WO2001069577A2

WO2001069577A2 - Fiber display module and panel assembly

Info

Publication number: WO2001069577A2
Application number: PCT/US2001/007317
Authority: WO
Inventors: William R. Roach
Original assignee: Sarnoff Corp
Current assignee: Sarnoff Corp
Priority date: 2000-03-14
Filing date: 2001-03-08
Publication date: 2001-09-20
Anticipated expiration: 2002-09-14
Also published as: WO2001069577A3; AU2001243486A1

Abstract

A number of light-emitting fibers (200) in side-by-side array comprise a module (10) which may be or may be assembled into a display (20). Each fiber (200) includes a number of light-emitting elements (290) disposed along an optical fiber (210), such as an electro-luminescent material (270), e.g., an OLED material, disposed between hole injecting and electron injecting electrodes (260, 280). A module (10) includes a bent printed circuit board (100) having conductors (140, 142) connected to contacts on the light-emitting fibers (200), such as by solder, conductive adhesive and the like (145). The circuit board (100) is formed by cutting a groove (124) therein, bending the circuit board (100) and securing the bent shape with adhesive (120). A display (20) is formed of modules ( 10) mounted to a faceplate (30) and preferably has moisture resistant sealant (40, 42, 44) applied around the perimeter.

Description

FIBER DISPLAY MODULE AND PANEL ASSEMBLY

This Application claims the benefit of U.S. Provisional Application Serial Number 60/189,221 filed March 14, 2000.

The present invention relates to a circuit board and a fiber display employing same, and, in particular, to an electrical module therefor.

It has long been desired that electronic displays be made with larger screen sizes and also be very thin, ultimately reaching a configuration that may be hung on a wall. Inherent physical limitations preclude conventional cathode ray tubes, such as the color picture tubes and display tubes utilized in televisions, computer displays, monitors and the like, from achieving such desired result. While plasma displays have been proposed to satisfy such desire, the large glass vacuum envelope they require is both heavy and expensive, which is not desirable. The entire display screen of such plasma devices must be fabricated as a single piece and must reproduce many thousands of pixels. Any significant defect that results in faulty pixels or in a non-uniform brightness across the screen, even if confined to a relatively small area, renders the entire screen defective. Such defects cannot be tested or detected until the entire screen is processed, and are either not susceptible of repair or are very expensive to repair, thereby substantially reducing the yield and increasing the cost of each satisfactory plasma display.

One attractive approach for producing a large, thin display screen is to provide an array of a large number of adjacent light-emitting fibers. An advantage of such light-emitting fiber display is that each fiber is relatively inexpensive and may be separately tested before assembly into a display. Because defective fibers are detected and discarded before assembly into a display, the yield of a display which is made from known good light-emitting fibers is increased and the cost thereof is reduced. One such fiber display is described in U.S. Patent entitled "FIBER- BASED FLAT PANEL DISPLAY" (U.S. Patent Application No. 09/418,454 filed October 15, 1999).

With regard to such fiber-based displays, it is desirable that the light-emitting fibers therefor be connected reliably and inexpensively, e.g., in a way that provides suitable performance, facilitates assembly of fibers into a display, and/or reduces cost. This is particularly of interest regarding connections to conductors that are disposed transversely with respect to the side-by-side light-emitting fibers. In the arrangement of U.S. Patent (Application No. 09/418,454), a large multi-layer circuit substrate or printed circuit board 210 shown in Figures 3 and 4 thereof is substantially the same size as the viewing screen of the display 10 and is connected to the light-emitting fibers 100 by a large number of conductive bump connections 232. The fabrication of such large substrate is likely to be complex and possibly costly, as may be the alignment and connection of such substrate to the light- emitting fibers. In addition, such large one-piece circuit substrate departs from the benefits of a modular display as set forth therein.

U.S. Patent (Application No. 09/418,454) also describes a flexible circuit board 360 which is suitable for a display module 310, both shown in Figures 8, 9A and 9B thereof, to facilitate assembly of many flexible circuit boards into modules for a display. Electronic circuits employing either a flexible printed circuit substrate or a combination of a rigid printed circuit board and a flexible cable tend to be more expensive than conventional rigid circuit boards.

Accordingly, there is a need for an improved module arrangement for light- emitting fibers, and desirably one that is low in cost

To this end, the circuit board of the present invention comprises a circuit board substrate having a conductor layer on at least a first surface thereof and having a groove in a second surface thereof opposite the first surface defining first and second substantially planar portions of the substrate, wherein the substrate is bent in a direction that tends to close the groove and bring the first and second portions of said circuit board into an angled position with respect to each other, and wherein the first and second substantially planar portions are held in the angled position by adhesive proximate the groove.

Further, a light-emitting display comprises a plurality of lengths of light- emitting fiber each having a plurality of light-emitting elements along a first surface thereof, each light-emitting element having at least one exposed contact; wherein the plural light-emitting fibers are disposed side-by-side one another. A circuit board having first and second portions joined in angled positions with respect to each other, has the first portion of the circuit board disposed proximal the plurality of light- emitting fibers and has at least one elongated electrical conductor thereon disposed substantially transverse to the lengths of the light-emitting fibers. At least one elongated conductor is electrically connected to at least one of the exposed contacts on each of the plurality of light-emitting fibers.

BRIEF DESCRIPTION OF THE DRAWING

The detailed description of the preferred embodiments of the present invention will be more easily and better understood when read in conjunction with the FIGURES of the Drawing which include:

FIGURE 1 is a perspective view schematic diagram of an exemplary embodiment of a display module including a circuit board and light-emitting fibers and illustrating the arrangement thereof in accordance with the invention;

FIGURES 2A, and 2B are a back-side plan view and a front-side plan view schematic diagram, respectively, of the exemplary embodiment of a circuit board of FIGURE 1 illustrating the arrangement thereof in relation to one step in the fabrication thereof;

FIGURES 3A, 3B and 3C are a bottom view, a side view and an end view schematic diagram, respectively, of the exemplary embodiment of a circuit board of FIGURE 1 illustrating the arrangement thereof in relation to a further step in the fabrication thereof; FIGURES 4A through 4F are schematic diagrams illustrating the steps in the assembly of an exemplary display module of a light-emitting fiber display including the electronic circuit of FIGURE 1;

FIGURES 5A, 5B and 5C are a bottom view, a side view and an end view schematic diagram, respectively, of the exemplary embodiment of a display module of FIGURES 4A through 4F;

FIGURE 6 is a rear plan view schematic diagram of an exemplary light- emitting display including a plurality of the display modules of FIGURES 5A through 5C;

FIGURES 7A and 7B are a side view and an end view schematic diagram, respectively, of the exemplary light-emitting display of FIGURE 6; and FIGURES 8A and 8B are cross-sectional views taken along cross-section lines

8A-8A and 8B-8B, respectively, in FIGURE 6;

FIGURE 9 is an exemplary mechanical mask for defining the shape and size of conductors transverse to a plurality of light-emitting fibers in relation to FIGURES 4 A to 4F; and FIGURE 10 is a side view schematic diagram illustrating exemplary dimensions of a portion of an exemplary light-emitting fiber.

In the Drawing, where an element or feature is shown in more than one drawing figure, the same alphanumeric designation may be used to designate such element or feature in each figure, and where a closely related or modified element is shown in a figure, the same alphanumerical designation primed may be used to designate the modified element or feature. It is noted that, according to common practice, the various features of the drawing are not to scale, and the dimensions of the various features are arbitrarily expanded or reduced for clarity.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A plurality of light-emitting fibers are arrayed in side-by-side array, preferably being substantially contiguous, and are connected to appropriate electrical driver circuits for selectively and controllably energizing each light-emitting element (pixel) to produce a light-emitting display for displaying an image or information. Image and/or information are used interchangeably with respect to what is displayed on a display device, and are intended to encompass any and all of the wide variety of displays that a user may desire, including, but not limited to, visual images and pictures, whether still or moving, whether generated by a camera, computer or any other source, whether true, representative or abstract or arbitrary, whether or not including symbols or characters such as alphanumeric characters or mathematical notations, whether displayed in black and white, monochrome, polychrome or full color.

A light-emitting fiber is fabricated, for example, on an optical fiber of conventional optically transmissive material, such as glass, borosilicate glass, soda- lime glass, quartz, sapphire, plastic, polymethyl-methacrylate (PMMA), polycarbonate, acrylic, Mylar, polyester, polyimide or other suitable material, to have along its length on one of its surfaces a plurality of light-emitting elements 180. Light-emitting elements 180 include an electro-luminescent material, preferably an Organic Light-Emitting Diode (OLED) material, disposed between suitable electrodes. Each light-emitting element or OLED "stack" includes a hole-injecting electrode, a layer of OLED material and an electron-injecting electrode, and is independently operable to produce one pixel of the image or information to be displayed. In a color display, three physical pixel elements may each produce one of three color sub-pixels that emit light of three different colors that together produce one color pixel of a color image.

Each light-emitting fiber includes a conductor along its length for applying select signals to each of the light-emitting elements disposed along the length of that fiber. Each light-emitting fiber also includes a plurality of contacts along its length, one contact for each light-emitting element, to which conductors providing pixel data signals are connected. Such data signal conductors lie transverse to the length direction of the light-emitting fibers for interconnecting such fibers in an array of a light-emitting display, as described herein. Thus, suitable electrical connections can be made to couple the select signal and the data signal to respective electrodes of each light-emitting element for controllably and selectively energizing each light-emitting element to produce the pixels of an image to be displayed by a light-emitting display including a plurality of light-emitting fibers in parallel side-by-side array. These connections are made to the surface of the light-emitting fibers on which the light- emitting elements are formed, and the light emitted thereby passes through the optical fiber away from the light-emitting elements to be observed by a viewer of such display.

It is noted that because the light-emitting fibers may be of any desired length, and because any desired number of such fibers may arrayed side-by-side, a thin panel display of virtually any desired size (height and width) may be assembled utilizing the present invention.

An exemplary optical fiber is typically about 0.25 mm (about 0.010 inch) wide, and has light-emitting elements disposed along its length on a pitch of about

0.75 mm (about 30 mils). Where the light-emitting fibers are utilized in a color display, light-emitting elements emitting three different colors of light, such as red (R), green (G) and blue (B), are utilized. The three different color light-emitting elements are arranged to be in adjacent sets of R, G, B elements, each set providing a color pixel. Such arrangement of light-emitting elements may be provided by sequencing R, G and B OLED materials along the length of each light-emitting fiber or may be provided by placing fibers of different colors side-by-side in an R-G-B sequence, i.e. a red-emitting fiber next to a green-emitting fiber next to a blue- emitting fiber, and so forth. Light-emitting fibers are described, for example, in U.S. Patent (Application No. 09/418,454) and in U.S. Patent Application

Serial No. 09/ entitled "ELECTRICAL INTERCONNECTION OF

LIGHT-EMITTING FIBERS, AND METHOD THEREFOR" (SAR13830) filed on even date herewith.

FIGURE 1 is a perspective view schematic diagram of an exemplary embodiment of a display module 10 including a circuit board 100 and light-emitting fibers 200 and illustrating the arrangement thereof in accordance with the invention. Circuit board 100 includes a first portion 110 and a second portion 130 that are positioned at about a right angle to each other, although a greater or lesser angle could be utilized. First portion 110 of circuit board 100 has edge connections 112, 114, 116 at which printed conductors 142, 144 are arrayed for being engaged by a conventional edge connector (not shown) through which electrical signals are provided to and received from the electronic circuits on circuit board 100. Electronic devices 150, such as integrated circuits, hybrid circuits electronic circuit modules and the like, are mounted to first portion 110 for operating on the signals received via edge connections 112, 114, 116 and for providing drive signals, such as select signals and/or data signals, to light-emitting fibers 200. Second portion 130 of circuit board 100 includes electrical conductors 140, 142 on one side thereof through which signals, e.g., data signals via conductors 140 from electronic devices 150 and select signals via conductors 142 from edge connections 112, 116, are applied to plural light-emitting fibers 200 that are arrayed side-by-side. Conductors 144 couple drive signals from edge connection 114 to electronic device 150. The surface 202 of light-emitting fibers 200 from which light is emitted faces away from second portion 130 of circuit board 100. For example, conductive "dots" 145 such as small drops of solder or electrically conductive epoxy may be applied to the contacts of the light-emitting elements of fibers 200, or to conductors formed across several fibers in a direction transverse to the length thereof, and the second portion 130 of circuit board 100 pressed thereagainst for connecting ones of conductors 140 on second portion 130 to the contacts of fibers 200. Where fibers 200 include a contact at one or both ends thereof for receiving a second signal or select signal, conductors 142 on circuit board 100 connect thereto by like conductive dots 145. Thus, signals from electronic devices 150 are applied to ones of the light-emitting elements of side-by-side arrayed fibers 200 to display information. Circuit board 100 together with the side-by-side array of light-emitting fibers 200 provide a light-emitting display module 10.

First portion 110 and second portion 130 are maintained in the desired relative positions by a fillet of epoxy 120 along the inside corner formed where the two portions 110, 130 meet. An advantageous arrangement for circuit board 100 and for the fabrication thereof obtains where both portions 110, 130 are made as a single printed circuit board, such as is described below. The structure of display module 10 is advantageous because circuit board 100 provides support for light-emitting fibers 200 so as to facilitate the placement of fibers 200 as modules 10 in close proximity on a common faceplate, thereby to provide a light-emitting display comprising a plurality of light-emitting display modules 10. Desirably, such arrangement may be utilized to provide a display that is economical, reliable and rugged.

FIGURES 2A, and 2B are a back-side plan view and a front-side (or active- side) plan view schematic diagram, respectively, of the exemplary embodiment of a circuit board 100 of FIGURE 1 illustrating the arrangement of portions 110, 130 thereof in relation to one step in their fabrication. A planar "double-sided" printed circuit board 100' is fabricated in conventional manner of conventional materials, for example, a sheet 102 of FR4 circuit board substrate material clad on both sides with a thin layer of copper that is etched or otherwise patterned to form a pattern of copper conductors that are plated or tinned, e.g., with tin, silver or solder, for solderability.

Such conductors include conductors providing edge connections 112, 114, 116, providing conductors 140 for data signals and providing conductors 142 for select signals, as well as conductors 144 coupling signals and power supply potential into and out of electronic devices 150. Data signal conductors 140 are on the same surface of circuit board 100' as are electronic devices 150, as shown in FIGURE 2B. Edge connection 112, 114, 116 conductors 142, 144 may be on either or both sides of circuit board 100' and may include conventional "plated- through holes" or vias to provide electrical connection between conductors on the opposing surfaces of circuit board 100'. A line defining the intersection of first portion 110 and second portion 130 of circuit board 100 is identified as groove line 122. After the conductor patterns are formed on circuit board 100', a groove 124 is cut into circuit board 100' from the back side thereof (FIGURE 2A) to a depth not exceeding the thickness of the circuit substrate 102, and preferably slightly less than the thickness of substrate 102, so as to not disturb or cut into the conductors, e.g., conductors 140, 142 on the front or active surface of circuit board 100' (FIGURE 2B). Preferably, a 90° V-shaped groove is ground into substrate 102, e.g., as by a grinding wheel, thereby to provide for a 90° angle between first and second portions 110 and 130. Alternatively, groove 124 may be cut by any suitable method, such as grinding, routing, sawing or machining, as is convenient. Grooved circuit board 100' is then folded at groove 124 to move portions

110 and 130 into substantially perpendicular relative positions, i.e. lifting the edges of portions 110, 130 in a direction up out of the paper of FIGURE 2A.

As a result of the folding of circuit substrate 102, the copper conductors 140, 142 on the active side of circuit board 100, including conductors from edge connections 112, 114, 116 and conductors 140, 142, bend 90° and V-groove 124 closes. Portions 110, 130 are then secured in their desired relative position by applying a fillet of epoxy 120 along all, or at least along selected parts, of the closed groove 124 on the back side of circuit board 100. Preferably, the epoxy 120 is deposited in the groove shortly before board 100' is folded and the folding action tends to squeeze the as-yet uncured epoxy out to form the fillet 120 along the inside corner at the intersection of first and second portions 110 and 130.

The result is the circuit board 100 of FIGURES 3A, 3B and 3C, which are a bottom view, a side view and an end view schematic diagram, respectively, of the exemplary embodiment of a circuit board 100 of FIGURE 1. FIGURES 3 A through 3C illustrate the arrangement of circuit board 100 in the processing sequence after the folding and epoxying, and after the mounting of electronic devices 150 thereon. The structure thus formed is in effect a beam having an L-shaped cross-section as visible in FIGURE 3C and so is quite rigid, especially in the longer dimension, thereby to provide substantial support to the light-emitting fibers 200 to which it is later attached. Electronic drive circuit 150 is, for example, an integrated circuit, hybrid circuit, microelectronic circuit or other electronic device that produces drive signals, such as data drive signals and/or select drive signals, to be applied to the data and/or select electrodes of the light-emitting elements of the fibers 200. Patterned conductors 140 are preferably in substantially parallel spaced-apart relationship at the end of second portion 130 of circuit substrate 100 distal driver circuit 150 and proximal fibers 200 to which they are attached.

More particularly, patterned conductors 140 are preferably substantially parallel and spaced apart at like pitch to the substantially parallel spaced-apart transverse conductors 350 on fibers 200, thereby providing conductors 140 that facilitate a direct and simple interconnection between ones of the patterned conductors

140 of electronic circuit 100 and the corresponding conductors 350 of fibers 200.

At this juncture in the processing of circuit board 100, it is electrically complete and can be tested, either fully or to any desired degree, prior to assembly to light-emitting fibers 200. Thus, any inoperative function or out of specification condition can be identified and rectified at a lower assembly level, before circuit board 100 is assembled to any light-emitting fibers 200 and the cost of troubleshooting and repair, or of scrapping the item, is much greater.

An exemplary circuit board of 0.060 inch (about 1.5 mm) thick fiberglass/epoxy material (e.g., FR4) with 0.001 inch (about 0.025 mm) thick copper conductors that were solder tinned was prepared with 16 conductors positioned transverse to and crossing the groove line. The conductors were 0.010 inch (about

0.25 mm) wide and separated by 0.18 inch (about 4.5 mm) wide spaces. The 90° V- groove was ground into the back of the circuit board using a grinding wheel. In some places, the V-groove was deep enough to expose the 0.010 inch (about 0.25 mm) wide copper conductors, and, in other places, the V-groove depth was slightly less and did not expose the 0.010 inch (about 0.25 mm) wide copper conductors. The circuit board was bent 90° and secured with a five-minute curing commercial epoxy without damage to the bent copper conductors, as determined by visual inspection and electrical continuity testing.

It is noted that the second portion of circuit board 100 preferably includes only the conductors 140 that will be attached to contacts on light-emitting fibers 200 by electrically-conductive adhesive or low-temperature solder, i.e. the data signal conductors, and also the select signal conductors where fibers 200 have contacts for receiving the select signals that are on the same surface thereof as are the data signal contacts. Thus, the second portion 130 of circuit board 100 may have only a "single- sided" conductor pattern.

The first portion 110 of circuit board 100 preferably includes conductor patterns to which the leads of electronic devices 150 connect and conductors for edge connections 112, 114, 116, and may have a "single-sided" or a "double-sided" conductor pattern as is convenient. Conductors 118 between edge connections 114, for example, and electronic devices 150 may include connections between conductors on the two opposing surfaces of circuit board 100 for providing cross overs and the like, as may be necessary or convenient. Conventional edge connectors are available for connecting to either "single-sided" or "double-sided" conductor patterns.

FIGURES 4A through 4F are schematic diagrams illustrating the steps in the assembly of an exemplary display module 10 of a light-emitting fiber display including the exemplary bent electronic circuit 100 of FIGURE 1. A flat plate 300 of length exceeding the length of light-emitting fibers 200 and of width exceeding that of the plurality of fibers 200 to be assembled is provided, as shown in FIGURE 4A. Flat plate 300 includes a fixed stop plate 310 that is either attached to or integral with plate 300. A plurality of light-emitting fibers 200 are placed side-by-side on flat plate 300 adjacent to fixed stop plate 310 with their respective surfaces 202 from which light is emitted against plate 300 and with their respective surfaces having light-emitting elements thereon facing away from plate 300. Each light-emitting element has an exposed data contact 220 at which data signals are to be applied and preferably has a select contact 210 at one or both ends thereof. A clamp plate 320 is placed against fibers 200 to press them against fixed plate 310. The plurality of fibers are placed on flat plate 300 with their respective ends substantially aligned and clamping plates 330 are placed at the respective ends of fibers 200 to maintain the desired alignment, as shown in FIGURE 4B. Thus, light- emitting fibers 200 are firmly held in substantially the positions in which they will be disposed in the final assembly of a display module 10.

A mechanical deposition mask 340 is placed over the ends of light-emitting fibers 200 to mask select contacts 210, as shown in FIGURE 4C, and an electrode or contact metal is deposited onto the exposed surfaces of light-emitting fibers 200, i.e. the surfaces on which the light-emitting elements thereof are disposed. Suitable metals include copper, aluminum, gold, silver, chromium, alloys thereof, and combinations thereof, which may be deposited by evaporation, sputtering, spraying or other suitable method. A small fillet of adhesive, epoxy, optical cement and the like may be deposited at the gap, if any, between adjacent ones of fibers 200 at the positions where conductor metal is to be deposited so as to decrease or bridge the gap, if any. Preferably, aluminum metal is evaporated onto fibers 200. With light-emitting fibers 200 held in place by fixed plate 310 and clamp 320, and by a vacuum applied through holes (not visible) in flat plate 300, clamps 330 are removed and the deposited electrode metal is scribed in a direction transverse to the long dimension (i.e. the length) of light-emitting fibers 200, thereby to form a plurality of conductors or data buses 350 disposed transverse to light-emitting fibers 200 and connecting the data electrodes 220 of similarly situated light-emitting elements of each of the plurality of light-emitting fibers 200, as shown in FIGURE 4D. These transverse conductors 350 may be referred to as data buses because they are utilized to couple data signals to side-by-side ones of data contacts 220 of the light-emitting elements disposed along each of the plurality of adjacent fibers 200 of display module 10. In general, transverse electrical interconnecting conductors 350 may be formed by evaporating or otherwise depositing metal strips 350 across the array of light- emitting fibers 200 and overlying the top contacts 220 thereof for interconnecting contacts 220 and applying the data drive signals thereto. The small gap, if any, between adjacent light-emitting fibers 200 may be bridged by deposited metal if sufficiently small and/or by a drop or dollop of electrically insulating material applied at the locations where conductors 350 bridge between adjacent fibers 200. Suitable materials include, for example, adhesive, epoxy, optical cement and the like, to provide a fillet surface on which the metal of conductor 350 lies.

Alternatively, mask 340 may be replaced by a more complex mask that includes transverse obstructions to deposition of the electrode or contact metal so that the deposition directly produces a pattern of a plurality of transversely disposed data bus conductors 350 across the plurality of light-emitting fibers 200 in positions that overlie side-by-side ones of the data contacts 220 of adjacent fibers 200, as described in relation to FIGURE 9. In either case, it is preferred that a patterned passivating material, such as silicon carbide, silicon nitride, silicon dioxide, silicon oxynitride or diamond-like carbon, be deposited onto the plurality of fibers 200 in areas not containing conductors 350, thereby to "seal" there areas against the intrusion of moisture, oxygen, and/or other foreign matter, i.e. to slow the permeation of moisture and oxygen to the OLED material of the light-emitting elements of fibers 200. Next, small "dots" or spots 145 of electrically conductive adhesive or of low- temperature solder are deposited on each of the data bus conductors 350, as shown in FIGURE 4E. Preferably the dots 145 are on areas thereof that do not overlie the active or light-producing area of the OLED material of the light-emitting elements of fibers 200. Also preferably, dots 145 are deposited along each data bus conductor 350 to provide for redundant connection to improve reliability. In like manner, light- emitting fibers 200 may have select bus contacts 224 on the top surface thereof along with their light-emitting elements. The select bus contacts 224 may be at one or both ends of fibers 200. In such case, conductive dots 145 may be deposited on these select bus contacts 224 as well.

Next, a bent printed circuit board 100 is placed over the plurality of side-by- side light-emitting fibers 200 with its data bus conductors 140 parallel to and aligned along the data bus conductors 350 which are disposed transversely across light- emitting fibers 200, as shown in FIGURES 4E and 4F. Circuit board 100 is moved toward fibers 200 until conductive dots 145 are in position to form electrical connections between the respective data bus conductors 140 of circuit board 100 and the corresponding data bus conductors 350 across fibers 200. Connections 145 may be completed by heating, laser heating, and/or exposure to ultraviolet (UV), as is appropriate to the material utilized for dots 145. For example, where dots 145 are of solder, heat is applied to melt the solder dots 145 to form permanent solder connections. Where dots 145 are of conductive adhesive, suitable temperature for tacking and/or curing the adhesive is applied. Where the select bus conductors 224 are also on the top surfaces of fibers 200, connections between those select bus conductors 224 and corresponding select conductors 142 on circuit board 100 are likewise made by ones of conductive dots 145.

It is noted that the plural conductive dots 145 provide plural or redundant connections between data bus conductors 350 and data bus conductors 140, thereby improving reliability and allowing satisfactory operation without loss of even one light-emitting element or pixel even where one or more dot 145 connections may have been missed or may have failed.

Then, after the conductive adhesive dots 145 are cured or the solder dots 145 are reflowed to provide the desired electrical connections between circuit board 100 and the plurality of light-emitting fibers 200, clamp 320 is removed to release circuit board 100 and the plurality of light-emitting fibers 200 which comprise display module 10. Display module 10, as shown in FIGURES 5A, 5B and 5C, is then removed from flat plate 300. Alternatively, display module 10 may employ light-emitting fibers 200 that have had a long metal conductor deposited over the data contacts of all of the light- emitting elements on each fiber to allow testing of all the light-emitting elements on a fiber at one time. After testing, the long metal conductor is scribed, as by a mechanical or laser scribe, to provide a data contact 220 for each light-emitting element, and a passivating layer is deposited to seal the scribed regions on each fiber. Conductive adhesive dots 145, may then be deposited directly onto each data contact

220 and circuit board 100 may be pressed into place, thereby making electrical connection between the data conductors 140 of circuit board 100 and the data contacts 220 of the light-emitting elements of fibers 200. This alternative is advantageous in that it allows each fiber to be positioned longitudinally at the time of attachment of circuit board 100 and eliminates the deposition of transverse data conductors 140, however, it is disadvantageous in that the connection to each light-emitting element depends upon one conductive dot 145 due to the lack of redundant electrical paths provided by transverse conductors 350 in the embodiment of FIGURES 4A to 4F.

FIGURES 5A, 5B and 5C are a bottom view, a side view and an end view schematic diagram, respectively, of the exemplary embodiment of a display module

10 according to FIGURES 4A through 4F. Display module 10 comprises a bent electronic circuit board 100 having a plurality of electronic devices 150 on the first portion 110 thereof and having a plurality of light-emitting fibers 200 attached to the second portion 130 thereof. The surface 202 of light-emitting fibers 200 from which light is emitted faces away from second portion 130 and together provide a viewing surface 12 on which a viewer may observe the information displayed. The plurality of light-emitting fibers 200 are attached to the second portion 130 by a plurality of conductive dots 145. Conductive dots 145 connect ones of data bus conductors 140 of circuit board 100 to corresponding ones of data bus conductors 350 disposed on and transversely to plural fibers 200, and may also connect conductors 144 of circuit board 100 to select contacts 210 of fibers 200, where fibers 200 include select contacts.

Display module 10 includes plural light-emitting fibers 200 arrayed in parallel side-by-side arrangement and an electronic circuit board 100 coupled thereto for providing electrical drive signals, such as select signals and/or data signals, for the light-emitting elements thereon. The array of side-by-side fibers 200 includes transverse conductors 350 as described above.

Advantages of this arrangement include that the interconnection between electronic circuit 100 and fibers 200 is by plural connections 145, thereby providing redundancy and increasing reliability, as well as increased mechanical support as the number of connections increases. Moreover, if conductor 350 were to develop a break, it is likely that electrical connection to each pixel element of each fiber 200 will be maintained because most locations along each conductor 350 connect to a conductor 140 via two independent circuit paths. As a result, the coupling of electrical drive signals to each pixel element of each fiber 200 of module 10 is likely to be maintained despite a number of breaks or faults, thereby providing a robust and reliable product.

Another advantage is that each fiber 200 does not have to be connected to each drive conductor 140, thereby eliminating the necessity to make a direct connection between a conductor 140 on circuit board 100 and the light-emitting fibers 200 at or near the edges of module 10. This advantage provides for convenient positioning of circuit boards 100 in modules 10 in ways that do not interfere with adjacent modules 10, even if certain components of a particular module extend beyond the edges of that module 10. In addition, electrical drive device 150 and circuit board 100 are easily tested before assembly to fibers 200 and only a conventional printed circuit board 100 is needed.

While a light-emitting display may be provided by one display module 10 as thus far described, it is desirable to employ a plurality of display modules 10 to provide a larger light-emitting display. FIGURE 6 is a rear plan view schematic diagram of an exemplary light-emitting display 20 including a plurality of the display modules 10 of FIGURES 5 A through 5C. FIGURE 6 is described below in conjunction with FIGURES 7 A and 7B which are a side view and an end view schematic diagram, respectively, of the exemplary light-emitting display of FIGURE 6, and in conjunction with FIGURES 8A and 8B which are cross-sectional views taken along cross-section lines 8A-8A and 8B-8B, respectively, in FIGURE 6. Display 20 is typically a planar panel comprising a plurality of display modules 10 with the light-emitting surface 202 of light-emitting fibers 200 mounted to a planar faceplate 30, such as a sheet of glass or transparent plastic, having a surface defining a viewing surface 32 at which a viewer can perceive the information displayed on display 20. The modules 10 may be mounted by adhesively attaching the fibers 200 of modules 100 to faceplate 30, such as by an optically transparent adhesive having an index of refraction suitably matched to the indices of refraction of the fibers 200 and faceplate 30. Alternatively, modules 10 may be mounted with the light-emitting surfaces 202 of fibers 200 spaced away from faceplate 30.

Adjacent modules 10 may be insulated from each other by a thin insulating spacer or shim (not visible) that prevents contacts or other electrical conductors of the end light-emitting fibers 200 that abut each other to not short circuit. The spacer may be a sheet of Mylar or other plastic, e.g. about ^lA to ^x mil (about 6 - 13 μm) thick, or may be provided by an insulating layer deposited on at least the ones of fibers 200 that are at the edge on module 10 or by spacing the ends of conductors 350 away from the edge of the end ones of fibers 200. Modules 10 are connected to each other and to other apparatus (not shown), such as an RF tuner, video processor and drive circuits of a television receiver, or to video processing and drive circuits of a video recorder, video disk player, computer or the like, by ribbon cables or other cables having edge connectors that engage edge connections 112, 114, 116 of circuit boards 100 of modules 10. Modules 10 are passivated or sealed to faceplate 30 and to each other to prevent or at least retard the entry of moisture into display 20. Peripheral seals 40 around the periphery of faceplate 30 and back seals 46 between modules 10 may be a solid fillet of a single- or two-component sealing material, such as epoxy, silicone, or polyimide. Alternatively, peripheral seal 40 may include plural seals such as edge seals 42 and end seals 44 each formed of a glass strip that is sealed to the adjacent faceplate 30 and module 10 by a thin seal of adhesive, epoxy, silicone or polyimide. An advantage of such glass strip seals is that because the glass is impervious to moisture, the sealant or epoxy is much smaller than for a fillet seal and so presents a smaller cross-sectional area through which moisture can permeate. The sealing may be made by applying the edge seals 42 and back seals 46, and then applying the end seal 44, Any one or more of these seals, or all of the seals, may be either a fillet of epoxy or other adhesive or the preferred adhesively-attached glass strip seal, or a combination thereof. Dessicant material may be placed within the volume within display 20 sealed by seals 40, 46, preferably in one or more cavities behind faceplate 30 and along one or more edges thereof, for absorbing any residual moisture that may be sealed within the sealed volume of display 20 or that may penetrate seals 40, 46. The sealed volume of display 20 may also be filled with dry gas, such as dry nitrogen or other inert gas, prior to sealing.

FIGURE 9 is an exemplary mechanical mask 520 for defining the shape and size of conductors 350 transverse to a plurality of light-emitting fibers 200 that may be utilized alternatively to mask 340 described above. Mechanical mask 520 has a peripheral masking portion 522 and transverse bridging masking portions 524 bridging between opposite sides of mask 520 to define plural mask openings 526 through which conductive metal conductor material such as aluminum, copper, gold or other suitable metal is deposited for forming conductors 350 on a plurality of light- emitting fibers 200 that are arranged in side-by-side touching relationship, as illustrated. Bridging mask portions 524 extend in a direction transverse to the long dimension of fibers 200. Bridging mask portions 524 block areas of each of fibers 200 on which metal conductor material is not deposited, i.e. the areas of light-emitting elements. End portion 522 of mask 520 masks a portion of fibers 200 proximate the ends thereof at which are disposed contacts 224 to which select signals are applied. Insulation 270, 272 on fibers 200 separate select contacts 224. Also shown in FIGURE 9 are the small drops 204 of adhesive or epoxy that may be utilized to bridge any gap between adjacent ones of fibers 200. Conductor metal may be deposited by any convenient method, such as by sputtering or evaporation. For example, on an optical fiber of about 0.25 mm (about 0.010 inch) width, mask slots 526 may be about 100 μm (about 0.004 inch) wide in the direction along the length of optical fibers 110 and on a pitch of about 0.75 mm (about 0.030 inch), thereby to define conductors 200 that are about 25 μm (about 0.004 inch) wide.

FIGURE 10 is a side view schematic diagram illustrating exemplary dimensions of a portion of an exemplary light emitting fiber 200 having light-emitting elements 290 on a surface 212 thereof that is opposite the surface 202 from which light is emitted for viewing. For example, in a high-definition television (HDTV)di splay having a screen diagonal measurement of about 175 cm (about 66 inches) and a 16:9 aspect ratio, the image includes 1920 x 1080 full color pixels and each full color pixel includes three monochrome (red, green and blue) pixels. Transverse alignment and longitudinal registration of the optical fibers 200 is required for placement of conductors 350. Such longitudinal registration is less than about 25-50 μm (about 1-2 mils) given the about 0.1 mm (about 0.004 inch) width of contacts 254.

Typical dimensions for an about 0.25 mm (about 10 mil) wide optical fiber 200 include: about 0.50 x 0.25 mm (about 0.020 x 0.010 inch) pixels on an about 0.75 mm (about 0.030 inch) pitch, and having a contact 250 layer of about 0.70 x 0.25 mm (about 0.028 x 0.010 inch) thereover. This allows a spacing of about 50 μm (about 0.002 inch) between adjacent contact layers 250 and a contact 254 area of about 0.1 x

0.25 mm (about 0.004 x 0.010 inch) at one end of contact layer 250. It also allows OLED layer 270 and top electrode 280 to overlap ITO electrode 260 by about 25 μm (0.001 inch) at each end. It is noted that it is desirable that the contact 254 not overlie OLED layer 270 which is the active area of light-emitting element 290 so that OLED layer 270 is not damaged when connection is made to contact 254, such as by probe for testing or by attachment to an external conductor 350 by compression, solder or electrically conductive epoxy 145. Conductors 350 (not shown) have a width of about 0.1 mm (about 0.004 inch) corresponding to contact 254 and extend a sufficient length to lie across the desired the number of about 0.25 mm (about 10 mil) wide fibers 200.

While the present invention has been described in terms of the foregoing exemplary embodiments, variations within the scope and spirit of the present invention as defined by the claims following will be apparent to those skilled in the art. For example, while first and second portions 110, 130 of circuit board 100 are conductors 350 are illustrated in exemplary fashion as being perpendicular, e.g., at a right angle to each other, as are conductors 350 illustrated relative to the lengths of the light-emitting fibers, such circuit boards and conductors need not be at a right angle, but may be angled as convenient. Also, first and second portions 110, 130 of board 100 are preferably secured in an L-shape by epoxy or other adhesive, but may be secured by tape, mechanical brackets, braces or other convenient means. Further, conductive dots 145 may be applied in any convenient number regarding each transverse conductor 350 taking account of the desired cost, strength, electrical conductivity and reliability desired. Conductors 200 need not be straight, as illustrated, by may curve or be non-lineal, also as is convenient. Such angled and/or non-lineal conductors may be referred to as being substantially transverse to the fibers. Other materials and dimensions may be utilized in making the light-emitting fibers, display modules and displays according to the invention, as well as the circuit modules and components thereof.

In addition, circuit boards 100 do not have to include electronic devices 150 as shown, but may only include printed wiring for providing direct conductive connections between edge connectors and the contacts of fibers 200. In such arrangement, electronic devices for processing and generating display signals, e.g., select signals and data signals, are located remotely from circuit board 100.

Claims

WHAT IS CLAIMED IS:

1. A light-emitting display comprising: a plurality of lengths of light-emitting fiber each having a plurality of light-emitting elements along a first surface thereof, each light-emitting element having at least one exposed contact; wherein said plural light-emitting fibers are disposed side-by-side one another; a circuit board having first and second portions joined in angled positions with respect to each other, the first portion of said circuit board being disposed proximal said plurality of light-emitting fibers and having at least one elongated electrical conductor thereon disposed substantially transverse to the lengths of said light-emitting fibers; and means electrically connecting said at least one elongated conductor to at least one of the exposed contacts on each of said plurality of light-emitting fibers.

2. The display of claim 1 wherein said circuit board includes a substrate having a plurality of conductors on a first surface thereof, said circuit board having a groove in said substrate on a second surface thereof opposite the first surface thereof, wherein the groove defines the first and second portions of said circuit board, and wherein said substrate is bent in a direction that tends to close said groove and bring the first and second portions of said circuit board into said angled positions.

3. The display of claim 1 wherein said circuit board includes at least one of (a) at least one electronic device on the second portion thereof and coupled to said elongated conductor, and (b) connection means on the second portion thereof adapted for receiving electrical signal and for coupling said electrical signal to said electronic device .

4. The display of claim 1 further comprising at least one second elongated electrical conductor disposed on said plurality of light-emitting fibers substantially transverse to the length thereof for connecting ones of the exposed contacts of adjacent ones of said plurality of light-emitting fibers, wherein said at least one second elongated electrical conductor is substantially parallel to said at least one elongated electrical conductor and is connected thereto by said means electrically connecting.

5. The display of claim 1 wherein said means electrically connecting includes at least one of solder, electrically conductive epoxy and silver filled epoxy.

6. The display of claim 1 further comprising a plurality of the display of claim 1 disposed side-by-side with the plurality of light-emitting fibers thereof substantially on a transparent faceplate.

7. A display comprising: a transparent faceplate; a plurality of display modules in side-by-side abutting relationship on said faceplate; each said display module comprising: a plurality of lengths of light-emitting fiber each having a plurality of light-emitting elements along a first surface thereof, each light-emitting element having at least one exposed contact, wherein said plural light-emitting fibers are disposed side-by-side one another with second surfaces opposite the first surfaces thereof proximate said faceplate for providing a viewing surface for the display; a circuit board having first and second portions joined in angled positions with respect to each other, the first portion of said circuit board being disposed proximal the first surface of said plurality of light-emitting fibers, said circuit board having at least one elongated electrical conductor on the first portion thereof disposed substantially transverse to the lengths of said light-emitting fibers; an electronic device on said circuit board and coupled to said at least one elongated electrical conductor for applying an electrical signal thereto; and means electrically connecting said at least one elongated conductor to at least one of the exposed contacts on each of said plurality of light-emitting fibers.

8. The display of claim 7 wherein the second surfaces of said plurality of light- emitting fibers are attached to said faceplate.

9. A method for making a light-emitting display comprising: placing side-by-side one another a plurality of lengths of light-emitting fiber each having a plurality of light-emitting elements along a first surface thereof and having a second surface opposite the first surface thereof for providing a viewing surface for the display, each light-emitting element having at least one exposed contact; providing a circuit board substrate having an electrical conductor layer on at least a first surface thereof and having a second surface thereof opposite the first surface, wherein the electrical conductor layer includes at least one elongated conductor; making a groove in the second surface of said substrate defining first and second substantially planar portions of said substrate, the groove extending into the circuit board substrate substantially to the electrical conductor layer but not severing the electrical conductor layer; bending said substrate and electrical conductor layer in a direction that tends to close the groove and bring the first and second portions of said circuit board into an angled position with respect to each other, wherein said angled position includes one of a right angle, an angle less than a right angle and an angle greater than a right angle; and electrically connecting the at least one elongated conductor to at least one of the exposed contacts on each of said plurality of light-emitting fibers.

10. The method of claim 9 wherein said electrically connecting includes placing dots of an electrically conductive connection material on at least one of the exposed contacts on each of said plurality of light-emitting fibers, and placing the at least one elongated conductor in contact with the electrically conductive connection material.

11. A method for making a circuit board comprising: providing a circuit board substrate having an electrical conductor layer on at least a first surface thereof and having a second surface thereof opposite the first surface; making a groove in the second surface of said substrate defining first and second substantially planar portions of said substrate, the groove extending into the circuit board substrate substantially to the electrical conductor layer but not severing the electrical conductor layer; bending said substrate and electrical conductor layer in a direction that tends to close the groove and bring the first and second portions of said circuit board into an angled position with respect to each other, wherein said angled position includes one of a right angle, an angle less than a right angle and an angle greater than a right angle; and applying an adhesive proximate the groove to secure said first and second substantially planar portions in said angled position.

12. A circuit board comprising a circuit board substrate having a conductor layer on at least a first surface thereof and having a groove in a second surface thereof opposite the first surface defining first and second substantially planar portions of said substrate, wherein said substrate is bent in a direction that tends to close the groove and bring the first and second portions of said circuit board into an angled position with respect to each other, wherein said first and second substantially planar portions are held in said angled position by adhesive proximate the groove, and wherein said angled position includes one of a right angle, an angle less than a right angle and an angle greater than a right angle.