JPH11237584A - Picture display device, head-mount type display using the picture display device, and video communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a picture display device capable of reducing the thickness and weight of an optical device for enlarging and displaying an image and displaying pictures of high luminance and high quality, a head-mount type display(HMD) using the picture display device and a video communication equipment. SOLUTION: Exist light constituting a linearly polarized light from a liquid crystal display 22 is converted into circularly polarized light by wide band wavelength plates 23, 24 and sent to wide band wavelength plates 27, 26 arranged near a thin film reflection type polarizing film 25. When the circularly polarizesd light is converted into linearly polarized light by the plates 27, 26 and the linearly polarized light is allowed to coincide with the polarized light reflection axis of the film 25, reflected light is converted into circularly polarized light again by the plates 26, 27 and sent to a reflection/refraction means 28, which execute conversion and reflection to form an enlarged virtual image. The direction of the circularly polarized light is inverted by reflection and light allowed to exit from the plates 26, 27 is converted into linearly polarized light having a polarization direction rectangular to that of incidence, passes through the film 25 and finally reaches the eyes. Consequently, a loss due to the optical system is not generated, the spectral transmissivity is uniformed with the respective wide band wavelength plates, unnecessary reflection is reduced, and the contrast of a picture is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display apparatus using a polarizing optical system, and more particularly, to enlarge an image displayed on an image display element by catadioptric means to present a virtual image to an observer. In the image display device, a small and lightweight magnifying optical device is configured by a catadioptric means and a polarizing optical system,
A head-mounted display using this video display device (Hea
d MountedDisplay: hereinafter referred to as “HMD”), and a video communication device using the video display device.

[0002]

2. Description of the Related Art In recent years, an HMD having a configuration as shown in FIG. 30 has attracted attention as a portable display. The entire structure is housed in an eyeglass-shaped case 301 and mounted on the head for use. The constituent elements are arranged in the order of a backlight 302, a liquid crystal panel 303, and a lens 304 from the outside in a portion corresponding to a lens of the eyeglasses. Thus, the viewer 305 wearing the device can view the enlarged large-screen image of the liquid crystal panel 303. Until now, there have been many uses for industrial purposes such as research on virtual reality, but in the future, home and portable AV devices (TV,
R, DVD, etc.)
May be widely spread in general. Then, higher image quality, smaller size and lighter weight of the HMD become even more important.

In terms of miniaturization among the development elements of the HMD, it is necessary to minimize the amount of projection from the face of the observer forward in order to realize a comfortable wearing feeling. Was desired.

[0004] As a small and light optical system in a conventional HMD, for example, an optical system as shown in FIG. 32 is used. This is done by installing the backlight 321 and the liquid crystal panel 322 on the upper surface, changing the direction of the light beam emitted from the liquid crystal panel 322 to the outward direction with the semi-transparent mirror 323, enlarging and reflecting the light with the concave mirror 324, and then changing the semi-transparent mirror 323 again. Pass through to the eye 325 of the observer.

According to this, the semi-transparent mirror 323 and the concave mirror 3
Since the optical path is folded at 24, the size of the optical system can be reduced as compared with the case where the optical elements are arranged linearly.

[0006] Among the development elements of the HMD, liquid crystal panels have been improved in image quality and reduced in size, but required performance has not been achieved in optical systems. As one conventional example of such an optical system, there is a method described in JP-A-6-59217, one of which is shown in FIG. Explaining the configuration and operation of the optical system shown in FIG. 31, a liquid crystal display element (display) 312 is installed on the upper surface, and a light beam emitted from the liquid crystal display element 312 is reflected and expanded by a polarizing beam splitter 313 and a concave mirror 315. After that, the light again passes through the polarizing beam splitter 313 and reaches the eye 316. At this time, since the light beam emitted from the liquid crystal display element 312 is set to the polarized light reflected in the polarization beam splitter 313, the light beam is guided to the concave mirror 315. The quarter-wave plate 314 provided between the polarizing beam splitter 313 and the concave mirror 315 has a slow axis inclined 45 degrees with respect to the direction of linearly polarized light, is reflected by the concave mirror 315, and The direction of polarization of light coming out of the wave plate 314 is set to be rotated by 90 degrees with respect to the time of incidence. Accordingly, the light beam enlarged by the concave mirror 315 passes through the polarizing beam splitter 313 and reaches the observer's eye 316.

[0007]

However, in the case of the above-described conventional HMD optical system shown in FIG. 32, the light beam emitted from the liquid crystal panel 322 is transmitted through the semi-transparent mirror 323 before reaching the eye 325 of the observer. Passes twice, so that the luminance is 1
Since the frequency is reduced to 1/2, the frequency is attenuated to 1/4 as a whole. Furthermore, the multilayer coating used for the semi-transparent mirror 323 has a problem that it is difficult to uniformly produce the reflection and transmission spectrum characteristics in the visible light range, so that the color reproducibility deteriorates.

Further, in the case of the prior art illustrated in FIG. 31, the following problem occurs. 1. Aberration (field curvature, astigmatism) characteristics of concave mirror When creating a virtual image enlarged by a concave mirror, the field curvature or astigmatism tends to increase, and the resolution of the peripheral portion of the screen is impaired. In addition, it is necessary to reduce the radius of curvature in order to secure a necessary magnification, and the thickness of the concave mirror increases. 2. Since the polarizing beam splitter has been manufactured by a multilayer coating, there are the following four problems. (1) It is difficult to uniformly produce the wavelength characteristics and the angle characteristics of the polarizing beam splitter, and the image is colored, which causes a deterioration in color reproducibility. (2) Since the polarization beam splitter has a characteristic of reflecting an S wave and transmitting a P wave, the degree of freedom in designing polarization is limited. (3) Since the deflection beam splitter is often manufactured in a prism and is heavy, it is not suitable for a lightweight HMD. (4) In general, multilayer coatings are expensive and
Not suitable for MD. 3. Spectral Characteristics of Wave Plate Retardation The retardation-spectral characteristics of commonly used wavelength waves are not uniform. Therefore, when the 従 来 wavelength plate is used alone as in the above-described conventional example, there is a problem that the transmittance of the optical system is reduced at wavelengths other than the design wavelength. 4. Unnecessary reflection increase and cost increase when filter is inserted When a quarter-wave plate is inserted between the polarizing beam splitter and the concave mirror, unnecessary reflection on the surface of the quarter-wave plate and the surface of the indicator substrate such as glass increases, and contrast increases. This causes problems such as deterioration. In addition, the quarter-wave plate must be supported independently of the polarizing beam splitter and the concave mirror, which complicates the mechanism and increases the cost. 5. Restriction of Viewing Angle In the above-described conventional method, if the viewing angle is increased, the focal length cannot be secured, so that there is a limit to the realizable viewing angle. Considering that an image with a wide viewing angle is also a feature of the HMD, an optical system that is thin even with a wide viewing angle is required.

The present invention has been made in view of the above-mentioned problems in the prior art, and realizes a thin and lightweight optical device for enlarging an image and presenting it to an observer, and has high brightness and high brightness. An object of the present invention is to provide an image display device capable of presenting an image of high quality, an HMD and a video communication device using the image display device.

[0010]

According to a first aspect of the present invention, there is provided an image display apparatus for enlarging an image displayed on an image display section using an optical enlarging means having a reflective element and presenting the image as a virtual image. An image display comprising: a thin-film reflective polarizing film that selectively reflects or transmits polarized light according to the polarization direction; and a wave plate provided in a reciprocating optical path between the thin-film reflective polarizing film and the optical magnification unit having the reflective element. In the apparatus, the optical magnifying means having the reflection element constitutes a catadioptric means having a total reflection coating, and the wave plate is formed by bonding a quarter wave plate and a half wave plate at a specific angle to form a wide band wave plate. It is characterized by.

According to a second aspect of the present invention, in the image display device according to the first aspect, the display surface of the image display unit and the catadioptric means are arranged at an angle of 90 degrees, and the thin-film reflective polarizing film is provided. It is characterized in that the display device and the reflection / refraction means of the image display section are arranged at an inclination of 45 degrees.

According to a third aspect of the present invention, in the image display device according to the first aspect, the display element of the image display section and the catadioptric means are arranged at an angle of 100 degrees or more, and the thin-film reflective polarizing film is provided. Are arranged with an inclination of 40 degrees or less with respect to the image display element and the catadioptric means.

According to a fourth aspect of the present invention, in the image display device according to any one of the first to third aspects, the equivalent slow axis of the broadband wave plate is -55 to the polarization transmission axis of the thin-film reflective polarizing film. It is characterized by being arranged at an angle of -35 degrees or 35 to 55 degrees.

According to a fifth aspect of the present invention, in the image display device according to any one of the first to fourth aspects, the equivalent slow axis of the broadband wavelength plate is -55 to -35 with respect to the polarization transmission axis on the liquid crystal display emission side. Or at an angle of 35 to 55 degrees.

According to a sixth aspect of the present invention, in the image display device according to any one of the first to third aspects, the catadioptric means is arranged to adjust a center of a screen of the image display unit and a center of a pupil of the observer. It is characterized in that it is arranged to be inclined with respect to the optical path to be connected. Thereby, the central axis of the catadioptric means is inclined with respect to the optical path connecting the center of the screen of the image display element and the center of the pupil of the observer, so that the device can be made thinner and the specific direction can be reduced. Since the thin-film reflective polarizing film that transmits linearly polarized light and reflects the linearly polarized light in the orthogonal direction and the broadband wavelength plate are provided, it is possible to improve the image without lowering the luminance.

According to a seventh aspect of the present invention, there is provided an image display apparatus for enlarging an image displayed on an image display section by using an optical enlarging means having a reflecting element and presenting the image as a virtual image, wherein linearly polarized light is selected according to a polarization direction. An image display apparatus comprising: a thin-film reflective polarizing film that reflects or transmits light; and a wave plate provided in a reciprocating optical path between the thin-film reflective polarizing film and an optical magnification unit having a reflective element. The optical magnifying means constitutes a catadioptric means coated with a semi-transparent mirror, and the surface of the image display section, the thin-film reflective polarizing film and the catadioptric means are arranged in parallel.

According to an eighth aspect of the present invention, in the image display device of the seventh aspect, the wave plate is a quarter wave plate or one wave plate.
The present invention is characterized in that a 波長 wavelength plate and a 波長 wavelength plate are bonded at a specific angle to form a broadband wavelength plate.

According to a ninth aspect of the present invention, in the image display device according to the sixth or seventh aspect, the slow axis of the １ ／ wavelength plate or the equivalent slow axis of the broadband wavelength plate corresponds to the thin film reflective polarizing film. Polarization transmission axis and -55 to -35 degrees or 35 to 5
It is characterized by being arranged at an angle of 5 degrees.

According to a tenth aspect of the present invention, in the image display device according to any one of the seventh to ninth aspects, a polarizing plate is provided at an output end of the image enlarged by the catadioptric means. Things.

The invention according to claim 11 is the invention according to claims 1 to 10
The image display device according to any one of the above, wherein the image display unit is a liquid crystal display.

The twelfth aspect of the present invention provides the first to eleventh aspects.
An HMD comprising: a glasses-type case incorporating the image display device according to any one of the inventions; Is provided.

The invention of claim 13 is the invention of claims 1 to 12
A video communication device comprising a telephone having a built-in image display device according to any one of the above inventions, wherein video communication is enabled in addition to voice communication.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) This embodiment of the image display apparatus according to the present invention comprises an image display element, a thin-film reflective polarizing film for selectively reflecting or transmitting linearly polarized light depending on the polarization direction, and A broadband wave plate and a catadioptric means in which one surface of the refracting means is totally reflected coated are used. With respect to the thin-film reflective polarizing film, the merits of using the thin-film reflective polarizing film in this apparatus as compared with the conventional polarizing beam splitter are as follows. (1) Since the wavelength characteristics and the angle characteristics are uniform, the spectral transmittance of the optical system can be improved, and the color reproducibility of the display can be improved. (2) The polarization beam splitter has characteristics of reflecting the S wave and transmitting the P wave depending on the direction in which the splitter is tilted, so that the design of the polarization direction is restricted. Since the film itself has anisotropy, it is possible to reflect polarized light in a designed direction and transmit polarized light orthogonal to the designed direction according to the direction in which the film is arranged, regardless of the direction in which the film is tilted. Therefore, the degree of freedom in polarization design is large. (3) Since the thin-film reflective polarizing film is in the form of a film, it is sufficiently lightweight, and is suitable for a lightweight HMD. (4) Since the thin-film reflective polarizing film can be mass-produced and is inexpensive, it is suitable for a consumer HMD.

The catadioptric means, in which one surface of the deflecting means is totally reflected, can realize the same optical power with a reduced thickness as compared with a simple concave mirror, thus contributing to a reduction in the thickness of the optical system and reducing the field curvature. Therefore, an enlarged image with low aberration can be realized. Further, if the aberration correction is performed using the refraction surface on the side not having the total reflection coating, the aberration can be further reduced. Therefore, if the above two measures are used,
A high-quality HMD can be realized. Further, the use of a broadband wave plate can achieve a uniform spectral transmittance. Therefore, a high-quality HMD can be realized by these means.

(Embodiment 2) Further, the present embodiment of the image display apparatus according to the present invention comprises an image display element, a thin-film reflective deflection film for selectively reflecting or transmitting linearly polarized light depending on the polarization direction, and a wave plate. And a catadioptric means in which one side of the refracting means is totally reflected coated. And
The image display element and the catadioptric means are arranged at an angle of about 90 degrees, and the thin-film reflective polarizing film is arranged with an inclination of about 45 degrees with respect to the image display element and the catadioptric means. I have. Since this arrangement is a so-called coaxial system in which the catadioptric means is used from the direction along the optical axis, an optical system with less aberration can be realized using an axially symmetric lens which is easy to manufacture.

(Embodiment 3) Further, the present embodiment of the image display apparatus according to the present invention comprises an image display element, a thin film reflective polarizing film for selectively reflecting or transmitting linearly polarized light depending on the polarization direction, and a wave plate. And a catadioptric means in which one surface of the refracting means is totally reflected coated. The image display element and the catadioptric means are arranged at an angle of 100 degrees or more, and the thin-film reflective polarizing film is arranged with an inclination of 40 degrees or less with respect to the image display element and the catadioptric means. I have. With this arrangement, the thickness of the optical system can be reduced and a thin HMD can be realized as compared with the case where the image display device and the catadioptric means are arranged at an angle of about 90 degrees. However, the aberration tends to increase as compared with the case where the image display element and the catadioptric means are arranged at an angle of about 90 degrees. The angle can be selected.

(Embodiment 4) Further, in this embodiment of the image display apparatus according to the present invention, as shown in FIG. 1, the liquid crystal display 12 selectively reflects or transmits linearly polarized light according to the polarization direction. And a reflection / refraction means 16 having a total reflection coating 17 on one surface of the refraction means.
Note that the liquid crystal display 12 is illuminated by the backlight 11. The wave plate is a quarter wave plate 15.
A half-wave plate 14 and a half-wave plate 14 attached at a specific angle, and the wave plates 14 and 15 are disposed between the thin-film reflective polarizing film 13 and the catadioptric means 16; The equivalent slow axis of the broadband wave plates 14 and 15 is -55 to -3 with the polarization transmission axis of the thin-film reflective polarizing film 13.
They are arranged at an angle of 5 degrees or 35-55 degrees.

This optical system operates as follows. The light emitted from the liquid crystal display 12 is converted into linearly polarized light in a specific direction by a polarizing plate provided in the liquid crystal display 12. This light beam is reflected by the thin-film reflective polarizing film 13 and guided to the broadband wave plates 14 and 15. The purpose of the wave plates 14 and 15 is to convert linearly polarized light into circularly polarized light, and the broadband wave plates 14 and 15 are arranged to achieve this purpose. Broadband wave plate 1
The equivalent slow axes 4 and 15 are defined as specific axes in the wavelength plate that are converted to circularly polarized light when set at 45 degrees with the polarization direction of linearly polarized light at the design wavelength. Therefore, at the design wavelength, the broadband wave plates 14 and 15 change the slow axis or the equivalent slow axis to + or -4 with respect to the polarization direction.
It may be set at 5 degrees. However, when desired characteristics are to be obtained in a certain wavelength band, the angle of the slow axis or the equivalent slow axis with respect to the polarization direction is changed from ± 45 degrees to about ± 1.
It is necessary to adjust the angle in the range of 0 degrees.

Here, the light beams that have passed through the broadband wave plates 14 and 15 are converted by the catadioptric means 16 so as to form an enlarged virtual image, reflected, and returned to the wave plate again. Then, the circularly polarized light is again converted into the linearly polarized light. However, as is well known in the optical field, the direction of the circularly polarized light is inverted by reflection. It becomes linearly polarized light having a polarization direction that is orthogonal. On the other hand, the thin-film reflective deflecting film 13 has a characteristic of reflecting linearly polarized light in a specific direction and passing linearly polarized light in a direction perpendicular to the specific direction. Therefore, the broadband wave plate 1
The light emitted from each of the thin film reflective polarizing films 13 and
And finally reaches the user's eyes 18.

As described above, the present display device is different from the display device according to the second or third embodiment in that the type and the position of the wave plate are limited so that the loss of the optical system can be eliminated in principle and the half mirror or the like can be used. The efficiency is improved as compared with the case of using. Further, a means for making the spectral transmittance uniform by using a broadband wave plate is provided. Therefore, a high quality HMD can be realized by using these means.

(Embodiment 5) FIG. 2 shows another embodiment of the image display apparatus according to the present invention. As shown in FIG. 2, the liquid crystal display 22, a thin-film reflective polarizing film 25 for selectively reflecting or transmitting linearly polarized light depending on the polarization direction, wave plates 23, 24, 26, and 27, and one side of the refraction means are entirely covered. A catadioptric means 28 having a reflective coating 29 is used. The liquid crystal display 22 is illuminated by the backlight 21. The wave plate is a wide band wave plate in which quarter wave plates 24 and 27 and half wave plates 23 and 26 are bonded at a specific angle, and a pair of the wave plates is composed of the liquid crystal display 22 and the thin film. Broadband wave plates 23 and 24 and wide band wave plates 26 and 27 which are arranged near the respective surfaces between the reflective polarizing films 25.
Is arranged at an angle of -55 to -35 degrees or 35 to 55 degrees with respect to the polarization transmission axis on the liquid crystal display 22 emission side or the polarization transmission axis of the thin film reflective polarizing film 25.

This optical system operates as follows. Light emitted from the liquid crystal display 22 is converted into linearly polarized light in a specific direction by a polarizing plate provided in the liquid crystal display 22. The purpose of the wave plate is to convert linearly polarized light into circularly polarized light, as in the case of the display device according to the above-described invention.
3, 24 are arranged. Therefore, the broadband wave plates 23 and 24 arranged near the liquid crystal display 22
The light becomes circularly polarized light and is sent to wave plates 27 and 26 near the thin-film reflective polarizing film 25. This broadband wave plate 2
At 7,26, the light beam is converted from circular to linear polarization,
The thin film reflection type polarizing film 25 is reached. If it is designed that the polarization reflection axis of the thin film reflection type polarizing film 25 and the polarization axis of the light beam reaching the thin film reflection type polarization film 25 coincide with each other, the light beam is reflected and again the wave plates 26 and 2.
The light is converted into circularly polarized light at 7 and sent to the catadioptric means 28.

The light is converted by the catadioptric means 28 so as to form an enlarged virtual image, is reflected, and returns to the broadband wave plates 26 and 27 near the thin-film reflective polarizing film 25 again. Then, the circularly polarized light is again converted to linearly polarized light, but as is well known in the optical field, the direction of the circularly polarized light is inverted by reflection, so that the light beam emitted from the wave plate is polarized in a direction orthogonal to the incident light. Becomes linearly polarized light having
On the other hand, the thin-film reflective polarizing film 25 has a characteristic of reflecting linearly polarized light in a specific direction and passing linearly polarized light in a direction orthogonal to the specific direction. Therefore, this time, the wave plate 26,
The light emitted from 27 passes through the thin reflective polarizing film 25 and finally reaches the user's eyes 210. As described above, in the present display device, as in the case of the display device described in Embodiment 4, by limiting the type and position of the wave plate, the loss of the optical system is eliminated in principle, and a half mirror or the like is used. The present invention provides a means for improving the efficiency as compared with the case in which the spectral transmittance is increased, and for making the spectral transmittance uniform by using a broadband wave plate. In addition, the present display device has an effect of reducing unnecessary reflection on the liquid crystal display 22 and improving image contrast by the following mechanism.

As an example, as shown in FIG. 2, the liquid crystal display 22 starts from the liquid crystal display 22, passes through the wave plates 23 and 24 near the liquid crystal display 22, and is placed on the surface of the wave plate near the thin-film reflective polarizing film 25 or the inner surface of the case. Consider a light ray 211 that is reflected back to the liquid crystal display again. When there are no wave plates 23 and 24 near the liquid crystal display 22, the light rays 211 returning to the liquid crystal display are reflected by the black matrix inside the liquid crystal display 22, and are exposed to the user's eyes by the optical system in the same manner as the light rays carrying images. 210
Will be sent to. As a result, there is a problem that the contrast of an image is reduced. On the other hand, when the wave plates 23 and 24 near the liquid crystal display 22 are provided as in the present invention, the polarizer on the emission side of the liquid crystal display 22 and the wave plates 23 and 24 form a circular polarizer. Starting from the display 22, the light rays 211 reflected and returned outside are absorbed by the polarizing plate on the liquid crystal display 22 emission side. Therefore, reflection does not occur on the black matrix, and a decrease in contrast can be prevented. Therefore, a high quality HMD can be realized by using these means.

(Embodiment 6) Further, the present embodiment of the image display apparatus according to the present invention comprises an image display element, a thin-film reflective polarizing film for selectively reflecting or transmitting linearly polarized light depending on the polarization direction, and a wave plate. And a catadioptric means in which one surface of the refracting means is semi-transparent mirror coated. And
All elements and components are arranged in parallel. With this arrangement, the optical path is folded.
The thickness of the optical system can be reduced even when designing a display device having a wide viewing angle as compared with the display devices of Nos. 5 to 5. However, in this arrangement, there is a possibility that unnecessary light may be generated due to the polarization element not having ideal characteristics, so the designer selects a configuration according to the thickness of the optical system and the priority of the image quality. can do.

(Embodiment 7) Further, this embodiment of the image display apparatus according to the present invention is shown in FIG. As shown in FIG. 3, a liquid crystal display 32, a thin-film reflective polarizing film 39 for selectively reflecting or transmitting linearly polarized light depending on the polarization direction, wave plates 33, 34, 37, and 38, and one side of the refracting means are half-finished. A catadioptric means 36 coated with a mirror is used. The liquid crystal display 32 has a backlight 3
Illuminated by 1. The wave plate is a quarter wave plate, or the quarter wave plates 34 and 37 and the half wave plate 3
Broadband wave plate 33, in which 3, 38 are bonded at a specific angle.
34 and the broadband wave plates 37 and 38, and the wave plate 3
3, 34 and the wave plates 37, 38 are the liquid crystal display 32.
And between the catadioptric means 36 and the catadioptric means 36 and the thin-film reflective polarizing film 39, and
The slow axis of the four-wavelength plate or the broadband waveplates 33, 34 is the same as the slow axis of the wideband waveplates 37, 38.
(2) The polarization transmission axis of the exit side or the polarization transmission axis of the thin-film reflective polarizing film 39 is -55 to -35 degrees or 35 to 55.
They are arranged at an angle of degrees.

This optical system operates as follows by a mechanism similar to that of the above-described display device shown in the fifth embodiment. Light emitted from the liquid crystal display 32 is converted into linearly polarized light in a specific direction by a polarizing plate provided in the liquid crystal display 32. The wave plate is
The purpose is to convert linearly polarized light to circularly polarized light as in the case of each of the above-described display devices.
A four-wave plate or a broad-band wave plate is provided. Therefore, the light beams are circularly polarized by the broadband wave plates 33 and 34 disposed between the liquid crystal display 32 and the catadioptric means 36 and pass through the catadioptric means. Are sent to the broadband wave plates 37 and 38 provided between the two. This broadband wave plate 37, 3
At 8, the light beam is converted from circularly polarized light to linearly polarized light and reaches the thin film reflective polarizing film 39.

Assuming that the polarization axis of the thin-film reflective polarizing film 39 is designed to coincide with the polarization axis of the light beam that has reached the thin-film reflective polarizing film 39, the light beam is reflected and is again reflected by the broadband wave plate 37. , 38, and is sent to the catadioptric means 36. Catadioptric means 36
The light rays are converted so as to form an enlarged virtual image, are reflected, and are again reflected by the broadband wave plates 37 and 38 provided between the thin reflective polarizing film 39 and the catadioptric means 36.
Come back to. Then, the circularly polarized light is again converted to linearly polarized light, but as is well known in the optical field, the direction of the circularly polarized light is inverted by reflection, so that the light beam emitted from the wave plate is polarized in a direction orthogonal to the incident light. Becomes linearly polarized light having
On the other hand, the thin-film reflective polarizing film 39 has a property of reflecting linearly polarized light in a specific direction and passing linearly polarized light in a direction orthogonal to the specific direction. Therefore, this time, the light emitted from the wave plate 38 passes through the thin-film reflective polarizing film 39,
Eventually the user's eyes 310 are reached. As described above, the display device of the present embodiment is different from the display device of the sixth embodiment in that the types and positions of the wave plates are limited.
This provides a means for improving the efficiency as compared with the case where no wave plate is used, and for making the spectral transmittance uniform by using a broadband wave plate.

In addition, the present display device has the effect of reducing unnecessary reflection on the liquid crystal display 32 and improving the contrast of an image by the following mechanism. As an example, as shown in FIG. 3, the liquid crystal display 32 starts from the liquid crystal display 32, passes through the wave plates 33 and 34 provided between the liquid crystal display 32 and the catadioptric means 36, and receives the half mirror coating 35 of the catadioptric means and the catadioptric function. The light beam 31 reflected by the refraction surface of the means 36 and returned to the liquid crystal display 32 again
Think one. Wave plate 33 near liquid crystal display 32,
If there is no light 34, the light beam 311 returning to the liquid crystal display 32 is reflected by the black matrix inside the liquid crystal display 32, and is sent to the user's eyes 310 by the optical system in the same manner as the light beam carrying the image. As a result, there is a problem that the contrast of an image is reduced.

On the other hand, when the wave plates 33 and 34 near the liquid crystal display 32 are provided as in the present invention, the polarizing plate on the liquid crystal display emission side and this wave plate form a circular polarizing plate. Starting from 32, the light beam 311 that is reflected and returned outside is absorbed by the deflection plate on the liquid crystal display 32 emission side. Therefore,
Reflection on the black matrix does not occur, and a decrease in contrast can be prevented. Therefore, if these means are used,
A high-quality HMD can be realized.

(Eighth Embodiment) FIG. 4 shows an eighth embodiment of the image display device according to the present invention. As shown in FIG. 4, a liquid crystal display 42, a thin-film reflective polarizing film 43 for selectively reflecting or transmitting linearly polarized light depending on the polarization direction, wave plates 44, 45, 48, and 49, and one side of the refracting means are half-finished. A catadioptric means 46 with a transparent mirror coating 47 is used. The liquid crystal display 42 is illuminated by the backlight 41. The wave plate is a quarter wave plate, or the quarter wave plates 45 and 48 and the half wave plate 4
Broadband wave plate 4 with 4,49 bonded at a specific angle
4, 45 and broadband wave plates 48 and 49, and the wave plates are disposed between the thin-film reflective polarizing film 43 and the catadioptric means 46, and the slow axis of the quarter wave plate or the wide band wave plates 44, The equivalent slow axis of 45 is -55 to -35 degrees or 35 to 5 with respect to the polarization transmission axis of the thin reflective polarizing film 43.
It is arranged at an angle of 5 degrees and has a circular polarizer comprising broadband wave plates 48 and 49 and a polarizer 410 between the catadioptric means and the user.

This optical system operates as follows. The light emitted from the liquid crystal display 42 is
The light is converted into linearly polarized light in a specific direction by the polarizing plate provided in 2. Thin-film reflective polarizing film 43 provided between liquid crystal display 42 and catadioptric means 46
It is assumed that the polarization transmission axis coincides with the polarization plate transmission axis on the exit side of the liquid crystal display 42. Here, the light beam passes through the thin-film reflective polarizing film 43, and subsequently, the wave plate 4
Pass through 4,45. The purpose of the wave plate is to convert linearly polarized light into circularly polarized light as in the case of the display device of the fourth embodiment, and quarter wave plates or broadband wave plates 44 and 45 are arranged so as to achieve this purpose. Have been. The light beam is circularly polarized by the broadband wave plates 44 and 45 and reaches the catadioptric means 46. The light is converted by the catadioptric means 46 so as to form an enlarged virtual image, is reflected, and returns to the broadband wave plates 44 and 45 provided between the thin-film reflective polarizing film 43 and the catadioptric means 46 again.

Then, the circularly polarized light is again converted to linearly polarized light. However, as is well known in the optical field, the direction of the circularly polarized light is inverted by reflection, so that the light beam emitted from the wave plate is orthogonal to that at the time of incidence. It becomes the linearly polarized light having the polarized direction.
On the other hand, the thin-film reflective polarizing film 43 has a property of transmitting linearly polarized light in a specific direction and reflecting linearly polarized light in a direction orthogonal to the specific direction. Therefore, this time, the light emitted from the wave plate 44 is reflected by the thin-film reflective polarizing film 43 and passes through the wave plate for the third time, and finally the wavelength forming the catadioptric means 46 and the circularly polarizing plate. The light passes through the plates 48 and 49 and the polarizing plate 410 and reaches the user's eye 411.

As described above, the present display device is used in the sixth embodiment.
Provides a means to improve the efficiency compared to the case where no wave plate is used by limiting the type and position of the wave plate, and to provide a means for making the spectral transmittance uniform by using a wide band wave plate. It is possible to do. In addition, the present display device has an effect of reducing the reflection of external light and improving the contrast of an image by the following mechanism. As shown in FIG. 4, external light 412 enters and the catadioptric means 4
When reflected by the half mirror coating of No. 6,
If there is no circular polarizer between the catadioptric means 46 and the user,
A problem occurs in which external light is superimposed on the image and the contrast is reduced. However, in the case of the present invention, since the wave plates 48 and 49 and the polarizing plate 410 constituting the circularly polarizing plate are provided, an effect of absorbing the reflected light and improving the contrast is obtained. Therefore, if these means are used, a high-quality HMD
Can be realized.

(Embodiment 9) Further, an embodiment of a head mounted display according to the present invention can be shown, which comprises a glasses-type case and each of the display devices of Embodiments 1 to 8 above. When attached to the eyes of the user,
Preferably, images can be presented to the left and right eyes. Therefore, as is clear from the above description of the operation of the display device using the optical system, it is possible to realize a small, lightweight, head-mounted display with high image quality. (Embodiment 10) Further, an embodiment of a video communication apparatus according to the present invention can be shown, which comprises a telephone and a display device according to each of the first to eighth embodiments, and performs video communication while performing voice communication. Can be seen. Therefore, as is clear from the above description of the operation of the display device using the optical system, it is possible to realize a small, lightweight video communication device with high image quality.

Here, a coordinate system used in the description of the following embodiment is defined with reference to FIG. As shown in FIG. 5A, the optical axis direction connecting the user's eye and the center of the catadioptric means is Z.
The axis is perpendicular to the axis, the horizontal direction is the X axis, and the vertical direction is the Y axis. In addition, in order to represent the inclined plane S, a coordinate system in which the XY plane is inclined by 45 degrees about the X axis is defined as shown in FIG. Within the plane S, the axis common to the X axis is the P axis, and the plane S
Within, the axis orthogonal to the P axis is the Q axis, the axis orthogonal to the P and Q axes,
That is, the normal to the plane S is defined as the R axis. Also, the rotation direction is
In the case of the XZ plane, as shown in FIG. 5 (C), it is represented by a counterclockwise angle with respect to the Z axis as viewed along the Y axis, and in the case of the XY plane, as shown in FIG. 5 (D). , Viewed along the Z axis, Y
It is expressed by an angle counterclockwise with respect to the axis, and in the PQ plane, as shown in FIG. 7E, by an angle counterclockwise with respect to the Q axis as viewed along the R axis.

(Eleventh Embodiment) FIG. 6 shows an eleventh embodiment of the present invention. The display device of Embodiment 11 includes a backlight 61, a liquid crystal light valve 62, a thin-film reflective polarizing film 65, a glass plate 64, a polarizing plate 63, an anti-reflection film 66, a half-wave plate 67, 1/4 wavelength plate 68
And a mirror-coated lens 69 in which the convex surface of the plano-convex lens has a total reflection coating 610. And
Each optical element is arranged as shown in FIG. 6, that is, the backlight 61 and the liquid crystal light valve 62
The thin-film reflective polarizing film 65, the glass plate 64, and the polarizing plate 63 are provided in the upper part along the Z plane, and are provided in front of the user 611 along the PQ plane. A two-wave plate 67, a quarter-wave plate 68,
The mirror-coated lens 69 having the convex surface of the plano-convex lens and the total reflection coating 610 is provided on the side far from the user in parallel to the XY plane.

Further, regarding the polarization characteristics, the following assumption is made. The polarization transmission direction of the polarizing plate built in the emission side of the liquid crystal light valve 62 is the Z-axis direction, the polarization reflection direction of the thin-film reflective polarizing film 65 is the Q-axis direction, and the polarizing plate 63
Is the P axis direction, and the slow axis of the half-wave plate is +
The direction of 15 degrees, the slow axis of the quarter-wave plate is in the direction of +70 degrees, and the backlight 61, glass 64, antireflection film 66, and catadioptric means 69 have no anisotropy in polarization characteristics. However, this arrangement is merely an example, and there are many other combinations of polarization characteristics for realizing the functions described below. Therefore, other combinations can be used depending on the manufacturing convenience. In FIG. 6, the optical elements are illustrated separately for convenience of description. However, in reality, unnecessary reflection can be reduced and the size can be reduced by bonding the optical elements together.

Next, how the image of the liquid crystal light valve 62 is converted and reaches the user's eye 611 will be described. The light beam emitted from the backlight 61 becomes an emission light modulated by the liquid crystal light valve 62 and carrying image information. This light beam is converted into linearly polarized light in the Z direction by the polarizing plate provided in the liquid crystal light valve 62 based on the above assumption. Therefore, based on the above assumption, this light ray is reflected in the Z-axis direction when it reaches the thin-film reflective polarizing film 65. Next, the light passes through the antireflection film 66 and passes through the half-wave plate 67. Since the half-wave plate 67 has its slow axis inclined at 15 degrees with respect to the polarization direction, the direction of linearly polarized light is converted to approximately 30 degrees. Then the ray is 1 /
The four-wavelength plate 68 converts the linearly polarized light into substantially circularly polarized light. The reason why the state of an accurate light ray is not determined is that the retardation of the wave plates 67 and 68 varies depending on the wavelength, as will be described later in detail. Here, the assumed setting angle of the wave plate is such that when a polycarbonate wave plate is used, visible light (400 nm to 700 nm) is used.
Is designed such that the transmittance of the optical system becomes uniform in the range of. That is, by using a combination of a half-wave plate and a quarter-wave plate in this manner, conversion between linearly polarized light and circularly polarized light can be accurately performed in a wide band.

Next, the light beam that has passed through the quarter-wave plate 68 reaches a mirror coating lens 69 in which the convex surface of the plano-convex lens has a total reflection coating 610. The light rays are converted and reflected so as to form an enlarged virtual image by the internal reflection of the convex surface. Then, the 1/4 wavelength plate 68 and 1 /
The light passes through the two-wavelength plate 67 and the antireflection film 66 and is converted into linearly polarized light. However, as is well known as an optical law, the direction of rotation of circularly polarized light is reversed by reflection, so that light emitted from the antireflection film is in the X-axis direction orthogonal to the time of incidence. Therefore, the light beam passes through the thin-film reflective polarizing film 65, the glass 64, and the polarizing plate 63 and reaches the user's eyes.
2 can be viewed as an enlarged virtual image in front of the eyes.

Hereinafter, an implementation method and its function will be described in detail for each component. 1. Thin Film Reflective Polarizing Film-DBEF (Comparison of Spectral Transmittance) In this embodiment, a thin film reflective polarizing film (trade name: DBEF) is used to reflect linearly polarized light in a specific direction and transmit linearly polarized light in a direction orthogonal thereto. , 3M). For this purpose, a thin-film reflective polarizing film is superior to a polarizing beam splitter in its characteristics as shown below, in that a multi-layer coating is applied to the slope of a conventional right-angle prism and two prisms are bonded together. I have.

(1) Since the wavelength characteristics and the angle characteristics are uniform, the spectral transmittance of the optical system can be improved, and the color reproducibility of the display can be improved. (2) The polarization beam splitter has characteristics of reflecting the S wave and transmitting the P wave depending on the direction in which the splitter is tilted, so that the design of the polarization direction is restricted. Since the film itself has anisotropy, it is possible to reflect polarized light in a designed direction and transmit polarized light orthogonal to the designed direction according to the direction in which the film is arranged, regardless of the direction in which the film is tilted. Therefore, the degree of freedom in polarization design is large. (3) The polarizing beam splitter is often made by coating the inner surfaces of two right-angle prisms with a multi-layer coating and bonding them together, and has the drawback of becoming heavy. On the other hand, the thin-film reflective polarizing film is sufficiently lightweight because it is in the form of a film, and is suitable for a lightweight HMD. (4) Since the thin-film reflective polarizing film can be mass-produced and is inexpensive, it is suitable for a consumer HMD.

In particular, the difference between the wavelength characteristics will be described below. FIG. 7 shows the spectral characteristics of the polarizing beam splitter and the thin-film reflective polarizing film. The graph of FIG. 7A shows that the reflecting surface of the polarizing beam splitter is 45
FIG. 7B shows the transmittance characteristics of the S-polarized light and the P-polarized light when tilted at an angle, and FIG. It shows the transmittance characteristics of the polarized light in the axial direction. FIG. 7 (A), FIG.
As is clear from (B), in the polarization beam splitter,
Although it functions only in the range of 500 to 610 nm, a thin film reflective polarizing film can realize uniform characteristics over the entire visible light range of 400 to 700 nm. Therefore, the spectral transmittance of the optical system can be improved, and the color reproducibility of the display can be improved.

2. Spectral Characteristics of Broadband Wavelength Plate Similar to the above-mentioned mirror, it is necessary to realize a wavelength plate with constant characteristics over the entire visible light range. Conventionally, a sheet obtained by stretching polycarbonate in one direction is often used as a wavelength wave. When the retardation characteristic of this quarter-wave plate with respect to the wavelength is measured, a graph 81 in FIG.
And it is not uniform with respect to wavelength. Therefore,
FIG. 9 shows the transmission spectrum characteristics of the entire optical system when such a single quarter-wave plate is used in the optical system of the present embodiment. In the red region, the transmittance decreases and the color balance deteriorates. In the optical system of the present invention, 1
Since the 波長 wavelength plate is used for mutual conversion between linearly polarized light and circularly polarized light, a broadband wavelength plate that has a constant conversion performance in the visible light range is required. Such an optical element is described in Japanese Patent Application No. 9-2718,
There is a technique by the same inventor as the inventor. Hereinafter, this element will be described.

This broadband wave plate is constituted by bonding a half-wave plate having a slow axis in the +15 degree direction and a quarter wave plate having a slow axis in the +70 degree direction. When the transmission spectrum characteristic of the entire optical system when this broadband wave plate is used for the optical system of the present embodiment is calculated, it is as shown in a graph 101 of FIG. As compared to 9) 91), uniform characteristics can be obtained in the visible light range. The Poincare sphere, whose mechanism is described below using a Poincare sphere,
This is a method in which the polarization state of a light beam is represented by a point on a sphere.
FIG. 11 shows an overview of the Poincare sphere. When this sphere is considered to be the earth, the points of the north pole 112 and the south pole 113 indicate left-handed circularly polarized light and right-handed circularly polarized light, respectively, points on the equator indicate linearly polarized light, and longitude on the equator indicates the angle of linearly polarized light. It corresponds to twice of.

Therefore, if the -Z-axis direction is defined as 0 degree longitude, a point 111 on the equator in this direction represents vertical linearly polarized light, and a point 114 in the X-axis direction represents 45 degree linearly polarized light. ing. Hereinafter, similarly, a point 116 in the Z-axis direction represents horizontal polarization, and a point 115 in the -X axis direction represents linear polarization in a linear direction of -45 degrees. Also, between the equator and the pole 1
Reference numeral 17 denotes elliptically polarized light. In this way, any polarization state is represented as one point on the Poincare sphere.
The function of the wave plate is expressed as an action of rotating the Poincare sphere by the amount of retardation measured by an angle. At this time, the rotation axis is defined as a straight line connecting the center of the Poincare sphere and the corresponding point on the equator corresponding to twice the longitude in the direction of the optical axis of the wave plate.

Using the above Poincare sphere, the broadband wave plate will be described as follows with reference to FIG. The broadband wave plate is composed of a half-wave plate with a slow axis of 15 degrees and a quarter-wave plate with a slow axis of 70 degrees. Therefore, on the Poincare sphere, the slow axis of the half-wave plate is used. Is a straight line F, and the slow axis of the quarter-wave plate is a straight line G. Each operation is performed by rotating the half-wave plate by 180 degrees and the quarter-wave plate by 9 degrees.
This is a rotation of 0 degrees. When vertical linearly polarized light enters, the incident point corresponds to point A. First, 1 for the reference wavelength
Since it is moved to the point H by the wavelength plate and further moved to the point C (North Pole) by the 波長 wavelength plate, it can be seen that it can be converted into complete left-handed circularly polarized light in the same manner as a single 波長 wavelength plate.

Next, in the case of a wavelength shorter than the reference wavelength, 1/2
Since the retardation of the wave plate becomes excessive, the wave is moved to the point J. The deviation from the point H cancels the excess of the retardation of the next quarter-wave plate, and is finally moved near the point C. . Similarly, when the wavelength is longer than the reference wavelength, 1 /
Since the retardation of the two-wavelength plate is insufficient, the point is shifted to the point K. The deviation from the point H compensates for the insufficient retardation of the next quarter-wave plate, and is finally shifted to the point C again. . In this way, almost perfect left-handed circularly polarized light is obtained at any wavelength. Therefore, when a broadband wavelength plate is used in the present optical system, the optical system functions in meganism according to the description of the above embodiment, and the transmission spectrum of the optical system is almost equal to the visible light range as shown by a graph 101 in FIG. Become uniform. The arrangement of the slow axis angles of the half-wave plate and the quarter-wave plate constituting the broadband wave plate is not limited to the value of the present embodiment, but may be changed to some extent according to the required transmission spectrum characteristics. can do.

3. Angle Characteristics of Z-Value Wave Plate The optical characteristics with respect to wavelength have been described above. In the optical system of the present invention, as shown in the optical path diagram in FIG. There is. The main tendency is to pass almost vertically at the center and pass at a relatively shallow angle at the periphery. Therefore, the retardation characteristics need to be uniform with respect to the passing angle.
Otherwise, due to the same discussion as in the case of the above-mentioned spectral characteristics, a luminance difference occurs near the center of the image that is incident substantially perpendicularly to the wave plate and in the peripheral portion where the light is obliquely incident.

To cope with this, in this embodiment, a wave plate (trade name: NRZ, manufactured by Nitto Denko Corporation) having a birefringence characteristic in the thickness direction is used. Japanese Patent Application No. 9-271 by the same inventor as the present application also relates to a technique of using this wave plate in an optical system.
No. 8, the contents of which are described here. In a conventional simple wave plate, as shown in FIG. 14, when a slow axis and an axis perpendicular to the slow axis are X and Y and a normal axis of the plane is Z in a wave plate plane, nx> ny = nz It had a refractive index characteristic that satisfied the formula. However, when the retardation of such a wave plate is calculated with respect to the light ray 141 obliquely incident on the wave plate in the XZ plane, the retardation with respect to the incident angle 142 measured from the perpendicular is shown in FIG.
The characteristic becomes as shown in the graph 151 of FIG. 5, and the retardation is reduced by half at 60 degrees. When such a wave plate is used in the optical system of the present invention, the transmittance of the optical system is reduced at the end of the field of view where the light beam obliquely passes through the optical system, which causes uneven brightness and color.

As a solution to this, in the present embodiment, 1/4
The refractive index nz in the thickness direction of the wave plate is changed to the refractive index nx in the wave plate.
And ny. As an example of this, when retardation is calculated again with nx = 1.5922 ny = 1.5900 nz = 1.5908 so as to satisfy nx>nz> ny, a graph 152 in FIG. 15 is obtained. Compared with the conventional wave plate, the change in retardation is greatly suppressed. Therefore, when this wavelength plate is employed, uneven brightness and uneven color can be suppressed, and a high-quality display device can be realized.

4. Reflection and Refraction Means-Comparison of Aberration In this embodiment, an element in which the convex surface of the plano-convex lens is coated with aluminum is used as the reflection and refraction means. Glass is the best lens material because of its birefringence characteristics, but if further weight reduction is required, a low birefringence plastic lens material (trade name: Optrez, manufactured by Hitachi Chemical Co., Ltd.)
Can be used. The advantages of using a plano-convex lens as the back mirror as compared with the concave mirror as in the present embodiment are as follows.

First, the plano-convex lens used as the back mirror is
To realize the same optical power, the radius of curvature may be large, that is, the optical system can be made thin. Further, since the field curvature is reduced, the aberration of the optical system can be reduced. The design example is shown below. FIG. 16 (A) shows a concave mirror, and FIG. 16 (B) shows a mirror-coated lens in which a convex mirror of a plano-convex lens is coated with a reflective mirror, and both are designed to have a focal length of 24 mm. At this time,
Calculating the Petzval radius as a criterion for determining the curvature of field and astigmatism gives 24 mm for a concave mirror and 55 mm for a coated lens. As is well known, the smaller the Petzval radius, the larger the curvature of field, and the larger the astigmatism even if the curvature of field is reduced by other methods. As an actual image, when focusing on the center of the image, there is a problem that the periphery is blurred. Therefore, the above calculation results show that the coated lens has less aberrations than using a simple concave mirror.

A second merit is that, although not used in the present embodiment, a lens can be designed for aberration correction using a refracting surface of the lens. FIG. 17 shows an example of the design. This is an example in which a biconvex lens is used instead of the plano-convex lens in FIG. The focal length is the same as in FIG.
Although it is 24 mm, the Petzval radius is further improved from that of the plano-convex lens to 66 mm. Further, if the refracting surface is made aspherical, the effect of aberration correction can be enhanced.

5. Correction Lens, Viewing Angle Improvement Film Further, as shown in FIG. 18, a correction lens 183 can be provided immediately after the liquid crystal light valve to correct aberration and distortion. In the design example shown in FIG.
The Petzval radius is 166 mm, which is more than twice as much as the plano-convex lens alone.
However, when such a correction lens 183 is used, a situation arises in which the angle of the light beam with respect to the liquid crystal light valve becomes shallow in the peripheral portion. As is well known, the liquid crystal light valve has a characteristic that the contrast is reduced when viewed from a shallow angle. Therefore, if no countermeasure is taken, there occurs a problem that the contrast in the peripheral portion of the image is reduced. Therefore, in this embodiment, instead of the ordinary polarizing plate attached to the liquid crystal light valve,
A viewing angle improving film (manufactured by Fuji Film Co., Ltd.) is applied to ensure uniformity of the image.

6. Method of Implementing Backlight A cold cathode tube conventionally used can be used as the backlight. However, in recent years, the influence of the electromagnetic field leaking from the electronic device on the human body is becoming a problem, and the cold cathode tube generates a large amount of the electromagnetic field from the inverter. In responding to HMDs and telephones envisioned by the present invention, since both are used in close proximity to the human body, it is required to minimize leakage electromagnetic fields. For this purpose, in this embodiment, a white LED (manufactured by Nichia Corporation) is used. LED is low voltage (about 3V) DC drive,
Almost no leakage electromagnetic field is generated.

7. Unnecessary reflection countermeasures, external light reflection countermeasures, panel reflection countermeasures Unnecessary reflections inside the optical system cause a decrease in image contrast. Therefore, in the present embodiment, the following antireflection countermeasures are taken. (1) The form in which unnecessary reflection or external light impinges on the liquid crystal light valve is due to reflection on the black matrix of the liquid crystal light valve. To prevent this, chrome plating is performed on the black matrix. (2) Since an AR coating cannot be applied to a polycarbonate wave plate, an antireflection sheet made by AR coating an acrylic sheet is attached on the wave plate, and a half wave plate and a half wave plate constituting a broadband wave plate are attached. A / 4 wavelength plate and a plano-convex lens are also attached. However, when the refraction surface of the catadioptric means is curved, the wave plate may be fixed on another supporting substrate, and the refraction surface of the catadioptric means may be coated with an AR coating. (3) Laminate the thin-film reflective polarizing film, the glass plate and the polarizing plate. This polarizing plate is stuck to prevent reflection of external light. The absorption axis of the polarizing plate coincides with the opposite axis of the thin film reflective polarizing film on the inside, preventing external light from being reflected by the thin film reflective polarizing film and reflected toward the user. . The surface is coated with an anti-reflection coating to prevent unnecessary reflection on the polarizing plate surface. With the above configuration, a small, lightweight, and high-quality image display device can be realized.

(Twelfth Embodiment) FIG. 19 shows a twelfth embodiment of the present invention. The display device of the present embodiment includes a backlight 191, a liquid crystal light valve 192, a thin-film reflective polarizing film 198, a glass plate 197, a polarizing plate 196, antireflection films 195, 1911, and a half-wave plate 19.
3, 199, quarter-wave plates 194, 1910, and a mirror-coated lens 1912 in which the convex surface of the plano-convex lens is totally reflected coating 1913 is used. Each optical element is arranged as shown in FIG. That is, the backlight 191 and the liquid crystal light valve 192
, A 波長 wavelength plate 193, a 波長 wavelength plate 194, and an antireflection film 195 are provided at an upper portion along the XZ plane, and the antireflection film 1911, the ４ wavelength plate 19
10, a half-wave plate 199, a thin-film reflective polarizing film 198, a glass plate 197, and a polarizing plate 196
A mirror coating lens 1912 provided in front of the user along the plane and having a plano-convex lens with a convex surface of a total reflection coating 1913 is provided on a side far from the user in parallel with the XY plane.

Further, it is assumed that the polarization characteristics are as follows. The polarization transmission direction of the polarizing plate built in the emission side of the liquid crystal light valve 192 is the Z-axis direction, the slow axis of the half-wave plate 193 provided near the liquid crystal light valve is the +15 degree direction, and the quarter wavelength. The slow axis of the plate 194 is in the direction of +70 degrees, and the slow axis of the quarter-wave plate 1910 provided near the thin-film reflective polarizing film 198 is in the direction of -20 degrees.
The slow axis of the half-wave plate 199 is in the −75 degree direction, the polarization reflection axis of the thin-film reflective polarizing film 198 is the Q-axis direction, the polarization transmission axis of the polarizing plate 196 is the P-axis direction, and the backlight 191.
The glass 197, the antireflection films 195 and 1911, and the catadioptric means 1912 do not have anisotropy with respect to polarization characteristics. However, this arrangement is merely an example, and there are many other methods of combining polarization characteristics to realize the functions described below. Therefore, other combinations can be used depending on the manufacturing convenience. Note that, in FIG. 19, the optical elements are illustrated separately for convenience of description, but in practice, by bonding the optical elements together, unnecessary reflection can be reduced and the size can be reduced.

Next, how the image of the liquid crystal light valve is converted and reaches the eyes of the user will be described. The light emitted from the backlight 191 is the liquid crystal light valve 1
The output light is modulated by 92 and carries image information. This light beam is converted into linearly polarized light in the Z-axis direction by the polarizing plate provided in the liquid crystal light valve 192 based on the above assumption. Next, the passing half-wave plates 193 and ４
The wave plate 194 is a wide band wave plate that converts linearly polarized light and circularly polarized light over a wide band as described in the eleventh embodiment. Accordingly, the light beam becomes circularly polarized light and travels in the direction of the thin-film reflective polarizing film 198. The thin-film reflective deflection film 198 is also close to the quarter-wave plate 1910 and 1 /
A two-wave plate 199 is provided, which has a function of converting circularly polarized light and linearly polarized light over a wide band, similarly to the wave plate provided near the liquid crystal light valve 192. However, since the bonding angle is perpendicular to the above case, when the light beam passes, it is returned to the polarization state at the time when the light beam is emitted from the liquid crystal light valve, that is, the linearly polarized light in the Z-axis direction.

Therefore, based on the above assumption, this light ray is reflected in the Z-axis direction when it reaches the thin film reflection type deflection film 198. Next, the light beam is again applied to the half-wave plate 199, 1/4.
The light passes through the wave plate 1910 and is converted into circularly polarized light, and reaches the mirror coating lens 1912 in which the convex surface of the plano-convex lens is totally reflected and coated 1913. The light rays are converted and reflected so as to form an enlarged virtual image by the internal reflection of the convex surface. As is well known as the law of optics, the direction of rotation of circularly polarized light is reversed by reflection, so that the third time the antireflection film 1911, the quarter-wave plate 1910,
After passing through the half-wave plate 199, the light is converted into linearly polarized light in the X-axis direction orthogonal to the time when the light was reflected by the thin-film reflective polarizing film 198 last time. Accordingly, the light beam passes through the thin-film reflective polarizing film 198 and the polarizing plate 196 and reaches the user's eye 1914, and the user can view the image of the liquid crystal light valve 192 as an enlarged virtual image in front of his / her eyes. Will be able to

Hereinafter, the implementation method and functions of each component will be described in detail. 1. Anti-reflection effect by liquid crystal light valve Absorbs light rays that return due to unnecessary reflection without special treatment on the black matrix of liquid crystal light valve 192,
This has the effect of preventing a decrease in contrast. 2. Measures for Reducing Aberration of Lens Refraction Surface As in the case of the eleventh embodiment, the refraction surface of the catadioptric means can be curved and used for lens design. At this time, in the case of the eleventh embodiment, the wave plate is bonded to the plane of the plano-convex lens. However, when the refraction surface of the lens is curved, the wave plate cannot be bonded to the curved surface. It was necessary to prepare a new substrate. But,
In this embodiment, since there is no wave plate to be attached to the lens, it is not necessary to add a new component. Therefore, the present embodiment is suitable for a method in which the refractive surface is also a curved surface. 3. Unnecessary Reflection Prevention Measures As in the eleventh embodiment, unnecessary reflection on the surface is reduced by bonding each optical element and AR coating the refraction surface of the catadioptric means. Further, a polarizing plate is provided to prevent external light reflection on the user side of the thin-film reflective polarizing film.

(Thirteenth Embodiment) FIG. 20 shows a thirteenth embodiment of the present invention. The display device of Embodiment 13 includes a backlight 201, a glass plate 2012, a polarizing plate 2013,
Anti-reflection films 205 and 208 and half-wave plate 20
3, 2010, quarter-wave plates 204, 209 and a half mirror coating lens 206 in which the convex surface of a plano-convex lens is half mirror coated 207 are used.

All the optical elements are arranged in parallel on the Z axis as shown in FIG. The order is
From the side far from the user, a backlight 201, a liquid crystal light valve 202, a half-wave plate 203, a quarter-wave plate 20
4, an anti-reflection film 205, a half mirror coating lens 206, an anti-reflection film 208, a 波長 wavelength plate 209, a 波長 wavelength plate 2010, a thin film reflection type polarizing film 2011, a glass plate 2012, and a polarizing plate 2013. In FIG. 20, each optical element is referred to for convenience of description.
Although shown separately, in reality, except for the surface of the catadioptric means, it can be manufactured to be thin by bonding all.

In the present embodiment, the polarization characteristics are assumed as follows. The polarization transmission direction of the polarizing plate built in the emission side of the liquid crystal light valve 202 is the Y-axis direction, the slow axis of the half-wave plate 203 provided near the liquid crystal light valve 202 is the +15 degree direction, and 1/4. Wave plate 20
4, the slow axis of the quarter-wave plate 209 provided near the thin-film reflective polarizing film 2011 is -20 degrees, and the slow axis of the half-wave plate 2010 is , -75 ° direction, the polarization reflection axis of the thin-film reflection type polarizing film 2011 is the Y-axis direction, the polarization transmission axis of the polarizing plate 2013 is the X-axis direction, It is assumed that the coating lens 206 has no anisotropy with respect to polarization characteristics. However, this arrangement is merely an example, and there are many other combinations of polarization characteristics for realizing the functions described below. Therefore, other combinations can be used depending on the manufacturing convenience.

Next, how the image of the liquid crystal light valve 202 is converted and reaches the user's eye 2014 will be described. The light beam emitted from the backlight 201 becomes an emission light modulated by the liquid crystal light valve 202 and carrying image information. This light beam is converted into linearly polarized light in the Y direction by the polarizing plate provided in the liquid crystal light valve 202 based on the above assumption. Next, the passing half-wave plate 2
As described in the eleventh embodiment, the 03 and quarter wave plates 204 are wide band wave plates that convert linearly polarized light and circularly polarized light over a wide band. Accordingly, the light beam becomes circularly polarized light, passes through the half mirror coating lens 206, and travels in the direction of the thin-film reflective polarizing film 2011. A quarter-wave plate 209 is also provided near the thin-film reflective polarizing film 2011.
And a half-wave plate 2010 are provided.
It has a function of converting circularly polarized light and linearly polarized light over a wide band, similarly to the wavelength plate provided near the liquid crystal light valve 202. However, since the bonding angle is orthogonal to the above case, when the light beam passes, the polarization state at the time of emission from the liquid crystal light valve 202, that is,
The light is returned to linearly polarized light in the Y-axis direction.

Therefore, based on the above assumption, this light ray is reflected in the Z-axis direction when it reaches the thin-film reflective polarizing film 2011. Next, the light beam is again applied to the half-wave plate 209,1 /
The light passes through the four-wavelength plate 2010 and is converted into circularly polarized light, and reaches the half mirror coating lens 206. The light rays are converted and reflected so as to form an enlarged virtual image by the internal reflection of the convex surface. As is well known as the law of optics, the direction of rotation of circularly polarized light is reversed by reflection,
Third time, antireflection film 208, quarter wave plate 201
After passing through the 0,1 / 2 wavelength plate 209, the light is converted into linearly polarized light in the X-axis direction orthogonal to the time when the light was reflected by the thin-film reflective polarizing film 2011 last time. Accordingly, the light beam passes through the polarizing plate 2013 and reaches the user's eye 2014, so that the user can view the image on the liquid crystal light valve 202 as an enlarged virtual image in front of the user.

The thirteenth embodiment differs from the twelfth embodiment in that the lens used for the catadioptric means is a half mirror coating and that the optical elements are arranged in parallel. The features are described below. A system in which the mirror is arranged obliquely with respect to the catadioptric means as in the eleventh and twelfth embodiments is called a mirror system, and a system in which the mirror is arranged parallel to the catadioptric means as in the present embodiment is called a parallel mirror system. . The feature of the parallel mirror method is that images with a wide viewing angle can be realized with a thin optical system. In the case of the tilting mirror system, if the catadioptric means is increased in order to increase the viewing angle, an intermediate tilting mirror also needs to be large, and eventually the thickness increases almost in proportion to the size of the catadioptric means. Resulting in. The maximum designable viewing angle is 90 degrees. On the other hand, in the case of the parallel mirror system, even if the catadioptric means is enlarged to increase the viewing angle, the thickness hardly changes. As shown in the design example below, a viewing angle of 120 degrees can be designed.

FIG. 21 shows a design example of the parallel mirror system. The specifications of the lens used are as follows. Material: glass or low birefringent plastic Shape: plano-convex shape Diameter: 60 mm Focal length: 120 mm Convex radius of curvature: 60 mm Center thickness: 10 mm And a parallel mirror type optical system manufactured by coating the convex surface of this lens with a half mirror. Is as follows. Synthetic focal length: 23 mm Viewing angle: 120 degrees Optical system thickness: 17 mm As in the design example above, a thin HMD with a wide viewing angle can be realized. It is particularly suitable for applications requiring a thin display device, such as video communication equipment.

(Embodiment 14) This embodiment has a configuration as shown in FIG. 22 by partially changing the order of Embodiment 13 (see FIG. 20). The changed points are that the position of the thin-film reflective film 223 is moved next to the liquid crystal light valve 222 and that the direction of the half mirror coating lens 227 is reversed. The mechanism of this optical system is basically the same as in Embodiment 13, but
There is an advantage that the present invention can be applied to the case of a short focus which cannot be realized in the thirteenth embodiment. The specifications of this embodiment are described below. Lens used: Material: glass or low birefringent plastic Shape: Plano-convex shape Diameter: 30 mm Focal length: 50 mm Convex radius of curvature: 25 mm Center thickness: 5 mm

The specifications of an optical system of a parallel mirror system manufactured by coating the convex surface of this lens with a half mirror are as follows. Synthetic focal length: 8 mm Viewing angle: 30 degrees Thickness of optical system: 6 mm According to the arrangement of the present embodiment, a short-focus and thin optical system can be realized as in the above numerical examples. It is suitable for use in a portable video communication device for presenting an image of an ultra-small panel in an enlarged manner.

(Embodiment 15) Embodiments 11 and 12
And 13 is one of the main applications of the display device is an HMD (Head Mounted Display). The embodiment is shown in FIG. In this example, a backlight 232, a liquid crystal light valve 233, a thin-film reflective polarizing film, an element 234 composed of a glass plate and a polarizing plate 83, an antireflection film 1
An element 235 composed of a 波長 wavelength plate and a 波長 wavelength plate, and a mirror coating lens 236 in which the convex surface of a plano-convex lens is subjected to total reflection coating are used. The display device according to the eleventh embodiment is provided vertically in two sets, left and right, and they are housed in a glasses-type case 231. The user can watch the image enlarged by the optical system by wearing this device like glasses. As described in the above embodiments, since these display devices are small and lightweight and have high image quality, the HMD itself is also small and lightweight and has high image quality, and provides comfortable wearing and high-quality images. be able to.

The display device can be arranged horizontally. As shown in FIG. 24, display elements 242 such as liquid crystal light valves are disposed on both outer sides, and light rays are introduced into the inner eyes by a thin reflective polarizing film 243 and catadioptric means 244. The function of the display device itself is the same as that described in the above embodiment, but by arranging it sideways, the face side of the HMD can be made concave along the face. Then, it becomes possible to mount the HMD closer to the face, and it is possible to enhance the mountability.

Next, the display device of the thirteenth embodiment is set to the HM
The embodiment used for D is shown in FIG. In this example, a backlight 252, a liquid crystal light valve 253, a thin-film reflective polarizing film, a glass plate, a polarizing plate, an anti-reflection film, a half-wave plate and a quarter-wave plate element 256,
An element 254 composed of an antireflection film, a half-wave plate and a quarter-wave plate, and a half mirror coated lens 255 in which the convex surface of a plano-convex lens is half-mirror coated. The display device according to the thirteenth embodiment is provided with two sets of left and right, which are housed in a glasses-type case. By wearing this device like glasses, the user can see an ultra-wide-angle image magnified by the optical system, and can have an experience as if he / she entered the image world. As described in the above embodiments, since these display devices are thin, the HMD
The user can also reduce the amount of protrusion from the face, and can provide comfortable wearability and a high sense of presence. Therefore, this type of HMD provides a VR (Virtua) that provides a virtual experience.
l Reality) It is suitable for the display of the system.

(Embodiment 16) The display device of Embodiment 14 provides a method of realizing a thin optical system having a high magnification. Therefore, if an ultra-small display of about 0.5 inch is used, the display device can be made thin and low. A display device with low power consumption can be realized. Therefore, it is suitable for use in portable TV phones.
FIG. 26 shows a portable video communication device according to the present embodiment.
This is because, in addition to the components of the mobile phone such as the speaker 261, the microphone 262, the dial device 263, and the wireless device 264, in this example, the display device 26 of the fourteenth embodiment is used.
5 is provided. Therefore, it is possible to make a telephone call while looking at the other party's face of the videophone or checking the document sent by fax.

(Embodiment 17) The embodiment 14
Although the display device has a fixed magnification, it can be made variable in two stages of high magnification and low magnification by making the following changes, and such an embodiment will be described. In the fourteenth embodiment, as shown in FIG.
210, 2211 and a polarizing plate 2213 were provided.
A rotation mechanism 275 as shown in FIG. 27 is provided so that the polarizing plate can be rotated by 90 degrees. Then, when the polarizing plate is placed in the arrangement assumed in the fourteenth embodiment, the light beam 278 turned back by the same half mirror lens 273 as described above is selected and becomes a high-magnification optical system. The light beam 279 which has been refracted only once by the half mirror lens 273 is selected, and the optical system has a low magnification. Actually, when the calculation is performed by the optical system according to the fourteenth embodiment, the focal length is 8 mm in the case of the high magnification, and the focal length is 48 mm and the magnification is 5.2 in the case of the low magnification in contrast to 31 times.

When such a display device is provided in a portable video communication device, when the user wants to look at the display device closely to see a detailed image, use it at a high magnification. When used at a low magnification and it is desired to look away from the eyes to see the whole outline, it can be used at a low magnification and the function of the display device can be expanded. Further, the display device of the present invention,
It can be incorporated not only into so-called mobile phones but also into any portable devices such as so-called pagers and portable information tools.
Since it is lightweight and has high image quality, it is possible to provide a high-quality image display function without impairing portability of a portable device.

Embodiment 18 Hereinafter, an embodiment of an image display device according to the present invention and an HMD using the same will be described with reference to FIGS. 28 and 29. Here, FIG.
8 shows an optical system in the image display device of the present embodiment, and FIG. 29 shows an HM using the image display device of the present embodiment.
It is explanatory drawing which shows D.

As shown in FIG. 28, the optical system of this embodiment is provided with a sub-lens 283 for correcting aberrations and distortions caused by the decentered optical system with respect to the light emitted from the liquid crystal panel 282. , A polarization selection mirror 284 that transmits linearly polarized light in a specific direction and reflects linearly polarized light in a direction orthogonal to the specific direction.
, A quarter-wave plate 285, and a main lens (reflection / refraction means) 286 composed of a coated lens having one surface mirror-coated.

In the above configuration, the polarization selection mirrors 284, 1
The 波長 wavelength plate 285 and the main lens 286
Is inclined with respect to an optical path (hereinafter, referred to as a principal ray) connecting the center of the screen with the center of the eye 287 of the observer.
Here, the polarization selection mirror 284 is a thin film reflection type polarization film having a multi-layer of an anisotropic thin film formed on a resin film. For example, a product name “DBE” manufactured by 3M
F ".

When the optical system having the above-described configuration is employed in an HMD, as shown in FIG.
An image display device including a liquid crystal panel 92, a liquid crystal panel 293, a polarization selection mirror 294, a quarter-wave plate 295, and a main lens 296 may be arranged so as to present enlarged images to the right and left eyes.

Next, the operation of the present embodiment will be described in detail. Here, regarding the direction of polarization, a ray included in the paper plane, that is, a ray polarized in a direction parallel to the paper plane is denoted by P.
A wave, a light beam orthogonal to the wave, that is, a light beam polarized in a direction perpendicular to the paper surface, is defined as an S wave. The liquid crystal panel 282 outputs an S-wave, the polarization selection mirror 284 reflects the S-wave, and transmits the P-wave. It is assumed that they are arranged in rotation.

The light beam emitted from the liquid crystal panel 282 passes through the sub-lens 283 and is corrected for aberration and distortion, and then reaches the polarization selection mirror 284. When passing through the sub-lens 283, the beam is not subjected to polarization conversion, so that the light beam remains as an S-wave and is reflected by the polarization selection mirror 284. The reflected light reaches the quarter wave plate 285. Since the stretching axis of the 波長 wavelength plate 285 is tilted by 45 degrees, it is converted from linearly polarized light to circularly polarized light, reflected and expanded by the main lens 286, and then re-exposed.
It reaches the four-wavelength plate 285.

Here, as is well known, since the rotation direction of the circularly polarized light is inverted by reflection, the quarter wave plate 285
Is converted into a P-wave orthogonal to the polarization direction at the time of incidence. As a result, the polarization selection mirror 28
4 and reaches the observer's eye 287. This allows the observer to view an enlarged image of the liquid crystal panel 282.

As described above, in the image display apparatus of the present embodiment, since the luminance does not decrease in principle, it is possible to improve the luminance four times as compared with the above-described conventional example. is there. Moreover, since the polarization selecting mirror 284 having uniform characteristics in the visible light range is used, the image quality can be improved without impairing the color reproducibility.

Also, since the catadioptric means (main lens) optical element is inclined with respect to the main ray, the thickness of the optical device can be reduced. Can be reduced, so that HM
The wearing feeling of D can be improved. For example, when the horizontal viewing angle is 30 degrees, the thickness of the optical device of the present embodiment can be reduced by half as compared with the conventional device described above with reference to FIG.

In the above embodiment, for convenience of explanation, the case where the emission of the liquid crystal panel 282 is an S-wave is described. However, the present invention is not limited to this. Even if the polarized light of the direction is output, the polarization selecting mirrors 284 and 1 /
The amount of rotation of the four-wavelength plate 285 may be adjusted, and the present invention is not limited to this embodiment.

[0098]

According to the first aspect of the present invention, there is provided an image display apparatus comprising: an image display apparatus; a thin-film reflective polarizing film which selectively reflects or transmits linearly polarized light according to a polarization direction; It is characterized by the use of catadioptric means having one surface totally reflected. The thin-film reflective polarizing film is superior to the conventional polarizing beam splitter in the following points. (1) Since the wavelength characteristics and the angle characteristics are uniform, the spectral transmittance of the optical system can be improved, and the color reproducibility of the display can be improved. (2) The polarization beam splitter has characteristics of reflecting the S wave and transmitting the P wave depending on the direction in which the splitter is tilted, so that the design of the polarization direction is restricted. Since the film itself has anisotropy, it is possible to reflect polarized light in a designed direction and transmit polarized light orthogonal to the designed direction according to the direction in which the film is arranged, regardless of the direction in which the film is tilted. Therefore, the degree of freedom in polarization design is large. (3) The polarizing beam splitter is often made by coating the inner surfaces of two right-angle prisms with a multi-layer coating and bonding them together, and has the drawback of becoming heavy. On the other hand, the thin-film reflective polarizing film is sufficiently lightweight because it is in the form of a film, and is suitable for a lightweight HMD. (4) Since the thin-film reflective polarizing film can be mass-produced and is inexpensive, it is suitable for a consumer HMD.

The catadioptric means, in which one surface of the deflecting means is totally reflected, has less field curvature than a simple concave mirror, and can perform aberration correction using the refracting surface on the side not coated with total reflection. Thus, the aberration of the optical system can be reduced. Further, a means for making the spectral transmittance uniform by using a broadband wave plate is provided. Therefore, a high quality image display device can be realized by using the above means.

The image display device according to the second aspect of the present invention
An image display device, a thin-film reflective polarizing film that selectively reflects or transmits linearly polarized light according to the polarization direction, a broadband wave plate, and a catadioptric means having one surface of the refracting means totally-reflected coated are used. The image display element and the catadioptric means are arranged at an angle of about 90 degrees, and the thin-film reflective polarizing film is arranged with an inclination of about 45 degrees with respect to the image display element and the catadioptric means. Have been. Since this arrangement is a so-called coaxial system in which the catadioptric means is used from the direction along the optical axis, an optical system with less aberration can be realized by using an axially symmetric lens which is easy to manufacture.

The image display device according to the third aspect of the present invention
An image display device, a thin-film reflective film that selectively reflects or transmits linearly polarized light depending on the polarization direction, a broadband wave plate, and a catadioptric means having one surface of the refracting means totally-reflected coated are used. The image display element and the catadioptric means are arranged at an angle of 100 degrees or more, and the thin-film reflective polarizing film is arranged with an inclination of 40 degrees or less with respect to the image display element and the catadioptric means. I have. With this arrangement, the thickness of the optical system can be reduced as compared with the case where the image display element and the catadioptric means are arranged at an angle of about 90 degrees, and a thin image display device can be realized.
However, the aberration tends to increase as compared with the case where the image display element and the catadioptric means are arranged at an angle of about 90 degrees. The angle can be selected.

An image display device according to a fourth aspect of the present invention comprises an image display element, a thin-film reflective polarizing film for selectively reflecting or transmitting linearly polarized light depending on the polarization direction, a broadband wave plate, and one side of a refracting means. A catadioptric means with a reflective coating is used. The broadband wave plate is disposed between the thin-film reflective polarizing film and the catadioptric means, and the equivalent slow axis of the broad-band wave plate is -55 to -35 degrees with respect to the polarized light transmission axis of the thin-film reflective polarizing film. Or 35-5
They are arranged at an angle of 5 degrees. An image display device according to a fourth aspect is the display device according to the second to fourth aspects of the present invention, in which the type and the position of the wave plate are limited so that the loss of the optical system is eliminated in principle, and a half mirror or the like is used. Efficiency is improved compared to the case of using. Therefore, a high quality image display device can be realized by using these means.

An image display device according to a fifth aspect of the present invention comprises:
An image display device, a thin-film reflective polarizing film that selectively reflects or transmits linearly polarized light depending on the polarization direction, a broadband wave plate, and a catadioptric means having one surface of the refracting means totally coated with reflection are used. The wave plate is a broadband wave plate obtained by bonding a quarter wave plate and a half wave plate at a specific angle, and a pair of the wave plates is disposed between a display and a thin-film reflective polarizing film. The １ ／ wavelength plate is disposed near each surface, and the slow axis of the 波長 wavelength plate is disposed at an angle of −55 to −35 degrees or 35 to 55 degrees in the polarization transmission axis on the liquid crystal display emission side. . Claim 5
The image display device according to the first aspect of the invention is the display device according to the second to fourth aspects of the present invention, in which the types and positions of the wave plates are limited to eliminate the loss of the optical system in principle.
Efficiency is improved compared to the case of using a half mirror, etc., the spectral transmittance is made uniform by using a broadband wave plate, and a wave plate near the image display element is provided. Since the polarizer on the side and this wave plate form a circular polarizer, the rays that start from the liquid crystal display and are reflected and returned outside are absorbed by the polarizer on the exit side of the liquid crystal display and are reflected by the black matrix. Reflection does not occur, and a decrease in contrast can be prevented. Therefore, a high quality image display device can be realized by using these means.

In the HMD according to the sixth aspect, the central axis of the catadioptric means is inclined with respect to the optical path connecting the center of the screen of the image display element and the center of the pupil of the observer. In addition to being able to be realized, the image display device is provided with a polarization selection mirror that transmits linearly polarized light in a specific direction and reflects in a direction perpendicular to the direction, and a wavelength plate, so that it is possible to improve luminance and image quality. It becomes possible.

An image display device according to a seventh aspect of the present invention comprises:
An image display element, a thin-film reflective polarizing film for selectively reflecting or transmitting linearly polarized light depending on the polarization direction, a wave plate, and a catadioptric means having one surface of the refracting means antireflection coated are used. All the elements are arranged substantially in parallel. Since the optical path is folded by this arrangement, the thickness of the optical system can be reduced even when designing a display device having a wide viewing angle as compared with the first to sixth aspects. However, in this arrangement, there is a possibility that unnecessary light may be generated due to the polarization element not having ideal characteristics, so the designer selects a configuration according to the thickness of the optical system and the priority of the image quality. can do.

The image display device according to the eighth and ninth aspects of the present invention provides an image display element, a thin-film reflective polarizing film for selectively reflecting or transmitting linearly polarized light depending on the polarization direction, a wave plate, and one surface of a refracting means. Is used. The wave plate is a quarter wave plate or a wide band wave plate in which a quarter wave plate and a half wave plate are bonded at a specific angle, and the wave plate is an image display element and a catadioptric means. And the slow axis of the 手段 wavelength plate, or the equivalent slow axis of the broadband wavelength plate, is the deflection transmission axis on the liquid crystal display emission side, The polarization transmission axis of the thin-film reflective polarizing film and -55 to -35 degrees or 35 to 5
They are arranged at an angle of 5 degrees. Claim 8,
According to the image display device of the ninth aspect, from the display device of the seventh aspect, by limiting the type and position of the wave plate, the efficiency is improved as compared with the case where the wave plate is not used.
Further, a means for making the spectral transmittance uniform by using a broadband wave plate is provided. In addition, since the image display device according to the eighth and ninth aspects includes the wavelength plate near the image display element, the polarization plate on the liquid crystal display emission side and the wavelength plate form a circular polarization plate. Therefore, the light rays that start from the liquid crystal display and are reflected and returned outside are absorbed by the polarizing plate on the liquid crystal display emission side, do not cause reflection on the black matrix, and can prevent a decrease in contrast. Therefore, a high quality image display device can be realized by using these means.

An image display device according to a tenth aspect of the present invention is an image display device, a thin-film reflective polarizing film for selectively reflecting or transmitting linearly polarized light depending on the polarization direction, a wave plate, and a half of one side of the refraction means. A catadioptric means coated with a mirror is used. The wavelength plate is a quarter-wave plate or a wide-band wavelength obtained by bonding a quarter-wave plate and a half-wave plate at a specific angle, and the wave plate is a thin-film reflective polarizing film and a catadioptric means. And the slow axis of the ４ wavelength or the equivalent slow axis of the broadband wave plate is −55 to −3 with the polarization transmission axis of the thin-film reflective polarizing film.
It is arranged at an angle of 5 degrees or 35 to 55 degrees, and has a circularly polarizing plate between the catadioptric means and the user. The image display device according to claim 10 is the image display device according to any one of claims 7 to 9, wherein the type and the position of the wave plate are limited to improve the efficiency as compared with the case where the wave plate is not used. Further, a means for making the spectral transmittance uniform by using a broadband wave plate is provided. In addition, the image display device according to the tenth aspect has an effect of reducing external light reflection and improving contrast of an image. Therefore, a high quality image display device can be realized by using these means.

The image display device according to the eleventh aspect uses a liquid crystal display as an image display section (element), so that it has higher image quality than a conventional device of this type which is also used as a portable image display device. A compact and lightweight image display device can be provided.

The head mounted display according to claim 12 (H
The MD) comprises a glasses-type case and the display device according to any one of claims 1 to 10, and is capable of presenting an image to each of the right and left eyes when worn on the head. Therefore, a small and light head-mounted display with high image quality can be realized. A video communication device according to a thirteenth aspect includes a telephone and the display device according to the first to twelfth aspects, and is capable of watching an image while performing voice communication. Therefore, it is possible to realize a small and lightweight video communication device with high image quality.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment of an image display device according to the present invention and explaining the operation thereof.

FIG. 2 is a diagram illustrating an embodiment of an image display device according to the present invention and explaining the operation thereof.

FIG. 3 is a diagram illustrating an embodiment of an image display device according to the present invention, and explaining the operation thereof.

FIG. 4 is a diagram illustrating an embodiment of the image display device according to the present invention, and explaining the operation thereof.

FIG. 5 is a diagram illustrating the definition of coordinate axes used for components of the optical system of the image display device according to the present invention.

FIG. 6 is a diagram illustrating an embodiment of an image display device according to the present invention and explaining the operation thereof.

FIG. 7 is a diagram showing characteristics of a thin-film reflective polarizing film, which is an optical element of the image display device according to the present invention, in comparison with a conventional example.

FIG. 8 is a diagram illustrating retardation characteristics of a 波長 wavelength plate.

FIG. 9 is a diagram showing the spectral transmittance of an optical system that can be used in the present invention when a quarter-wave plate is used as a component.

FIG. 10 is a diagram showing the spectral transmittance of an optical system that can be used in the present invention when a broadband wave plate is used as a component.

FIG. 11 is a diagram illustrating the definition of a Poincare sphere.

FIG. 12 is a diagram for explaining the operation based on the characteristics of the broadband wave plate on a Poincare sphere.

FIG. 13 is a diagram showing an operation optical path of the image display device.

FIG. 14 is an explanatory diagram of oblique incidence on a wave plate.

15 is a diagram illustrating retardation characteristics with respect to an incident angle in the wavelength plate illustrated in FIG.

FIG. 16 is a diagram illustrating a Petzval radius of a plano-convex lens in comparison with a concave mirror.

FIG. 17 is a diagram illustrating an example of a Petzval radius of a biconvex lens.

FIG. 18 is a diagram illustrating an example of a Petzval radius of a plano-convex lens when a correction lens is used.

FIG. 19 is a diagram illustrating the configuration of an embodiment of an image display device according to the present invention, and explaining the operation thereof.

FIG. 20 is a diagram showing a configuration of an embodiment of an image display device according to the present invention, and explaining its operation.

21 is a configuration diagram showing an example in which the embodiment shown in FIG. 20 is embodied.

FIG. 22 is a diagram illustrating a configuration of an embodiment of an image display device according to the present invention, and explaining the operation thereof.

FIG. 23 is a diagram showing a configuration of an embodiment of an HMD according to the present invention and explaining its operation.

FIG. 24 is a diagram illustrating a configuration of an embodiment of an HMD according to the present invention and explaining the operation thereof.

FIG. 25 is a diagram showing a configuration of an embodiment of an HMD according to the present invention.

FIG. 26 is a diagram illustrating a video communication device according to an embodiment of the present invention.

FIG. 27 is a diagram showing another embodiment in which the optical system in the image display device of FIG. 24 is changed.

FIG. 28 is a diagram showing and explaining the configuration of an optical system in an embodiment of the image display device according to the present invention.

FIG. 29 is a diagram illustrating and explaining a configuration of an embodiment in which the image display device of FIG. 28 is adopted in an HMD.

FIG. 30 is a diagram showing a configuration of a conventional HMD.

FIG. 31 is a diagram showing a configuration of a conventional video display device and explaining its operation.

FIG. 32 is a diagram showing a configuration of a conventional video display device and explaining its operation.

[Explanation of symbols]

11, 21, 31, 41, 61, 191, 201, 22
1,232,241,281,292,302,32
1,252 ... backlight, 12, 22, 32, 42,
62, 192, 202, 222, 233, 253 ... liquid crystal light valve, 13, 25, 39, 43, 65, 19
8, 2011, 223, 243 ... Thin reflective polarizing film, 14, 23, 26, 33, 38, 44, 49, 6
7,193,199,203,2010,224,22
11 1/2 wavelength plate, 15, 24, 27, 34, 37,
45, 48, 68, 194, 1910, 204, 20
9,225,2210,285,295,314 ... 1 /
4-wavelength plate, 16, 28, 36, 46, 69, 163, 1
71, 181, 226, 227, 236, 244 ... catadioptric means, 17, 29, 610, 162, 172, 18
2,1913 ... total reflection coating, 18,210,3
10,411,611,1914,2014,2214
... user's eyes, 35, 47, 207, 228 ... half mirror coating, 64, 197, 2012, 2212
... glass plate, 161, 315, 324 ... concave mirror, 183
... Correction lens, 66, 195, 1911, 205, 20
8,226,229 ... Anti-reflection film, 410,6
3, 196, 2013, 2213, 83 ... polarizing plate, 28
2, 293, 303, 322: liquid crystal panel, 283: sub lens, 284, 294: polarization selecting mirror, 286, 296
... Main lenses, 231,291,301 ... Cases of glasses type 312 ... Liquid crystal display, 313 ... Polarizing beam splitters, 287,316,325 ... Eyes of observer, 32
3 ... Semi-transparent mirror.

Claims (13)

[Claims] 1. An image display device for enlarging an image displayed on an image display unit using an optical enlarging means having a reflective element and presenting it as a virtual image, wherein the linearly polarized light is selectively reflected or transmitted depending on the polarization direction. An image display apparatus comprising: a reflective thin-film polarizing film; and a wave plate provided in a reciprocating optical path between the thin-film reflective polarizing film and the optical magnifying means having the reflective element. Constitutes catadioptric means with total reflection coating,
An image display device, wherein the wave plate forms a broadband wave plate by bonding a quarter wave plate and a half wave plate at a specific angle. 2. The image display device according to claim 1, wherein a display surface of said image display section and said catadioptric means are arranged in a plane.
An image display device arranged at an angle of 0 degrees, and wherein the thin-film reflective polarizing film is arranged at an angle of 45 degrees with respect to the display element of the image display unit and the catadioptric means. . 3. The image display device according to claim 1, wherein the display element of the image display section and the catadioptric means are arranged at an angle of 100 degrees or more, and the thin-film reflective polarizing film is used to display the image. An image display device, wherein the image display device is disposed with an inclination of 40 degrees or less with respect to an element and the catadioptric means. 4. The image display device according to claim 1, wherein an equivalent slow axis of the broadband wave plate is -55 to -a polarization transmission axis of the thin-film reflective polarizing film.
An image display device characterized by being arranged at an angle of 35 degrees or 35 to 55 degrees. 5. The image display device according to claim 1, wherein an equivalent slow axis of the broadband wave plate is −55 to −35 with respect to a polarization transmission axis on a liquid crystal display emission side.
An image display device characterized by being arranged at an angle of 35 degrees or 35 to 55 degrees. 6. The image display device according to claim 1, wherein the catadioptric means is inclined with respect to an optical path connecting a center of a screen of the image display unit and a center of a pupil of the observer. An image display device characterized in that the image display device is arranged to be arranged. 7. An image display device for enlarging an image displayed on an image display unit using an optical enlarging means having a reflective element and presenting it as a virtual image, wherein the linearly polarized light is selectively reflected or transmitted depending on the polarization direction. An image display apparatus comprising: a thin film reflective polarizing film; and a wave plate provided in a reciprocating optical path between the thin film reflective polarizing film and the optical magnifying means having the reflective element. An image display device, comprising a reflection / reflection means coated with a mirror, wherein the surface of the image display section, the thin-film reflection type polarizing film, and the reflection / refraction means are arranged in parallel. 8. The image display device according to claim 7, wherein
The wave plate is a quarter wave plate, or a quarter wave plate and
An image display device characterized in that a two-wavelength plate is bonded at a specific angle to form a broadband wavelength plate. 9. The image display device according to claim 6, wherein a slow axis of the quarter-wave plate or an equivalent slow axis of the broadband wave plate is different from a polarization transmission axis of the thin-film reflective polarizing film. An image display device characterized by being arranged at an angle of 55 to -35 degrees or 35 to 55 degrees. 10. The image display device according to claim 7, further comprising a polarizing plate at an output end of the image enlarged by said catadioptric means. 11. The image display device according to claim 1, wherein said image display section is a liquid crystal display. 12. A glasses-type case incorporating the display device according to claim 1, and means for attaching the glasses-type case to a head so that an image can be presented to an observer's eyes. A head mounted display characterized by the following. 13. A video communication device comprising a telephone having the display device according to claim 1 incorporated therein, wherein video communication is enabled in addition to voice communication.