Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
2000-06-14
2002-08-06
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
Reexamination Certificate
active
06428377
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a DC plasma display panel, and more specifically to a DC plasma display panel having holes in the cathodes for confining the plasma discharge within a discrete area of a plasma display panel cell. The present invention also relates to methods of making the DC plasma display panel of the present invention.
Color plasma display panels are considered by many to be the future of large-screen TVs, mainly because high quality CRT TVs tend to be bulky, and larger projection screen TVs typically have a poor image quality and limited viewing angles. In addition, the plasma display panels are ideal for the new digital HDTV format. Currently, there are two types of color plasma display panel devices; the DC plasma display panel and the AC plasma display panel. Both the AC-type and DC-type plasma display panels operate on the same general principles. That is, a gas discharge in each individual display cell (also known as a sub-pixel) generates ultraviolet light which excites a phosphor layer that fluoresces visible light. Differing phosphors are used for the red, green and blue primary colors, and full color moving images are obtained by modulating each primary color sub-pixel to one of typically 256 intensity levels at about 60 times a second.
The AC-type color plasma display panels typically are divided into two categories; surface discharge type AC plasma display panels, and opposed discharge type AC plasma display panels.
FIG. 1
shows a typical surface discharge type AC plasma display panel
100
. AC plasma display panel
100
suitably comprises a front glass substrate
102
, and a rear glass substrate
104
. Front glass substrate
102
comprises a plurality of display or sustain electrodes
106
, and rear glass substrate
104
includes a plurality of address electrodes
108
running substantially orthogonal to sustain electrodes
106
. During operation, an AC voltage source is applied to sustain electrodes
106
, and the fringing electro-magnetic fields created by these excited electrodes reach into the gas in the plasma display panel cell and create a gas or plasma discharge. The discharge creates ultraviolet light which excites phosphor layers deposited on rear substrate
104
. Rear substrate
104
also includes a plurality of barrier ribs
110
which separate each sub-pixel. The barrier ribs
110
prevent emitted light radiation in one display cell from seeping over into adjacent display cells, thus, reducing cross-talk between display cells.
FIG. 2
illustrates an opposed discharge type AC plasma display panel
200
. As with the surface discharge type AC plasma display panel
100
, opposed discharge type AC plasma display panel
200
comprises a front substrate
202
having a first electrode
206
, and a rear substrate
204
having an second electrode
208
substantially orthogonal to first electrode
206
. During operation of the opposed discharge type AC plasma display panel
200
, an AC plasma discharge is generated between an electrically excited first electrode
206
and an electrically excited second electrode
208
. The plasma discharge is generated on the surface of dielectric layer
212
and the ultraviolet light created by the discharge excites the phosphor on rear substrate
204
. Opposed discharge type AC plasma display panel
200
also includes a plurality of barrier ribs
210
which help prevent the plasma discharges in each display cell from spreading to other cells in the plasma display panel.
One advantage of the AC-type plasma display panels is that they tend to have longer lifetimes than the DC-type displays because the AC-type displays include dielectric layers (
112
,
212
) deposited on the substrates which help to protect the display electrodes from plasma discharge sputtering. However, the AC-type display panels have various limitations also. For example, even though both AC-type plasma display panels include barrier ribs for reducing cross-talk between display cells, the barrier ribs do not stop all the discharge bleeding between the cells, so the contrast ratio of the AC-type plasma display panels tends to be poor. In addition, dielectric layers (
112
,
212
) which are deposited on the AC-type display panel substrates have a high capacitance, causing the AC-type plasma display panels to have a much slower response time than the DC plasma display panel counterparts.
Referring now to
FIGS. 3 and 4
, typical DC-type plasma display panels currently known in the art are shown. Specifically,
FIG. 3
shows a monochrome DC plasma display panel, while
FIG. 4
shows a color DC plasma display panel. As illustrated in
FIG. 3
, a typical monochrome DC plasma display panel
300
comprises a first substrate
302
having a plurality of rows of cathodes
306
, and a second substrate
304
having a plurality of rows of anodes
308
running substantially orthogonal to cathodes
306
. In DC plasma display panel
300
, DC discharges are generated between electrically activated cathodes
306
and electrically activated anodes
308
. Second substrate
304
of monochrome DC plasma display panel
300
further includes a plurality of barrier ribs
310
for separating anodes
308
. The barrier ribs also help define the individual display cells of DC plasma display panel
300
.
Color DC plasma display panel
400
, as illustrated in
FIG. 4
, is similar to the monochrome DC plasma display panel of
FIG. 3
, except color DC plasma display panel
400
includes red, green and blue phosphors for generating the color display. As shown in
FIG. 4
, color DC plasma display panel
400
includes a front plate
402
having a plurality of cathodes
404
thereon. Color DC plasma display panel
400
further includes a rear plate
406
having a plurality of display anodes
408
thereon. Each display anode
408
is connected to a display anode bus lines
410
with a resistor
412
. Covering anodes
408
, anode bus lines
410
, and resistors
412
is an insulating dielectric layer
414
which also covers substantially all of rear plate
406
. Color DC plasma display panel
400
is made up of a large number of display cells
416
which are defined by barrier ribs
418
, priming ribs
420
, and cathodes
404
. Within each display cell
416
is one of three types of phosphor
422
; red, green or blue. Excitation of these three phosphors in a predetermined fashion creates the color display on front plate
402
of color DC plasma display panel
400
.
Conventional DC plasma display panels typically utilize the abnormal glow or normal glow regions of a DC glow discharge at or below
400
. Torr gas pressure. At these pressures, conventional color DC plasma display panels exhibit poor luminous efficiency and typically have low display lifetimes due to cathode sputtering. One method of improving the lifetime of the DC plasma display panel is to increase the gas pressure in the glow discharge. However, this typically causes more current to flow in the discharge cell, reducing the self-stabilizing function of the glow discharge. To reduce the discharge current at the increased gas pressures, resistors are used to limit the current flow in the discharge cells. As shown in
FIG. 4
, this is a well known method of creating color DC plasma display panels. However, for large sized plasma display panels, a large number of resistors (usually several million) are needed to produce a stable operating plasma display panel. Adding these individual resistors decreases the uniformity of the display panel, and complicates the plasma display panel manufacturing process.
SUMMARY OF THE INVENTION
Accordingly, it is an advantage of the present invention to provide a novel color DC plasma display panel which overcomes the shortcomings of the prior art.
Another advantage of the present invention is to provide a DC plasma display panel with holes spaced along the cathode lines for confining the glow discharge of each display cell within the cathode holes.
Yet another advantage of the present invention is to provide a DC plasma display panel which utilize
Hynix / Semiconductor Inc.
Ramsey Kenneth J.
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