JP3396074B2 - Video display device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device capable of observing a stereoscopic image by guiding the image to the left and right eyes of an observer.

[0002]

2. Description of the Related Art As a conventional example of an image display apparatus capable of observing a stereoscopic image, there is one disclosed in, for example, Japanese Patent Laid-Open No. 5-260527. In this conventional example, an image including an image for the left eye and an image for the right eye is displayed on a liquid crystal panel (LCD) as an image display unit commonly used for the left and right eyes of an observer, and this image is displayed on the liquid crystal panel. It is divided into left and right by the lenticular lens provided on the front surface, and the divided left and right eye images are enlarged and projected on the left and right eyeballs of the observer through the eyepiece optical system to enlarge the stereoscopic image. I try to observe it.

In the above-mentioned conventional example, when the image displayed on the liquid crystal panel arranged so that the center of the eye width of the observer and the center of the panel correspond to each other, the image is directly observed by the pair of left and right eyepiece optical systems. Since the virtual image of the image displayed on the liquid crystal panel is tilted, or the convergence angle becomes too large and fusion of the left and right images becomes extremely difficult, it is configured as an image display device capable of observing stereoscopic images. Not preferred above. Therefore, a pair of right and left wedge-shaped prisms are provided between the liquid crystal panel and the eyepiece optical system to cope with the problems of the image plane tilt and the convergence angle.

[0004]

In the above-mentioned conventional example, a prism is interposed between the liquid crystal panel and the eyepiece optical system in order to solve the above two problems. However, the prism makes the vergence angle suitable for stereoscopic observation. It is not possible to completely correct the image plane tilt by adjusting to, on the contrary, if the prism is completely corrected for the image plane tilt, it is not possible to adjust the convergence angle to a value suitable for stereoscopic observation by the prism. It becomes an off relationship. In addition, since prisms are used, the occurrence of chromatic aberration due to prisms cannot be avoided.

The present invention has been made in view of these problems, and the convergence angle is set to be suitable for stereoscopic observation.
Moreover, it is an object of the present invention to provide an image display device capable of reducing the inclination of the image plane.

[0006]

To this end, the structure of claim 1 of the present invention comprises a video display means for displaying a video,
An image display device comprising: an image distribution unit that distributes an image light beam from the image display unit to the left and right eyes of an observer; and an eyepiece optical system that magnifies and projects the image light beam that is distributed to the left and right eyes to the left and right eyes. The optical system is an optical system having a pair of left and right openings corresponding to the left and right eyeballs, with a straight line passing through the center of the image display means and orthogonal to the image display means as an optical axis, and the eyepiece optical system is The optical path for the left eye that guides the image light flux to the left eye and the optical path for the right eye that guides the image light flux to the right eye have at least one optical surface commonly used, and the left and right openings are formed in this optical surface. It is characterized by that.

A second aspect of the present invention is characterized in that the eyepiece optical system has a Fresnel lens or a diffractive optical element.

A third aspect of the present invention is characterized in that the eyepiece optical system has a magnifying reflecting mirror.

The fourth aspect of the present invention is characterized in that the image distribution means is a lenticular lens.

According to a fifth aspect of the present invention, the image display means is a liquid crystal display element, and the image distribution means is means for changing the direction of illumination light for illuminating the liquid crystal display element. It is characterized by being configured as follows.

[0011]

According to the structure of claim 1 of the present invention, the image light flux from the image display means is distributed to the left and right eyeballs of the observer by the image distribution means, and the image light fluxes distributed to the left and right are respectively in the eyepiece optical system. As a result, the image light flux for the left eye and the image light flux for the right eye are enlarged and projected on the right and left eyes. At that time, the eyepiece optical system is an optical system having a pair of left and right openings corresponding to the left and right eyeballs, with a straight line passing through the center of the image display means and orthogonal to the image display means as an optical axis, The eyepiece optical system has at least one optical surface commonly used by the optical path for the left eye that guides the image light flux to the left eye and the optical path for the right eye that guides the image light flux to the right eye. Since it is formed on the optical surface, the image display means and the eyepiece optical system are arranged on the same axis, and the virtual image of the image on the image display means is also formed on the same axis without being inclined. Therefore, the observer observes different images having no image plane inclination with the left and right eyes, which enables stereoscopic observation. Also,
Since the image light flux emitted from the center of the image display means is refracted by the eyepiece optical system when entering the center of the left and right eyes of the observer, the vergence angle can be set to a value suitable for stereoscopic observation. Further, since the eyepiece optical system does not use a prism, chromatic aberration does not occur.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. In the image display device in which the image displayed on the image display means is magnified and projected on the eyeball of the observer by the eyepiece optical system, in order to project the image as a virtual image sufficiently far, in the vicinity of the front focus position of the eyepiece optical system. It is necessary to arrange a video display element in the. Further, when a liquid crystal (LCD) is used as the image display means, it is desirable that the viewing angles are the same or substantially constant over the entire area of the image display screen. For that purpose, it is desirable to dispose the eye point near the rear focal position of the eyepiece optical system.

FIG. 1 shows an example of an optical system which satisfies such desirable conditions. FIG. 1 is a diagram showing a configuration of a first embodiment of a video display device of the present invention. The image display device of FIG. 1 has an LCD 1 as image display means, and a pair of left and right openings 3L, 3L corresponding to the left and right eyeballs 2L, 2R with an optical axis of a straight line L ₁ passing through the center of the LCD 1 and orthogonal to the LCD _1.
Left and right integrated eyepiece optical system 4 having R, and the LCD 1
And a lenticular lens 5 as an image distribution means arranged in front of the.

The distance L from the principal point on the LCD1 side of the eyepiece optical system 4 to the LCD1 is set to a value corresponding to the focal length f of the eyepiece optical system 4, and in this embodiment, the distance L is set to the focal length f. The settings are almost equal. Lenticular lens 5
As shown in FIG. 2, has a function of distributing the image light flux emitted from the LCD 1 in the direction toward the left and right eyes. That is, a large number of pixels 1b are formed on the image display surface 1a on the LCD 1, and an image in which a left-eye image (L) and a right-eye image (R) are alternately arranged is displayed on these pixels 1b. Thus, of all the image light fluxes, the light flux from the pixel indicated by L in FIG. 1 is distributed as the left-eye image light flux,
The light flux from the pixel indicated by R is distributed as a right-eye image light flux and guided to the left and right eyeballs 2L and 2R.

In the eyepiece optical system 4, as shown in FIG. 3, a pair of left and right openings 3L and 3R corresponding to the left and right eyeballs 2L and 2R are formed in an original lens 6 commonly used in the left and right optical systems, and the openings are formed. An eyepiece lens 7L, 7R is provided in each of the portions 3L, 3R. A diffractive optical element or the like may be used instead of the eyepiece lens. With this configuration,
In the eyepiece optical system, since the effective light beam actually passes through a part of the range, the eyepieces 7L and 7R are arranged so that the light beam passing through the part of the range is used to reduce the size of the eyepiece optical system. Becomes possible. Original lens 6
Since the eyepieces 7L and 7R are integrally arranged inside, there is no need to adjust the positions of the left and right eyepieces as in the case where the eyepieces are separated, and the manufacture of the eyepiece optical system becomes easy.

Next, the operation of the first embodiment will be described.
In FIG. 1, when the image light flux from the LCD 1 is guided to the left and right eyeballs 2L, 2R of the observer by the eyepiece optical system 4, the LCD 1 and the eyepiece optical system 4 are coaxially arranged as described above. The virtual image of the image is also formed without being coaxially inclined. At this time, the observer is
Although the virtual image of the same image displayed on the LCD 1 is observed by L and 2R, since the lenticular lens 5 is arranged in front of the LCD 1, the image light flux emitted from the LCD 1 is left and right by the lenticular lens 5. Are divided into the image light flux for the left eye and the image light flux for the right eye as described above. Therefore, the observer observes different images having no image plane inclination with the left and right eyes 2L and 2R, and stereoscopic observation becomes possible. At this time, since the eyepiece optical system 4 does not use a prism, chromatic aberration does not occur.

Further, since the image light flux emitted from the center of the LCD 1 is refracted by the eyepiece optical system when entering the center of the observer's eyes 3L, 3R, the vergence angle is set to a value suitable for stereoscopic observation. be able to. For example, the eyepiece optical system 4
When the distance L from the principal point on the LCD 1 side to the LCD 1 is matched with the focal length f of the eyepiece optical system 4, the vergence angle becomes 0 degree, which is a value suitable for stereoscopic observation, and the virtual image of the image on the LCD 1 is at infinity. Will be projected on.

Further, in order to set the distance L from the principal point on the LCD1 side of the eyepiece optical system 4 to the LCD1 to be slightly shorter than the focal length f of the eyepiece optical system 4, the distance L is calculated by the following equation.

If 0 ≦ {D (f−L) / (2fL)} ≦ 0.05− (1) (where D is the pupil distance, usually 65 mm), the congestion is The angle of convergence becomes 0 to 5 degrees, which is suitable for stereoscopic observation. In this case, the position of the virtual image approaches the observer side, but since the lenticular lens having a positive power is used as the image distribution unit in this embodiment, the virtual image can be projected sufficiently far. .

FIG. 4 is a diagram showing the configuration of the second embodiment of the image display apparatus of the present invention. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the second embodiment, the configuration of the eyepiece optical system 4 is partially changed from that of the first embodiment. That is, the left and right integrated eyepiece optical system 4 of the present embodiment.
As shown in FIG. 5, an original lens 6 commonly used in the left and right optical systems is provided with openings 8 corresponding to the left and right eyeballs 2L and 2R, and the left and right integrated eyepieces 9 are provided in the opening 8. Is used. A diffractive optical element or the like may be used instead of the eyepiece lens.

The second embodiment has the same effect as that of the first embodiment, and further has the effect of improving the manufacturability of the eyepiece optical system as compared with the first embodiment by integrating the left and right eyepieces. Is obtained.

FIG. 6 is a diagram showing the configuration of the third embodiment of the image display apparatus of the present invention. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the third embodiment, the configuration of the eyepiece optical system 4 is partially changed from that of the first embodiment,
Further, the reflecting mirror 10 is provided in the optical path from the LCD 1 to the eyepiece optical system 4 via the lenticular lens 5.

That is, in the left-right integrated eyepiece optical system 4 of this embodiment, as described above, the center portion of the original lens 6 is not used in the eyepiece optical system 4, and the center of the original lens 6 is considered. Cut out the part 6a as shown in FIG.
A space for accommodating the CD 1 and the lenticular lens 5 is formed, and in the space, the LCD 1 arranged so that the back surface faces the observer's eyeball side as shown in FIG. 6, and in the vicinity of the front surface (video display screen) of the LCD 1. It accommodates the arranged lenticular lens 5. Further, by disposing the reflecting mirror 10 on the optical axis L ₁ of the eyepiece optical system 4, the image light flux of the LCD 1 is divided into the left and right by the lenticular lens 5, and the left eye image light flux and the right eye image light flux are reflected respectively. Mirror 1
It is folded back at 0, and the eyepiece optical system 4 is moved along the same path as the first embodiment.
The light is incident on the eyepieces 7L and 7R.

In the third embodiment, the same effect as that of the first embodiment can be obtained, and in addition, only the necessary portion of the original lens 6 of the eyepiece optical system 4 is left and the unnecessary portion is hollowed out. Since the LCD 1 and the lenticular lens 5 are housed in and the optical path is folded back by the reflecting mirror, the effect of downsizing the entire device as compared with the first embodiment can be obtained.

FIG. 8 is a diagram showing the configuration of the first reference example of the video display device, the same parts as those of the third embodiment are designated by the same reference numerals, and the description thereof will be omitted. In the first reference example, the configuration of the eyepiece optical system 4 is partially changed from that of the third example. That is, the eyepiece optical system 4 of the present embodiment captures the left-eye image light flux and the right-eye image light flux folded back by the LCD 1, the lenticular lens 5 and the reflecting mirror 10 arranged as in the third embodiment ( That is, it is composed of a pair of left and right Fresnel lenses 11L and 11R arranged at the same position as the eyepiece optical system 4 of the third example.

In the first reference example, the same effects as those of the third example are obtained and, in addition, the original lenses of the eyepiece optical system 4 are replaced with left and right separation type Fresnel lenses 11L and 11R. The effect of reducing the weight as a whole as compared with the third embodiment is obtained.

FIG. 9 is a diagram showing the configuration of the second reference example of the video display device, the same parts as those of the first reference example are designated by the same reference numerals, and the description thereof will be omitted. In this second reference example, the eyepiece optical system 4, LCD 1, lenticular lens 5 and left and right pair of Fresnel lenses 11L and 11R are the same as those in the first reference example, but the lenticular lens 5 and left and right pair of Fresnel lenses are used. The configuration of the optical system between 11L and 11R is partially changed from that of the first reference example. That is,
In this reference example, a prism 12 is provided in front of the lenticular lens 5 located in front of the LCD 1, and a pair of left and right tilt mirrors 13L, 13R is provided between the prism 12 and the pair of left and right Fresnel lenses 11L, 11R. .

The prism 12 has a rectangular first surface 12a on which the left-eye image light flux and the right-eye image light flux are incident, the left-eye image light flux, and the right-eye image light flux. A rectangular prism having three surfaces, that is, a second surface 12b that emits the image light flux for the right eye and a third surface 12c that emits the image light flux for the left eye while emitting the image light flux for the left eye is used. For example, as shown in FIG. 9, the rectangular prism 12 has an isosceles triangle whose cross-sectional shape has equal sides of the second surface 12b and the third surface 12c, and an apex angle of the isosceles side of about 45 degrees. Therefore, when the left-eye image light flux and the right-eye image light flux distributed by the lenticular lens 5 having the illustrated distribution angle characteristic exit the prism 12, the second surface 12b and the third surface 12c are separated from each other. It becomes almost orthogonal. When using lenticular lenses having different distribution angle characteristics, it goes without saying that the apex angle of the prism 12 is adjusted according to the distribution angle characteristics.

In the second reference example, the same effect as that of the first reference example is obtained, and the image plane tilt is corrected by the action of the prism 12 and the tilt mirrors 13L and 13R, and in the eyepiece optical system 4. Since the principal ray emitted from the prism 12 is substantially orthogonal to the second surface 12 and the third surface 12c, an effect that almost no chromatic aberration occurs is obtained, and further, the influence of the light distribution characteristic of the LCD is reduced as compared with the conventional example. The effect that can be obtained is also obtained.

FIG. 10 is a diagram showing the configuration of the third reference example of the image display device, the same parts as those of the second reference example are designated by the same reference numerals, and the description thereof will be omitted. In the third reference example, the tilting mirrors 13L and 13R and the Fresnel lenses 11L and 11R of the second reference example are replaced with a single magnifying reflecting mirror 14, and other parts are the same as in the second reference example. Constitute.

FIG. 11 is an overall view of a head-mounted image display device constructed by using the image display device of FIG. This head-mounted image display device has an eyepiece optical system 4 that forms an exit pupil for guiding the image formed by the LCD 1 to an observer's eyeball, and the eyepiece optical system 4 emits the image to the exit pupil. It comprises a face mounting portion 16 having observation windows 15L and 15R, and a headband 17 as a supporting means for supporting the face mounting portion 16 on the observer's head. Here, since the LCD 1 is arranged on the face mounting portion 16 so that the back surface is located on the observation window side, the image display screen is located on the front surface side of the LCD 1.

A lenticular lens 5, which is an image distribution means for distributing the image, is provided on the front surface of the image display screen. The lenticular lens 5 guides the image light flux distributed to the left and right to the observer's eyeball. A rectangular prism 12 is provided between the No. 5 and the magnifying reflection mirror 14. The eyepiece optical system 4 may be configured without using the rectangular prism 12 by changing the curve of the magnifying mirror.

The third reference example has the same effects as those of the second reference example, and has the effect of simplifying the structure as compared with the second reference example by replacing the optical element. Further, a half mirror can be used instead of the magnifying reflecting mirror, and in that case, see-through can be realized.

FIG. 12 is a diagram showing the configuration of the fourth reference example of the video display device, the same parts as those of the third reference example are designated by the same reference numerals, and the description thereof will be omitted. In the fourth reference example, the magnifying reflection mirror 14 of the third reference example is replaced by a diffractive optical element 18L,
It is replaced with 8R, and other parts are configured similarly to the third reference example.

The fourth reference example has the same effect as that of the third reference example, and further, the effect of making the entire device lighter than that of the third reference example is obtained by replacing the above-mentioned optical element. .

FIG. 13 is a diagram showing the construction of the fourth embodiment of the image display apparatus of the present invention. The same parts as those of the second embodiment are designated by the same reference numerals and the description thereof will be omitted. In the fourth embodiment, the lenticular lens 5 which is the image distribution means in the second embodiment is replaced with a collimator lens 19 which is a means for changing the incident direction of the illumination light that illuminates the LCD 1. The part is constructed similarly to the second embodiment.

Specifically, the light sources 20L and 20R are respectively
On a plane including the center of the left and right eyeballs and the center of the LCD 1,
The light source 20L is arranged at a position symmetrical to the straight line L ₁ passing through the center of the LCD 1 and orthogonal to the LCD 1, and the collimator lens 19 is provided between the light sources 20L and 20R and the LCD 1, and the light source 20L is provided near the light source side focal plane of the collimator lens 19. , 20
Make R located.

In the fourth embodiment, the same effect as in the second embodiment is obtained, and the left and right images are interchanged and displayed on the LCD 1 for each frame, and the left eye image is displayed in synchronization with the image display. By turning on the light source 20L while displaying the image and turning on the light source 20R while displaying the image for the right eye, the images corresponding to the left and right eyes 2L and 2R are distributed and projected. Therefore, it is possible to observe a stereoscopic image.

The present invention is not limited to the above-mentioned examples, and various modifications and changes can be added. For example, in the configuration of claim 1, the distance between the principal point of the eyepiece optical system and the image display means can be made substantially equal to the focal length of the eyepiece optical system,
In that case, a virtual image of the image display element by the eyepiece optical system is projected far enough, the burden on the eyeball is reduced, and a powerful image can be observed.

Further, in the structure of claim 1, the eyepiece optical system may have a Fresnel lens or a diffractive optical element. In that case, the eyepiece optical system becomes thin and a large magnifying power is obtained. You can

In the structure of claim 1, the eyepiece optical system may have a magnifying reflecting mirror, and in that case, the structure of the device can be simplified and the entire device can be downsized.

Further, in the structure of the above-mentioned claim 1, it can be provided between the image display means and the eyepiece optical system, in which case the optical path can be bent to downsize the entire apparatus.

Further, in the structure of the above-mentioned claim 1, the image distribution means can be a lenticular lens, in which case the light beams emitted from the image display means to the left and right are distributed, and the distributed light beams are used for the left and right eyeballs. It is possible to observe stereoscopic images by associating different images.

Further, in the structure of the above-mentioned claim 1, the image display means may be a liquid crystal display element, and the image distribution means may be a means for changing a direction of illumination light for illuminating the liquid crystal display element. it can.

In that case, the image displayed on the liquid crystal display device is switched to the image for the left eye and the image for the right eye for each frame,
By changing the direction of the illumination light that illuminates the liquid crystal display element in synchronization with the switching, all the image light flux emitted from the liquid crystal display element is displayed while the image for the left eye is displayed on the liquid crystal display element. Illumination light illuminates the liquid crystal display element from the direction in which it is projected to the left eye through the eyepiece optical system for the left eye,
Similarly, in the next frame, while the image for the right eye is displayed on the liquid crystal display element, all the image light flux emitted from the liquid crystal display element is projected from the direction in which the image light flux is projected to the right eye through the eyepiece optical system for the right eye. The illumination light illuminates the liquid crystal display element.

Therefore, all the pixels of the liquid crystal display element can be used to form one image, and a fine image can be observed.

[0046]

As described above, according to the structure of claim 1 of the present invention, the image light flux from the image display means is distributed to the left and right eyeballs of the observer by the image distribution means, and the image is distributed to the left and right. The luminous fluxes are enlarged and projected on the left and right eyeballs as an image luminous flux for the left eye and an image luminous flux for the right eye by the eyepiece optical system. At that time, the eyepiece optical system is an optical system having a pair of left and right openings corresponding to the left and right eyeballs, with a straight line passing through the center of the image display means and orthogonal to the image display means as an optical axis, The eyepiece optical system has at least one optical surface commonly used by the optical path for the left eye that guides the image light flux to the left eye and the optical path for the right eye that guides the image light flux to the right eye. Since it is formed on the optical surface, the image display means and the eyepiece optical system are arranged on the same axis, and the virtual image of the image on the image display means is also formed on the same axis without being inclined. Therefore, the observer observes different images having no image plane inclination with the left and right eyes, which enables stereoscopic observation. Further, since the image light flux emitted from the center of the image display means is refracted by the eyepiece optical system when entering the center of the left and right eyes of the observer, the vergence angle can be set to a value suitable for stereoscopic observation. . Further, since the eyepiece optical system does not use a prism, chromatic aberration does not occur.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of an image display device of the present invention.

FIG. 2 is a diagram for explaining the operation of the lenticular lens of the first example.

FIG. 3 is a detailed diagram of an eyepiece optical system of the first embodiment.

FIG. 4 is a diagram showing a configuration of a second embodiment of an image display device of the present invention.

FIG. 5 is a detailed view of the eyepiece optical system of the second embodiment.

FIG. 6 is a diagram showing a configuration of a third embodiment of an image display device of the present invention.

FIG. 7 is a detailed diagram of an eyepiece optical system of a third embodiment.

FIG. 8 is a diagram showing a configuration of a first reference example of an image display device.

FIG. 9 is a diagram showing a configuration of a second reference example of an image display device.

FIG. 10 is a diagram showing a configuration of a third reference example of an image display device.

11 is an overall view of a head-mounted image display device configured by using the image display device of FIG.

FIG. 12 is a diagram showing a configuration of a fourth reference example of an image display device.

FIG. 13 is a diagram showing the configuration of a fourth embodiment of the video display device of the present invention.

[Explanation of symbols]

1 Video display device (LCD) 1a Image display surface 1b pixel 2L, 2R eyeball 3L, 3R opening 4 Eyepiece optical system 5 Lenticular lens 6 original lens 7L, 7R eyepiece

Claims (5)

(57) [Claims] 1. A video display means for displaying a video image, a video distribution means for distributing the video light flux from the video display means to the left and right eyeballs of an observer, and a video light flux distributed right and left is enlarged and projected to the left and right eyeballs. In an image display device comprising an eyepiece optical system, the eyepiece optical system has a pair of left and right openings corresponding to the left and right eyeballs with a straight line passing through the center of the image display means and orthogonal to the image display means as an optical axis. The eyepiece optical system has at least one optical surface commonly used for the left-eye optical path that guides the image light flux to the left eye and the right-eye optical path that guides the image light flux to the right eye. The left and right openings are formed on this optical surface. 2. The image display device according to claim 1, wherein the eyepiece optical system is configured to have a Fresnel lens or a diffractive optical element. 3. The image display device according to claim 1, wherein the eyepiece optical system has a magnifying mirror. 4. The image display device according to claim 1, wherein the image distribution means is a lenticular lens. 5. The image display means is a liquid crystal display element, and the image distribution means is a means for changing the direction of illumination light for illuminating the liquid crystal display element. The video display device according to claim 1.