Optical waveguides – Miscellaneous
Reexamination Certificate
2000-05-12
2002-07-09
Healy, Brian (Department: 2874)
Optical waveguides
Miscellaneous
C385S115000, C385S116000, C385S120000, C385S121000, C385S901000
Reexamination Certificate
active
06418267
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
Large Screen Displays (LSD's) can be defined as any dynamic display that can be viewed by more than one person and is at least two feet wide. The LSD market is diverse, with many differing products and technologies, each having certain strengths and weaknesses, competing to fill the needs of the end user. Applications requiring outdoor use in direct sunlight have traditionally been served best by CRT/LED displays, while indoor applications may be served by video walls or front/rear projection systems. The CRT/LED systems, while very bright (typically 4k-6k cd/m
2
), are very expensive, both in terms of initial cost and total cost of ownership, and offer only marginally acceptable resolution. Moreover, they can only be viewed at a distance because of the need for the discrete red, green, and blue (RGB) pixels to optically converge. Thus, they are not cost effective or suitable from either resolution or minimum viewing distance criteria for indoor applications.
Video walls are adequate for indoor use, but are bulky, not very bright (typically less than 500 cd/m
2
), and suffer from the appearance of mullions between each of the displays that comprise the video wall. Data projectors offer high resolution, yet, because of the relatively long “throw distance” required to project an image and other constraints of projection systems, they are not suitable for many applications.
Fiber optic LSD's offer substantial improvements over current CRT- and LED-based displays, due to their smaller depth, lighter weight, and elimination of sensitive and expensive electronic components on the surface of the display, while delivering superior resolution and adequate brightness for direct sunlight applications. Because there is no RGB convergence in fiber optic displays, the minimum viewing distance is considerably less than that of CRT/LED displays.
Fiber optic displays are superior to video walls because they lack mullions, are brighter, more rugged, and are much thinner. Fiber optic displays have an advantage over projection systems in that the display unit can be easily moved and easily installed.
Clearly, fiber optic displays have compelling advantages over competing technologies. Fiber optical displays, however, are not without shortcomings. In fabricating large displays (e.g., >100 inches diagonal), the cost of optical fiber becomes significant. The long, coherent fiber bundles become increasingly difficult to manage, and the bundles become increasingly susceptible to damage. This becomes particularly problematic when designing immersive LSD systems, such as an interactive gaming environment. The purpose of the present invention is to address these and other shortcomings of current large screen display technology. This application is a continuation in-part of application Ser. No. 09/482,290.
2. Description of Related Art
Several LSD's have been successfully constructed using optical fiber, and modular displays have been patented. However, because of the method by which the modules are joined, as well as the lack of a suitable light-shaping diffusion element at the display surface, current displays cannot be contoured. Moreover, the difficulty and cost of dealing with large fiber bundles still exists. The use of smaller tiles is based upon the concept of a “throw-away” display. In other words, if one or more of the tiles are damaged (e.g., by the impact of a rock or other hard object), they can be discarded and replaced in the field at minimal cost.
U.S. Pat. No. 4,299,447 discloses a transflective, liquid crystal display that utilizes a fused, tapered optical fiber block and front diffuser. This invention has several shortcomings as discussed by the author of U.S. Pat. No. 4,613,210. First, the optical tapers used in this invention are costly to produce in high quantities. Second, the imaging qualities of said tapers are not sufficient to render high quality graphics, as is the intent of the present invention. Because of the fabrication of the tapers, distortion occurs around the periphery of the display surface. Moreover, because of the diffuser plate, the transflective operation of the display would not deliver sufficient light to allow the display to operate under normal viewing conditions.
U.S. Pat. No. 4,613,210 purports to be an improvement to U.S. Pat. No. 4,299,447. This invention uses a monolithic integrated circuit chip that serves as the electro-optic transducer (image source). These integrated circuits are integrated circuit chip that serves as the electro-optic transducer (image source). These integrated circuits are coupled to a conjugate image expander and “recomposer” (depixelizing diffuser sheet). Displays of any size can be made by joining the modules. The author also claims contoured displays, yet offers no description of how to couple or bend the printed circuit boards onto which the transducer chips are attached. The invention described has several inherent problems. First, the electro-optic transducers described are relatively small and derive their power from the printed circuit board to which they are attached. This design does not permit the very high luminous flux levels necessary for viewing in high ambient light conditions. Moreover, the presence of the printed circuit board makes field replacement of the modules difficult. The invention described is comprised of a great many specialized parts and thus does not lend itself to volume production at low cost. The “recomposer” or diffuser in this invention is designed to completely depixelize the image. While this is commendable, it is highly impractical, particularly for high ambient light conditions. It is generally necessary to allow a portion of the display surface to be black or gray in color, so as to enhance the contrast and minimize specular reflection from the display surface.
U.S. Pat. No. 5,465,315 discloses a display comprised of a plurality of display devices. The purpose of this invention is to eliminate the mullions in tiled display systems. The display disclosed is not modular, nor are the fiber optic elements used to enlarge the input image.
U.S. Pat. No. 5,832,168 discloses a fiber optic LSD comprised of adjustable modules. However, only a single input surface is used, rather than a plurality. Moreover, the display is not contourable.
SUMMARY OF THE INVENTION
A novel solution to many of these limitations is the intent of the present invention. A contourable electro-optic display apparatus comprised of a plurality of modular, self-contained tiles is disclosed. Despite the possible contours introduced by the tiles, the display can be viewed from any angle because the luminance from each tile is essentially constant. A design for such an apparatus has been disclosed in applicant's invention with application Ser. No. 09/482,290, now U.S. Pat. No. 6,304,703. In this particular invention, each tile is driven by its own commercial off-the-shelf (COTS) micro-display. The overall display resolution is multiplied by the number of tiles, making the display ideal for large command and control centers. By locating a micro-display at each tile, the need for a costly data/video projector is averted and the cost for optical fiber is greatly reduced. Moreover, the assembly and maintenance of the display is simplified by eliminating bulky fiber optic bundles. The electronics for driving the micro display matrix are disposed in a separate enclosure remote from the display. Because of the low power consumption of the micro-displays, LSD's could be powered, in one embodiment, by batteries or solar energy, rather than from the power grid.
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patent: 5832168 (1998-11-01), Yenter
patent: 6219184 (2001-04-01), Nagat
Healy Brian
MediaPull, Inc.
Pepper Hamilton LLP
Singer James M.
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