JP2003222819A - Display optical system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized, bright display optical system capable of displaying an image of high resolution by using a reflection type image display element as an image display element. <P>SOLUTION: The display optical system is constituted of the reflection type display element 3 for displaying the image, an illuminating light source 5 for illuminating the reflection type display element 3, an illumination optical system for guiding the light emitted from the illuminating light source 5 to the reflection type display element 3, a relay optical system 21 for projecting the image displayed on the reflection type display element 3, and an eyepiece optical system 22 having a convergence work of converging the luminous flux from the relay optical system 21 toward observer's eyeball 1, and an image projected by the relay optical system 21 is formed near the eyepiece optical system 22. <P>COPYRIGHT: (C)2003,JPO

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, and more particularly to an optical system for a display device which uses a reflective display element and is small in size and portable in power consumption.

[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 applicant
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.

Furthermore, the applicant of the present invention has filed Japanese Patent Application No. 2001-66.
In 669, a small size in which an image displayed on a display element or an intermediate image thereof is projected by a relay optical system including a decentered prism optical system, and a light flux from the relay optical system is converged toward an eyeball of an observer by an eyepiece optical system. Has proposed a low power consumption display device. In this display device, a relay optical system projects a projected image in the vicinity of an eyepiece optical system, and an exit pupil of the relay optical system is projected on an observer's eyeball.

By the way, the reflection type liquid crystal display element has a large aperture ratio because the drive circuit such as wiring and electrodes in the transmission type liquid crystal display element can be arranged on the back surface. high. Therefore, it is possible to provide a display device with a bright image, easy densification, and high pixel count. In addition, as a reflective display element, DMD
(Digital Micromirror Device), and brighter display devices are also provided.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In a display device that projects a projection image in the vicinity of an eyepiece optical system with a relay optical system and projects the exit pupil of the relay optical system onto an observer's eye, proposed in 66669, a transmissive display element is used as a display element. Therefore, it requires an additional illumination optical system, and it is difficult to say that the size has always been sufficiently reduced.

The present invention has been made in view of such a situation of the prior art, and its object is to observe an image by directing a relay optical system and a light beam from the relay optical system toward an observer's eye by an eyepiece optical system. In a small size and low power consumption optical system for a display device, a reflective image display element is used as an image display element so that a bright, compact, and high-resolution image can be displayed.

[0009]

A display optical system according to the present invention which achieves the above object, comprises a reflective display element for displaying an image,
An illumination light source that illuminates the reflective display element, an illumination optical system that guides the light of the illumination light source to the reflective display element, a relay optical system that projects an image displayed on the reflective display element, and the relay. The eyepiece optical system having a converging action of converging the light flux from the optical system toward the eyeball of the observer, and the projection image by the relay optical system is formed in the vicinity of the eyepiece optical system. It is a thing.

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

Since small display elements have good productivity,
It is possible to obtain high-pixel ones at low cost. If possible, it is desirable to use a display element having a diagonal length of a display image of 1 inch or less, and it is more preferable to use a display element of 0.5 inch or less when constructing an inexpensive display device. Become.

When such a small display element is used, the enlargement magnification is insufficient only by enlarging with an optical system such as a magnifying glass, and it is not possible to observe as a sufficiently large image. Therefore, the relay optical system has a function of once enlarging and projecting the image of the display element, further enlarging the image projected by the relay optical system by the eyepiece optical system, and at the same time converging the light flux from the relay optical system to the observer's eyeball. It is important to construct with an eyepiece optical system.

In this case, by enlarging and projecting the image displayed on the display element in the vicinity of the eyepiece optical system,
It is possible to configure a compact and high-performance display optical system.

Further, by using the reflective display element as the display element, the transmissive display element in which the drive circuits such as wirings and electrodes are arranged in the display surface can be arranged in the back surface. The aperture ratio per pixel becomes large. Therefore, it is possible to provide a display device which has a bright image, facilitates high density, and has a large number of pixels.

Further, it is possible to provide an image with a higher number of pixels by causing the illumination light source to emit light in a frame sequential manner and synchronizing it with the image on the reflective display element.

In this case, the relay optical system is provided with at least one reflecting surface, and the reflecting surface has a curved surface shape for giving power to the luminous flux, and is a rotationally asymmetric curved reflecting surface having a decentering aberration correcting function. It is desirable to use the constructed decentered prism optical system.

A reflective optical element such as a mirror or a prism does not cause chromatic aberration in principle even if its reflecting surface has power, and another optical element is added only for the purpose of correcting chromatic aberration. No need. 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, the optical system itself can be made smaller than the refraction optical system.

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 reflection surface which are refracting surfaces, and has a greater degree of freedom in aberration correction than a mirror having only a reflection 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 display optical system is required to have good image forming performance not only in the center 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.

According to the present invention, an incident surface on which the light beam emitted from the display element is made incident on the prism, at least one reflecting surface for reflecting the light beam on the prism, and an emission surface for emitting the light beam to the outside of the prism. A prism member having at least one reflecting surface, which has a curved surface shape for giving power to a light beam, and the curved surface shape is constituted by a rotationally asymmetric surface shape for correcting an aberration generated by decentering, By correcting the eccentric aberration, it is possible to satisfactorily correct not only the center but also the off-axis aberration.

The rotationally asymmetric curved surface shape is not limited, but it is preferable to use a free curved surface. The free-form surface is, for example, the free-form surface defined by the equation (a) of US Pat. No. 6,124,989 (Japanese Patent Laid-Open No. 2000-66105), and the Z axis of the defining expression is the axis of the free-form surface.

For the above reason, the present invention uses the decentered prism optical system using the prism member as the relay optical system, and enlarges and projects the image displayed on the display element in the vicinity of the eyepiece optical system. It becomes possible to construct a compact and high-performance relay optical system.

In this case, the light flux which forms the primary image projected by the relay optical system forms the 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. If the eyepiece optical system does not have this converging action, the light flux forming the primary image reaches the observer while diverging, so that the light flux incident on the eyeball and recognized as an image is a light beam emitted from the display element. It becomes a very small part of the luminous flux in the sky, and only a very dark image can be observed.

With the above construction, the luminous flux emitted from the reflection type display element and passing through the relay optical system can be effectively gathered to the observer's eyeball, so that the display with good illumination efficiency can be obtained and at the same time in the train or the like. There is no need to worry about the display being viewed by a neighbor.

In such a configuration, the illumination optical system that guides the light from the illumination light source to the reflective display element may share at least one optical surface of the decentered prism optical system of the relay optical system. desirable.

By sharing at least one optical surface of the decentered prism optical system of the relay optical system with the illumination optical system, the number of parts can be reduced.
Since each optical path can use the same area redundantly,
It is desirable that the display optical system can be downsized.

When the inclination angle of the axial principal ray emitted from the reflective display element from the normal line passing through the center of the display surface of the reflective display element is θ, the following conditional expression (1) is satisfied. It is desirable to do.

0 ° ≦ θ <45 ° (1) When this angle becomes larger than the upper limit of 45 ° of the conditional expression (1), the effective viewing angle of the reflective display element is exceeded. A normal image cannot be obtained due to inversion of brightness or contrast.

More preferably,     0 ° ≦ θ <30 ° (1-1) It is desirable to satisfy     0 ° ≦ θ <20 ° (1-2) It is more desirable to satisfy.

In Example 1 described later, θ = 1
2.6 °, θ = 13.4 ° in the second embodiment, θ = 2.3 ° in the third embodiment, and θ = 2.3 ° in the third embodiment.
θ = 5.4 °.

If the decentered prism optical system of the relay optical system has a symmetric surface, it is preferable in terms of manufacturing and assembling such as prism processing and alignment of each member, which is preferable.

The decentered prism optical system may not have a plane of symmetry. In this case, in particular, since the incident direction of the illumination light on the decentered prism optical system can be freely set, the display optical system can be further downsized, which is advantageous for aberration correction.

In that case, a reflection type display of the decentered prism optical system, in which a central ray of the illumination light flux, which is a light ray in the illumination light flux from the illumination light source and reaches the center of the display surface, is used as the illumination light optical axis. The illumination light optical axis incident on the first reflecting surface counting from the element in the order in which the projection light rays pass is included in the plane passing through the principal ray on the projection optical axis reflected by the first reflecting surface and the center of the display surface. It is desirable to arrange the illumination light source so that it does not occur.

The meaning of such an optical axis of illumination light is that the decentered prism optical system configured as a relay optical system has the decentering direction of its reflecting surface reflected by the reflecting surface, except in the case of a special decentering structure. The direction of a plane passing through the principal ray on the projection optical axis and the center of the display surface. If the illumination light optical axis incident on the reflecting surface exists in this surface, the effective surface in the decentering direction of the reflecting surface must be made large for the illumination light path and the projection light path, and the decentering prism optical system is large. Or
Or, part of the light flux will be vignetting,
Bright and uniform projection becomes difficult.

On the other hand, the illumination light optical axis incident on the first reflecting surface is not included in the plane passing through the principal ray on the projection optical axis reflected by the reflecting surface and the center of the display surface. In this case, the effective surface direction of the reflecting surface, which must be made larger for the illumination light path and the projection light path, is generally the direction intersecting the decentering direction, which does not lead to an increase in size of the decentering prism optical system.

With this arrangement, when the refracting surface on which the illumination light beam enters the decentered prism optical system and the reflecting surface on which the projection light beam reflects near the refracting surface are common surfaces, the common surface It is not necessary to form the reflecting surface with a half mirror, and bright display is possible.

Next, it is preferable that the eyepiece optical system is composed of an optical element having a Fresnel surface because it can be made thin and lightweight. The Fresnel surface may be a reflective surface or a transmissive surface. The optical element whose Fresnel surface is a reflecting surface is a Fresnel reflecting mirror, and the optical element whose Fresnel surface is a transmitting surface is a Fresnel lens.

When the Fresnel surface is a rotationally symmetric surface, it is easy to manufacture. Further, when the Fresnel surface is a free-form surface, it is desirable that distortion and the like due to eccentricity can be corrected.

Further, in the decentered prism optical system of the relay optical system, for example, a half mirror or a polarization beam splitter can be used as the shared surface that has both the reflecting function of the projection optical path and the transmitting function of the illumination optical path.

Further, it is desirable to use the total reflection effect for the reflecting action on the common surface that has both the reflecting action of the projection optical path and the transmitting action of the illumination optical path, because the loss of the illumination light and the projection light can be reduced. .

If the effective diameter of the illumination light beam and the effective diameter of the projection light beam are arranged so as not to overlap each other on the shared surface that has both the reflection function of the projection optical path and the transmission function of the illumination optical path, a reflection area is formed on the shared surface. Separating the transmissive region is desirable because it can reduce the loss of illumination light and projection light.

Further, when the illumination light source is arranged in the vicinity of a position optically conjugate with the exit pupil of the display optical system, an image of the illumination light source is generated at the exit pupil position of the display optical system, which results in Koehler illumination and uniform brightness. It is preferable because it can be observed.

Furthermore, if the pupil position of the relay optical system is inside the decentered prism optical system, the effective diameter of the reflecting surface will be small, and the amount of decentering aberration generated there will be small, which is preferable in terms of optical performance.

In the present invention, as the decentering prism optical system used in the relay optical system, various decentering prisms having a number of internal reflections of 1 or more have been proposed by the present inventors, or decentering prisms composed of a plurality of decentering prisms. An optical system can be used. Among them, as a typical example, as in the decentering prisms of Examples 1 to 4 described later, two reflecting surfaces are provided, and the incident surface of the projection light beam, the first reflecting surface, and the second reflecting surface are provided.
An optical path consisting of a reflecting surface and an exit surface of the projection light ray, which connects the incident surface and the first reflecting surface intersects with an optical path connecting the second reflecting surface and the exit surface in the prism (in the case of a decentered prism having no symmetrical surface). Can be used as the optical path in the prism when one optical path is projected on a surface including the other optical path.

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.

[0048]

BEST MODE FOR CARRYING OUT THE INVENTION The display optical system of the present invention will be described below based on examples.

First of all, as shown in FIGS. 1 to 3, the way of obtaining the coordinates in the following embodiments is as follows: From the exit pupil 1 (observer's pupil) position of the display optical system 20 through the reflection type display element 3 to the illumination light source. In the backward ray tracing toward 5, the projection optical axis 2 is defined by a ray that passes through the center of the exit pupil 1 of the display optical system 20 vertically and reaches the center of the reflective display element 3. In addition, the illumination light optical axis 4 is similarly traced by the backward ray tracing from the center of the reflective display element 3 to the illumination light source 5.
It is defined by the ray reaching the center of.

In the backward ray tracing, the center of the exit pupil 1 is set as the origin of the decentered optical surface of the decentered optical system, and the final surface facing the exit pupil 1 of the display optical system 20 (FIGS.
In FIG. 3, the projection optical axis 2 is projected onto the exit surface 31) of the eyepiece optical system 22.
Is the Z-axis positive direction, the plane of FIG. 1 is the YZ plane, the origin is orthogonal to the YZ plane, and the direction from the front to the back of the paper of FIG. 1 is the X-axis positive direction. An axis forming a right-handed orthogonal coordinate system with the X axis and the Z axis is defined as a Y axis.

Example 1 In this example, the viewing angle of view is horizontal 20 °, vertical 15 °, the exit pupil diameter is φ10 mm, and the distance from the exit pupil 1 which is the observer's eyeball position to the image formed by the relay optical system 21 is: Four
The reflective display element 3 having a size of 0 cm and a length of 3.9 × 2.9 mm is used.

FIG. 1 is a sectional view taken along the YZ plane of the whole from the exit pupil 1 of this embodiment to the display optical system 20 (however, the eccentric prism 1 from the illumination light source 5 to the relay optical system 21).
The illumination optical path leading to 0 is omitted. ), FIG. 2 is a partially enlarged view of the display optical system 20 portion in FIG. 1, and FIG. 3 is a projection optical path diagram of the display optical system 20 portion on the XZ plane.

The display optical system 20 of this embodiment is an embodiment in which the decentering prism 10 which constitutes the relay optical system 21 has the YZ plane as a symmetric surface, and in the order of the backward ray tracing from the exit pupil 1 side. Fresnel reflector 30 forming the eyepiece optical system 22 and decentering prism 1 forming the relay optical system 21.
0, the reflective display element 3 facing the first surface 11 of the decentering prism 10, the illumination light introducing transparent body 15 and the illumination light introducing transparent body bonded to a part of the third surface 13 of the decentering prism 10. It is composed of an illumination light source 5 arranged facing 15
In the Fresnel reflecting mirror 30, the refracting surface 31 on the exit pupil 1 side is a free-form surface, and the Fresnel reflecting surface on the back surface 32 is a rotationally symmetric aspherical surface. The eccentric prism 10 includes a first surface 11 which is an incident surface facing the reflective display element 3, and a second surface 12 and a second surface 12 which are first reflecting surfaces that reflect the display light that has entered the prism from the first surface 11. The third surface 13 of the second reflection surface that reflects the display light reflected by the third surface 13 and the fourth surface 14 that is the exit surface that emits the display light reflected by the third surface 13 out of the prism. The projection light optical axis 2 extending from the second surface 12 to the second surface 12 intersects the projection light optical axis 2 extending from the third surface 13 to the fourth surface 14 in the prism.

An illuminating light introducing transparent body 15 is integrally bonded to a part of the third surface 13 of the decentering prism 10.
A surface 16 of the illuminating light introducing transparent body 15 facing the illuminating light source 5 is a Fresnel transmitting surface formed of a spherical surface.

In such an arrangement, the illumination light emitted from the illumination light source 5 passes through the Fresnel transmitting surface 16 of the illumination light introducing transparent body 15, passes through the illumination light introducing transparent body 15, and passes through the third surface 13 of the eccentric prism 10. After entering the decentered prism 10 through the portion where the reflective layer is not provided, the light is reflected by the first reflective surface 12,
The reflective display element 3 is illuminated from the first surface 11 outside the prism. The regular reflection light from the reflective display element 3 which is modulated according to the display state of the reflective display element 3 is the decentered prism 1
0 enters the prism from the first surface 11, is reflected in order by the second surface 12 and the third surface 13 and exits from the fourth surface 14, and the positive power of the eccentric prism 10 causes the Fresnel reflecting mirror 30.
A display image of the reflective display element 3 is formed in the vicinity of the Fresnel reflection surface 32. Then, the image of the exit pupil of the decentering prism 10 is formed on the exit pupil 1 by the positive power of the Fresnel reflecting mirror 30 of the eyepiece optical system 22. Since the power of the optical system between the exit pupil of the decentering prism 10 and the illumination light source 5 is set to be conjugate, the exit pupil 1 and the illumination light source 5 are also in a conjugate relationship. Therefore, since all the light emitted from the illumination light source 5 and modulated by the reflective display element 3 is converged on the exit pupil 1, a bright image can be observed with a small power consumption.

In this embodiment, the decentered prism 10
The first surface 11 is shared as a transmission surface of the illumination optical system and the relay optical system, the second surface 12 is also shared as a reflection surface of the illumination optical system and the relay optical system, and the third surface 13 is illuminated. The light transmission region and the projection light reflection region are separated in the direction of the symmetry plane (YZ plane) of the decentering prism 10 to form a shared surface that serves both as a transmission surface and a reflection surface.

Then, from the illumination light source 5 to the reflection type display element 3
From the reflection type display element 3 to the exit pupil 1
The optical axis 2 of the projection light that reaches the point exists in the YZ plane of the symmetry plane.

Each of the surfaces 11 to 14 of the decentering prism 10 of this embodiment is a decentered free-form surface.

The constituent parameters of the display optical system 20 of this embodiment will be described later.

Example 2 In this example, the viewing angle of view is horizontal 20 °, vertical 15 °, exit pupil diameter φ10 mm, and the distance from the exit pupil 1 which is the observer's eyeball position to the image formed by the relay optical system 21. Four
The reflective display element 3 having a size of 0 cm and a length of 3.9 × 2.9 mm is used. In this embodiment, the eccentricity is given to the third surface 13 of the eccentric prism 10 by giving the eccentricity also in the direction perpendicular to the symmetry plane of the eccentric prism 10 in the first embodiment, that is, by giving the eccentricity three-dimensionally. This is an example in which the effective diameter of the luminous flux and the effective diameter of the luminous flux of the projection light are separated in the direction perpendicular to the plane of symmetry, so that the third surface 13 is a shared surface that also serves as a transmission surface and a reflection surface.

FIG. 4 is a projection optical path diagram for the entire YZ plane from the exit pupil 1 of this embodiment to the display optical system 20 (however, the eccentric prism 1 from the illumination light source 5 to the relay optical system 21).
The illumination optical path leading to 0 is omitted. ), FIG. 5 is a partially enlarged view of the display optical system 20 portion in FIG. 4, and FIG. 6 is a projection optical path diagram of the display optical system 20 portion on the XZ plane.

The display optical system 20 of this embodiment is an embodiment in which the decentering prism 10 which constitutes the relay optical system 21 does not have a plane of symmetry, and the eyepiece optical system 22 is in the order of backward ray tracing from the exit pupil 1 side. Of the Fresnel reflecting mirror 30 constituting the above, the decentering prism 10 constituting the relay optical system 21, the reflection type display element 3 arranged facing the first surface 11 of the decentering prism 10, and the third surface 13 of the decentering prism 10. The Fresnel reflecting mirror 30 has a refracting surface 31 on the exit pupil 1 side as a free-form surface. And the Fresnel reflecting surface of the back surface 32 is a rotationally symmetric aspherical surface. The eccentric prism 10 includes a reflective display element 3
The first surface 11 of the incident surface facing the first surface, and the second surface 1 of the first reflecting surface for reflecting the display light incident on the prism from the first surface 11
2, the third surface 13 of the second reflecting surface that reflects the display light reflected by the second surface 12, and the fourth surface 14 of the exit surface that emits the display light reflected by the third surface 13 out of the prism Becomes
The projection optical axis 2 from the first surface 11 to the second surface 12 and the projection optical axis 2 from the third surface 13 to the fourth surface 14 project the other optical axis on a surface including one optical axis. When it does, it is configured to intersect within the prism.

An illuminating light introducing transparent body 15 is integrally bonded to a part of the third surface 13 of the decentering prism 10.
A surface 16 of the illuminating light introducing transparent body 15 facing the illuminating light source 5 is a Fresnel transmitting surface formed of a spherical surface.

In such an arrangement, the illumination light emitted from the illumination light source 5 passes through the Fresnel transmitting surface 16 of the illumination light introducing transparent body 15, passes through the illumination light introducing transparent body 15, and passes through the third surface 13 of the decentering prism 10. After entering the decentered prism 10 through the portion where the reflective layer is not provided, the light is reflected by the first reflective surface 12,
The reflective display element 3 is illuminated from the first surface 11 outside the prism. The regular reflection light from the reflective display element 3 which is modulated according to the display state of the reflective display element 3 is the decentered prism 1
0 enters the prism from the first surface 11, is reflected in order by the second surface 12 and the third surface 13 and exits from the fourth surface 14, and the positive power of the eccentric prism 10 causes the Fresnel reflecting mirror 30.
A display image of the reflective display element 3 is formed in the vicinity of the Fresnel reflection surface 32. Then, the image of the exit pupil of the decentering prism 10 is formed on the exit pupil 1 by the positive power of the Fresnel reflecting mirror 30 of the eyepiece optical system 22. Since the power of the optical system between the exit pupil of the decentering prism 10 and the illumination light source 5 is set to be conjugate, the exit pupil 1 and the illumination light source 5 are also in a conjugate relationship. Therefore, since all the light emitted from the illumination light source 5 and modulated by the reflective display element 3 is converged on the exit pupil 1, a bright image can be observed with a small power consumption.

In this embodiment, the decentered prism 10
The first surface 11 is shared as a transmission surface of the illumination optical system and the relay optical system, the second surface 12 is also shared as a reflection surface of the illumination optical system and the relay optical system, and the third surface 13 is illuminated. By separating the light transmission region and the projection light reflection region in the direction perpendicular to the YZ plane of the decentering prism 10, the light transmission region and the projection light serve as a common surface that serves both as a transmission surface and a reflection surface.

In this embodiment, the illumination light optical axis 4 from the illumination light source 5 to the reflection type display element 3 and the projection light optical axis 2 from the reflection type display element 3 to the exit pupil 1 are in the same plane. It doesn't exist.

Each of the surfaces 11 to 14 of the decentering prism 10 of this embodiment is a decentered free-form surface.

The constituent parameters of the display optical system 20 of this embodiment will be described later.

Example 3 In this example, the viewing angle of view is horizontal 20 °, vertical 15 °, the exit pupil diameter is φ10 mm, and the distance from the exit pupil 1 which is the observer's eyeball position to the image formed by the relay optical system 21 is: Four
The reflective display element 3 having a size of 0 cm and a length of 3.9 × 2.9 mm is used. This example is an example in which the second surface 12 of the decentering prism 10 in Example 1 is shared as a reflecting surface of the relay optical system and a transmitting surface of the illumination optical system, and this surface is used as a half mirror or a polarization beam splitter. To do.

FIG. 7 is a sectional view taken along the YZ plane of the entire exit pupil 1 to the display optical system 20 of the present embodiment (however, the eccentric prism 1 from the illumination light source 5 to the relay optical system 21).
The illumination optical path leading to 0 is omitted. ), FIG. 8 is a partially enlarged view of the display optical system 20 portion in FIG. 7, and FIG. 9 is a projection optical path diagram of the display optical system 20 portion on the XZ plane.

The display optical system 20 of this embodiment is an embodiment in which the decentered prism 10 which constitutes the relay optical system 21 has the YZ plane as a symmetric surface, and the backward ray tracing is performed from the exit pupil 1 side in this order. Fresnel reflector 30 forming the eyepiece optical system 22 and decentering prism 1 forming the relay optical system 21.
0, the reflective display element 3 arranged facing the first surface 11 of the decentering prism 10, the illumination light introducing transparent body 15 and the illumination light introducing transparent body adhered to a part of the second surface 12 of the decentering prism 10. It is composed of an illumination light source 5 arranged facing 15
In the Fresnel reflecting mirror 30, the refracting surface 31 on the exit pupil 1 side is a free-form surface, and the Fresnel reflecting surface on the back surface 32 is a rotationally symmetric aspherical surface. The eccentric prism 10 includes a first surface 11 which is an incident surface facing the reflective display element 3, and a second surface 12 and a second surface 12 which are first reflecting surfaces that reflect the display light that has entered the prism from the first surface 11. The third surface 13 of the second reflection surface that reflects the display light reflected by the third surface 13 and the fourth surface 14 that is the exit surface that emits the display light reflected by the third surface 13 out of the prism. The projection light optical axis 2 extending from the second surface 12 to the second surface 12 intersects the projection light optical axis 2 extending from the third surface 13 to the fourth surface 14 in the prism.

An illumination light introducing transparent body 15 is integrally bonded to a part of the second surface 12 of the decentering prism 10.
A surface 16 of the illuminating light introducing transparent body 15 facing the illuminating light source 5 is a Fresnel transmitting surface formed of a spherical surface.

In such an arrangement, the illumination light emitted from the illumination light source 5 passes through the Fresnel transmitting surface 16 of the illumination light introducing transparent body 15, passes through the illumination light introducing transparent body 15, and passes through the second surface 12 of the decentering prism 10. For example, the light enters the decentered prism 10 through the portion provided with the half mirror, and exits the prism from the first surface 11 to illuminate the reflective display element 3. The specularly reflected light from the reflective display element 3 that is modulated according to the display state of the reflective display element 3 enters the prism from the first surface 11 of the decentering prism 10, and is reflected by the second surface 12 and the third surface 13. The light is reflected in order, goes out from the fourth surface 14, and the positive power of the decentering prism 10 causes the Fresnel reflecting surface 32 of the Fresnel reflecting mirror 30.
A display image of the reflective display element 3 is formed in the vicinity. And
The image of the exit pupil of the decentered prism 10 is formed on the exit pupil 1 by the positive power of the Fresnel reflecting mirror 30 of the eyepiece optical system 22.
Since the exit pupil of the decentering prism 10 is conjugate with the illumination light source 5, the power of the optical system therebetween is set,
The exit pupil 1 and the illumination light source 5 are also in a conjugate relationship. Therefore, since all the light emitted from the illumination light source 5 and modulated by the reflective display element 3 is converged on the exit pupil 1, a bright image can be observed with a small power consumption.

In this embodiment, the decentering prism 10
The first surface 11 is shared by the illumination optical system and the relay optical system, and the second surface 12 is shared by the illumination optical system and the relay optical system.

Then, from the illumination light source 5 to the reflection type display element 3
From the reflection type display element 3 to the exit pupil 1
The optical axis 2 of the projection light that reaches the point exists in the YZ plane of the symmetry plane.

The surfaces 11 to 14 of the decentering prism 10 of this embodiment are all decentered free-form surfaces.

The constituent parameters of the display optical system 20 of this embodiment will be described later.

Example 4 In this example, the viewing angle of view is horizontal 20 °, vertical 15 °, exit pupil diameter φ10 mm, and the distance from the exit pupil 1 which is the observer's eyeball position to the image imaged by the relay optical system 21. Four
The reflective display element 3 having a size of 0 cm and a length of 3.9 × 2.9 mm is used. In this embodiment, the eccentricity is given to the fourth surface 14 of the eccentric prism 10 by giving the eccentricity also in the direction perpendicular to the symmetry plane of the eccentric prism 10 in the first embodiment, that is, by giving the eccentricity three-dimensionally. In this example, the effective diameter of the luminous flux and the effective diameter of the luminous flux of the projection light are separated in the direction perpendicular to the plane of symmetry so that the fourth surface 14 is shared as the transmitting surface.

FIG. 10 is a projection optical path diagram for the entire YZ plane from the exit pupil 1 to the display optical system 20 of this embodiment (however, the decentering prism 1 of the relay optical system 21 from the illumination light source 5).
The illumination optical path leading to 0 is omitted. ), FIG. 11 is a partially enlarged view of the display optical system 20 portion of FIG. 10, and FIG. 12 is a projection optical path diagram of the display optical system 20 portion on the XZ plane.

The display optical system 20 of this embodiment is an embodiment in which the decentering prism 10 constituting the relay optical system 21 does not have a plane of symmetry, and the eyepiece optical system 22 is in the order of backward ray tracing from the exit pupil 1 side. Of the Fresnel reflecting mirror 30, the decentering prism 10 forming the relay optical system 21, the reflective display element 3 arranged facing the first surface 11 of the decentering prism 10, and the fourth surface 14 of the decentering prism 10. The Fresnel reflecting mirror 30 has a refracting surface 31 on the exit pupil 1 side as a free-form surface. And the Fresnel reflecting surface of the back surface 32 is a rotationally symmetric aspherical surface. The eccentric prism 10 includes a reflective display element 3
The first surface 11 of the incident surface facing the first surface, and the second surface 1 of the first reflecting surface for reflecting the display light incident on the prism from the first surface 11
2, the third surface 13 of the second reflecting surface that reflects the display light reflected by the second surface 12, and the fourth surface 14 of the exit surface that emits the display light reflected by the third surface 13 out of the prism Becomes
The projection optical axis 2 from the first surface 11 to the second surface 12 and the projection optical axis 2 from the third surface 13 to the fourth surface 14 project the other optical axis on a surface including one optical axis. When it does, it is configured to intersect within the prism.

An illuminating light introducing transparent body 15 is integrally bonded to a part of the fourth surface 14 of the decentering prism 10.
A surface 16 of the illuminating light introducing transparent body 15 facing the illuminating light source 5 is a Fresnel transmitting surface formed of a spherical surface.

In such an arrangement, the illumination light emitted from the illumination light source 5 passes through the Fresnel transmitting surface 16 of the illumination light introducing transparent body 15, passes through the illumination light introducing transparent body 15, and passes through the fourth surface 14 of the decentering prism 10. After passing through a part, it enters the decentered prism 10 and is reflected in the order of the second reflecting surface 13 and the first reflecting surface 12,
The reflective display element 3 is illuminated from the first surface 11 outside the prism. The regular reflection light from the reflective display element 3 which is modulated according to the display state of the reflective display element 3 is the decentered prism 1
0 enters the prism from the first surface 11, is reflected in order by the second surface 12 and the third surface 13 and exits from the fourth surface 14, and the positive power of the eccentric prism 10 causes the Fresnel reflecting mirror 30.
A display image of the reflective display element 3 is formed in the vicinity of the Fresnel reflection surface 32. Then, the image of the exit pupil of the decentering prism 10 is formed on the exit pupil 1 by the positive power of the Fresnel reflecting mirror 30 of the eyepiece optical system 22. Since the power of the optical system between the exit pupil of the decentering prism 10 and the illumination light source 5 is set to be conjugate, the exit pupil 1 and the illumination light source 5 are also in a conjugate relationship. Therefore, since all the light emitted from the illumination light source 5 and modulated by the reflective display element 3 is converged on the exit pupil 1, a bright image can be observed with a small power consumption.

In this embodiment, the decentering prism 10
The first surface 11 is shared by the illumination optical system and the relay optical system, and the second surface 12 and the second surface 13 are also shared by the illumination optical system and the relay optical system. Surface 1
4 is shared as a transmission surface by separating the transmission area of the illumination light and the transmission area of the projection light in the direction perpendicular to the YZ plane of the eccentric prism 10.

In this embodiment, the illumination light optical axis 4 from the illumination light source 5 to the reflection type display element 3 and the projection light optical axis 2 from the reflection type display element 3 to the exit pupil 1 are in the same plane. It doesn't exist.

Each of the surfaces 11 to 14 of the decentering prism 10 of this embodiment is a decentered free-form surface.

The constituent parameters of the display optical system 20 of this embodiment will be described later.

Next, the display optical system 20 of Examples 1 to 4 above.
Shows the configuration parameters of. In the configuration parameters of each embodiment, as shown in FIGS. 1 to 3, the back ray tracing from the position of the exit pupil 1 (observer's pupil) of the display optical system 20 to the illumination light source 5 via the reflective display element 3, The projection light optical axis 2 is defined by a light ray that passes through the center of the exit pupil 1 of the display optical system 20 perpendicularly and reaches the center of the reflective display element 3. Similarly, the optical axis 4 of the illumination light is defined by the ray traced from the center of the reflective display element 3 to the center of the illumination light source 5 by backward ray tracing.

Then, in the backward ray tracing, the center of the exit pupil 1 is set as the origin of the decentered optical surface of the decentered optical system, and the final surface facing the exit pupil 1 of the display optical system 20 (FIGS.
In FIG. 3, the projection optical axis 2 is projected onto the exit surface 31) of the eyepiece optical system 22.
Is the Z-axis positive direction, the plane of FIG. 1 is the YZ plane, the origin is orthogonal to the YZ plane, and the direction from the front to the back of the paper of FIG. 1 is the X-axis positive direction. An axis forming a right-handed orthogonal coordinate system with the X axis and the Z axis is defined as a Y axis.

With respect to 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 central axis of the surface (for the free-form surface, the Z axis of the expression (a) in the cited document below).
The tilt angles (α, β, γ (°)) about the X axis, the Y axis, and the Z axis, respectively, 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. The rotation of α, β, γ of the center axis of the surface is performed by rotating the center axis of the surface and its XYZ orthogonal coordinate system by α counterclockwise around the X axis, and then rotating the same. The center axis of the surface is β counterclockwise around the Y axis of the new coordinate system.
The coordinate system that is rotated by 1 degree is also rotated counterclockwise by β around the Y axis, and then the center axis of the surface that is rotated by 2 degrees is rotated around the Z axis of the new coordinate system of the new coordinate system. It rotates by γ clockwise.

Further, among the optical action surfaces forming the optical system of each embodiment, when a specific surface and the surface following the specific surface form a coaxial optical system, a surface spacing is given, and other surfaces are given. The radius of curvature, the refractive index of the medium, and the Abbe number are given according to the conventional method.

The surface shape 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 concerning 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.

Numerical data of each of the above-mentioned examples 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 surface. Show. The object plane is the projected image plane of the relay optical system 21, and the image plane is the display plane of the reflective display element 3.

Example 1 Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object plane ∞ Eccentricity (1) 1 ∞ (pupil) 2 FFS Eccentricity (1) 1.5254 56.2 3 ASS (FR, RE) Eccentricity (2) 1.5254 56.2 4 FFS eccentricity (1) 5 FFS eccentricity (3) 1.5254 56.2 6 FFS (RE) eccentricity (4) 1.5254 56.2 7 FFS (RE) eccentricity (5) 1.5254 56.2 8 FFS eccentricity (6) image plane ∞ eccentricity (7) 10 FFS Eccentricity (6) 1.5254 56.2 11 FFS (RE) Eccentricity (5) 1.5254 56.2 12 FFS Eccentricity (4) 1.5254 56.2 13 3.37 (FR) Eccentricity (8) Light source ∞ Eccentricity (9) ASS R -201.20 K 4.6102 A 2.1348 × 10 ^-7 B -2.8210 × 10 ^-11 C 3.7292 × 10 ^-15 FFS C ₄ 1.5891 × 10 ^-3 C ₆ -1.0000 × 10 ^-3 C ₈ -4.8755 × 10 ^-5 C ₁₀ -4.6567 × 10 ^-5 C ₁₁ -3.6467 x 10 ^-7 C ₁₃ -4.1721 x 10 ^-7 FFS C ₄ -1.0260 x 10 ^-2 C ₆ -3.5937 x 10 ^-2 C ₈ -9.0101 x 10 ^-3 C ₁₀ -5.3472 x 10 ^-3 FFS C ₄ 1.1368 x 10 ^-2 C ₆ 7.588 1 x 10 ^-3 C ₈ -3.1294 x 10 ^-3 C ₁₀ -2.5324 x 10 ^-3 C ₁₁ 1.1681 x 10 ^-4 C ₁₃ -6.3376 x 10 ^-6 C ₁₅ -1.2382 x 10 ^-4 FFS C ₄ -1.8960 x 10 ^-2 C ₆ -8.3411 x 10 ^-3 C ₈ -4.0233 x 10 ^-3 C ₁₀ -4.1624 × 10 ^-3 C ₁₁ 2.4768 × 10 ^-4 C ₁₃ 8.5844 × 10 ^-4 C ₁₅ 4.460 2 × 10 ^-4 FFS C ₄ 5.2263 × 10 ^-2 C ₆ 6.0334 × 10 ^-2 C ₈ 9.6523 × 10 ^-3 C ₁₀ 6.3 677 × 10 ^-3 Eccentricity (1) X 0.00 Y 0.00 Z 400.00 α 0.00 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y -47.41 Z 402.00 α 0.00 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y -42.28 Z 349.62 α 12.54 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y -46.05 Z 343.02 α 49.62 β 0.00 γ 0.00 Eccentricity (5) X 0.00 Y -40.81 Z 344.98 α 95.96 β 0.00 γ 0.00 Eccentricity (6) X 0.00 Y -46.59 Z 348.65 α 130.36 β 0.00 γ 0.00 Eccentricity (7) X 0.00 Y -47.35 Z 349.06 α 129.74 β 0.00 γ 0.00 Eccentricity (8) X 0.00 Y -44.96 Z -59.23 α 66.19 β 0.00 γ 0.00 Eccentricity (9) X 0.00 Y- 45.87 Z -59.64 α 78.25 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 (1) 1.5254 56.2 3 ASS (FR, RE) Eccentricity (2) 1.5254 56.2 4 FFS eccentricity (1) 5 FFS eccentricity (3) 1.5254 56.2 6 FFS (RE) eccentricity (4) 1.5254 56.2 7 FFS (RE) eccentricity (5) 1.5254 56.2 8 FFS eccentricity (6) image plane ∞ eccentricity (7) 10 FFS eccentricity (6) 1.5254 56.2 11 FFS (RE) eccentricity (5) 1.5254 56.2 12 FFS eccentricity (4) 1.5254 56.2 13 10.37 (FR) eccentricity (8) light source ∞ eccentricity (9) ASS R -133.19 K 6.4555 × 10 ^-1 A 3.3841 x 10 ^-7 B -2.6319 x 10 ^-11 C 2.5165 x 10 ^-15 FFS C ₄ -1.9194 x 10 ^-4 C ₆ -1.0000 x 10 ^-3 C ₈ -3.2513 x 10 ^-6 C ₁₀ 7.2 414 x 10 ^-6 C ₁₁ 7.438 2 x 10 ^-8 C ₁₃ 1.8783 x 10 ^-7 FFS C ₄ 2.1 106 x 10 ^-2 C ₆ -5.3200 x 10 ^-2 C ₇ 3.7839 x 10 ^-4 C ₈ -6.9686 x 10 ^-3 C ₉ -1.1751 × 10 ^-5 C ₁₀ -2.7197 × 10 ^-3 FFS C ₄ 7.9 132 × 10 ^-3 C ₆ -2.0184 × 10 ^-2 C ₇ -1.6399 x 10 ^-4 C ₈ -2.3055 x 10 ^-3 C ₉ -7.4669 x 10 ^-4 C ₁₀ -1.9296 x 10 ^-3 C ₁₁ 2.8401 x 10 ^-4 C ₁₃ 3.0639 x 10 ^-4 C ₁₅ 5.0616 x 10 ^-5 FFS C ₄ -2.2791 x 10 ^-2 C ₆ -3.1161 x 10 ^-2 C ₇ -5.8291 x 10 ^-5 C ₈ -1.3962 x 10 ^-3 C ₉ -1.5979 x 10 ^-4 C ₁₀ -7.7693 × 10 ^-4 C ₁₁ 1.0836 × 10 ^-4 C ₁₃ 1.2384 × 10 ^-4 C ₁₅ 3.7512 × 10 ^-6 FFS C ₄ 2.6541 × 10 ^-2 C ₆ -2.9069 × 10 ^-2 C ₇ -7.5865 × 10 ^-4 C ₈ -1.8 137 × 10 ^-3 C ₉ -1.5343 × 10 ^-3 C ₁₀ 9.1238 × 10 ^-4 Eccentricity (1) X 0.00 Y 0.00 Z 400.00 α 0.00 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y -32.78 Z 402.00 α 0.00 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y -36.05 Z 357.04 α 18.27 β 0.30 γ 0.00 Eccentricity (4) X 0.02 Y -40.99 Z 349.09 α 55.65 β 3.11 γ 0.00 Eccentricity (5) X -0.75 Y -33.22 Z 350.52 α 95.68 β 2.50 γ 0.00 Eccentricity (6) X -0.87 Y -41.54 Z 353.83 α 119.99 β 11.82 γ 0.00 Eccentricity (7) X -1.02 Y -42.56 Z 354.15 α 119.83 β 5.32 γ -4.11 Eccentricity (8) X- 3.46 Y -40.60 Z -52.73 α 88.9 7 β -14.43 γ 0.00 Eccentricity (9) X -3.13 Y -41.74 Z -52.75 α 105.80 β 9.44 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 (1) 1.5254 56.2 3 ASS (FR, RE) Eccentricity (2) 1.5254 56.2 4 FFS eccentricity (1) 5 FFS eccentricity (3) 1.5254 56.2 6 FFS (RE) eccentricity (4) 1.5254 56.2 7 FFS (RE) eccentricity (5) 1.5254 56.2 8 FFS eccentricity (6) image plane ∞ eccentricity (7) 10 FFS eccentric (6) 1.5254 56.2 11 FFS eccentric (5) 1.5254 56.2 12 -4.17 ( FR) eccentric (8) light source ∞ eccentricity (9) ASS R -148.96 K 2.1285 A 2.8611 × 10 -7 B -1.5596 × 10 - ^{11 C 2.9945 × 10 -15 FFS C} 4 5.7142 × 10 -4 C 6 -1.0000 × 10 -3 C 8 -1.9170 × 10 -5 C 10 -7.0062 × 10 -6 C 11 -2.0543 × 10 -7 C 13 - 1.0578 × 10 ⁻⁷ FFS C ₄ 4.4129 × 10 ⁻² C ₆ −2.3084 × 10 ⁻² C ₈ −2.0324 × 10 ⁻² C ₁₀ −5.9502 × 10 ⁻³ FFS C ₄ 1.3264 × 10 ⁻² C ₆ 3.6547 × 10 ^-3 C ₈ -2.5516 x 10 ^-3 C ₁₀ -2.7908 x 10 ^-3 C ₁₁ -1.6791 x 10 ^-5 C ₁₃ -2.4067 x 10 ^-5 C ₁₅ -1.3790 x 10 ^-4 FFS C ₄ -1.8378 x 10 ^-2 C ₆ -1.0019 x 10 ^-2 C ₈ -1.8146 x 10 ^-3 C ₁₀ -1.6015 x 10 ^-3 C ₁₁ 3.0458 x 10 ^-5 C ₁₃ 1.1324 × 10 ^-4 C ₁₅ 1.2047 × 10 ^-4 FFS C ₄ 1.3484 × 10 ^-2 C ₆ 7.7581 × 10 ^-2 C ₈ 1.6390 × 10 ^-3 C ₁₀ -1.1533 × 10 ^-3 Eccentricity (1) X 0.00 Y 0.00 Z 400.00 α 0.00 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y -35.90 Z 402.00 α 0.00 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y -39.15 Z 353.34 α 36.66 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y -44.60 Z 346.47 α 55.53 β 0.00 γ 0.00 Eccentricity (5) X 0.00 Y -39.16 Z 348.17 α 105.86 β 0.00 γ 0.00 Eccentricity (6) X 0.00 Y -44.08 Z 353.84 α 128.13 β 0.00 γ 0.00 Eccentricity (7) X 0.00 Y- 45.68 Z 356.13 α 139.99 β 0.00 γ 0.00 Eccentricity (8) X 0.00 Y -37.92 Z -51.08 α 132.81 β 0.00 γ 0.00 Eccentricity (9) X 0.00 Y -35.93 Z -53.30 α 126.76 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 (1) 1.5254 56.2 3 ASS (FR, RE) Eccentricity (2) 1.5254 56.2 4 FFS eccentricity (1) 5 FFS eccentricity (3) 1.5254 56.2 6 FFS (RE) eccentricity (4) 1.5254 56.2 7 FFS (RE) eccentricity (5) 1.5254 56.2 8 FFS eccentricity (6) image plane ∞ eccentricity (7) 10 FFS eccentricity (6) 1.5254 56.2 11 FFS (RE) eccentricity (5) 1.5254 56.2 12 FFS (RE) eccentricity (4) 1.5254 56.2 13 FFS eccentricity (3) 1.5254 56.2 14 -6.69 (FR) eccentricity (8) light source ∞ Eccentricity (9) ASS R -199.86 K 2.6674 A 7.9237 × 10 ^-8 B -9.9684 × 10 ^-12 C 9.0846 × 10 ^-16 FFS C ₄ 1.7595 × 10 ^-3 C ₆ -1.0000 × 10 ^-3 C ₈ -6.2278 × 10 ^-5 C ₁₀ -5.9358 x 10 ^-5 C ₁₁ -5.6394 x 10 ^-7 C ₁₃ -7.2785 x 10 ^-8 FFS C ₄ 7.7494 x 10 ^-2 C ₆ 9.7789 x 10 ^-2 C ₈ -3.4926 x 10 ^{-3 _{FFS C 4 1.3745 × 10 -2 C}} 6 2.5221 × 10 -2 C 8 -8.6548 × 10 - ⁴ C ₁₀ -1.22 13 x 10 ^-4 C ₁₁ 1.1546 x 10 ^-5 FFS C ₄ -2.10 64 x 10 ^-2 C ₆ 2.0295 x 10 ^-3 C ₈ -5.2989 x 10 ^-4 C ₁₀ -4.5217 x 10 ^-4 C ₁₁ 1.3828 × 10 ^-6 FFS C ₄ -8.4997 × 10 ^-2 C ₆ -5.6269 × 10 ^-2 C ₈ 2.2737 × 10 ^-2 Eccentricity (1) X 0.00 Y 0.00 Z 400.00 α 0.00 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y -42.90 Z 402.00 α 0.00 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y -39.07 Z 353.43 α 21.32 β -4.91 γ 0.00 Eccentricity (4) X -0.24 Y -43.39 Z 346.79 α 58.48 β 1.17 γ 0.00 Eccentricity ( 5) X -0.63 Y -37.65 Z 347.39 α 108.20 β -8.02 γ 0.00 Eccentricity (6) X -3.54 Y -43.95 Z 353.43 α 142.72 β -5.56 γ 0.00 Eccentricity (7) X -4.17 Y -44.99 Z 354.25 α 130.03 β -10.18 γ 4.01 Eccentricity (8) X -2.85 Y -37.27 Z -44.92 α 31.59 β -6.87 γ 0.00 Eccentricity (9) X -2.63 Y -36.76 Z -44.09 α 36.23 β -4.55 γ 0.00.

The lateral aberrations of Examples 1 to 4 are shown in FIG.
3 to 16 are shown. In these lateral aberration diagrams, the numbers in parentheses represent (horizontal angle of view, vertical angle of view), and the lateral aberration at that angle of view.

By the way, the display device using the display optical system as exemplified in Examples 1 to 4 is, for example, shown in FIGS.
The present invention can be applied to the portable information terminal shown in FIG. 8 and the forms of mobile phones shown in FIGS. 19 and 20, and can provide a device which is inexpensive, consumes less power, and is extremely portable. it can.

FIG. 17 shows an example in which the eyepiece optical system 22 is composed of an optical element 34 such as a Fresnel reflecting mirror 30 having a reflecting action. In this case, it is desirable to dispose the operation button 41 on the main body 40 of the display device before the relay optical system 21 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 41. In addition, the relay optical system 2
By disposing No. 1 in front of the eyepiece optical system 22, it becomes possible to reasonably observe the image reflected by the eyepiece optical system 22. It should be noted that in FIG. 17, the observer's eyeball position is indicated by E, and the display image can be reasonably observed by matching both eyes or one eye E of the observer with the position of the exit pupil 1 of this display device. . Although the reflective display element 3 (FIGS. 1 to 12) is arranged on the main body 40 side of the relay optical system 21, the illustration is omitted.

Further, in the case of FIG. 18, the eyepiece optical system 22
With a mechanism that opens and closes from the main body 40, it can be stored in a pocket or the like when being carried. Also,
At this time, if the function of cutting off the power supply is added, the power saving effect is high.

Further, by opening and closing the observer side from the main body 40 in the opening and closing direction, the optical surface of the eyepiece optical system 22 is not exposed on the surface during storage, and the optical surface of the optical system is not contaminated. Is less likely to adhere, which is more preferable.

In the case of FIG. 18, the eyepiece optical system 22 is composed of at least an optical element 35 having a transmitting action such as a Fresnel lens. In this case, it is desirable to dispose the operation button 41 on the main body 40 of the display device before the eyepiece optical system 22 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 41. Further, by disposing the eyepiece optical system 22 in front of the relay optical system 21, it becomes possible to observe the image without difficulty.

Further, in the case of FIG. 18, it is preferable that the eyepiece optical system 22 is tilted toward the relay optical system 21 side to be housed. As a result, the surface of the eyepiece optical system 22 can be substituted for the role of the cover that protects the relay optical system 21.

Further, in both of the usage patterns of FIG. 17 and FIG. 18, the reflection mirror 37 (FIG. 18) is arranged between the relay optical system 21 and the eyepiece optical system 22, and the optical path is bent to thereby form the relay optical system. It is possible to shorten the distance from 21 to the eyepiece optical system 22. More preferably,
By giving the reflecting mirror 37 power, it is possible to disperse the power of the eyepiece optical system 22, and it is possible to clearly display an image on a larger screen. Further, by storing the reflecting mirror 37 under the eyepiece optical system 22, it is possible to prevent the optical element from being exposed and improve the dustproof property.

19 and 20, a display device including an eyepiece optical system 22 and a relay optical system 21 is provided in a mobile phone 38 so that the displayed image can be observed reasonably at the position of the exit pupil 1. The mobile phone 38 has a microphone section 51 for inputting the voice of the operator as information, a speaker section 52 for outputting the voice of the other party of the call, an antenna 53 for transmitting and receiving communication radio waves, and an operator for inputting information. An operation button 41 for inputting, and a display device of the present invention for projecting and displaying a photographed image of the operator himself / herself or a communication partner and information such as a telephone number are provided. FIG. 19 shows a configuration corresponding to that of FIG.
2 has a mechanism to open and close the mobile phone 38,
When carried, it can be folded and stored in a pocket or the like. In addition, FIG. 20 shows a configuration corresponding to FIG. 18, but the eyepiece optical system 22 is fixed to the surface of the main body of the mobile phone 38, and the relay optical system 21 and the reflecting mirror 37 are attached to the inside of the eyepiece optical system 22. It is to be stored in a pocket as it is.

The display optical system of the present invention described above can be constructed, for example, as follows.

[1] A reflective display element for displaying an image, an illumination light source for illuminating the reflective display element, an illumination optical system for guiding light from the illumination light source to the reflective display element, and the reflective display. A relay optical system for projecting an image displayed on the element, and an eyepiece optical system having a converging action for converging the light flux from the relay optical system toward an eyeball of an observer, and a projected image by the relay optical system. Is imaged in the vicinity of the eyepiece optical system.

[2] In the relay optical system, at least one reflecting surface is provided, and the reflecting surface has a curved surface shape for giving power to the light flux, and is a rotationally asymmetric curved reflecting surface having a decentering aberration correcting function. 2. The display optical system according to the above 1, wherein the decentered prism optical system configured is used.

[3] The illumination optical system includes at least one of the optical surfaces of the decentered prism optical system of the relay optical system.
3. The display optical system according to the above 2, wherein the two optical surfaces are shared.

[4] When the inclination angle of the axial chief ray emitted from the reflective display element from the normal line passing through the center of the display surface of the reflective display element is θ, the following conditional expression (1) is given.
4. The display optical system according to any one of 1 to 3 above, wherein

0 ° ≦ θ <45 ° (1) [5] The display optical system according to any one of 2 to 4 above, wherein the decentered prism optical system has a plane of symmetry.

[6] The display optical system described in any one of 2 to 4 above, wherein the decentered prism optical system does not have a plane of symmetry.

[7] In the illumination light flux from the illumination light source, a light ray reaching the center of the display surface of the reflection type display element and having a central light ray of the illumination light flux as an illumination light optical axis, the decentered prism optical system described above is used. The optical axis of the illumination light incident on the first reflecting surface counted from the reflective display element in the order in which the projection light beam passes is
7. The display optical system according to 6 above, wherein the illumination light source is arranged so as not to be included in a plane passing through a projection optical axis chief ray reflected on the th reflection surface and the center of the display surface. system.

[8] The decentered prism optical system is provided with two reflecting surfaces, the incident surface of the projection light beam, the first reflecting surface and the second reflecting surface.
When the other optical path is projected on a surface including one optical path, which is composed of a reflecting surface and an exit surface of the projection light beam, and an optical path connecting the incident surface and the first reflecting surface and an optical path connecting the second reflecting surface and the exit surface. 8. The display optical system according to any one of 2 to 7 above, which comprises decentered prisms intersecting each other in the prism.

[0118]

[9] The eyepiece optical system is composed of an optical element having a Fresnel surface.
9. The display optical system according to any one of items 1 to 8.

[0119]

As is apparent from the above description, according to the present invention, the relay optical system and the light flux from the relay optical system can be directed to the observer's eye by the eyepiece optical system, and the image can be observed in a small size and low in size. In an optical system for a power consuming display device, a reflective image display device can be used as an image display device to display a bright, compact and high-resolution image.

[Brief description of drawings]

FIG. 1 is a sectional view of an entire display optical system according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of a display optical system portion of FIG.

FIG. 3 is a projection optical path diagram of a display optical system portion of the first embodiment.

FIG. 4 is a projection optical path diagram of the entire display optical system of Example 2 of the present invention.

5 is a partially enlarged view of a display optical system portion of FIG.

FIG. 6 is a projection optical path diagram of a display optical system portion of a second embodiment.

FIG. 7 is a sectional view of the entire display optical system of Example 3 of the present invention.

8 is a partially enlarged view of a display optical system portion of FIG.

FIG. 9 is a projection optical path diagram of a display optical system portion of a third embodiment.

FIG. 10 is a projection optical path diagram of the entire display optical system of Example 4 of the present invention.

11 is a partially enlarged view of the display optical system portion of FIG.

FIG. 12 is a projection optical path diagram of a display optical system portion of the fourth embodiment.

FIG. 13 is a diagram showing lateral aberration of the first example.

FIG. 14 is a diagram showing lateral aberration of the second embodiment.

FIG. 15 is a diagram showing lateral aberration of the third embodiment.

FIG. 16 is a diagram showing lateral aberration of the fourth embodiment.

FIG. 17 is a perspective view when the display optical system of the present invention is applied to a portable information terminal.

FIG. 18 is a perspective view of another case in which the display optical system of the present invention is applied to a portable information terminal.

FIG. 19 is a perspective view when the display optical system of the present invention is applied to a mobile phone.

FIG. 20 is a perspective view of another case where the display optical system of the present invention is applied to a mobile phone.

[Explanation of symbols]

1 ... Exit pupil 2 ... Projection optical axis 3 ... Reflective display element 4 ... Illumination optical axis 5 ... Illumination light source 10 ... Decentered prism 11 ... First surface of decentered prism 12 ... Second surface of decentered prism 13 ... Third surface of decentered prism 14 ... Fourth surface of decentered prism 15 ... Transparent body for introducing illumination light 16 ... Fresnel transparent surface 20 ... Display optical system 21 ... Relay optical system 22 ... Eyepiece optical system 30 ... Fresnel reflector 31 ... Refractive surface of Fresnel reflector 32 ... Fresnel reflecting surface of Fresnel reflector 34 ... Optical element having reflection action 35 ... Optical element having transmissive action 37 ... Reflector 38 ... Mobile phone 40 ... Main body of display device 41 ... Operation button 51 ... Microphone 52 ... speaker section 53 ... Antenna E ... Eyeball position of observer

Claims (3)

[Claims] 1. A reflective display element for displaying an image, an illumination light source for illuminating the reflective display element, an illumination optical system for guiding light of the illumination light source to the reflective display element, and the reflective display element. And a relay optical system for projecting an image displayed on the display, and an eyepiece optical system having a converging action for converging the light flux from the relay optical system toward an eyeball of an observer, and a projection image by the relay optical system. A display optical system, wherein an image is formed in the vicinity of the eyepiece optical system. 2. The relay optical system comprises at least one relay optical system.
A decentered prism optical system having two reflecting surfaces, the reflecting surface having a curved surface shape for giving power to a light beam, and having a rotationally asymmetric curved reflecting surface having a decentering aberration correcting function is used. The display optical system according to claim 1, which is characterized in that: 3. The display optical system according to claim 2, wherein the illumination optical system shares at least one of the optical surfaces of the decentered prism optical system of the relay optical system.