according to any one of 9 to 13 above, which is provided with a plurality.

[16] The decentered prism has two reflecting surfaces, is composed of an entrance surface, a first reflecting surface, a second reflecting surface and an exit surface, and an optical path connecting the entering surface and the first reflecting surface is the second. 16. The projection-type optical device according to the above 15, wherein the optical path connecting the reflecting surface and the exit surface intersects in the prism.

[17] The decentered prism is provided with three reflecting surfaces, and the third reflecting surface of the decentering prism is formed as a surface which also serves as an incident surface on which light from the display element is made incident.
16. The projection type optical device according to the above 15, wherein the reflecting surface is formed as a surface which also serves as an exit surface.

[18] The projection according to the above item 15, characterized in that the decentered prism has two reflecting surfaces and comprises an entrance surface, a first reflecting surface which also serves as an exit surface, and a second reflecting surface. Type optical device.

[19] The projection according to the above item 15, characterized in that the decentering prism comprises two reflecting surfaces and is composed of a second reflecting surface also serving as an entrance surface, a first reflecting surface, and an exit surface. Type optical device.

[20] The projection type optical device described in any one of the above items 9 to 19, wherein the eyepiece optical system has a diffusive property.

[21] At least one eyepiece optical system
21. The projection type optical device according to any one of 9 to 20 above, which has a diffusivity in a dimension direction.

[22] The projection optical apparatus according to any one of 9 to 21 above, wherein the eyepiece optical system has diffusivity centering on two different directions.

[23] The projection optical apparatus according to any one of the above 9 to 21, wherein an intermediate image formed by the relay optical system is formed in the vicinity of the eyepiece optical system.

[24] Two display elements are provided, and two relay optical systems corresponding to the respective display elements are provided.
24. The projection optical apparatus according to any one of 9 to 23 above, further comprising the eyepiece optical system common to the two relay optical systems.

[25] The projection optical apparatus according to any one of the above items 9 to 24, wherein the eyepiece optical system is configured to be retractable from the optical path so that it can be used as a projector.

[26] The projection optical apparatus according to any one of items 9 to 25, wherein the position of the display element with respect to the relay optical system is adjustable.

[27] A light source for illuminating the display element, and an external light beam device attachable / detachable to / from the main body of the projection type optical device.
The projection type optical device according to any one of 1.

[0129]

As is apparent from the above description, according to the present invention, it becomes possible to provide an optical element which is small in size, is easy to manufacture, and is capable of correcting decentering aberrations. By using this optical element,
It is possible to configure an optical device such as a portable display device that is small in size, consumes less power, is inexpensive, and can obtain a good magnified image.

[Brief description of drawings]

FIG. 1 is a diagram for explaining one usage pattern of a projection display device according to the present invention.

FIG. 2 is a diagram for explaining another usage pattern of the projection display apparatus according to the present invention.

FIG. 3 is a diagram for explaining the scattering property of the eyepiece optical system of the projection display device of the present invention.

FIG. 4 is a diagram corresponding to FIG. 3 in the case where the scattering property is large.

FIG. 5 is a diagram showing a projection display device of the present invention in which the scattering range of the eyepiece optical system is larger than the vertical direction with respect to the horizontal direction corresponding to both eyes of an observer.

FIG. 6 is a diagram showing a projection display device of the present invention when a light beam emitted from a relay optical system is divided into two and goes to both eyes of an observer.

FIG. 7 is a diagram for explaining a configuration in which the projection display device of the present invention can be used as a projector.

FIG. 8 is a diagram for explaining the projection display device of the present invention in which an external light source device can be used.

FIG. 9 is a diagram for explaining the projection display device of the present invention in which a stereoscopic image is observed using two relay optical systems.

FIG. 10 is a diagram for explaining a case where the projection display device of the present invention is configured in the form of a handheld viewer type.

FIG. 11 is a diagram for explaining the projection display device of the present invention in which the support member of the relay optical system also serves as the protective cover of the eyepiece optical system.

FIG. 12 is a schematic sectional view of a possible form of an optical element according to the present invention.

FIG. 13 is a schematic diagram for explaining a Fresnel surface used in the present invention.

FIG. 14 is an optical path diagram of the entire optical system of Example 1 of the present invention.

FIG. 15 is an enlarged optical path diagram in which the optical path leading to the exit pupil of the optical system of Example 1 of the present invention is omitted.

FIG. 16 is an optical path diagram of the entire optical system of Example 3 of the present invention.

FIG. 17 is an enlarged optical path diagram in which an optical path leading to the exit pupil of the optical system of Example 3 of the present invention is omitted.

18 is a lateral aberration diagram for the optical system according to Example 1. FIG.

FIG. 19 is a diagram showing some examples of decentering prisms that can be used in the relay optical system of the projection optical apparatus according to the present invention.

[Explanation of symbols]

1 ... Exit pupil (observer's pupil) 2 ... axial chief ray 3 ... Display element 10 ... Decentered prism 11 ... First side 12 ... Second surface 13 ... Third side 14 ... Fourth surface 20 ... Optical element 21 ... Surface of incident side of optical element 22 ... Surface on the back side of the optical element 30 ... Display device main body 31, 31L, 32R ... Relay optical system 32 ... Eyepiece optical system 33 ... Operation button 34 ... Optical element having reflection action 35 ... Optical element having transmissive action 36 ... Reflecting mirror (flat mirror) 37 ... Built-in light source 38 ... External light source device 39 ... External light source 42 ... Support member for relay optical system 51 ... Incident light 52 ... scattered light 53 ... Range of scattering 54 ... Wall surface 60 ... Fresnel surface 61 ... Rotationally symmetric Fresnel transparent surface 62 ... Rotationally asymmetric transparent surface 63, 65, 67 ... Optical element 64 ... Reflective surface with rotationally asymmetric shape 66 ... Rotationally symmetric Fresnel reflecting surface E ... Eyeball position of observer

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Claims (3)

[Claims] 1. An optical element having at least two optically active surfaces, one of which is a rotationally asymmetric surface, and the other optically active surface is a Fresnel surface. Optical element to do. 2. The image display device according to claim 1, wherein the optical element has a positive power and is used together with a relay optical system for magnifying an image. 3. A display element for displaying an image or an intermediate image thereof, a relay optical system for projecting the image or the intermediate image displayed on the display element, and a light flux from the relay optical system toward an eyeball of an observer. A projection-type optical device comprising: an eyepiece optical system having a converging action for converging, the eyepiece optical system having at least one free-form surface and at least one Fresnel reflecting surface.