Optics: image projectors – Polarizer or interference filter
Reexamination Certificate
1996-03-19
2001-05-15
Dowling, William (Department: 2851)
Optics: image projectors
Polarizer or interference filter
C353S122000, C353S069000
Reexamination Certificate
active
06231189
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to optical systems and methods, and more particularly to optical projection systems and methods.
BACKGROUND OF THE INVENTION
Hemispherical optical projection systems and methods, i.e. systems and methods which project images at an angle of at least about 160 degrees, are used to project images onto the inner surfaces of domes. Hemispherical optical projection systems and methods have long been used in planetariums, commercial and military flight simulators and hemispherical theaters such as OMNIMAX® theaters. With the present interest in virtual reality, hemispherical optical projection systems and methods have been investigated for projecting images which simulate a real environment. Such images are typically computer-generated multimedia images including video, but they may also be generated using film or other media. Home theater has also generated much interest, and hemispherical optical projection systems and methods are also being investigated for home theater applications.
Heretofore, hemispherical optical projection systems and methods have generally been designed for projecting in a large dome having a predetermined radius. The orientation of the hemispherical projection has also generally been fixed. For example, planetarium projections typically project vertically upward, while flight simulators and hemispherical theaters typically project at an oblique angle from vertical, based upon the audience seating configuration. Hemispherical optical projection systems and methods have also generally required elaborate color correction and spatial correction of the image to be projected, so as to be able to project a high quality image over a hemisphere.
Virtual reality, home theater and other low cost applications generally require flexible hemispherical optical projection systems and methods which can project images onto different size domes and for different audience configurations. The optical projection systems and methods should also project with low optical distortion over a wide field of view, preferably at least about 160 degrees. Minimal color correction and spatial correction of the image to be projected should be required. A high intensity image should be projected, and it is desirable to have the capability of projecting three-dimensional images.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide improved optical projection systems and methods.
It is another object of the present invention to provide optical projection systems and methods which can project images with high intensity.
It is yet another object of the present invention to provide optical projection systems and methods which can project three-dimensional images.
These and other objects are provided, according to the present invention, by a projection system and method which combine the image generated by two image sources. The image generated by the first image source has a first polarization, and the image produced by the second image source has a second polarization orthogonal to the first polarization. The combined image thus includes two colineated beams (i.e., beams having the same optical axis) with orthogonal polarizations. The two images can be the same thereby increasing the intensity of the combined image, or the two images can represent right and left eye views thereby producing a three-dimensional effect. Alternatively, the two images can be offset by a sub-pixel, thereby providing higher resolution.
In particular, the first image source includes a first array of image pixels wherein the first image source generates a first pixel image having a first polarization. The second image source includes a second array of image pixels wherein the second image source generates a second pixel image having a second polarization orthogonal to the first polarization. The first pixel image having the first polarization is combined with the second pixel image having the second polarization to form a combined pixel image. Each pixel of the combined pixel image corresponds to a combination of a first pixel from the first array of image pixels having the first polarization and a second pixel from the second array of image pixels having the second polarization.
If the first and second pixel images comprise the same image, the combined pixel image can have an increased intensity. Alternately, if the first and second pixel images comprise different images, the combined pixel image can be used to project a three-dimensional image. That is, when projected onto a viewing surface, a viewer who wears glasses with orthogonal polarization filters will see a different image with each eye. In yet another alternative, the images can be offset by a sub-pixel to increase resolution. The image sources can include a reflective liquid crystal display (such as a ferroelectric liquid crystal display), a transmissive liquid crystal display, or a liquid crystal layer and an image generator for generating an image on the liquid crystal layer.
The dual polarization optical projection systems and methods may be used to project the combined pixel image onto any surface. However, the combined pixel image is preferably projected into a hemispherical projection having constant angular separation among adjacent pixels. Accordingly, the dual polarization optical projection systems and methods can project the combined pixel image onto hemispherical surfaces of varying radii without requiring spatial distortion correction of the first and second arrays of image pixels. The dual polarization optical projection systems and methods can also include a dome including a truncated spherical inner dome surface. The constant angular projecting system is preferably mounted at the center of the dome. to radially project the combined pixel image onto the inner dome surface.
The dual polarization optical projection systems and methods can also project the combined pixel image onto a hemispherical surface at a projection angle of at least 160 degrees. Furthermore, at least part of the projecting means can be tilted, such that the combined pixel image is projected in one of a plurality of selectable positions. Accordingly, the same projection systems and methods can be used both as a planetarium as well as a hemispherical theater, for example.
Each of the first and second pixel images preferably has a common image size. In addition, the projection systems and methods also preferably include a projection lens assembly which projects the combined pixel image onto a hemispherical surface at a projection angle of at least 160 degrees. This lens assembly is spaced apart from the first and second image sources by a separation distance which is at least six times the image size.
The dual polarization optical projection system and method may also include first and second filters adjacent respective first and second image sources. The first filter includes a first color portion adjacent a first pixel of the first image source which selectively passes a first color of light. The first filter also includes a second color portion adjacent a second pixel of the first image source which selectively passes a second color of light. The second filter includes a first color portion adjacent a first pixel of the second image source which selectively passes the first color of light, and a second color portion adjacent a second pixel of the second image source which selectively passes the second color of light. Accordingly, the combined pixel image includes the first and second colors. In a preferred embodiment, three colors, such as red, green, and blue, are projected to thereby project the entire visible spectrum.
Alternately, a multi-color light source can provide light having a first color to the first and second image sources during a first predetermined time period. The multi-color light source can then provide light having a second color to the first and second image sources during a second predetermined time period. Accordingly, the combined pixel image includes the first color durin
Bennett David T.
Colucci D'nardo
Idaszak Raymond L.
Zobel, Jr. Richard W.
Dowling William
Elumens Corporation
Myers Bigel & Sibley & Sajovec
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