This invention relates generally to the field of display devices, and more particularly to screens and related hardware employed in rear projection display devices.
Socially and professionally, most people rely upon video displays in one form or another for at least a portion of their work and/or recreation. With a growing demand for large screens and high definition television (HDTV), cathode ray tubes (CRTs) have largely given way to displays composed of liquid crystal devices (LCDs), light-emitting diodes (LEDs), plasma and front and rear projection systems.
A CRT operates by a scanning electron beam exciting phosphorous-based materials on the back side of a transparent screen, wherein the intensity of each pixel is commonly tied to the intensity of the electron beam. With an LED and plasma display, each pixel is an individual light emitting device capable of generating its own light. With an LCD display, each pixel is a transient light modulating device, individually adjusted to permit light to shine through the pixel.
As neither system utilizes a large tube, LCD, plasma and LED screens may be quite thin and often are lighter than comparable CRT displays. The individual nature of each pixel of a LED, plasma or LCD display introduces the possibility that each pixel may not provide the same quantity of light. One pixel may be brighter or darker than another, a difference that may be quite apparent to the viewer.
The human eye is able to perceive subtle differences in light intensity. This poses a challenge to display manufacturers. If the pixels in a display vary greatly in their light emitting ability, the display will be unacceptable to users.
To avoid such discrepancies in performance, great care is generally applied in the fabrication of LED, plasma and LCD displays in an attempt to insure that the pixels are as uniform and consistently alike as is possible. Frequently, especially with large displays, quality control measures discard a high percentage of displays before they are fully assembled. As such, displays are generally more expensive than they otherwise might be, as the manufacturers must recoup the costs for resources, time and precise tooling for the acceptable displays as well as the unacceptable displays.
Projection systems offer alternatives to LED, plasma and LCD based systems. In many cases, projection display systems are less expensive then comparably sized LED, plasma and LCD display systems. With a front projection system, the image is projected onto a screen from the same side as viewer. If the viewer stands, sits or otherwise blocks the projection the image will be compromised. Front projection systems are therefore often suspended from the ceiling or mounted high upon a rear wall.
In either case the projector remains openly visible and may be considered unsightly. As the screen is designed and intended to reflect the projected light back to the viewer, projection systems are highly susceptible to uncontrolled environmental light - an issue that may limit their applicability in many situations.
Rear projection display systems typically employ a wide angle projection lens, (or multiple lenses) operating in connection with one or more reflective surfaces to direct light received from the a projector through the lens(es) to the back of a screen. The lens and mirror arrangement typically enlarges the image as well.
To accommodate the projector, one or more lens, and reflectors, rear projection displays are typically 18 to 20 inches deep and not suitable for on-wall mounting. A typical rear projection system offering a 55 inch HDTV screen may weigh less than a comparable CRT, but at 200+ pounds it may be difficult and awkward to install and support.
Often rear projection display devices exhibit average or below average picture quality in certain environments. For example, rear projection displays may be difficult to see when viewed from particular angles within a room setting or when light varies within the environment. Aside from a theatrical setting, light output and contrast is a constant issue in most settings and viewing environments.
Despite advances in projectors and enhanced lens elements, the lens & reflector design remains generally unchanged and tends to be a limiting factor in both picture quality and overall display system thickness.
Weight, thickness, durability, cost, aesthetic appearance, and image quality are key considerations for rear projection display systems and display screens. From the manufacturing point of view, cost of production and increased yield are also important.
Hence, there is a need for a fiber optic rear projection display device that overcomes one or more of the drawbacks identified above.
This invention provides fiber optic rear projection displays.
In particular, and by way of example only, according to an embodiment of the present invention, this invention provides a fiber optic rear projection display including: a plurality of aligned magnifying layers providing a viewing surface, each magnifying layer including: a plurality of optical fibers, each fiber having an input end, a midsection and an output end, the output end configured to magnify an image presented to the input end; the plurality of input ends aligned as a parallel row square to the input ends; the plurality of output ends aligned in substantially contiguous parallel contact.
Before proceeding with the detailed description, it is to be appreciated that the present teaching is by way of example, not by limitation. The concepts herein are not limited to use or application with a specific fiber optic rear projection display system. Thus, although the instrumentalities described herein are for the convenience of explanation, shown and described with respect to exemplary embodiments, it will be appreciated that the principals herein may be equally applied in other types of fiber optic rear projection display systems.
Referring now to the drawings, and more specifically to
As shown in
Each optical fiber has an input end 202, a midsection 204, and a magnifying output end 206. In at least one embodiment, the midsection 204 is a flexible midsection. The magnifying output end 206 is configured to magnify an image presented to the input end 202. The plurality of input ends 202 are aligned. The plurality of magnifying output ends 206 are aligned in substantially contiguous parallel contact.
More specifically, the magnifying output ends 206 are in substantially contiguous intimate contact, without intervening spacers or material separating each individual magnifying output end 206 from its neighbors on either side. In other words, the magnifying output ends 206 lie next to one another and are in actual contact, touching along their outer surfaces at a point.
As is further illustrated and described below with reference to
In at least one embodiment, glue 208 bonds the aligned input ends 202 to define a portion of dotted line 240. The glue 208 bonding the input ends 202 may be more easily perceived in the enlarged end view bounded by dotted line 242. It is this portion of line 240 that serves as the input location 106 of the magnifying layer 102 shown in
Similarly, in at least one embodiment, glue 210 bonds the aligned magnifying output ends 206 into a uniform line defining a portion of dashed line 244. The glue 210 bonding the magnifying output ends 206 may be more easily perceived in the enlarged end view bounded by dotted line 246. In at least one embodiment, the glue 208 bonding the aligned input ends 202 is the same type of glue bonding the aligned magnifying output ends 206.
As shown in
As shown in
Image source 112 may be any device capable of providing a visual image, such as, for example, a projector. Image source 112 is not limited simply to this example, and may also include combinations of devices. For example, multiple light/image sources (such as red, green, and blue illuminated liquid crystal light valves) may be used as well. As is further explained below the image focused upon the input location 106 is expanded to appear upon the viewing surface 104.
Returning to
The substantially contiguous parallel contact between the magnifying output ends 206 of optical fibers 200 may also be more fully appreciated. As shown, optical fiber 320 is in intimate contact with optical fiber 322, lying to the left, and optical fiber 324, lying to the right.
In at least one embodiment, the core 400 is formed of a generally optically clear plastic or plastic-type material, including but not limited to plastic such as acrylic, Plexiglas, polycarbonate material, and combinations thereof. In an alternative embodiment, the core 400 is formed of a generally optically clear glass.
In at least one embodiment, each optical fiber 200 is preferably substantially totally internally reflecting such that the light, illustrated as lines 404, received at the input end 202 is substantially delivered to the magnifying output end 206 with minimal loss. Cladding 402 is a material having an index of refraction lower then that of the core 400. Total internal reflection, or TIR, is the reflection of all incident light off a boundary between cladding 402 and core 400. TIR occurs when a light ray is both in a medium of higher index of refraction and approaches a medium of lower index of refraction, and the angle of incidence for the light ray is greater than the “critical angle.”
The critical angle is defined as a the angle of incidence measured with respect to a line normal to the boundary between the two optical media for which light is refracted at an exit angle of 90 degrees—that is, the light propagates along the boundary—when the light impinges on the boundary from the side of the medium of higher index of refraction. For any angle of incidence greater than the critical angle, the light traveling through the medium with a higher index of refraction) will undergo total internal refraction. The value of the critical angle depends upon the combination of materials present on each side of the boundary.
As shown in
In at least one alternative embodiment, optical fibers 200 may have cross-sections relating to a square, triangle, octagon or other polygon.
With reference now to
In such a configuration, the top and bottom spacers 212, 224, or the single spacer described previously, provide apparent vertical magnification that is substantially the same as the horizontal magnification provided by each magnifying output end 206. In at least one embodiment, each magnifying output end 206 represents a display pixel 330.
The viewing surface 104 of FORPD 100 is largely composed of display pixels. In at least one embodiment, each display pixel is based upon the magnifying output end 206 of each optical fiber 200. As shown in
It is further understood and appreciated that the optical fibers 200, top spacers 212, bottom spacers 224, bonding glues 208, 210 and other components are drawn in an exaggerated scale for ease of discussion. In addition, the conventions of vertical and horizontal are used with reference to the orientation of the elements within each figure for ease of discussion.
In at least one embodiment the optical fibers 200 may each be one hundred micrometers in diameter. Where angle 406 (shown in
In a typical display screen, visual images are represented by a plurality of individual light points, commonly referred to as pixels. Each pixel may provide the same or different light as its neighbor pixels. As a whole, it is the patterns established by the varying lights provided by the pixels that are perceived by observers as shapes, pictures and images.
Due to the small size of each pixel, and/or the distance from the observer to the display, the independent nature of each pixel is not observed or perceived by the unaided eye. A typical standard TV display provides a vertical to horizontal resolution of 640:480 with about 307,200 pixels. A typical HDTV screen provides a vertical to horizontal resolution of 1920:1080 with about 2,116,800 pixels—a more than six-fold increase over a traditional TV display.
Various visual image projectors are known in the art. The selection of a particular type of image source 112 is a matter of fabrication preference and intended purpose for the FORPD 100. For a HDTV embodiment an appropriate image source 112 should be selected to render a high definition image upon the collective input location 106 as shown in
Where the magnifying layers 102 are vertically continuous across the screen (as shown in
By enclosing the FORPD 100, at least one lens 114 and at least one image source 112 within a case 700 as shown in
Changes may be made in the above methods, systems and structures without departing from the scope hereof. It should thus be noted that the matter contained in the above description and/or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover all generic and specific features described herein, as well as all statements of the scope of the present method, system and structure, which, as a matter of language, might be said to fall therebetween.
This application is related to U.S. patent application Ser. No.: 10/698829, filed on Oct. 31, 2003 by inventors Huei Pei Kuo, Lawrence M. Hubby, Jr. and Steven L. Naberhuis and entitled “Light Guide Apparatus For Use In Rear Projection Display Environments”, herein incorporated by reference.