Glass manufacturing – Processes – Fusion bonding of glass to a formed part
Reexamination Certificate
2000-06-20
2001-11-27
Vincent, Sean (Department: 1731)
Glass manufacturing
Processes
Fusion bonding of glass to a formed part
C065S043000, C065S058000, C065S059500
Reexamination Certificate
active
06321569
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a plasma display device and method of making the same, and, more particularly, to a plasma display in which the back panel is made of a metal core having layers of a dielectric material thereon and metal electrodes on and between the dielectric layers.
BACKGROUND OF THE INVENTION
A typical plasma display includes a front panel and a back panel both made of sheet glass (e.g. conventional float-glass). Electrical connections and mechanical structures are formed on one of both of the panels. For example, the back panel may have a ribbed structure formed on it such that the space between the ribs defines a pixel in a direct current (DC) display or column of pixels in an alternating current (AC) display. The ribs prevent optical cross-talk, that is to say, color from one pixel leaking into an adjacent pixel. Fabrication of these ribbed structures, called barrier ribs, poses a challenge both in the materials and manufacturing techniques that are used.
Plasma displays operate by selectively exciting an array of glow discharges in a confined rarefied noble gas. Full color displays are made by generating a glow discharge in a mixture of gases, such as He—Xe or Ne—Xe gas mixture to produce ultraviolet light. The ultraviolet light excites phosphors in the pixel cell, as defined by the barrier ribs, to produce light of desired color at the pixel position.
A typical plasma display back panel comprises a glass substrate having a plurality of substantially parallel, spaced first electrodes on a surface thereof. In AC displays, a thin layer of a dielectric material, such as a glass, covers the electrodes. Barrier ribs are formed on the surface of the glass substrate between the first electrodes. The barrier ribs project from the surface of the substrate at a distance greater than the thickness of the first electrodes. Red, green and blue (R-G-B) phosphor layers overlie alternating columns of the first electrodes in the spaces between the barriers and also overlie the walls of the barriers. A front transparent glass substrate, the front panel, overlies the rear panel and may rest on the barrier ribs so as to be spaced from the rear glass substrate by the barrier ribs.
Typically, the barrier ribs are walls which define troughs or channels on the back panel. Alternating current (AC) plasma displays typically have barriers that form the separators for the column pixels, and hence, have continuous vertical ribs on the back plate. By contrast, direct current (DC) plasma displays typically have ribbed barriers which isolate each pixel from all of its neighbors. Thus, for DC displays, the rib structure has a rectangular lattice-like layout. In either case, the desired resolution for the display device and its size determine the size of the ribbed barriers. In a typical display, the ribs are 0.1 to 0.2 mm in height, 0.03 to 0.2 mm wide and on a 0.1 to 1.0 mm pitch.
These barrier ribs may be formed separately from the back plate and attached using an adhesive or, as set forth in U.S. Pat. No. 5,674,634, entitled “INSULATOR COMPOSITION, GREEN TAPE, AND METHOD FOR FORMING PLASMA DISPLAY APPARATUS BARRIER RIB” to Wang et al., the barriers may be formed on the back plate by laminating a ceramic green tape to the back plate, sandblasting the green tape to form the channels between the barriers and then firing the back plate in a kiln to convert the green tape barriers into ceramic barriers.
The front panel includes an array of substantially parallel, spaced second electrodes on its inner surface. These second electrodes extend substantially orthogonally to the first electrodes. A layer of a dielectric material, typically glass, covers the second electrodes. A layer of MgO covers the dielectric layer. Voltages applied to the electrodes in the proper manner excite, maintain and extinguish a plasma in the gas within the region formed by the barriers. Addressing of individual pixels is done using external circuitry at the periphery of the panel. Barrier structures are typically used to confine the discharge to the addressed pixel, eliminating both electrical and optical cross talk between adjacent pixel elements. The columns of pixels are separated by the barriers, and the first electrodes are arranged beneath the gaps between the barriers. In a DC plasma display, the electrodes are not covered with glass or MgO, and the barrier structures are typically crossed, providing a box-like structure at each pixel element.
Although the structure described above provides a plasma display having satisfactory operating conditions, it does not solve certain problems. One problem arises from the fact that the materials used to form the back panel are desirably mutually compatible and compatible with the glass plate used for the front panel. In particular, the thermal expansion coefficient of the ceramic formed from the green tape should match the thermal expansion coefficient of the back panel and the thermal expansion coefficient of the composite back panel should match that of the front panel glass. This is to prevent the breaking of the seal which secures the back panel to the front panel during its operation.
SUMMARY OF THE INVENTION
A plasma display device of the type having a transparent glass front panel and a composite back plate including a metal substrate and a ceramic barrier rib structure, wherein the materials used to form the back panel are chosen so that the back plate has a thermal coefficient of expansion compatible with that of the front panel.
According to one aspect of the invention, channels are formed on the inner surface of the front or back panel by embossing a green tape which has been laminated onto a substrate and then cofiring the laminated panel.
According to another aspect of the invention, when the coefficients of thermal expansion of the front panel and back panel differ slightly, a method for bonding the front panel to the back panel heats the front panel and back panel to different temperatures before starting the bonding process.
According to yet another aspect of the invention, when the coefficients of thermal expansion of the front panel and metal core differ slightly, the materials used to form the dielectric which is laminated to the metal core to form the back panel assembly may be chosen such that the composite TCE of the cofired assembly matches the TCE of the front panel.
REFERENCES:
patent: 4963114 (1990-10-01), Andreadakis
patent: 5011391 (1991-04-01), Kawasaki et al.
patent: 5644327 (1997-07-01), Onyskevych et al.
patent: 5667418 (1997-09-01), Fahlen et al.
patent: 5674634 (1997-10-01), Wang et al.
patent: 5682081 (1997-10-01), Reynolds
patent: 5686790 (1997-11-01), Curtin et al.
patent: 5714840 (1998-02-01), Tanabe et al.
patent: 5772486 (1998-06-01), Seki
patent: 6140759 (2000-10-01), Sreeram et al.
patent: 6168490 (2001-01-01), Hozer et al.
patent: 06-168669 (1994-06-01), None
patent: 08-301631 (1996-11-01), None
patent: 97/28554 (1997-08-01), None
Mercier et al, “A New Video Storage Architecture for Plasma Display Panels,” IEEE Transactions on Consumer Electronics, vol. 42, No. 1, Feb. 1996.
Prabhu Ashok Narayan
Quinn Robert L.
Sreeram Attiganal Narayanswamy
Burke William J.
Sarnoff Corporation
Vincent Sean
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