Television – Video display
Reexamination Certificate
1996-08-05
2001-08-14
Eisenzopf, Reinhard J. (Department: 2614)
Television
Video display
C348S777000, C348S756000, C348S779000, C313S524000, C313S526000
Reexamination Certificate
active
06275270
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a novel and useful video display system.
Presently, producing video images is chiefly accomplished by the use of a cathode ray tube. Although successful in many aspects of the video technology, cathode ray tubes possess a number of disadvantages in that cathode ray tubes are not easily scaled upwardly in size. This is due to the fact that the weight of the vacuum tube becomes unmanageable with an increase in size, commensurate with a large increase in the cost of manufacture. However, cathode ray tubes produce a very high quality video image, via the fluorescing or phosphor display. Moreover, cathode ray tubes exhibit high brightness, speed, contrast, resolution, and color purity.
Liquid crystal displays (LCD) are lightweight and are capable of producing a video image on a flat screen. Unfortunately, the LCD technology produces a video image of low brightness, low efficiency, and low color purity, which has been described as a “washed-out” look. In addition, the LCD video image possesses low resolution and is not susceptible to wide-angle viewing since the Lambertian effect is not inherent in LCD displays. Moreover, LCDs are slow to display an image and are not cost effective.
Image intensifiers have been proposed such as that found in U.S. Pat. No. 5,029,009 where light is passed through a lens to focus the same onto a substrate having an array of gating electrodes, mounted thereupon. An electrode array and substrate are transparent to light in order to allow the light to pass to a photocathode. Thus, adaptive range gating is accomplished using a single imaging camera.
U.S. Pat. No. 3,864,595 describes an image intensifier tube having a photocathode element which converts incident radiation into corresponding electron images. A microchannel plate multiplies the electron image and sends the same to a phosphor screen to convert the electron image to a corresponding radiation image for viewing. The electron image is easily turned “on” and “off” by selectively applying a gating signal to the photocathode element.
U.S. Pat. No. 4,142,123 describes an image display device utilizing a photocathode, multiplier diodes, and an anode electrode in a cathode luminescent screen. The anode electrode is constructed of a material which exhibits slow fluorescence to permit emission of light energy after excitation has ceased. Electrons created in the discharge strike of the anode electrode are directed to the photocathode where they are converted into free electrons. Rapid initiation of subsequent electrical discharges is ensured by such free electrons.
U.S. Pat. No. 5,160,565 describes an image intensifier utilizing a fiber optic bundle which receives an image at one end and produces an intensified image at the other end of the bundle.
U.S. Pat. No. 3,742,285 teaches an image intensifier display system where a display tube having a fiber optic input window includes an electron emitting surface. Electrons impinge on a display window of larger diameter having a phosphor coated surface to provide a magnified image of a scene being viewed.
U.S. Pat. No. 4,694,171 describes an electron microscope imaging system which employs an image intensifier which receives light emitted from an image that is excited by an electron beam.
U.S. Pat. No. 4,213,055 shows an image intensifier tube which utilizes an entrance detection screen mounted in an envelope adjacent to an entrance window. An electron optical system also mounted in the envelope images electrons which pass to an exit screen in the envelope, resulting in a viewable video image.
U.S. Pat. No. 4,974,089 teaches a television camera in which an index rod lens is employed to relay a light image from an image intensifier to a filter which is coupled to a focal plane array assembly.
U.S. Pat. No. 3,757,351 illustrates an electrostatic printing system where light is reflected from a document, passed through a lens, and intensified by a container having a photocathode placed on a glass substrate. The cathode converts the photon image to an electron image which then passes through a microchannel plate and sends the image to a dielectric target in the form of an electro static charge. The electro static charge is then used to print a document.
A video display system which is capable of intensifying an image from a video source accurately and efficiently to produce a video display of very high quality would be a notable advance in the electronics field.
SUMMARY OF THE INVENTION
In accordance with the present invention, a novel and useful video display system is herein provided.
The video display system of the present invention utilizes a video image source which may take the form of a photocathode ray tube combined with an enlarging or focusing lens, a liquid crystal projector, and the like. Video image source may be monochromatic or simple non-color source. In addition, the video source may include video position data in the form of columns or rows, simple video intensity data, or a combination of any of these.
The display system of the present invention also includes an image intensifier unto which the video image source is remotely projected or is transferred by close coupling. In the former case, projection may be accomplished by employing a cathode ray tube as the video image source. In addition, projecting of the video image may take place by employing a liquid crystal display spacial light modulator combined with a point source of light. Any other suitable projecting arrangement may be employed herewith.
The video intensifier of the system of the present invention may be constructed with a first optically transparent body or panel which may be constructed of glass, crystalline material, or any other suitable transparent substance. The optically transparent body would include a first side and a second side. The video image source would be delivered to the first side of the optically transparent body either by projecting the same or through close coupling.
A photocathode layer is placed or positioned on the second side of the first optically transparent body. The photocathode layer may be constructed of any material which will convert photons to electrons. For example, multi-alkali type material such as a sodium, potassium, antimony, cesium compounds, a cesium silver oxide compound, and the like.
Alternately, the photon signal may be converted into electrons by providing a substrate in association with a video image source. The substrate may be an optically opaque body. Photocathode elements or a photocathode layer are formed adjacent the video image source for converting the photon signal of the video image source to electrons. This arrangement may also include photon baffles and channel multipliers, which eliminates the need for metallic coating on the fluorescing layer.
The image intensifier is also provided with a second optically transparent body which may be of the same structure as the first optically transparent body. Of course, the second optically transparent body may comprise the sole optically transparent body when used with the opaque substrate. Likewise, the second optically transparent body possesses a first side and a second side.
A fluorescent layer, which may be a phosphor material, is positioned on the first side of the second optically transparent body. The fluorescing material forming the fluorescing layer is capable of transforming electrons, emanating from the photocathode layer positioned on the second side of the first optically transparent body or from the photocathode elements adjacent the video image source, into photons. Photons are then transmitted through the second optically transparent body for viewing. The fluorescing layer may be in the form of phosphor dots and include a protecting layer of metallic material, such as aluminum, to prevent photons from returning to the photocathode layer on the second side of the first optically transparent body. Although the image viewed on the second side of the second optically transparent body may be monochromatic, a suit
Bielen, Jr. Theodore J.
Calvest Associates, Inc.
Eisenzopf Reinhard J.
Lo Linus H.
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