Patent Application
20060246809
The present invention generally relates to emission displays, and more particularly to a structure for, and method of, affixing spacers in field emission displays.
Spacers for field emission displays are known in the art. A field emission display includes an envelope structure having an evacuated interspace region between two display plates. Electrons travel across the interspace region from a cathode plate, upon which electron emitter structures, such as Spindt or carbon nanotubes, are fabricated, to an anode plate which includes deposits of light-emitting materials, or phosphors. Typically the pressure within the interspace region is less than or equal to 10−6 Torr.
The cathode plate and anode plate are thin in order to provide low display weight. These thin plates are not structurally sufficient to prevent collapse or bowing upon evacuation of the interspace region. Spacers are structures positioned between the anode and the cathode plate to provide standoff. As a result of the atmospheric pressure, spacers play an essential role in lightweight displays. The spacers, in conjunction with the thin, lightweight plates, support the atmospheric pressure allowing the display area to be increased with little or no increase in plate thickness.
Several schemes have been proposed for providing spacers. Some of these schemes include the affixation of structural members to the inner surface of a display plate, particularly, the anode plate. Such prior art schemes include the heating of the display plate and spacer in order to bond the spacer to the display plate. Such schemes require bonding spacers to the anode plate due to its robustness in heating and oxidizing environments compared to the cathode plate. This method has the disadvantage of spacer misalignment when contacting the cathode resulting in destruction of emitters and shorted column or row conductors. Other disadvantages of prior art schemes include large processing times required to heat display plate and spacers, oxidation of cathode bonding metals associated with high temperatures and glues thereby impacting the quality of the vacuum, and contamination caused by elaborate pick and place equipment required for spacer placement. Furthermore, the spacers may be troublesome to keep in an upright position while installing the second plate, and the pick and place method consumes valuable time, perhaps as much as 30 minutes for a large array.
Accordingly, it is desirable to provide an improved method of affixing, spacers in field emission displays. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.
An apparatus for, and method of, placing a plurality of spacers between a parallel opposed anode and cathode of an emissive display. The apparatus temporarily secures, by applying a vacuum for example, a first side of one of the anode or cathode to a base having a plurality of electromagnets positioned therein. The electromagnets attract a first side of each of the plurality of spacers, thereby positioning each of the spacers in a desired location on a second side of the one of the anode or cathode.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and
The following detailed description of the invention is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description of the invention.
Referring to
A spacer 12 is shown in
Referring to
The spacers 12 may be individually guided to the electromagnet 16 by the shuffle tray 40 illustrated in
If one or more spacers 12 are positioned incorrectly (misaligned), the apparatus 10 may be subjected to a localized vacuum from above and a selected one or more of the electromagnets 16 may be de-activated. The localized vacuum will then cause the spacer to be pulled from its position. The placing process may then be repeated for that specific location on the anode 20.
The invention described herein provides, in view of known art, improved accuracy in placement in a desired location, reduced contaminants that may degrade the emitters and the vacuum, less consumption of time in placement of the spacers, proper orientation of one or more spacers, and a way of correcting misplacement of the spacers.
While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.
