JP2000010041A - Picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To present a bright picture on a reflection type picture display element to an observer and to enable the observer to observe the distinct and clear picture even by comparatively simple device constitution. SOLUTION: This picture display device is constituted of a light source 1 radiating illuminating light, the picture display element 10 displaying the picture by the reflection of the illuminating light, and an observation optical system 3 guiding the picture to an observer's eyeball 4. In the device, the light source 1 is arranged proximately to the outside of the reflection surface 12 having power of the optical system 3, and the surface 12 is constituted of a polarizing half mirror surface transmitting light in a specified polarization direction and reflecting light in a polarization direction nearly orthogonally crossing the specified polarization direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device, and more particularly, to a small and lightweight image display device that can be mounted on the head of an observer.

[0002]

2. Description of the Related Art In recent years, head or face-mounted image display devices have been developed for the purpose of allowing individuals to enjoy large-screen images.

Under such circumstances, Japanese Patent Application Laid-Open No. Hei 7-333551 discloses three optical surfaces as an eyepiece optical system that guides a display image of an image display device including a liquid crystal display device (hereinafter, referred to as an LCD) to an observer's eyeball. A decentered optical system composed of a medium having a refractive index larger than 1 surrounded by, and a light beam from the liquid crystal display element is incident on the decentered optical system from the third surface,
Next, the light is totally reflected by the first surface inside, and then internally reflected by the second surface of the concave mirror. This time, the light is emitted outside the decentered optical system through the first surface, and the display image of the image display device is converted into an intermediate image. Are formed so as to be guided to the observer's eyeball without forming the eyeball.

In this case, the decentered optical system has three optical surfaces, and the number of reflections inside the decentered optical system is two.
In addition, various types of decentered optical systems having two or four or more surfaces and reflecting at least once inside the optical system have been proposed by the present applicant.

In Japanese Patent Application Laid-Open No. 7-333551, the LCD constituting the image display device is expected to be of a transmissive type, but a reflection type LCD is used as an image display element of the face-mounted image display device. See also JP-A-7-72
No. 446. FIG. 16 is a diagram showing an optical system of the image display device. Illumination light from a lamp light source 155 is collimated by a collimating optical system 156, and a part of the light (S-polarized light) is converted into a polarization beam splitter 157.
And illuminates the reflective LCD 158 from the front. The display image reflected and modulated by the reflective LCD 158 is projected on a screen 152 by a projection optical system 159,
The projected image is enlarged and observed by an observer through the eyepiece optical system 153.

As a reflection type image display device, an image display device called a DMD (digital micro device) has been proposed in addition to the reflection type LCD. This has a configuration as shown in FIG. That is, as shown in FIG. 7A, a plane is shown, and as shown in FIG. 7B, the configuration of each element, micro mirrors 160 corresponding to each pixel are two-dimensionally arranged. By inclining about the axis, light incident on the mirror 160 ′ from a certain direction is reflected in a direction different from that of the mirror that is not inclined, so that a two-dimensional image is displayed. A pair of electrodes 164 provided on the substrate 161 provided on the rear side of the mirror 160 by applying a voltage to one of a pair of electrodes 164 provided on the substrate 161 on the rear side of the mirror 160 by being supported by support posts 162 erected on the substrate 161 at a pair of diagonal corners. When applied, the hinge 16
The mirror 160 is rotatable around a diagonal line between the three (IEEE Spectrum Vol. 30,
No. 11, pp. 27-31).

[0007]

When an eccentric optical system is used as an optical system of a head or face-mounted image display device, the entire device can be reduced in size and weight while maintaining high optical performance (angle of view, resolution, etc.). There is an advantage that a bright image display device can be configured. However, as the image display device used with the decentering optical system, only the transmission type LCD has been conventionally planned.

By the way, a transmission type L as an image display device
CDs have a lower pixel aperture ratio than reflective LCDs,
Because the black matrix part between pixels becomes conspicuous,
It is necessary to make it inconspicuous by using a low-pass filter or the like. On the other hand, the reflection type LCD can increase the aperture ratio of the pixel, and the above-mentioned problem is small. However, in JP-A-7-72446, the optical system other than the beam splitter is not refractive. Type projection optical system, and because the image displayed on the screen is observed, the observed image becomes dark,
The entire optical system is very large.

The present invention has been made in view of such a situation of the prior art, and an object thereof is to present a bright image of a reflection type image display element to an observer even with a relatively simple apparatus configuration. Another object of the present invention is to provide an image display device that allows an observer to observe a clear and clear image.

[0010]

According to the present invention, there is provided an image display apparatus comprising: a light source for emitting illumination light; an image display element for displaying an image by reflecting the illumination light; In an image display apparatus including an observation optical system for guiding an image, the light source is disposed in proximity to a reflection surface having the power of the observation optical system, and the reflection surface transmits light in a specific polarization direction. The light having a polarization direction substantially orthogonal to the light is formed by a polarization half mirror surface that reflects the light.

Another image display apparatus of the present invention comprises a light source that emits illumination light, an image display element that displays an image by reflecting the illumination light, and an observation optical system that guides the image to an observer's eyeball. In the image display device, the observation optical system has a polarization half mirror surface inclined at approximately 45 ° with respect to the image display device, and is disposed to face the image display device with the polarization half mirror surface interposed therebetween. The concave mirror is configured to magnify and project the image of the image display device onto the observer's eyeball as an enlarged virtual image, and the light source is disposed at a position facing the observer's eyeball with the observation optical system interposed therebetween. A polarizing plate is provided between the light source and the observation optical system to change the polarization state to light polarized only in a specific direction, and a quarter-wave plate is provided between the concave mirror and the polarizing half mirror surface. And it is characterized in and.

Hereinafter, the reason and operation of the above-described configuration in the present invention will be described. FIG. 1 illustrates a typical image display device according to the present invention. In FIG. 1, 1 is a light source, 2 is an optical axis, 3 is an observation optical system, 4 is an observer's eyeball, 5 is an illumination optical system, 10 is an image display element, 11 is a first surface of the observation optical system, and 12 is observation. This is the second surface of the optical system 3. The light source 1 is provided below the observation optical system 3, and light is emitted in one direction by an illumination optical system 5 configured by a reflecting mirror. The image display element 10 is disposed obliquely forward of the observer's eyeball 4. The observation optical system 3
It comprises a first surface 11 which is a transmission surface, and a concave mirror surface 12 which is constituted by a rotationally asymmetric aspherical surface and is provided with a polarization half mirror coating. This concave mirror surface 1
2 is disposed at a position facing the observer's eyeball 4 so as to be inclined with respect to the optical axis 2, so that the image display element 10 and the observer can be arranged without interference. Also,
The image display element 10 is a reflective twisted nematic liquid crystal (TN liquid crystal) display element, and the twist angle in this case is set to 45 °. The image display element is the same in all the embodiments described below. Light source 1
The ray path including the actual polarization state of the ray from the lens to the observer's eyeball 4 will be described below.

When the polarization state of the illumination light is random, the illumination light becomes linearly polarized light having a certain polarization direction by the second surface 12 which is a polarization half mirror surface, and illuminates the liquid crystal display element 10 via the observation optical system 3. I do. For example, when the second surface 12, which is a polarization half mirror surface, is set to reflect an s-wave and transmit a p-wave, the illumination light passing through the second surface 12 is a p-wave.

The illumination light illuminates a liquid crystal display device 10 as an image display device via an observation optical system 3. Liquid crystal display element 1
At 0, the light passes through the pixel to which the voltage is applied, passes through the liquid crystal layer, and is reflected at the lower portion, whereby the light is emitted with the polarization direction rotated by 90 °. Therefore, the light modulated by the liquid crystal display element 10 is emitted as an s-wave. As an s-wave, it is incident on the first surface 11 of the observation optical system 3 again,
Almost all light is reflected on the surface 12, passes through the first surface 11 again, and reaches the observer's eyeball 4. Therefore, a small and light optical system is configured that can be used effectively with a small loss of the amount of light emitted from the light source 1, and the observer perceives the image of the image display device 10 as an enlarged virtual image by the action of the concave mirror surface 12. become.

In this case, the light beam emitted from the light source 1 is transmitted through the second surface 12 of the polarization half mirror surface, and
And an observation optical path through which the luminous flux reflected by the image display element 10 is guided to the observer's eyeball 4 via the second surface 12 of the polarization half mirror surface, and the second surface 12 and the image display element 10 Observation optical system 3 so as to form a reciprocating optical path between
It is desirable to constitute.

With such a configuration, the illumination optical path and the observation optical path inside the observation optical system can be used for the forward path and the return path, so that useless optical elements are required as compared with the case where different optical paths are provided inside the optical system. (Transmissive surface and reflective surface) and space can be omitted, so that the image display device can be made compact. It also helps prevent flare light.

Further, it is effective for the construction of the optical system that the observation optical system be a prism body in which a space composed of at least two surfaces is filled with a medium having a refractive index larger than 1. FIG. 2 shows the configuration in that case.

In FIG. 2, the observation optical system 3 fills a space composed of three surfaces arranged eccentrically with respect to the optical axis 2 with an optical plastic having a refractive index of about 1.5. The light source 1 is provided with an illumination optical system 5 composed of a concave mirror on the side opposite to the direction of illumination, and emits light in one direction. The actual ray path is such that light emitted from the light source 1 disposed outside the second surface 22 having the main positive power of the observation optical system 3 is only a p-wave by the second surface 22 coated with the polarization half mirror. Is transmitted, totally reflected by the first surface 21, and transmitted through the third surface 23 to illuminate the image display element 10. The light modulated by the image display element 10 enters from the third surface 23 of the observation optical system, is totally reflected by the first surface 21, and substantially all light is reflected by the second surface 22 which is a polarization half mirror surface. ,
The light passes through the first surface 21 and enters the observer's eyeball 4. In this case, most of the optical path from immediately after the image display element 10 to the observer's eyeball 4 is made of optical plastic having a refractive index of about 1.5. Air equivalent length in optical plastic is about 1 /
Since the magnification is 1.5 times, the focal length can be set shorter than that of the concave mirror 12 in FIG. 1, and the observation angle of view can be widened. Further, as shown in FIG. 2, even when the entire optical system is made thinner by reflecting a plurality of times, the number of optical members can be reduced to one. And the cost can be reduced.

It is important that at least one surface of the observation optical system is an aspheric surface decentered with respect to the optical axis. As shown in FIGS. 1 and 2, when the concave mirrors 12 and 22 are arranged to be inclined with respect to the optical axis, coma and astigmatism also occur on the axis, and distortion due to eccentricity occurs off the axis. Then, field curvature occurs. In order to correct these aberrations due to eccentricity, it is necessary for at least one surface of the observation optical system to be an aspheric surface decentered with respect to the optical axis in order to correct the various aberrations.

Further, in order to further correct the above-mentioned various aberrations, it is important that at least one surface of the observation optical system is constituted by a rotationally asymmetric aspheric surface decentered with respect to the optical axis. For example, in order to correct axial astigmatism, it is necessary that the power of the horizontal principal axis and that of the vertical axis at the point where the axial chief ray is reflected by the concave mirror be different. For that purpose, it is desirable to use a rotationally asymmetric aspherical surface. The fact that the arrangement of the concave mirror and the convex mirror exerts a good effect on the field curvature aberration is described in detail in Japanese Patent Application No. Hei 5-264828 of the present applicant. −
No. 127453. The astigmatism generated by the inclined concave mirror is also described in Japanese Patent Application Nos. 6-210167 and 6-256676 of the present applicant.
No. Regarding image distortion such as trapezoid or bow caused by an inclined concave mirror, see Japanese Patent Laid-Open No. 5-303.
No. 056.

Further, these aberrations are simultaneously and satisfactorily corrected by an eccentric prism using a plane-symmetric free-form surface having no in-plane and out-of-plane rotational symmetry axes and having only one symmetry plane. Regarding the matter, Japanese Patent Application No. Hei 9
No. 318811.

Here, the free-form surface of the present invention is defined by the following equation. _{Z = C 2 + C 3 Y} + C 4 X + C 5 Y 2 + C 6 YX + C 7 X 2 + C 8 Y 3 + C 9 Y 2 X + C 10 YX 2 + C 11 X 3 + C 12 Y 4 + C 13 Y 3 X + C 14 Y 2 X 2 + C ₁₅ YX ³ + C ₁₆ X ⁴ + C ₁₇ Y ⁵ + C ₁₈ Y ⁴ X + C ₁₉ Y ³ X ² + C ₂₀ Y ² X ³ + C ₂₁ YX ⁴ + C ₂₂ X ⁵ + C ₂₃ Y ⁶ + C ₂₄ Y ⁵ X + C ₂₅ Y ⁴ X ² + C ^{_{26 Y 3 X 3 + C 27}} Y 2 X 4 + C 28 YX 5 + C 29 X 6 + C 30 Y 7 + C 31 Y 6 X + C 32 Y 5 X 2 + C 33 Y 4 X 3 + C 34 Y 3 X 4 + C 35 Y 2 X ^{_{5 + C 36 YX 6 + C}} 37 X 7 ····· ··· (a) although, Z is the amount of deviation from a plane tangent to the origin of the surface shape (the m 2 or more integer) C _m is the coefficient .

By using such a decentered prism using a rotationally asymmetric aspherical surface as the observation optical system, a bright and high-resolution image having a wide observation angle of view and a wide observation angle is provided to the observer while being compact and lightweight. It becomes possible.

The observation optical system is also effective if it has a non-polarization half mirror surface inclined at approximately 45 ° to the image display element and a concave mirror facing the image display element. FIG.
The configuration in that case is shown in FIG.

In FIG. 3, a light source 1 is provided below an observation optical system 3 and has an illumination optical system 5 composed of a concave mirror.
Light is emitted in one direction. The observation optical system 3 includes a non-polarization half mirror 9 and a concave mirror 8 whose surface 32 is coated with a polarization half mirror. The non-polarizing half mirror 9 is disposed at a position sufficiently inclined so as not to interfere with an observer by inclining by about 45 ° with respect to the image display element 10, and the concave mirror 8 is disposed below the non-polarizing half mirror 9. An image display element 10 is disposed diagonally above the observer's eyeball 4 so as to face the eyeball 8. The light source 1 is arranged outside the concave mirror 8.

The concave mirror surface 32 which is the polarization half mirror surface has p
Assuming that the wave is transmitted and the s-wave is reflected, the ray path emitted from the light source 1 assumes that the light emitted from the light source 1 is in a random polarization state, and only the p-wave is generated on the concave mirror surface 32. The light passes through the first surface 31, passes through the non-polarizing half mirror 9, and illuminates the image display device 10. As in the case of FIG. 1, the twist angle of the image display element 10 is set. Since the image display element 10 was illuminated with a p-wave, the light modulated by the image display element 10 was s.
Emit as waves. Light emitted from the liquid crystal display element 10 passes through the non-polarization half mirror 9, and all light is reflected by the concave mirror 32, which is the polarization half mirror surface, and is reflected by the non-polarization half mirror 9 to reach the observer's eyeball 4. . Therefore, the observer can operate the image display device 1 by the action of the concave mirror 32.
The image 0 is perceived as an enlarged virtual image. Even if the optical path of the observation optical system 3 is folded, the optical system can be handled as a coaxial system, so that there is no occurrence of aberration due to eccentricity, and the design and manufacture of the optical system are easy. Nevertheless, the entire device is very compact and lightweight, and a high-resolution image display device can be realized at low cost.

The observation optical system has a substantially right-angle prism shape in which a non-polarization half mirror surface is sandwiched by a medium having a refractive index of more than 1, and has a concave mirror surface at a position facing the image display device. is there. FIG. 4 shows the configuration in that case.

In FIG. 4, the observation optical system 3 has a right-angle prism shape, and a non-polarization half mirror surface exists therein. The first surface 41 of the transmission surface on the observer's eyeball side, the second surface 42 which is a non-polarization half mirror surface arranged at an angle of approximately 45 ° with respect to the first surface 41, and the second surface 42 orthogonal to the first surface 41 The third surface 43, which is a concave mirror surface coated with a polarizing half-mirror and is disposed below the third surface 43, is a fourth surface 44, which is a transmission surface that is close to the image display element 10 and is close to the image display element 10. The light source 1 is provided below the third surface 43.
Is in a random polarization state. It is assumed that the third surface 43, which is a polarization half mirror surface, transmits p-waves and reflects s-waves.

The light path from the light source 1 to the observer's eyeball 4 will be described below, including the polarization state. As for the light emitted from the light source 1, only the p-wave passes through the third surface 43, a part of the light passes through the second surface 42, which is a non-polarization half mirror surface, and the fourth surface 44.
To illuminate the image display element 10. As in the case of FIG.
The light modulated by is emitted as an s-wave. Liquid crystal display element 1
The light emitted from 0 passes through the fourth surface 44, passes through the second surface 42 of the non-polarization half mirror surface, and almost all light is reflected by the third surface 43, which is the polarization half mirror surface, and is again unpolarized light. Partially reflected by the second surface 42 of the half mirror surface, the first surface 4
1 and reaches the observer's eyeball 4. Therefore, in addition to the operation and effect of FIG. 3, most of the optical path from immediately after the image display element 10 to the observer's eyeball 4 is an optical plastic having a refractive index of about 1.5. The air-equivalent length of the inside is about 1 / 1.5 times, so that the focal length can be set shorter than in the case of using only the concave mirror, and the observation angle of view can be widened.

It is desirable to dispose a polarizing plate between the light source and the reflecting surface having the polarization half mirror coated power. Light emitted from a light source is usually in a random polarization state, and if the light is directly incident on the polarization half mirror surface, light that does not pass therethrough may be reflected and scattered on that surface to become unnecessary light. Therefore, it is desirable to prevent unnecessary light from being generated by selecting the polarization state of transmitted light in advance by using a polarizing plate. Further, even if the polarizing plate is disposed between the observer's eyeball and the observation optical system, an effect of blocking unnecessary light can be obtained.

The observation optical system is composed of an eccentric prism filled with a medium having a refractive index of greater than 1 in a space composed of at least two surfaces decentered with respect to the optical axis, and a transmission surface arranged on the observer side. When the first surface is a second surface that is a polarizing half mirror surface and a concave mirror surface facing the first surface, the light source may be provided outside the second surface. Effective for placement.

FIG. 5 shows the configuration in that case. In FIG. 5, the observation optical system 3 fills a space formed by two surfaces eccentrically arranged with respect to the optical axis 2 with optical plastic having a refractive index of about 1.5. Is provided with an illumination optical system 5 composed of a concave mirror on the side opposite to the direction of illumination, and emits light in one direction. The actual ray path is such that light emitted from the light source 1 disposed outside the second surface 52 having the main positive power of the observation optical system 3 is only a p-wave by the second surface 52 coated with the polarization half mirror. Is transmitted, enters the observation optical system 3, and passes through the first surface 51 to illuminate the image display element 10. The light modulated by the image display element 10 enters from the first surface 51 of the observation optical system,
Since the light is an s-wave on the second surface 52, which is a polarization half mirror surface, almost all the light is reflected, passes through the first surface 51, and enters the observer's eyeball 4. Since the second surface 52 has the function of a concave mirror, the observer can perceive the enlarged image of the image display device 10 as a virtual image.

As described above, when the observation optical system 3 is at least 2
In the case of a decentered prism composed of surfaces, the second surface 52, which is an internal reflection surface having main positive power, is a surface inclined with respect to the observer's visual axis 2, so that the second surface 52 is provided outside the second surface 52. Space is created. By arranging the light source 1 outside the second surface 52, the image display element 10 can be illuminated without excessively increasing the thickness of the entire apparatus, and an image can be projected on the observer's eyeball 4.

The observation optical system is composed of an eccentric prism filled with a medium having a refractive index greater than 1 in a space composed of at least three surfaces decentered with respect to the optical axis. When a first surface having a reflecting action, a second surface that is a polarizing half mirror surface and a concave mirror surface facing the first surface, and a third surface that is a transmission surface close to and facing the image display element, It is effective for the arrangement of the optical elements of the image display device to arrange the light source outside the second surface. FIG. 2 shows the configuration in that case.

As shown in FIG. 2, the decentered prism having such a configuration has a space outside the second surface 22, so that even if the light source 1 and the reflection plate 5 are provided there, the thickness of the optical system is reduced. The device can be configured without much change.

The observation optical system comprises an eccentric prism filled with a medium having a refractive index greater than 1 in a space formed by at least four surfaces decentered with respect to the optical axis. A first surface having a reflecting function, a second surface facing the first surface and being a polarizing half mirror surface and a concave mirror surface, and a third surface being a reflecting surface adjacent to the second surface.
Surface, a transmission surface which is close to and opposed to the image display element.
When it is a surface, it is effective that the light source is disposed outside the second surface. FIG. 6 shows the configuration in that case.

In FIG. 6, the observation optical system 3 fills a space composed of four surfaces arranged eccentrically with respect to the optical axis 2 with an optical plastic having a refractive index of about 1.5. The light source 1 is provided with an illumination optical system 5 composed of a concave mirror on the side opposite to the direction of illumination, and emits light in one direction. The actual ray path is such that the light emitted from the light source 1 disposed outside the second surface 62 having the main positive power of the observation optical system 3 is the second half mirror-coated with the polarization half mirror.
Only the p-wave is transmitted by the surface 62, internally reflected by the first surface 61 and the third surface 63, and transmitted through the fourth surface 64 to illuminate the image display device 10. The light modulated by the image display element 10 is
The light enters the fourth surface 64 of the observation optical system, and the third surface 63
The light is internally reflected at the surface 61 and substantially all light is reflected at the second surface 62, which is a polarization half mirror surface, because the light is an s-wave.
The light passes through the surface 61 and enters the observer's eyeball 4.

As described above, when the observation optical system 3 is at least 4
In the case of a decentered prism composed of surfaces, the second surface 62, which is an internal reflection surface having main positive power, is a surface inclined with respect to the observer's visual axis 2, so that the outside of the second surface 62 Space is created. By arranging the light source 1 outside the second surface 62, it is possible to illuminate the image display element without increasing the thickness of the entire device too much, and to project an image to the observer's eyeball. It goes without saying that the same effect can be obtained in a decentered prism having four or more surfaces by disposing a light source outside the reflecting surface having a positive power facing the observer's eyeball 4.

The observation optical system is composed of an eccentric prism filled with a medium having a refractive index greater than 1 in a space constituted by at least four surfaces decentered with respect to the optical axis. A first surface having a reflecting action, a second surface which is opposite to the first surface and which is a concave mirror surface, a third surface which is a reflecting surface and a transmitting surface adjacent to the second surface, and a second surface which is opposite to the third surface. When the fourth surface is a polarization half mirror surface having power adjacent to one surface, it is effective that the light source is disposed outside the fourth surface. FIG. 7 shows the configuration in that case.

In FIG. 7, the observation optical system 3 has a space defined by four surfaces eccentrically arranged with respect to the optical axis 2 and is filled with an optical plastic having a refractive index of about 1.5. The light source 1 is provided with an illumination optical system 5 composed of a concave mirror on the side opposite to the direction of illumination, and emits light in one direction. The actual light path is such that light emitted from the light source 1 disposed outside the fourth surface 74 which is a reflecting surface inclined to face the image display element 10 is p-polarized by the fourth surface 74 coated with the polarization half mirror. Only waves are transmitted, and the third surface 73
To illuminate the image display element 10. The light modulated by the image display element 10 becomes an s-wave, enters from the third surface 73 of the observation optical system, and becomes a fourth surface 74 that is a polarization half mirror surface.
Since the light is an s-wave, almost all of the light is reflected, and is internally reflected by the third surface 73, the first surface 71, and the second surface 72, and the first surface 7
1 and enters the observer's eyeball 4.

As shown in FIG. 7, in the eccentric prism having at least four surfaces, the outside of the fourth surface 74 which is the internal reflection surface facing the image display element 10 is the same as the second surface 72 described above. Even if the light source 1 is provided in a space, a predetermined effect can be obtained without increasing the thickness and the entire length of the entire optical system. This is because the observation optical system 3 is 5
It is needless to say that the same effect can be obtained even if an eccentric prism having more than two surfaces is arranged outside the reflection surface facing the image display element 10.

It is preferable that at least one of the incident surface on which the light from the image display element enters the observation optical system and the exit surface on which the light exits the observer's eyeball is constituted by a surface having power. Above. On the incident surface, which is a surface close to the image display element, since the light beam emitted from the image display element is not very wide, the correction of the off-axis aberration, which is an off-axis aberration, is performed without significantly affecting the dependent light rays. It is possible. This shows the same operation and effect in any of the above-described eccentric prism and right-angle prism.

The operation of the exit surface for exiting to the observer's eyeball will be described. A case of an eccentric prism in which a space formed by at least two surfaces is filled with a medium having a refractive index larger than 1 will be described with reference to FIG. On the second surface 22, which is a concave mirror surface having a positive power, aberrations including decentering aberrations occur. By making the first surface 21 that is the exit surface that exits to the observer's eyeball 4 concave with respect to the observer, the second surface 21
It becomes possible to correct aberrations generated on the surface 22, especially correction of eccentric coma.

In the case of a right-angle prism, by making the exit surface convex to the observer, aberration correction can be effectively applied. This will be described with reference to FIG. Considering the reverse ray tracing from the observer to the image display element 10, the first surface 41 which is the surface incident on the observation optical system 3
Has a positive power, so that it is strongly refracted when passing through the first surface 41, so that the height of the reflection point on the third surface 43, which is a reflection surface having the main positive power, can be reduced. Wide angle of view can be achieved. Further, the dependent light is also transmitted to the first surface 4.
Since the effect of reducing the luminous flux by the positive power of 1 is obtained, it is possible to reduce the coma aberration generated on the third surface 43.

It is preferable that an illuminating means for irradiating the illuminating light emitted from the light source in one direction is provided. The light emitted from the light source varies depending on the type of the light source. In the present optical system, it is desirable that the light emitted from the light source be emitted in one direction. It is desirable that the illumination light be emitted more efficiently in one direction.

The illumination optical system may of course be a reflector disposed behind the light source. Further, by disposing the refractive optical system immediately after the light source, it is possible to more easily handle the illumination light thereafter.

Next, a second image display device according to the present invention will be described. As described above, the image display device includes an image display including a light source that emits illumination light, an image display element that displays an image by reflection of the illumination light, and an observation optical system that guides the image to an observer's eyeball. In the apparatus, the observation optical system has a polarization half mirror surface inclined at approximately 45 ° with respect to the image display element, and includes a concave mirror arranged to face the image display element with the polarization half mirror surface interposed therebetween. The image of the image display element is configured to be enlarged and projected on an observer's eyeball as an enlarged virtual image, and the light source is disposed at a position facing the observer's eyeball with the observation optical system interposed therebetween. A polarizing plate is provided between the observation optical systems to change the polarization state into light polarized only in a specific direction,
A quarter-wave plate is provided between the concave mirror and the polarizing half mirror surface. The image display element is illuminated by effectively using the light from the light source, and the image of the reflective image display element is displayed. It is possible to achieve an image display device that guides the observer's eyeball to observe an enlarged image.

FIG. 8 shows a conceptual diagram of the second image display device of the present invention. 8, the image display device includes a light source 1 serving as a light source unit, a reflection plate 5, a polarizing plate 7, an observation optical system 3, and an image display element 10. The observation optical system 3 includes a polarization half mirror 16, a concave mirror 17 whose surface 82 is mirror-coated, and a 波長 wavelength plate 6.

The light source 1 is arranged to face the observer's eyeball 4 with the polarization half mirror 16 interposed therebetween, and the illumination light is emitted in one direction by the reflector 5 behind the light source. The configuration of the observation optical system 3 is approximately 45 ° with respect to the image display element 10.
The polarization half mirror 16, which is arranged at a position sufficiently distant so as not to tilt and interfere with the observer, and the polarization half mirror 1
6, a quarter-wave plate 6 arranged opposite to the image display element 10 and a concave mirror 17 arranged below the quarter-wave plate 6. The image display element 10 faces the concave mirror 17 and is disposed obliquely above the observer's eyeball 4. The light emitted from the light source 1 is in a random polarization state,
The polarization half mirror 16 is set to transmit the p-wave and reflect the s-wave.

Hereinafter, the light path from the light source 1 to the observer's eyeball 4 will be described including the polarization state. Only the s-wave of the light emitted from the light source 1 is transmitted through the polarizing plate 7, and almost all the light is reflected upward by the polarizing half mirror 16, and illuminates the image display device 10. The image display element 10 is the above-mentioned reflective TN liquid crystal display element, and the illuminated light is rotated by 90 ° in the polarization state, and the modulated light to be emitted is a p-wave. Almost all of the light emitted from the liquid crystal display element 10 is transmitted through the polarization half mirror 9 and enters the quarter-wave plate 6. At this time, after the p-wave of linearly polarized light is converted into circularly polarized light, it is incident on the first surface 81 of the concave mirror 17 and is reflected by the reflecting surface 82,
The light exits from the transmission surface 81 again and passes through the quarter-wave plate 6 again. At this time, the p-wave at the time of incidence of the circularly polarized light is converted into an s-wave, which is linearly polarized light whose polarization direction is rotated by 90 °, and enters the polarization half mirror 16. Here, almost all light is reflected and reaches the observer's eyeball 4. Therefore, the light emitted from the light source 1 and having passed through the polarizing plate 7 has a small light amount loss and is efficiently guided to the observer's eyeball, so that a clear image can be provided to the observer. Further, as described above, even though the optical path in the observation optical system 3 is turned back, the optical system can be treated as a coaxial system.
There is no aberration due to eccentricity, and the design and manufacture of the optical system are easy. Nevertheless, the entire device is very compact and lightweight, and a high-resolution image display device can be realized at low cost.

It is more preferable that the polarizing half mirror surface is included in an optical element having a rectangular prism shape with a triangular prism made of a medium having a refractive index larger than 1 and sandwiching the polarizing half mirror surface. FIG. 9 shows the configuration in that case.

In FIG. 9, a right-angle prism-shaped polarizing optical element 90 has four surfaces, and a polarizing half-mirror surface exists therein. First surface 9 of the transmission surface on the observer's eyeball 4 side
1. a second surface 92, which is a half mirror surface arranged at an angle of approximately 45 ° with respect to the first surface, and a third surface 93, which is a transmission surface orthogonal to the first surface 91 and disposed below the second surface 92. , The fourth surface 94 and the second surface 92 that are transmission surfaces close to the image display element 10
Fifth surface 95 that is a transmission surface facing first surface 91 across
And The quarter-wave plate 6 is provided substantially parallel to and below the third surface 93. The back surface concave mirror 17 is constituted by a first surface 96 which is a transmission surface and a second surface 97 which is a reflection surface, and is provided below and close to the ４ wavelength plate 6. The light source 1 is provided outside the polarizing plate 7 provided so as to be opposed to and close to the fifth surface 95. The polarizing plate 7 is set to transmit only the s-wave. It is assumed that the second surface 92, which is a polarization half mirror surface, transmits the p-wave and reflects the s-wave, and the light emitted from the light source 1 is in a random polarization state.

In the light beam path in such an optical system, only the s-wave of the illumination light from the light source 1 passes through the polarizing plate 7,
The light enters the polarization optical element 90 from the fifth surface 95. Almost all light is reflected on the second surface 92, which is a polarization half mirror surface, and passes through the fourth surface 94 to illuminate the image display device 10. The light modulated by the liquid crystal display element 10 is emitted as a p-wave. Light emitted from the liquid crystal display element 10 passes through the fourth surface 94, substantially all light passes through the second surface 92 of the polarization half mirror surface, and is emitted from the third surface 93. 1/4 wavelength plate 6
, The linearly polarized p-wave is converted to circularly polarized light,
The light enters from the transmission surface 96 of the back mirror 17, is reflected by the reflection surface 97, exits from the transmission surface 96, and passes through the quarter-wave plate 6 again. At this time, the circularly polarized light is converted from the p-wave at the time of incidence into an s-wave, which is linearly polarized light whose polarization direction is rotated by 90 °, and enters the polarization optical element 90 again. On the polarization half mirror surface 92, almost all light is reflected at a reflection angle of 45 °, exits from the first surface 91 of the polarization optical element 90, and is
To reach. Therefore, in addition to the operation and effect of FIG.
Most of the optical path from immediately after the image display element 10 to the observer's eyeball is filled with optical plastic having a refractive index of about 1.5, so that the air equivalent length in the optical plastic is about 1/1. 0.5 times, so that the focal length can be set shorter than in the case of using only a concave mirror that does not use a prism, and the observation angle of view can be widened.

Incidentally, even if the polarizing plate 7 is arranged between the observer's eyeball and the observation optical system, the effect of blocking unnecessary light can be obtained.

Further, it is preferable that an illumination optical system for converting illumination light emitted from the light source into illumination light emitted in substantially one direction is provided. The light emitted from the light source varies depending on the type of the light source. However, in the present optical system, it is desirable that the light emitted from the light source be emitted in one direction. It is desirable that the illumination light is emitted in the direction so that the illumination light is taken in more efficiently.

The illumination optical system may of course be a reflector provided behind the light source. Further, by disposing the refraction optical system immediately after the light source to make the light beam a substantially parallel light beam, it is possible to more easily handle the illumination light thereafter.

[0057]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments 1 to 5 of the image display device of the present invention will be described below. Examples 1 to 4 to be described later
As shown in FIG. 10, the coordinates of the configuration parameters of (1) and (2) are such that the exit pupil 19 of the observation optical system 3 is set as the origin of the optical system, the optical axis 2 is the display center of the image display element 10, and
9 is defined by a light ray passing through the center (origin) of the lens 9, the direction from the exit pupil 19 to the optical axis 2 is the Z-axis direction, and the ray is bent by the observation optical system 3 through the center of the exit pupil 19 at right angles to the Z axis. The direction in the plane to be taken is the Y-axis direction, the Z-axis, the direction orthogonal to the Y-axis and passing through the center of the exit pupil 19 is the X-axis direction, and the direction from the exit pupil 19 toward the observation optical system 3 is the positive direction of the Z-axis. The direction from the axis 2 to the image display element 10 is defined as the positive direction of the Y axis, and the direction forming the right-handed coordinate system with the Z axis and the Y axis is defined as the positive direction of the X axis. The ray tracing is performed by the exit pupil 19 of the observation optical system 3.
Is set as the object side, and the reverse ray tracing is performed with the image display element 10 side as the image plane side.

Then, for a plane having eccentricity, eccentricity in the X-axis direction, Y-axis direction, and Z-axis direction from the center of the exit pupil 19, which is the origin of the observation optical system 3 at the top of the surface. The quantity and the central axis of the surface (free-form surface, anamorphic surface, rotationally symmetric aspherical surface,
The inclination angles (α, β, and γ, respectively) centered on the X-axis, Y-axis, and Z-axis of the equations, (b), and (c).
(°)). In this case, α and β
Is positive counterclockwise with respect to the positive direction of each axis,
Positive γ means clockwise with respect to the positive direction of the Z axis.
In addition, the radius of curvature of the spherical surface, the spacing between the surfaces, the refractive index of the medium, and the Abbe number are given according to conventional methods.

The configuration parameters of the fifth embodiment are the same as those for the reverse ray tracing, wherein the radius of curvature of the spherical surface, the surface interval, the refractive index of the medium, and the Abbe number are given according to a conventional method, and the eccentricity is given. , The optical axis emitted from the surface immediately before that surface is defined as the positive direction of the Z axis, and the direction orthogonal to the Z axis and directed from the front to the back of the drawing is defined as the positive direction of the X axis.
The direction forming the X-axis and the right-handed coordinate system is defined as the positive direction of the Y-axis,
A point on the Z-axis given by a surface interval from the immediately preceding plane is set as each origin, and the eccentricity in the X-axis direction, the Y-axis direction, the Z-axis direction (only in the Y-axis direction) from the origin, and the plane And the inclination angles (α, β, and γ, respectively) centered on the X axis, Y axis, and Z axis of the central axis (only α). The definition of the sign of the angle is as described above.

The shape of the free-form surface is defined by the following equation. The Z axis of the definition is the axis of the free-form surface. _{Z = C 2 + C 3 Y} + C 4 X + C 5 Y 2 + C 6 YX + C 7 X 2 + C 8 Y 3 + C 9 Y 2 X + C 10 YX 2 + C 11 X 3 + C 12 Y 4 + C 13 Y 3 X + C 14 Y 2 X 2 + C ₁₅ YX ³ + C ₁₆ X ⁴ + C ₁₇ Y ⁵ + C ₁₈ Y ⁴ X + C ₁₉ Y ³ X ² + C ₂₀ Y ² X ³ + C ₂₁ YX ⁴ + C ₂₂ X ⁵ + C ₂₃ Y ⁶ + C ₂₄ Y ⁵ X + C ₂₅ Y ⁴ X ² + C ^{_{26 Y 3 X 3 + C 27}} Y 2 X 4 + C 28 YX 5 + C 29 X 6 + C 30 Y 7 + C 31 Y 6 X + C 32 Y 5 X 2 + C 33 Y 4 X 3 + C 34 Y 3 X 4 + C 35 Y 2 X ⁵ + C ₃₆ YX ⁶ + C ₃₇ X ⁷ ····· (a) Of course, the expression representing the free-form surface is not limited to this, and may be a surface having no symmetric surface outside or inside the surface or outside the surface. An expression according to any definition may be used as long as the surface can be configured as a surface having only one symmetric surface.

The shape of the anamorphic surface is defined by the following equation. A straight line passing through the origin of the surface shape and perpendicular to the optical surface is the axis of the anamorphic surface. ^{Z = (Cx · X 2 +} Cy · Y 2) / [1+ {1- (1 + Kx) Cx 2 · X 2 - (1 + Ky) Cy 2 · Y 2} 1/2] + ΣRn {(1-Pn) X 2 + (1 + Pn) Y ² ｝ ^{(n + 1)} Here, when n = 4 (fourth-order term) is considered as an example, when expanded, it can be expressed by the following equation (b).

Z = (Cx · X ² + Cy · Y ² ) / [1+ {1− (1 + Kx) Cx ² · X ² − (1 + Ky) Cy ² · Y ² ｝ ^1/2 ] + R1} (1-P1) ^{X 2 + (1 + P1)} Y 2} 2 + R2 {(1-P2) X 2 + (1 + P2) Y 2} 3 + R3 {(1-P3) X 2 + (1 + P3) Y 2} 4 + R4 {(1-P4 ) X ² + (1 + P4) Y ² ｝ ⁵ (b) where Z is the amount of deviation from the tangent plane to the origin of the surface shape, Cx is the curvature in the X-axis direction, Cy is the curvature in the Y-axis direction, and Kx is X An axial conic coefficient, Ky is a Y-axial conic coefficient, Rn is an aspherical term rotationally symmetric component, and Pn is an aspherical term rotationally asymmetric component. In the configuration parameters of the embodiment described later, X
The curvature radius Rx in the axial direction and the curvature radius Ry in the Y-axis direction are used, and the curvatures Cx and Cy are in the relationship of Rx = 1 / Cx, Ry = 1 / Cy.

The shape of the rotationally symmetric aspherical surface is defined by the following equation. The Z axis in the definition formula is the axis of the rotationally symmetric aspherical surface. ^{Z = (Y 2 / R)} / [1+ {1- (1 + K) (Y 2 / R 2)} 1/2] + A 4 Y 4 + A 6 Y 6 + A 8 Y 8 + A 10 Y 10 ··· ·· (C) where Y is a direction perpendicular to Z, R is a paraxial radius of curvature, K is a conical coefficient, and A ₄ , A ₆ , A ₈ , and A ₁₀ are aspherical coefficients.

Note that the term relating to the aspherical surface for which no data is described is zero. Regarding the refractive index, d-line (wavelength 5
87.56 nm). The unit of the length is mm.

FIGS. 10 to 14 are YZ sectional views including the optical axis 2 of the optical system of the image display apparatus according to the first to fifth embodiments of the present invention. In these embodiments, the pupil of the observer is used as the exit pupil 19 of the observation optical system 3, and the light beam emitted from the light source 1 disposed at a position substantially conjugate with the exit pupil 19 is transmitted by the illumination optical system 5 to the observation optical system 3. To illuminate the image display element surface 10. The light reflected by the image display element 10 is again transmitted to the observation optical system 3.
At the exit pupil 19 by the observation optical system 3, and the observer perceives the enlarged observation image as a virtual image.

It should be noted that the reflection type image display element 10 has a screen size of 0.4 inch in the first and second embodiments, 0.7 inch in the third embodiment, and 1 inch in the fourth and fifth embodiments. , And the angle of view to be observed is as in Examples 1, 2,
3 and 4 have a horizontal angle of view of 30 ° and a vertical angle of view of 22.7 °, and the fifth embodiment has a horizontal angle of view of 35 ° and a vertical angle of view of 26.6 °. The pupil diameter was 2.3 mm in Examples 1 and 2, and 4 in Examples 3, 4, and 5.
mm.

The first embodiment shown in FIG. 10 corresponds to the configuration shown in FIG. 2, and the observation optical system 3 has a refractive index of about 1 in a space composed of three surfaces arranged eccentrically with respect to the optical axis 2. The light source 1 is provided with an illumination optical system 5 composed of a concave mirror on the opposite side of the illumination direction. Light emitted from the light source 1 disposed outside the second surface 22 of the observation optical system 3 is directed in one direction by the illumination optical system 5 and is polarized second half mirror-coated second surface 22.
Thus, for example, only the p-wave is transmitted, totally reflected by the first surface 21 and transmitted through the third surface 23 to illuminate the image display element 10. The light modulated by the image display element 10 enters from the third surface 23 of the observation optical system, is totally reflected by the first surface 21, and substantially all light is reflected by the second surface 22 which is a polarization half mirror surface. ,
The light is transmitted through the first surface 21 and enters the observer's eyeball, and an enlarged image of the reflective image display device 10 is presented to the observer.

Embodiment 2 of FIG. 11 is a modification of Embodiment 1, in which the same observation optical system 3 is used, and only the illumination optical system 5 is slightly different. That is, the illumination optical system 5 is made eccentric aspherical concave mirror 5 ₁ and eccentric biconvex positive lens 5 ₂ Prefecture, the second surface 22 of the observation optical system 3 in the illumination optical system 5
The light emitted from the light source 1 disposed outside the camera is directed in one direction and transmitted through the second surface 22 coated with the polarization half mirror in the same manner. An enlarged image of the display element 10 is presented.

The third embodiment shown in FIG. 12 corresponds to the configuration shown in FIG. 5. The observation optical system 3 has a first surface 51 which is a transmission surface eccentrically arranged with respect to the optical axis 2 and a rotationally asymmetrical surface. The light source 1 is provided with an illumination optical system 5 composed of a concave mirror on the side opposite to the direction of illumination. I have. Light emitted from the light source 1 disposed outside the second surface 52 of the observation optical system 3
For example, only the p-wave is transmitted by the second surface 52 coated with the polarization half mirror, and the first surface 51
To illuminate the image display element 10. The light modulated by the image display element 10 enters from the first surface 51 of the observation optical system 3, and substantially all light is reflected by the second surface 52, which is a polarization half mirror surface, and passes through the first surface 51. And enters the observer's eyeball to present an enlarged image of the reflective image display device 10 to the observer.

The fourth embodiment shown in FIG. 13 corresponds to the configuration shown in FIG. 6, and the observation optical system 3 has a refractive index of about 1 in a space composed of four surfaces arranged eccentrically with respect to the optical axis 2. The light source 1 is provided with an illumination optical system 5 composed of a concave mirror on the opposite side of the illumination direction. The light emitted from the light source 1 disposed outside the second surface 62 of the observation optical system 3 is directed in one direction by the illumination optical system 5 and the second surface 62 coated with a polarization half mirror.
Thus, for example, only the p-wave is transmitted, internally reflected by the first surface 61 and the third surface 63, and transmitted through the fourth surface 64 to illuminate the image display element 10. The light modulated by the image display element 10 is
The light enters the fourth surface 64 of the observation optical system, and the third surface 63
The light is internally reflected by the surface 61, and substantially all light is reflected by the second surface 62, which is a polarizing half mirror surface, passes through the first surface 61, enters the observer's eyeball, and is reflected to the observer. Is presented.

Embodiment 5 of FIG. 14 corresponds to the configuration of FIG. 9. The polarizing optical element 90 in the form of a right-angle prism is inclined by 45 ° with respect to the first surface 91 of the transmission surface on the exit pupil 19 side and the first surface. Surface 92 and first surface 91 which are half mirror surfaces arranged in
A third surface 93 which is a transmission surface disposed below the second surface 92 at right angles to the second surface 92, a fourth surface 94 which is a transmission surface close to the image display element 10, and a first surface 91 with the second surface 92 interposed therebetween. And a fifth surface 95 which is a transmission surface having a positive power and facing
The 波長 wavelength plate 6 is disposed substantially parallel to and below the third surface 93. The back concave mirror 17 is provided on the first surface 9 which is a transmission surface.
6. The second surface 97, which is a reflection surface having a positive power, is provided below and close to the quarter-wave plate 6. The light source 1 is disposed outside a polarizing plate (not shown) disposed close to and opposed to the fifth surface 95.
Is provided with an illumination optical system 5 composed of a concave mirror having a free-form surface decentered on the opposite side to the direction of illumination.
The light emitted from the light source 1 is directed in one direction by the illumination optical system 5. For example, only the s-wave passes through the polarizing plate and enters the polarizing optical element 90 from the fifth surface 95. Almost all light is reflected on the second surface 92, which is a polarization half mirror surface, and the fourth surface 9
4 illuminates the image display element 10. The light modulated by the liquid crystal display element 10 is emitted as a p-wave. The light emitted from the liquid crystal display element 10 passes through the fourth surface 94, and substantially all light passes through the second surface 92 of the polarization half mirror surface, and the third surface 94.
Emitted from surface 93. When passing through the quarter-wave plate 6, the p-wave of linearly polarized light is converted into circularly polarized light, enters from the transmission surface 96 of the back mirror 17, is reflected by the reflection surface 97, exits from the transmission surface 96, and returns again. The light passes through the 波長 wavelength plate 6. At this time, the polarization direction is 90 ° with respect to the p-wave when the circularly polarized light is incident.
The light is converted into s-wave, which is rotated linearly polarized light, and again enters the polarization optical element 90. On the polarization half mirror surface 92, almost all light is reflected at a reflection angle of 45 °, and the polarization optical element 90
From the first surface 91, reaches the observer's eyeball, and presents an enlarged image of the reflective image display element 10 to the observer.

Hereinafter, the configuration parameters of the above-described first to fifth embodiments will be described.

Example 1 Surface Number Curvature Radius Interval Eccentricity Refractive Index Abbe Number Object Surface ∞ -1000.00 1 ∞ (Exit Pupil) 2 Free-form Surface Eccentricity (1) 1.4922 57.5 3 Free-form Surface Eccentricity (2) 1.4922 57.5 4 Free-form Surface Eccentricity ( 1) 1.4922 57.5 5 Free-form surface Eccentricity (3) Image plane ∞ Eccentricity (4) 7 Free-form surface Eccentricity (3) 1.4922 57.5 8 Free-form surface Eccentricity (1) 1.4922 57.5 9 Free-form surface Eccentricity (2) 10 -6.75 (Aspheric) eccentric (5) light source ∞ eccentricity (6) aspheric coefficients face ^{number: 10 K = -1.3472 × 10 1} A 4 = -4.4738 × 10 -3 A 6 = 4.7966 × 10 -4 A 8 = -3.5188 × 10 - ⁵ A ₁₀ = 1.1353 × 10 ^-6 Free-form surface C ₅ -3.4641 × 10 ^-3 C ₇ -4.6167 × 10 ^-3 C ₈ -1.0 380 × 10 ^-4 C ₁₀ 6.4921 × 10 ^-5 C ₁₂ -1.0386 × 10 ^-6 C ₁₄ 6.2825 × 10 ^-6 C ₁₆ -2.6279 × 10 ^-6 Free-form surface C ₅ -1.1917 × 10 ^-2 C ₇ -1.3399 × 10 ^-2 C ₈ 5.5902 × 10 ^-5 C ₁₀ 9.9924 × 10 ^-5 C ₁₂ 4.5147 × 10 ^-6 C ₁₄ -1.0236 × 10 ^-6 C ₁₆ -3.5173 × 10 ^-6 Free-form surface C ₅ -1.8257 × 10 ^-2 C ₇ -1.2487 × 10 ^-2 C ₈ -1.1011 × 10 ^-3 C ₁₀ 1.0622 × 10 ^-3 C ₁₂ 4.7881 × 10 ^-5 C ₁₄ -2.5937 × 10 ^-5 C ₁₆ 3.8442 × 10 ^-5 Eccentricity (1) X 0.00 Y 5.38 Z 17.49 α 16.71 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y 0.49 Z 24.61 α -14.73 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y 12.80 Z 20.50 α 83.99 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y 16.24 Z 22.52 α 58.67 β 0.00 γ 0.00 Eccentricity (5) X 0.00 Y- 3.37 Z 28.91 α -40.42 β 0.00 γ 0.00 Eccentricity (6) X 0.00 Y -0.99 Z 25.73 α -29.00 β 0.00 γ 0.00.

Example 2 Surface Number Curvature Radius Interval Eccentricity Refractive Index Abbe Number Object Surface -100 -1000.00 1 ∞ (Exit Pupil) 2 Freeform Surface Eccentricity (1) 1.4922 57.5 3 Freeform Surface Eccentricity (2) 1.4922 57.5 4 Freeform Surface Eccentricity ( 1) 1.4922 57.5 5 Free-form surface Eccentricity (3) Image plane 偏 Eccentricity (4) 7 Free-form surface Eccentricity (3) 1.4922 57.5 8 Free-form surface Eccentricity (1) 1.4922 57.5 9 Free-form surface Eccentricity (2) 10 5.96 2.50 Eccentricity (5) 1.5163 64.1 11 -64.05 12 -9.80 (Aspherical surface) Eccentricity (6) Light source 偏 Eccentricity (7) Aspherical surface coefficient Surface number: 12 K = -5.0694 x 10 ^-1 A ₄ = -4.8424 x 10 ^-5 A ₆ = 3.5920 × 10 ^-6 Free-form surface C ₅ -3.4641 × 10 ^-3 C ₇ -4.6167 × 10 ^-3 C ₈ -1.0 380 × 10 ^-4 C ₁₀ 6.4921 × 10 ^-5 C ₁₂ -1.0386 × 10 ^-6 C ₁₄ 6.2825 × 10 ^-6 C ₁₆ -2.6279 × 10 ^-6 Free-form surface C ₅ -1.1917 × 10 ^-2 C ₇ -1.3399 × 10 ^-2 C ₈ 5.5902 × 10 ^-5 C ₁₀ 9.9924 × 10 ^-5 C ₁₂ 4.5147 × 10 ^-6 C ₁₄ -1.0236 × 10 ^-6 C ₁₆ -3.5173 × 10 ^-6 Free-form surface C ₅ -1.8257 × 10 ^-2 C ₇ -1.2487 × 10 ^-2 C ₈ -1.1011 × 10 ^-3 C ₁₀ 1 .0622 × 10 ^-3 C ₁₂ 4.7881 × 10 ^-5 C ₁₄ -2.5937 × 10 ^-5 C ₁₆ 3.8442 × 10 ^-5 Eccentricity (1) X 0.00 Y 5.38 Z 17.49 α 16.71 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y 0.49 Z 24.61 α -14.73 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y 12.80 Z 20.50 α 83.99 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y 16.24 Z 22.52 α 58.67 β 0.00 γ 0.00 Eccentricity (5) X 0.00 Y 1.85 Z 26.61 α -52.17 β 0.00 γ 0.00 Eccentricity (6) X 0.00 Y -6.64 Z 28.56 α -25.44 β 0.00 γ 0.00 Eccentricity (7) X 0.00 Y -4.61 Z 25.74 α 26.64 β 0.00 γ 0.00.

Example 3 Surface Number Curvature Radius Interval Eccentricity Refractive Index Abbe Number Object Surface -100 -1000.00 1 ∞ (Exit Pupil) 2 Freeform Surface Eccentricity (1) 1.5254 56.2 3 Freeform Surface Eccentricity (2) 1.5254 56.2 4 Freeform Surface Eccentricity ( 1) Image surface ∞ Eccentricity (3) 6 Free-form surface Eccentricity (1) 1.5254 56.2 7 Free-form surface Eccentricity (2) 8 Anamorphic surface Eccentricity (4) Light source ∞ Eccentricity (5) Anamorphic surface Rx = -7.75 Ry = -10.28 Kx = 0.0000 Ky = 0.0000 R1 = -2.9628 × 10 ^-4 R2 = -1.7254 × 10 ^-8 P1 = 2.5451 × 10 ^-1 P2 = -9.5015 × 10 ^-1 Free-form surface C ₅ 3.4330 × 10 ^-2 C _{^{7 2.9001 × 10 -2 C 8 -1.9945}} × 10 -4 C 10 -3.0127 × 10 -4 C 12 -2.3176 × 10 -5 C 14 2.8944 × 10 -5 C 16 4.4995 × 10 -6 C 17 1.3547 × 10 - ⁶ C ₁₉ -3.1884 × 10 ^-7 C ₂₁ 1.0836 × 10 ^-6 Free-form surface C ₅ -9.2001 × 10 ^-2 C ₇ 1.4217 × 10 ^-2 C ₈ -2.3556 × 10 ^-3 C ₁₀ 1.6596 × 10 ^-3 C ₁₂ -2.1214 × 10 ^-5 C ₁₄ -1.3810 × 10 ^-6 C ₁₆ 1.8014 × 10 ^-5 C ₁₇ -1.3047 × 10 ^-7 C ₁₉ -2.2559 × 10 ^-6 C ₂₁ -8.9263 × 10 ^-8 Eccentricity (1) X 0.00 Y -2.17 Z 25.70 α -3.60 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y 22.43 Z 48.54 α 29.81 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y 14.96 Z 27.76 α -46.70 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y -1.29 Z 49.06 α -13.76 β 0.00 γ 0.00 Eccentricity (5) X 0.00 Y -2.50 Z 44.21 α -35.00 β 0.00 γ 0.00.

Example 4 Surface Number Curvature Radius Interval Eccentricity Refractive Index Abbe Number Object Surface ∞ -500.00 1 ∞ (Exit Pupil) 2 Free-form Surface Eccentricity (1) 1.5254 56.2 3 Free-form Surface Eccentricity (2) 1.5254 56.2 4 Free-form Surface Eccentricity ( 1) 1.5254 56.2 5 Free-form surface Eccentricity (3) 1.5254 56.2 6 Free-form surface Eccentricity (4) Image surface 偏 Eccentricity (5) 8 Free-form surface Eccentricity (4) 1.5254 56.2 9 Free-form surface Eccentricity (3) 1.5254 56.2 10 Free-form surface Eccentricity ( 1) 1.5254 56.2 11 free curved eccentric (2) 12 free curved eccentric (6) light source ∞ eccentricity (7) free curved surface ^{_{C 5 -5.8240 × 10 -4 C 7}} -9.1541 × 10 -3 C 8 -6.5889 × 10 - ⁵ C ₁₀ -1.6698 × 10 ^-4 C ₁₂ -4.2380 × 10 ^-7 C ₁₄ -3.7726 × 10 ^-6 C ₁₆ 2.7951 × 10 ^-6 C ₁₇ 2.9801 × 10 ^-10 C ₁₉ -7.7228 × 10 ^-8 C ₂₁ 1.2588 × 10 ^-7 Free-form surface C ₅ -4.3831 × 10 ^-3 C ₇ -8.7087 × 10 ^-3 C ₈ -5.4 360 × 10 ^-5 C ₁₀ -2.5394 × 10 ^-5 C ₁₂ 1.1420 × 10 ^-6 C ₁₄ -1.1045 × 10 ^-6 C ₁₆ 7.5556 × 10 ^-8 C ₁₇ -3.0899 × 10 ^-8 C ₁₉ -2.6370 × 10 ^-8 C ₂₁ -1.2114 × 10 ^-8 Free-form surface C ₅ -5.9115 × 10 ^-4 C ₇ -3.8122 × 10 ^-3 C ₈ -8.9978 × 10 ^-5 C ₁₀ -9.9086 × 10 ^-5 C ₁₂ -7.3098 × 10 ^-7 C ₁₄ -1.4829 × 10 ^-6 C ₁₆ 1.1213 × 10 ^-6 C ₁₇ 3.6498 × 10 ^-8 C ₁₉ -3.8757 × 10 ^-8 C ₂₁ 3.2832 × 10 ^-7 Free-form surface C ₅ 6.9509 × 10 ^-3 C ₇ 1.4423 × 10 ^-2 C ₈ -2.8052 × 10 ^-4 C ₁₀ -4.4112 × 10 ^-4 C ₁₂ 3.4813 × 10 ^-5 C ₁₄ -8.1159 × 10 ^-5 C ₁₆ -2.4314 × 10 ^-5 C ₁₇ -9.6514 × 10 ^-7 C ₁₉ -4.7714 × 10 ^-6 C ₂₁ 5.7643 × 10 ^-6 Free Curved surface C ₅ -4.7686 × 10 ^-2 C ₇ -5.0227 × 10 ^-2 C ₈ -1.1648 × 10 ^-3 C ₁₀ -1.5945 × 10 ^-3 Eccentricity (1) X 0.00 Y 9.99 Z 38.60 α -0.32 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y 0.00 Z 47.87 α -26.60 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y 30.02 Z 51.90 α 5.63 β 0.00 γ 0.00 Eccentricity (4) X 0.00 Y 38.22 Z 42.79 α -43.70 β 0.00 γ 0.00 Eccentricity (5) X 0.00 Y 39.81 Z 40.85 α -38.00 β 0.00 γ 0.00 Eccentricity (6) X 0.00 Y -7.48 Z 50.13 α -75.59 β 0.00 γ 0.00 Eccentricity (7) X 0.00 Y -1.80 Z 49.23 α -62.06 β 0.00 γ 0.00.

Example 5 Surface Number Curvature Radius Interval Eccentricity Refractive Index Abbe Number Object Surface ∞ -1000.00 1 ∞ (Exit Pupil) 20.00 2 ∞ 11.50 1.4922 57.5 3 ∞ -12.00 Eccentricity (1) 1.4922 57.5 4 ∞ -1.00 5 ∞- 2.00 1.4922 57.5 6 ∞ -1.00 7 ∞ -4.00 1.4922 57.5 8 100.00 4.00 1.4922 57.5 9 ∞ 1.00 10 ∞ 2.00 1.4922 57.5 11 ∞ 1.00 12 ∞ 24.00 1.4922 57.5 13 ∞ 10.27 Image plane ∞ -10.27 15 ∞ -12.00 1.4922 57.5 16 ∞ 15.00 Eccentricity (2) 1.4922 57.5 17 -36.23 9.00 18 -46.69 -12.50 Eccentricity (3) (Aspheric) Light source ∞ Aspheric coefficient Surface number: 18 K = 0.0000 A ₄ = -3.3586 × 10 ^-6 A ₆ =- 6.0354 × 10 ^-10 A ₈ = 2.1163 × 10 ^-10 A ₁₀ = 3.7515 × 10 ^-12 Eccentricity (1) X 0.00 Y 0.00 Z 0.00 α 45.00 β 0.00 γ 0.00 Eccentricity (2) X 0.00 Y 0.00 Z 0.00 α -45.00 β 0.00 γ 0.00 Eccentricity (3) X 0.00 Y 0.52 Z 0.00 α 25.63 β 0.00 γ 0.00.

In the above embodiments, the free-form surface of the definition formula (a) is used, but it goes without saying that any surface of any definition can be used. However, it is needless to say that an observation optical system in which aberration is well corrected can be obtained irrespective of the definition formula.

A pair of left and right pairs of the observation optical system and the image display element of the image display apparatus of the present invention as described above is prepared, and they are supported by being separated from each other by the eye distance, so that they can be observed with both eyes. Alternatively, it can be configured as a portable image display device such as a head mounted image display device. FIG. 15 shows the overall configuration of an example of such a portable image display device. The display device body 100 is provided with a pair of left and right eyepiece optical systems as described above, and an image display element composed of a liquid crystal display element is arranged on the image plane corresponding to the pair. A temporal frame 101 as shown in the figure is provided on the main body 100 continuously on the left and right sides, the temporal frames 101 on both sides are connected by a parietal frame 102, and a leaf spring 103 is provided between the temporal frames 101 on both sides.
A rear frame 104 is provided through the rear of the display device main body 100. The rear frame 104 is placed on the back of both ears of the observer like vines of glasses, and the parietal frame 102 is placed on the top of the observer. Can be held in front of the observer. Note that a parietal pad 10 made of an elastic body such as a sponge is provided inside the parietal frame 102.
A similar pad is also attached to the inside of the rear frame 104 so that when the display device is attached to the head, a feeling of strangeness is not felt.

The speaker 1 is mounted on the rear frame 104.
06 is provided so that stereoscopic sound can be heard together with image observation. Thus, the speaker 1
Since the playback device 108 such as a portable video cassette or the like is connected to the display device main body 100 having the video signal transmission code 107 through the video / audio transmission code 107, the observer can attach the playback device 108 to the belt portion or the like as shown in the figure. The video and sound can be enjoyed while being held at an arbitrary position. The reference numeral 109 denotes an adjustment unit such as a switch and a volume of the playback device 108. Note that electronic components such as a video processing / audio processing circuit are built in the top frame 102.

The cord 107 may have a jack at the tip so that it can be attached to an existing video deck or the like. Furthermore, it is connected to a tuner for TV radio wave reception,
It may be used for viewing, or may be connected to a computer to receive computer graphics images, message images from the computer, and the like. Also, in order to reject an obstructive code, an antenna may be connected to receive an external signal by radio waves.

Although the image display device of the present invention has been described based on several embodiments, the present invention is not limited to these embodiments, and various modifications can be made.

The above-described image display device of the present invention can be configured, for example, as follows.

[1] An image display apparatus comprising: a light source that emits illumination light; an image display element that displays an image by reflecting the illumination light; and an observation optical system that guides the image to an observer's eyeball. A polarizing half-mirror surface disposed close to the outside of a reflecting surface having the power of the observation optical system, wherein the reflecting surface transmits light in a specific polarization direction and reflects light in a polarization direction substantially orthogonal thereto. An image display device comprising:

[2] The illumination light path through which the light beam emitted from the light source passes through the reflecting surface and enters the image display device, and the light beam reflected by the image display device passes through the reflecting surface to the observer's eyeball. The observation optical system described above, wherein the observation optical system is formed such that a guided observation optical path forms a reciprocating optical path between the reflection surface and the image display element.
The image display device as described in the above.

[3] The observation optical system has at least
3. The image display device according to the above item 1 or 2, wherein the space defined by the surface is formed by a prism body filled with a medium having a refractive index larger than 1.

[4] The image display apparatus according to the above item 3, wherein at least one surface of the observation optical system is an aspheric surface decentered with respect to an optical axis.

[5] The image display apparatus according to the above item 2, wherein at least one surface of the observation optical system is a rotationally asymmetric aspheric surface decentered with respect to an optical axis.

[6] The observation optical system includes a non-polarization half mirror surface inclined at approximately 45 ° with respect to the image display element,
3. The image display device according to the above item 1 or 2, wherein the image display device comprises a concave mirror facing the image display element.

[7] The observation optical system has a substantially rectangular prism shape in which the non-polarization half mirror surface is sandwiched by a medium having a refractive index larger than 1, and has a concave mirror surface at a position facing the image display element. 7. The image display device according to the above 1, 2, or 6, wherein

[8] Any one of the above items 1 to 7, wherein a polarizing plate is disposed between the light source and the reflection surface.
An image display device according to the item.

[0092]

[9] A polarizing plate is disposed between the observer's eyeball and the observation optical system.
The image display device according to claim 1.

[10] The observation optical system is composed of an eccentric prism filled with a medium having a refractive index larger than 1 and has a space defined by at least two surfaces decentered with respect to the optical axis, and is arranged on the observer side. The light source is provided outside the second surface when the first surface is a transmission surface and the second surface is a concave mirror surface opposite to the first surface and is a polarization half mirror surface. 3. The image display device according to 1 or 2 above.

[11] The observation optical system is composed of an eccentric prism filled with a medium having a refractive index of greater than 1 in a space constituted by at least three surfaces decentered with respect to the optical axis, and is arranged on the observer side. A first surface having a transmitting and reflecting action, a second surface facing the first surface, being a polarizing half mirror surface and being a concave mirror surface, and a third surface being a transmitting surface proximate to and facing the image display element. 3. The image display device according to claim 1, wherein the light source is disposed outside the second surface.

[12] The observation optical system is composed of an eccentric prism filled with a medium having a refractive index greater than 1 and has a space composed of at least four surfaces decentered with respect to the optical axis, and is arranged on the observer side. A first surface having a transmitting and reflecting action, a second surface facing the first surface and being a polarizing half mirror surface and a concave mirror surface, a third surface being a reflection surface adjacent to the second surface and the image display; The image display device according to claim 1 or 2, wherein the light source is provided outside the second surface when the fourth surface is a transmission surface that is opposed to and close to the element.

[13] The observation optical system is composed of an eccentric prism filled with a medium having a refractive index of greater than 1 in a space composed of at least four surfaces decentered with respect to the optical axis, and is arranged on the observer side. A first surface having a transmitting and reflecting action, a second surface facing the first surface and a concave mirror surface, a reflecting surface adjacent to the second surface and a third surface being a transmitting surface, facing the third surface; The image display according to claim 1 or 2, wherein the light source is provided outside the fourth surface when the fourth surface is a polarization half mirror surface having power adjacent to the first surface. apparatus.

[14] At least one of the incident surface on which the light from the image display element enters the observation optical system and the exit surface from which the light exits the observer's eyeball is constituted by a surface having power. Any one of the above 10 to 13
An image display device according to the item.

[15] The image display device as described in any one of [1] to [14] above, further comprising an illuminating unit that emits the illumination light emitted from the light source in one direction.

[16] The illumination means may be a reflector disposed behind the light source.
The image display device as described in the above.

[17] The image display device as described in the above item 15 or 16, wherein the illuminating means is a refraction optical system disposed immediately after the light source.

[18] A light source that emits illumination light, an image display element that displays an image by reflecting the illumination light,
In an image display device including an observation optical system that guides the image to an observer's eyeball, the observation optical system has a polarization half mirror surface inclined at approximately 45 ° with respect to the image display element,
A configuration in which an image of the image display element is magnified and projected on an observer's eyeball as a magnified virtual image by a concave mirror disposed opposite to the image display element with the polarization half mirror surface interposed therebetween, and A polarizing plate is provided at a position facing the observer's eyeball with an optical system interposed therebetween, and a polarizing plate is provided between the light source and the observation optical system to change the polarization state to light polarized only in a specific direction. An image display device, wherein a quarter-wave plate is provided between polarizing half mirror surfaces.

[19] The polarizing half mirror surface is included in an optical element having a right-angle prism shape sandwiching the polarizing half mirror surface with a triangular prism made of a medium having a refractive index larger than 1. 19. The image display device according to the above item 18, wherein

[20] The image display device as described in the above item 18 or 19, wherein a polarizing plate is arranged between the observer's eyeball and the observation optical system.

[21] The image display apparatus according to the above item 19, wherein the light source is provided with an illuminating means for emitting illumination light emitted from the light source in substantially one direction.

[22] The image display apparatus according to the above item 21, wherein the illuminating means is a reflector disposed behind the light source.

[23] The illumination device as described in item 2 above, wherein the illuminating means is a refractive optical system disposed immediately after the light source.
23. The image display device according to 1 or 22.

[0107]

As is apparent from the above description, according to the present invention, even with a relatively simple device configuration, a bright image of the reflection type image display element is presented to the observer, and the observer can clearly see the image. An image display device capable of observing a clear image can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating the concept of an image display device according to a first embodiment of the present invention.

FIG. 2 is a sectional view illustrating the concept of an image display device according to a second embodiment of the present invention.

FIG. 3 is a sectional view illustrating the concept of an image display device according to a third embodiment of the present invention.

FIG. 4 is a sectional view illustrating the concept of an image display device according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view illustrating the concept of an image display device according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view illustrating the concept of an image display device according to a sixth embodiment of the present invention.

FIG. 7 is a sectional view illustrating the concept of an image display device according to a seventh embodiment of the present invention.

FIG. 8 is a sectional view illustrating the concept of an image display device according to an eighth embodiment of the present invention.

FIG. 9 is a cross-sectional view illustrating the concept of an image display device according to a ninth embodiment of the present invention.

FIG. 10 is a cross-sectional view of the image display device according to the first embodiment of the present invention.

FIG. 11 is a sectional view of an image display device according to a second embodiment of the present invention.

FIG. 12 is a sectional view of an image display device according to a third embodiment of the present invention.

FIG. 13 is a sectional view of an image display device according to a fourth embodiment of the present invention.

FIG. 14 is a sectional view of an image display device according to a fifth embodiment of the present invention.

FIG. 15 is a diagram showing an overall configuration of an example of a portable image display device incorporating an observation optical system according to the present invention.

FIG. 16 is a diagram showing an optical system of an image display device using a conventional reflective LCD.

FIG. 17 is a diagram illustrating a configuration of a known DMD.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... Optical axis (on-axis principal ray) 3 ... Observation optical system 4 ... Observer's eyeball 5 ... Illumination optical system (reflection plate) 5 ₁ ... Concave mirror 52 ₂ ... Biconvex positive lens 6 ... λ / 4 plate 7 ... Polarizing plate 8 ... Backside mirror coated with polarizing half mirror 9 ... Non-polarizing half mirror 10 ... Image display element 11 ... First surface of observation optical system 12 ... Second surface of observation optical system 16 ... Polarization half mirror 17 ... Mirror coating Back mirror 19 ... exit pupil 21 ... first surface of observation optical system 22 ... second surface of observation optical system 23 ... third surface of observation optical system 31 ... first surface of observation optical system 32 ... first of observation optical system 2 surface 41: first surface of observation optical system 42: second surface of observation optical system 43: third surface of observation optical system 44: fourth surface of observation optical system 51: first surface of observation optical system 52: observation Second surface of optical system 61: first surface of observation optical system 62: second surface of observation optical system 6 ... Third surface 64 of the observation optical system 64 Fourth surface 71 of the observation optical system 71 First surface 72 of the observation optical system 73 Second surface 73 of the observation optical system 73 Third surface 74 of the observation optical system 74 Fourth surface 81: first surface of observation optical system 82: second surface of observation optical system 90: polarizing optical element 91: first surface of observation optical system 92: second surface of observation optical system 93: observation optical system Third surface 94: fourth surface of observation optical system 95: fifth surface of observation optical system 96: sixth surface of observation optical system 97: seventh surface of observation optical system 100: display device body 101: temporal frame 102 … Top frame 103… leaf spring 104… rear frame 105… top pad 106… speaker 107… video and audio transmission code 108… playback device 109… adjustment section for switches, volume, etc.

Claims (3)

[Claims] 1. An image display apparatus comprising: a light source that emits illumination light; an image display element that displays an image by reflecting the illumination light; and an observation optical system that guides the image to an observer's eyeball. Is disposed in proximity to a reflection surface having the power of the observation optical system, wherein the reflection surface transmits light in a specific polarization direction and reflects light in a polarization direction substantially orthogonal to the polarization half mirror surface. An image display device, comprising: 2. An illumination light path through which a light beam emitted from the light source passes through the reflection surface and enters the image display element, and a light beam reflected by the image display element is guided to an observer's eye via the reflection surface. 2. The image display device according to claim 1, wherein the observation optical system is formed such that the observation optical path formed forms a reciprocating optical path between the reflection surface and the image display element. 3. An image display apparatus comprising: a light source that emits illumination light; an image display element that displays an image by reflecting the illumination light; and an observation optical system that guides the image to an observer's eyeball. The system is approximately 45 ° with respect to the image display element.
An image of the image display element is magnified and projected to the observer's eyeball as a magnified virtual image by a concave mirror arranged to face the image display element with the polarization half mirror surface interposed therebetween with an inclined polarization half mirror surface. Wherein the light source is disposed at a position facing the observer's eyeball with the observation optical system interposed therebetween, and between the light source and the observation optical system, changes the polarization state into light polarized only in a specific direction. An image display device comprising: a polarizing plate; and a quarter-wave plate provided between the concave mirror and the polarizing half mirror surface.