Three dimensional virtual image system

I claim:

1. A display comprising:

a first image source;

a second image source;

a first beam splitter positioned such that a first image from said first image source is reflected by said first beam splitter and a second image from said second image source is transmitted through said first beam splitter so as to provide a third image as a composite image of said first and second images;

a third image source;

a second beam splitter positioned such that said third image is reflected by said second beam splitter and a fourth image from said third image source is transmitted through said second beam splitter so as to provide fifth image as a composite image of said third and fourth images.

2. The display of claim 1 wherein said first beam splitter and said second beam splitter are included in an optical labyrinth.

3. The display of claim 2 wherein said optical labyrinth is based on angles that are multiples of 60.degree..

4. The display of claim 2 wherein said optical labyrinth is based on angles that are multiples of 45.degree..

5. A display comprising:

a first image source;

a second image source;

a first beam splitter positioned such that a first image from said first image source is reflected by said first splitter and a second image from said second image source is transmitted through said first beam splitter so as to provide a third image as a composite image of said first and second images;

a third image source;

a second beam splitter positioned such that said third image is transmitted through said second beam splitter and a fourth image from said third image source is reflected by said second beam splitter so as to provide a fifth image.

6. The display of claim 5 wherein said first beam splitter and said second beam splitter are included in an optical labyrinth.

7. The display of claim 6 wherein said optical labyrinth is based on angles that are multiples of 60.degree..

8. The display of claim 6 wherein said optical labyrinth is based on angles that are multiples of 45.degree..

9. A display comprising:

a first image source;

a second image source;

a first beam splitter having a first surface and a second surface, said first beam splitter positioned such that said first image source is in a first line of sight to said first surface of said first beam splitter and said second image source is in a second line of sight to said second surface of said first beam splitter, said first beam splitter for reflecting a first set of light rays from said first image source and for transmitting a second set of light rays from said second image source so as to provide a third set of light rays as a composite of said first and second set of light rays;

a third image source

a second beam splitter having a third surface and fourth surface, said second beam splitter positioned such that said third image source is in a third line of sight to said fourth surface of said second beam splitter, said third set of light rays is incident upon said third surface of said second beam splitter, said second beam splitter for reflecting said third set of light rays and for transmitting a fourth set of light rays from said third image source so as to provide a fifth set of light rays as a composite of said third and fourth set of light rays;

wherein said first beam splitter and said second beam splitter are included in an optical labyrinth.

10. The display of claim 9 wherein said optical labyrinth is based on angles that are multiples of 60.degree..

11. The display of claim 9 wherein said optical labyrinth is based on angles that are multiples of 45.degree..

12. A method for displaying an apparent three dimensional image comprising the steps of:

reflecting a first image along an optical path toward a viewer;

transmitting a second image along said optical path toward said viewer;

transmitting a third image along said optical path toward said viewer, thereby providing said viewer with a composite image of said first, second, and third images;

wherein said first image is made to appear a first distance away from said viewer, said second image is made to appear a second distance away from said viewer, and said third image is made to appear a third distance away from said viewer.

13. The method of claim 12 wherein said first distance and said second distance are equal to each other.

14. The method of claim 12 wherein said first distance and said second distance are not equal to each other.

15. The method of claim 12 further comprising the step of reflecting a combination of said first image and said second image along said optical path toward said viewer.

16. The method of claim 12 wherein said first image is reflected at a 60.degree. angle.

17. The method of claim 12 wherein said first image is reflected at a 45.degree. angle.

18. A method for displaying an apparent three dimensional image comprising the steps of:

reflecting a first image along an optical path toward a viewer;

transmitting a second image along said optical path toward said viewer;

reflecting a third image along said optical path toward said viewer, thereby providing said viewer with a composite image of said first, second, and third images;

wherein said first image is made to appear a first distance away from said viewer, said second image is made to appear a second distance away from said viewer, and said third image is made to appear a third distance away from said viewer.

19. The method of claim 18 wherein said first distance and said second distance are equal to each other.

20. The method of claim 18 wherein said first distance and said second distance are not equal to each other.

21. The method of claim 18 further comprising the step of reflecting a combination of said first image and said second image along said optical path toward said viewer.

22. The method of claim 18 wherein said first image is reflected at a 60.degree. angle.

23. The method of claim 18 wherein said first image is reflected at a 45.degree. angle.

24. A method for displaying an apparent three dimensional image comprising the step of:

arranging a plurality of beam splitters so as to transmit and reflect a plurality of images such that said plurality of images are combined to form said apparent three dimensional image;

producing at least one of said plurality of images using visible light; and

producing at least one of said plurality of images using ultraviolet light.

25. The method of claim 24 wherein said step of producing at least one of said plurality of images using visible light comprises the step of:

using an incandescent light source to produce visible light.

26. The method of claim 24 further comprising the step of:

making said plurality of images appear to move relative to one another such that said plurality of images appear to pass through one another.

27. A method for displaying an apparent three dimensional image comprising the steps of:

arranging a plurality of beam splitters so as to transmit and reflect a plurality of images such that said plurality of images are combined to form an apparent three dimensional image;

producing at least one of said plurality of images using visible light; and

producing at least one of said plurality of images using ultraviolet light.

28. The method of claim 27 wherein said step of producing at least one of said plurality of images using visible light comprises the steps of:

using an incandescent light source to produce visible light.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to virtual image systems.

2. Background Art

It is difficult to display three dimensional images on most present display devices. Images may be displayed on a two dimensional display device such as a CRT, and the images may be displayed in perspective so as to give the appearance of three dimensions. However, the image size must be adjusted to provide perspective. Portions of an image intended to appear more distant must be reduced in size relative to portions intended to appear closer. While two dimensional images in perspective may have the correct proportions to simulate three dimensional images, they do not provide parallax. Without the proper parallax, a viewer can easily distinguish a two dimensional image in perspective from a true three dimensional image.

Other approaches have been used to provide parallax as well as proportion. Mirror mazes or labyrinths have been constructed to provide the illusion of hallways, rooms and other objects in locations where they did not actually exist. An article entitled "The Amateur Scientist; Mirrors Make a Maze So Bewildering That the Explorer Must Rely on a Map" by Jearl Walker on pages 120-126 of Scientific American, volume 254 (June 1986) discloses a number of mirror labyrinths and method for designing and analyzing mirror labyrinths. The mirror labyrinths are constructed using mirrors aligned along the edges of equilateral triangles. Thus, the mirrors meet each other at angles that are multiples of 60.degree.. The mirrors produce regularly repeated images around the borders of a "hallway" when viewed from the proper location and direction. The image that appears at the distant end of a "hallway" can be controlled. However, traditional mirror labyrinths do not provide for images having some degree of transparency to be interposed between the viewer and the distant end of a "hallway" such that objects at the distant end of the hallway can still be seen through the interposed images. Furthermore, traditional mirror labyrinths do not allow images to pass through mirrors and do not provide images originating behind exterior mirrors to be seen within the labyrinth.

Other approaches have been used to simulate stereo vision, where each eye sees a different image so as to provide a three dimensional effect. One prior art method of providing stereo vision involved a viewer with spectrally filtered eyeglasses viewing an image having spectrally encoded stereo information. For this approach, the viewer wears eyeglasses that typically have a red lens over one eye and a green or blue lens over the opposite eye. The viewer views an image that includes a left component and a right component. The left component is of the color of the lens covering the left eye, while the right component is of the color of the lens covering the right eye. The left component provides the left eye with a view representative of what the left eye would see if the image were three dimensional. The right component provides the right eye with a view representative of what the right eye would see if the image were three dimensional. The views seen by the right and left eyes are mentally combined to form a three dimensional perception of the image. However, since colors are used to encode stereo vision information, the colors of the image must be carefully controlled, and the image cannot be naturally colored. Thus, while the images may appear three dimensional, they are unnaturally colored. Furthermore, the three dimensional effect is lost unless the viewer wears the filtering eyeglasses.

Another approach involves the viewer wearing orthogonally oriented polarizing filters over each eye. An image having stereo vision information encoded with orthogonal polarization is viewed by the viewer. Stereo vision information relevant to the left eye is encoded with a polarization matching the polarization of the lens over the left eye, while stereo vision information relevant to the right eye is encoded with a polarization matching the polarization of the lens over the right eye. Thus, the left and right eyes receive their respective stereo vision information, which is mentally combined to form a three dimensional perception. However, the three dimensional effect is lost unless the viewer wears cross polarized eyeglasses.

Another approach involves a viewer wearing (liquid crystal display) LCD shuttered eyeglasses and viewing an image that alternates between a left component and a fight component while the LCD shutters alternate between blocking vision of the right eye and left eye, respectively. The eyeglasses contain individually controllable LCD shutters over the left eye and over the right eye. The eyeglasses are used to view a display device, such as a cathode ray tube (CRT) that can rapidly change the image it is displaying. When the display device displays a left component of stereo vision information, the LCD shutter over the left eye is opened and the LCD shutter over the right eye is closed. When the display device displays a right component of stereo vision information, the LCD shutter over the right eye is opened and the LCD shutter over the left eye is closed. Thus, the left and right eyes receive their respective left and right components of stereo vision information. The left and right components of stereo vision information are combined mentally to form a three dimensional perception. However, the three dimensional effect is lost unless the viewer wears the LCD shutter eyeglasses.

One method of the prior art for causing a semi-transparent image to appear in front of a background is known as "Pepper's Ghost" and involves reflecting an image from a beam splitter placed in front of a scene. "Pepper's Ghost" provides only a single reflection. It does not allow multiple planes of transparent images. Furthermore, it cannot produce images that pass through each other in a direction parallel to the optical path to the viewer. Also, to produce expansive three dimensional images, the "Pepper's Ghost" technique requires a large three dimensional volume.

Another prior art method has been used for displaying the image of an object located behind a beam splitter. This method involves placing an object in an opaque enclosure having one side constructed of a beam splitter. A lamp that may be dimmed is placed inside the enclosure to illuminate the surface of the object facing the beam splitter. When the lamp is off, the object is not visible from outside the enclosure, and the beam splitter appears to be a mirror when viewed from the outside. When the lamp is on, the object can be seen through the beam splitter. This method does not allow multiple images to be superimposed on one another. This method cannot provide multiple planes of transparent images. Also, this method does not allow the image to be made to disappear without reverting to a mirror condition. Additionally, this method cannot produce images that pass through each other in a direction parallel to the optical path to the viewer. Furthermore, to provide large expansive three dimensional images, this technique requires a large three dimensional volume.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for displaying three-dimensional virtual images. The present invention provides perspective and parallax automatically without adjusting the actual size of images to be displayed. The present invention provides stereo vision perceptual cues without the need for special eyeglasses or lenses over the eyes. The present invention allows multiple planes or volumes of semitransparent two or three dimensional images to overlap and/or pass through each other, even in directions towards and away from the viewer. The present invention also allows images beyond the walls of a labyrinth to seem to appear and disappear within the labyrinth. Furthermore, the present invention may be used to produce the perception of a deep volume while occupying only a compact space.

In the present invention, a series of beam splitters is configured as an optical labyrinth whereby multiple extended optical paths are constructed by positioning the beam splitters in planes that include the sides of equilateral triangles. The equilateral triangles are positioned adjacent to one another so as to create a network of equilateral triangles having common sides. By positioning objects, images or animated sequences of images behind the beam splitters and selectively lighting each of them, optical paths that appear to contain partially transparent images in three dimensions can be created. Several images can be simultaneously displayed in different regions of three dimensional space. An optical labyrinth provides a carefully planned path for light rays, but it need not have the form of a physical labyrinth.

In the preferred embodiment of the present invention, a series of beam splitters is used to construct an optical labyrinth. The beam splitters are two-way mirrors that differ from regular mirrors in that they have a coating, such as a partially silvered coating, that reflects a portion of the incident light striking the front surface, but also allows a portion of the incident light striking the rear surface to be transmitted through the two-way mirror. This property of beam splitters also allows them to be used as beam combiners. A first light beam can be reflected by the beam splitter, and a second light beam can be transmitted through the beam splitter. If the angles of reflection and transmission are properly aligned, light from the first and second light beams can be combined to form a third light beam. By controlling the amount of incident light on each side of the beam splitter, the images seen from each side can be controlled. In the preferred embodiment of the present invention, both sides of the beam splitters are maintained relatively unilluminated, while the images to be presented are illuminated. The beam splitters are positioned in planes that contain the common sides of a grid of adjacent equilateral triangles. Objects for producing images are positioned exterior to the labyrinth at locations relative to the beam splitters that result in the appearance of the objects at the desired location along an optical path.

Light from the object intended to have the most distant appearance radiates from that object and is reflected by a beam splitter placed in front of the object intended to have the second most distant appearance. In addition to reflecting the light from the object intended to have the most distant appearance, the beam splitter placed in front of the object intended to have the second most distant appearance also transmits light from the object intended to have the second most distant appearance through the beam splitter and into the optical path toward the viewer. The light from both the object intended to have the most distant appearance and the object intended to have the second most distant appearance is then reflected by a beam splitter positioned in front of an object intended to have the third most distant appearance. In addition to reflecting the light from the more distant appearing objects, the beam splitter in front of the object intended to have the third most distant appearance transmits the light from the object intended to have the third most distant appearance through the beam splitter and into the optical path toward the viewer. This process continues with subsequent beam splitters with the light from additional objects or images being added to the optical path directed toward the viewer. Ultimately, light from all of the objects or images reaches the viewer, and the viewer sees a composite image that includes the light from all of the objects or images. The light from the various objects or images is additively combined, causing the images to appear to be superimposed upon one another. Since light from the various objects and images travels different distances before reaching the viewer, the various images appear in perspective and with parallax at their respective apparent distances. The images can also be made to move and to pass through each other by moving their positions relative to their respective beam splitters. Thus, the disadvantages of the prior art have been overcome.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross section of the preferred embodiment of the present invention.

FIG. 1B is a cross section illustrating the apparent arrangement of the embodiment of FIG. 1A as viewed by viewer 101.

FIG. 2A is a cross section of an alternate embodiment of the present invention.

FIG. 2B is a cross section illustrating the apparent arrangement of the embodiment of FIG. 2A as viewed by viewer 201.

FIG. 3A illustrates a cross section of an alternate embodiment of the present invention.

FIG. 3B is a cross section illustrating the apparent arrangement of the embodiment of FIG. 3A as viewed by viewer 301.

FIG. 4 is a cross section of an embodiment of the present invention with a large angle of incidence.

FIG. 5 is a cross section of an embodiment of the present invention with a large angle of incidence.

FIG. 6 is a cross section of an embodiment of the present invention with small angles of incidence.

FIG. 7 is a cross section of an embodiment of the present invention with small angles of incidence.

FIG. 8 is a cross section of a beam splitter of the present invention showing angles of incidence, reflection, and transmission.

FIG. 9 is a cross section of an embodiment of the present invention that allows incandescent and ultraviolet (UV) lighting effects to be combined.

DETAILED DESCRIPTION OF THE INVENTION

A method and apparatus for displaying a three dimensional virtual image are described, In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention, It will be apparent, however, to one skilled in the art, that the present invention may be practiced without these specific details, In other instances, well-known features have not been described in detail in order not to unnecessarily obscure the present invention,

In the past, it has not been possible to display a three dimensional virtual image that can include visual components derived from different sources, each of which can be individually controlled, such that the components appear superimposed on each other with the proper perspective and parallax. Such a display system would be useful for entertainment, production of animated sequences and three dimensional imaging applications, such as architecture and engineering. Therefore, there is a need for such a system.

The present invention avoids these problems by using beam splitters oriented to allow multiple images to be introduced into an optical path to a viewer with the appearance that the images are at different distances from the viewer. The beam splitters allow transmission of light from a light source through the beam splitter and reflection of light from an incident optical path to a reflected optical path. If the light source producing the light transmitted through the beam splitter is aligned properly, the transmitted light can be made to join the reflected optical path. Thus, a viewer of the reflected optical path will see the transmitted light from the light source superimposed on the incident light from the incident optica