JPH06324286A - Video display device - Google Patents

Abstract

PURPOSE:To provide a video display device in which the utilization efficiency of light is improved by compact constitution using one semi-transmissive reflecting surface and two reflecting surfaces which have the nearly equal length of optical path from the semi-transmissive reflecting surface and have the same curved surface. CONSTITUTION:A half mirror 3 is inclined and arranged near the intersection of the optical axis of an LCD 1 forming a video with the visual line of an observer, and an enlarging reflection mirror (1st reflecting surface) 4 having positive power is arranged to be opposed to the LCD 1 through the half mirror 3, and an enlarging reflection mirror (2nd reflecting surface) 5 having the positive power in a direction where a video luminous flux from the LCD 1 is reflected by the half mirror 3 is arranged to be opposed to the eyeball 2 of the observer through the half mirror 3. The same curved surface is formed on the reflection mirrors 4 and 5 and the length of the optical path from the LCD 1 to the mirror 4 and that from the LCD 1 to the mirror 5 are made nearly equal, so that light quantity guided to the eyeball 2 is set about twice as much as the case that one enlarging reflection mirror is used.

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 for displaying an image by projecting it on the eyes of an observer.

[0002]

2. Description of the Related Art As a conventional image display device for displaying an image on the eyes of an observer, for example, there is one disclosed in Japanese Patent Laid-Open No. 3-191389, and FIG. 4 shows the image display device described in the above publication. It is a figure which shows schematic structure of. The image display device of FIG. 4 includes an LCD 51, which is an image display element that forms an image,
A half mirror 52 that is inclined at the intersection of the optical axis of the LCD 51 and the visual axis of the observer to guide the image light flux formed by the LCD 51 to the eyeball of the observer The LCD 51 and the magnifying reflection mirror 53 arranged to face each other.

In this prior art example, the image light flux of the image light flux from the LCD 51 that has passed through the half mirror 52 is reflected by the magnifying reflection mirror 53, guided again to the half mirror 52, and then reflected by the half mirror 52. Only the image luminous flux is guided to the eyeball of the observer.

[0004]

In the above-described conventional example, as described above, the image light flux from the LCD 51 passes through the half mirror 52 twice until it reaches the observer's eyeball, so that the image is finally reflected on the observer's eyeball. The amount of light guided to is only (1/2) ² = 25% of the amount of light generated in the LCD 51, and the light utilization efficiency becomes low. Therefore, small output L
When a CD is used, the desired amount of light cannot be secured, so
Large output (large size) LCD to secure desired light intensity
Must be used, and the video display device becomes large.

The present invention improves the utilization efficiency of light by a compact structure using one semi-transmissive reflective surface and two reflective surfaces having substantially the same optical path length from the semi-transmissive reflective surface and having the same curved surface. An object of the present invention is to provide a video display device of the type.

[0006]

To this end, the present invention provides an image display element for forming an image, an optical axis of the image display element and an observation for guiding the formed image light flux to an eyeball of an observer. A semi-transmissive reflective surface inclined near the intersection of the human visual axis and a first reflective surface having a positive power and opposed to the image display element via the semi-transmissive reflective surface. An image reflected by the semi-transmissive reflection surface after the image light flux transmitted from the video display element from the semi-transmissive reflection surface is reflected by the first reflection surface and guided to the semi-transmission reflection surface again In the image display device in which only the light flux is guided to the eyeball of the observer, the first light flux from the semi-transmissive reflection surface in the direction in which the video light flux from the video display element is reflected by the semi-transmissive reflection surface. At the position of the optical path length almost equal to the optical path length to the reflecting surface Is characterized in that comprising providing a second reflecting surface having a first reflecting surface and the same curved surface which has a positive power.

[0007]

According to the present invention, between the semi-transmissive reflective surface disposed near the intersection of the optical axis of the image display element and the visual axis of the observer's eyeball, and the first and second reflective surfaces. Since the optical path lengths are substantially equal to each other and the first and second reflecting surfaces have the same curved surface, the image light flux from the image display element is transmitted and reflected by the semi-transmissive reflecting surface. After that, the light is reflected by the first and second reflective surfaces and again enters the semi-transmissive reflective surface, is reflected and transmitted by the semi-transmissive reflective surface, and reaches the eyeball of the observer. Therefore, about twice the amount of light as in the case of the conventional example using one semi-transmissive reflective surface and one reflective surface can be obtained by the image display element having the same output as that of the conventional example, thus increasing the size of the image display device. The light utilization efficiency can be improved without doing so.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. 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 the first embodiment is intended to be downsized in consideration of the case of being configured as a head-mounted (or face-mounted) image display device, and as shown in FIG. 3, for example. It is configured as a goggle type display device. Note that FIG. 1 shows only the projection system for one of the left and right eyeballs of the observer for the sake of simplification of the description. Therefore, when actually configured as an image display device, the projection system for each of the left and right eyeballs. Shall be used.

In the first embodiment, the LCD 1 which is an image display element for forming an image, and the optical axis of the LCD 1 and 90 ° with respect to the optical axis for guiding the image light flux formed by the LCD 1 to the eyeball 2 of the observer. The half mirror 3 that is arranged in the vicinity of the intersection of the visual axes of the observers, and the magnifying reflection mirror (first reflection surface) 4 that is arranged to face the LCD 1 via the half mirror 3 and the half mirror 3. It is provided with a magnifying reflection mirror (second reflection surface) 5 which is arranged so as to face the eyeball 2 of the observer. The magnifying mirrors 4 and 5 have positive power and are formed with the same curved surface. The magnifying mirrors 4 and 5 are arranged so that the distances (optical path lengths) from the center of the half mirror 3 are equal to each other.

Next, the operation of the first embodiment will be described. LC
The image light flux from D1 enters the half mirror 3 and is split into transmitted light and reflected light. The image light flux transmitted through the half mirror 3 is magnified and reflected by the magnifying reflection mirror 4, and then enters the half mirror 3 again. Similarly, the image light flux reflected by the half mirror 3 is magnified and reflected by the magnifying reflection mirror 5 and again. It is incident on the half mirror 3. The image light flux that has entered the half mirror 3 again is divided into two light fluxes that are reflected and transmitted by the half mirror 3, and one of the light fluxes is one eyeball 2 of the observer.
Be led to.

In the first embodiment, since the magnifying reflection mirror 5 is provided to utilize the light beam reflected from the LCD 1 to the half mirror 3, the light beam reflected from the LCD 51 to the half mirror 53 is reflected. Not using Figure 4
The light utilization efficiency is about double that of the conventional example. Therefore, it is possible to configure a video display device that can obtain a larger amount of light when the video display element having the same output as that of the conventional example is used.

If one of the magnifying reflection mirrors 4 and 5 is arranged so as to be slightly decentered with respect to the incident optical axis, two images that are laterally displaced from each other are projected on the eyeball 2 of the observer. Therefore, the pixel boundary of the LCD 1 can be made inconspicuous.

By the way, in the first embodiment, for example, the image light flux from the LCD 1 is transmitted through the half mirror 3 and is enlarged and reflected by the magnifying reflection mirror 4, and is again reflected by the half mirror 3.
After entering the observer's eyeball 2, the light is transmitted through the half mirror 3 without returning to the observer's eyeball 2 and returns to the LCD 1, and a light loop is formed such that the light is reflected by the LCD 1 and heads again to the half mirror 3, and air and half There is a fear that the optical path may be deviated to become a ghost due to the difference in the refractive index between the mirror 3 and the medium.
Therefore, in order to reduce the ghost, the configuration of the following second embodiment is suitable.

FIG. 2 is a diagram showing the configuration of a second embodiment of the video display device of the present invention. The video display device according to the second embodiment is intended to be downsized in consideration of the case of being configured as a head-mounted (or face-mounted) video display device. For example, as shown in FIG. It is configured as a goggle type display device. Note that FIG. 2 shows only the projection system for one of the left and right eyeballs of the observer as in the first embodiment.

In the second embodiment, the half mirror 3 of the first embodiment is replaced with a prism beam splitter 6,
The magnifying reflecting mirrors 4 and 5 are replaced with back magnifying reflecting mirrors 7 and 8, respectively, and a lens (or surface) 9 having a positive refractive power between the eyeball 2 and the prism beam splitter 6 on the visual axis of the observer. And a lens (or surface) 10 having a negative refracting power and arranged to face the eyeball 2 of the observer via the prism beam splitter 6 and shutter means (for example, a liquid crystal shutter) 11 are provided. ,
The rear surface magnifying reflection mirror 7 is composed of a total reflection mirror, and the rear surface magnifying reflection mirror 8 is composed of a half mirror. In addition,
The lens (or surface) 10 having negative refracting power is for correcting the positive refracting power of the lens (or surface) 9 and the rear surface magnifying reflecting mirror 8.

Next, the operation of the second embodiment will be described. LC
The image light flux from D1 enters the half mirror surface 12 of the prism beam splitter 6 and is split into transmitted light and reflected light. The image light flux transmitted through the half mirror surface 12 is expanded and reflected by the rear surface magnifying reflection mirror 7 and is again reflected by the half mirror surface 1.
Half of the image light flux incident on the second mirror 2 and similarly reflected on the half mirror surface 12 is magnified and reflected by the rear surface magnifying reflecting mirror 8 and again enters the half mirror surface 12, and the other half is reflected on the rear surface magnifying reflecting mirror 8. Through. The image luminous fluxes incident on the half mirror surface 12 again are reflected by the half mirror surface 12,
It is divided into two light fluxes that are transmitted, and one of the light fluxes is guided to the eyeball 2 of the observer through the lens (or surface) 9 having a positive refractive power.

In the second embodiment, the back magnifying reflecting mirror 8 is used in order to utilize a part of the light beam which is incident on the prism beam splitter 6 from the LCD 1 and reflected by the half mirror surface 12.
The use efficiency of light is about 1.5 times that of the conventional example shown in FIG. Therefore, it is possible to configure a video display device that can obtain a larger amount of light when the video display element having the same output as that of the conventional example is used.

In the second embodiment, the image light flux traveling from the half mirror surface 12 of the prism beam splitter 6 to the eyeball 2 of the observer is collected on the eyeball 2 by the lens (or surface) 9 having a positive refractive power. Since it is illuminated, an image with a wider angle of view can be obtained compared to the first embodiment. In addition, in this second embodiment, since the prism beam splitter 6 is used instead of the half mirror 3, there is no deviation of the optical path due to the difference in refractive index as in the above-mentioned first embodiment, and compared with the first embodiment. Ghosts are reduced.

Further, in the second embodiment, the see-through is composed of the rear surface magnifying reflecting mirror 8 configured as a half mirror on the optical axis of the observer, the lens (or surface) 10 having a negative refractive power, and the shutter means 11. Since the mechanism is provided, in addition to closing the shutter means 11 for normal image display, the shutter means 11 is opened during image display to display an electronic image and an external image at the same time, and the shutter means 11 is displayed during image non-display. It can be opened to display only the external image, and safety is ensured when the observer wears the image display device outdoors or the like.

In the structure shown in FIG. 1, the magnifying reflecting mirror 5 is used.
Is replaced with a half mirror, and a see-through mechanism is constructed by combining the lens (or surface) 10 having a negative refractive power and the shutter means 11 of the second embodiment to form a see-through type image display device. Can be

[0021]

As described above, according to the present invention, the semi-transmissive reflective surface disposed near the intersection of the optical axis of the image display element and the visual axis of the eyeball of the observer, and the first and second aspects. The optical path length between the reflective surface and the
Further, since the first and second reflection surfaces have the same curved surface, the image light flux from the image display element is transmitted and reflected by the semi-transmissive reflection surface, and then the first and second reflection surfaces. The light is reflected by the surface and again enters the semi-transmissive reflective surface, is reflected and transmitted by the semi-transmissive reflective surface, and reaches the eyeball of the observer. Therefore, about twice the amount of light as in the case of the conventional example using one semi-transmissive reflective surface and one reflective surface can be obtained by the image display element having the same output as that of the conventional example, thus increasing the size of the image display device. The light utilization efficiency can be improved without doing so.

[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 showing a configuration of a second embodiment of an image display device of the present invention.

FIG. 3 is a diagram illustrating a configuration in which the image display device of the present invention is a goggle-type head-mounted display device.

FIG. 4 is a diagram for explaining a conventional technique.

[Explanation of symbols]

 1 LCD (image display element) 2 Eyeball of observer 3 Half mirror (semi-transmissive reflection surface) 4 Magnifying reflection mirror (first reflection surface) 5 Magnification reflection mirror (second reflection surface) 6 Prism beam splitter 7 Rear surface magnification Reflecting mirror (first reflecting surface) 8 Rear surface magnifying reflecting mirror (second reflecting surface) 9 Lens (or surface) having positive refractive power 10 Lens (or surface) having negative refractive power 11 Shutter means (liquid crystal) Shutter) 12 Half mirror surface (semi-transmissive reflective surface)

Claims (1)

[Claims] 1. An image display element for forming an image, and an inclined arrangement near an intersection of an optical axis of the image display element and a visual axis of an observer for guiding the formed image light flux to an eyeball of the observer. The image display element having a semi-transmissive reflection surface and a first reflection surface having a positive power and arranged to face the image display element via the semi-transmission reflection surface, and which transmits the semi-transmission reflection surface. So that only the image light flux reflected by the semi-transmissive reflection surface is guided to the eyeball of the observer after the image light flux from is reflected by the first reflection surface and guided again to the semi-transmission reflection surface. In the image display device described above, a position of an optical path length substantially equal to an optical path length from the semi-transmissive reflective surface to the first reflective surface in a direction in which an image light flux from the video display element is reflected by the semi-transmissive reflective surface. Has a positive power, and Characterized by comprising providing a second reflecting surface having a surface and identical curved, the image display device.