Electric lamp and discharge devices – Discharge devices having a thermionic or emissive cathode
Reexamination Certificate
2000-09-12
2003-03-04
Day, Michael H. (Department: 2879)
Electric lamp and discharge devices
Discharge devices having a thermionic or emissive cathode
C313S309000
Reexamination Certificate
active
06528930
ABSTRACT:
FIELD OF THE INVENTION
The present claimed invention relates to the field of flat panel displays. More particularly, the present claimed invention relates to the “focus waffle” of a flat panel display screen structure.
BACKGROUND ART
Flat panel display devices often operate using electron emitting structures, such as, for example, Spindt-type field emitters. These types of flat panel displays often employ a polyimide structure to focus or define the path of electrons emitted from the electron emitting structures. In one prior art approach, the polyimide structure is referred to as a “focus waffle.” The structure is comprised of a plurality of rows which are parallel to each other and a plurality of columns which are parallel to each other but which are substantially orthogonal to the plurality of rows. The plurality of rows and columns of polyimide material define openings therebetween. The focus waffle is disposed between the electron emitting structures and the faceplate such that emitted electrons pass through openings in the focus waffle structure, and are directed towards corresponding sub-pixel regions.
Unfortunately, such prior art polyimide focus waffle structures are extremely expensive and, thus, introduce additional costs for flat panel display fabrication. As yet another disadvantage, such prior art polyimide focus waffle structures are a major source of contamination in flat panel display devices. That is, such “dirty” polyimide focus waffle structures introduce contaminate particles into the evacuated environment of the flat panel display device. These contaminate particles degrade the performance of the flat panel display device, may cause discoloration, and reduce the effective lifetime of the flat panel display device. In addition to emitting contaminate particles, such prior art focus waffle structures also outgas material (e.g. organics) due to electron desorbtion and thermal stresses induced during flat panel display fabrication steps.
As yet another drawback, the application of conductive coatings (e.g. aluminum) applied to polyimide focus waffle structures introduces considerable difficulty and complexity during the fabrication of conventional flat panel display devices. More specifically, in conventional flat panel display fabrication, the conductive coatings are applied using an angled evaporation process. The angled evaporation process is difficult, time-consuming, and expensive. In addition to being difficult to perform, the time-consuming nature of the angled evaporation process reduces throughput and yield during the fabrication of flat panel display devices.
Thus, a need exists for a focus waffle structure which does not suffer from significant expense, contaminate emission, and outgassing. A further need exists for a focus waffle structure which meets the above-listed need and also eliminates the requirement for complex and difficult angled evaporation processing steps. Still another need exists for a focus waffle structure which meets the above-listed needs and further improves focus waffle manufacturing throughput and yield.
SUMMARY OF INVENTION
The present invention provides a focus waffle structure which does not suffer from significant contaminate emission and outgassing. The present invention further provides a focus waffle structure which also eliminates the requirement for complex and difficult angled evaporation processing steps. Additionally, the present invention also invention provides a focus waffle structure which improves focus waffle manufacturing throughput and yield. The invention described herein provides a conductive focus waffle structure for focusing electrons emitted from a cathode portion of a flat panel display device, and a method for forming the conductive focus waffle structure. Also, it will be understood that the focus waffle structure of the present invention is applicable in numerous types of flat panel displays.
Specifically, in one embodiment, the present invention applies a first layer of photo-imagable material above a cathode portion of a flat panel display device. This embodiment then removes portions of the layer of photo-imagable material such that openings are formed therein. A layer of conductive material is then applied over the cathode such that conductive material is disposed within the openings in the layer of photo-imagable material. A dielectric layer of material is also disposed between the cathode and the bottom surface of the conductive material. This embodiment of the present invention then removes the layer of photo-imagable material such that at least a portion of the conductive focus waffle structure is formed disposed above the cathode. In so doing, at least a first portion of a conductive focus waffle structure is formed.
In one embodiment, the present invention includes the steps of the above-described embodiment and further recites applying dielectric material above said cathode portion before applying photo-imagable material. In so doing, the layer of photo-imagable material is separated from the cathode portion of the flat panel display device by the layer of dielectric material. Thus, the conductive material disposed into the openings in the layer of the photo-imagable material is not in direct electrical contact with the cathode portion of the flat panel display device.
In still another embodiment, the present invention includes the steps of the first above-described embodiment and further recites applying dielectric material into the openings formed in the photo-imagable material prior to applying the conductive material above the photo-imagable material. In so doing, the conductive material disposed into the openings in the layer of the photo-imagable material is not in direct electrical contact with the cathode portion of the flat panel display device.
These and other benefits and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments which are illustrated in the various drawing figures.
REFERENCES:
patent: 5528103 (1996-06-01), Spindt et al.
patent: 5650690 (1997-07-01), Haven
patent: 5920151 (1999-07-01), Barton et al.
patent: 6002199 (1999-12-01), Spindt et al.
patent: 6010383 (2000-01-01), Knall
Chang David C.
Drumm Paul M.
Learn Arthur J.
Mackey Bob L.
Morris David L.
Candescent Intellectual Property Services Inc.
Day Michael H.
Wagner , Murabito & Hao LLP
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