Liquid manufacturing processes for panel layer fabrication

Details Liquid manufacturing processes for panel layer fabrication Liquid manufacturing processes for panel layer fabrication

2002-08-09

2004-07-20

Ramsey, Kenneth J. (Department: 2879)

Electric lamp or space discharge component or device manufacturi

Process

With assembly or disassembly

C445S058000

Reexamination Certificate

active

06764367

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is relates to a method for manufacturing a light-emitting panel and more particularly to a web fabrication process for manufacturing a light-emitting panel.
2. Description of Related Art
A number of different methods have been used or proposed for construction of plasma panel display devices in which a plasma-forming gas is enclosed between sets of electrodes which are used to excite the plasma. In one type of plasma display panel, wire electrodes are placed on the surfaces of parallel plates of glass so that they are spaced uniformly apart. The plates are then sealed together at the outer edges with the plasma forming gas filling the cavity formed between the parallel plates. Although widely used, this type of open display structure suffers from numerous disadvantages. The sealing of the outer edges of the parallel plates and the introduction of the plasma forming gas are both expensive and time-consuming processes, resulting in a costly end product. In addition, it is particularly difficult to achieve a good seal at the sites where the electrodes are fed through the ends of the parallel plates, which can result in gas leakage and a shortened product life. Another disadvantage is that individual pixels are not segregated within the parallel plates. As a result, gas ionization activity in a selected pixel during a write operation may spill over to adjacent pixels, thereby raising the undesirable prospect of possibly igniting adjacent pixels. Even if adjacent pixels are not ignited, the ionization activity can change the turn-on and turn-off characteristics of the nearby pixels.
In another type of known plasma display, individual pixels are mechanically isolated either by forming trenches in one of the parallel plates or by adding a perforated insulating layer sandwiched between the parallel plates. These mechanically isolated pixels, however, are not completely enclosed or isolated from one another because there is a need for the free passage of the plasma forming gas between the pixels to assure uniform gas pressure throughout the panel. While this type of display structure decreases spill over, spill over is still possible because the pixels are not in total electrical isolation from one another. In addition, in this type of display panel it is difficult to properly align the electrodes and the gas chambers, which may cause pixels to misfire. As with the open display structure, it is also difficult to get a good seal at the plate edges. Furthermore, it is expensive and time consuming to introduce the plasma producing gas and seal the outer edges of the parallel plates.
In yet another type of known plasma display, individual pixels are also mechanically isolated between parallel plates. In this type of display, the plasma forming gas is contained in transparent spheres formed of a closed transparent shell. Various methods have been used to contain the gas filled spheres between the parallel plates. In one method, spheres of varying sizes are tightly bunched and randomly distributed throughout a single layer, and sandwiched between the parallel plates. In a second method, spheres are embedded in a sheet of transparent dielectric material and that material is then sandwiched between the parallel plates. In a third method, a perforated sheet of electrically nonconductive material is sandwiched between the parallel plates with the gas filled spheres distributed in the perforations.
While each of the types of displays discussed above are based on different design concepts, the manufacturing approach used in their fabrication is generally the same: a batch fabrication process. It would be desirable to simplify and streamline the manufacturing process and to eliminate at least a portion of the steps which can have a negative impact on process yield and/or cost. The present invention is directed to such a method.
BRIEF SUMMARY OF THE INVENTION
According to the present invention, a novel flexible plasma display panel and methods for making such a panel involve a web fabrication process. In this display panel, the plasma forming gas is sealed in transparent micro-components formed of a closed transparent shell. The micro-components, which may be spheres, capillaries or virtually any other three-dimensional shape, are then coated with phosphors to emit one of the primary colors: red, green or blue. In the web fabrication process, a nonconductive flexible first substrate has electrodes imprinted thereon using known printing techniques, such as lithography or screen printing. In one variation, dimples are embossed in the first substrate to define locations at which micro-components are to be placed relative to the electrodes. In another variation, the micro-components are electrostatically drawn to the correct locations relative to the electrodes. After affixing the micro-components in place, and possibly testing to ensure complete and proper placement of the micro-components, a second substrate, also in web form, is disposed over the first substrate so that the micro-components are sandwiched between the first and second substrates. Additional electrodes may be patterned on the second substrate, and the second substrate may be applied as more than one layer to create one or more dielectric/electrode sandwiches near the micro-component to provide additional sustain electrodes or addressing electrodes. Alternatively, the second substrate can be preformed with embedded electrodes which are then aligned with the micro-components when the second substrate is applied. A protective layer may be placed on top of the second substrate, then the layered assembly is diced to form individual light-emitting panels of the desired size.
In a second embodiment of the present invention, a light-emitting panel is formed on a first substrate comprising a flexible web material. A conductive film is patterned on the first substrate to define a plurality of electrodes and dimples are formed to define locations in which gas-filled micro-components, which emit light when excited, are to be located. An adhesive material may be deposited into the dimples. The micro-components are then applied to fill the dimples, where they are held in place by the adhesive. Application of the micro-components to the first substrate can be achieved by a number of different methods including use of a drop tower or an ink-jet type dispenser, or by running the first substrate through a shaker bath filled with an excess of micro-components. An electrostatic charge may be applied to the first substrate to draw the micro-components to the desired locations. After the micro-components are affixed to the first substrate, a liquid dielectric material is applied to the surface of the first substrate using known methods such a vacuum or atmospheric coating, which may include chemical vapor deposition (CVD), plasma sputtering, electron-beam deposition, injection of coating fluid under pressure, screen printing or similar processes. The conditions under which the liquid dielectric are applied, e.g., the surface energy and surface tension of the liquid, are selected to ensure good wetting of the micro-components, i.e., so that the dielectric material is in contact with the surfaces of the micro-components without bubbles or gaps. Further, the liquid dielectric should be applied with a uniform thickness across the first substrate so that the spacing between the excitation electrodes is uniform across the display. Depending on the deposition process that was used, the liquid dielectric is then cured to remove any solvents and other volatile agents that were included in the liquid to facilitate fluid delivery, leaving the micro-components embedded in the flexible, cured dielectric layer. In a preferred embodiment, the liquid dielectric is coated so as to form a dielectric layer with a thickness corresponding to about half the height of the micro-component, allowing a mid-plane conductor to be formed near the micro-components.
Electrodes are formed by applying a conductive

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