Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2002-06-13
2003-11-11
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S485000
Reexamination Certificate
active
06646378
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
This invention relates to a plasma display panel, which is favorable as a flat display panel, and a manufacture method thereof, and in particular relates to a plasma display panel and a manufacturing method thereof, with which the productivity is improved by reduction of the number of manufacturing processes.
2. Description of the Related Art
Plasma display panels (PDP) can be classified according to the operation method into an AC type, in which the electrodes are covered with a dielectric and which is operated indirectly in the AC discharge condition, and a DC type, in which the electrodes are exposed to the discharge space and which is operated in the DC discharge condition. AC type plasma display panels can furthermore be classified according to drive method into a memory operation type, with which the memory of a display cell is used, and a refresh operation type, with which the memory of a display cell is not used. The luminance of a plasma display is proportional to the number of times of discharge. Since the luminance decreases as the display capacity increases in the case of said refresh type, this type is mainly used as plasma displays of low display capacity.
FIG. 1
is an exploded perspective view, which shows a display cell of a prior-art AC type plasma display panel. The display cell is provided with two insulating substrates
101
and
102
that are formed of glass. Insulating substrate
101
serves as the rear panel substrate and insulating substrate
102
serves as the front panel substrate.
Transparent electrodes
103
and
104
are provided at the side of insulating substrate
102
that opposes insulating substrate
101
. Transparent electrodes
103
and
104
extend in the horizontal direction (transverse direction) of the panel. Also, bus electrodes
105
and
106
are disposed so as to overlap with transparent electrode
103
and common electrode
104
, respectively. Each of bus electrodes
105
and
106
is a thin film electrode of approximately 1 to 4 &mgr;m thickness comprising, for example, a CrCu thin film or Cr thin film and is provided to lessen the electrode resistance value between each electrode and an external drive device. A scanning electrode
115
is arranged from transparent electrode
103
and bus electrode
105
, and a common electrode
116
is arranged from transparent electrode
104
and bus electrode
106
. Furthermore a dielectric layer
112
, which covers transparent electrodes
103
and
104
, and a protective layer
114
, which is formed of magnesium oxide, etc. and protects the dielectric layer
112
from discharge, are provided.
A data electrode
107
, which is perpendicular to scanning electrode
103
and common electrode
104
, is disposed at the side of insulating substrate
101
that opposes insulating substrate
102
. Data electrode
107
thus extends in the vertical direction (longitudinal direction) of the panel. Barrier ribs
109
, each of which extends in the longitudinal direction and partitions display cells that neighbor each other in the horizontal direction, are also provided. A dielectric layer
113
, which covers data electrode
107
, is provided, and on the side faces of barrier ribs
109
and the top surface of dielectric layer
113
is formed a fluorescent layer
111
, which converts ultraviolet rays, which are generated by discharge of discharge gas, into visible light
110
. A discharge gas space
108
is secured in the space between insulating substrates
101
and
102
by barrier ribs
109
, and the interior of this discharge gas space
108
is filled with helium, neon, or xenon, etc. or a mixed gas of such gases.
Barrier ribs
109
are formed for example by layering a layer of frit glass on dielectric layer
113
and processing this layer to a predetermined shape by the sand blasting method.
With a plasma display panel that has been arranged thus, when the potential difference between scanning electrode
115
and common electrode
116
exceeds a predetermined value, discharge occurs and an emission
110
is thereby obtained.
Recently, plasma display panels that are finer are being required and the narrowing of the pitch of scanning electrode
103
and common electrode
104
, which are the row electrodes, is deemed necessary. However, with a prior-art plasma display panel with the above-described arrangement, if just the pitch of the row electrodes is simply narrowed, erroneous discharge can occur due to interference of discharge among display cells that neighbor each other in the vertical direction and the image quality degrades accordingly in some cases.
Thus various plasma display panels have been proposed with which the rear panel substrate is provided with barrier ribs that take on a crisscross form and extend not only in the vertical direction but are also equipped with parts that extend in the horizontal direction and partition display cells that neighbor each other in the vertical direction (Japanese Unexamined Patent Publication No. 2001-93425, etc.).
If in the case where barrier ribs of crisscross form are employed, the height of the barrier ribs are made uniform, gas paths cannot be secured for the exhausting of the interior of the discharge space and the sealing of discharge gas in the discharge space, which are to be performed after adhering the front panel substrate and rear panel substrate together, and the manufacture process is thus made extremely difficult. Though it is possible for some amount of gas to flow since the surfaces of the barrier ribs and the surface of the protective layer are not perfectly flat, with just these conditions, the efficiency is extremely low and the productivity is significantly lowered.
Thus with the plasma display panel described in Japanese Unexamined Patent Publication No. 2001-93425, the height of the parts that extend in the longitudinal direction is made higher than the height of the parts that extend in the horizontal direction and the height of the intersections of these parts is made higher than the height of the parts that extend in the longitudinal direction.
With such a structure, gas paths for the exhausting and sealing processes can be secured and the efficiency is improved.
However, in manufacturing the plasma display panel described in Japanese Unexamined Patent Publication No. 2001-93425, the barrier rib parts that extend in the longitudinal direction must be formed after forming the parts that extend in the transverse direction. Thus in comparison to a prior arrangement provided with barrier walls comprising just parts that extend in the longitudinal direction, the number of processes is increased by the amount corresponding to the process of forming the barrier rib parts that extend in the transverse direction and the cost is thus increased.
Also, though barrier rib forming methods besides the sand blasting method include the printing method, etc., in the case where barrier ribs are to be provided with height differences, the number of processes will be increased correspondingly, no matter which method is employed.
Meanwhile, a plasma display panel, with which protruding parts are provided at regions of the dielectric layer of the front panel substrate that oppose the barrier ribs, has been disclosed for example in Japanese Unexamined Patent Publication No. Hei-8-250029, and by combining such a front panel substrate with barrier ribs of crisscross form of uniform height, gas paths may be secured while avoiding an increase in the number of processes for forming the barrier ribs.
However, since a process for forming protruding parts on the dielectric layer is newly required, increase of the overall number of processes cannot be avoided, and thus the productivity is lowered and the cost is increased in this case as well.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a plasma display panel, which can be accommodated for increased fineness without lowering of productivity, and a manufacture method thereof.
A plasma display panel according to the present in
NEC Corporation
Patel Vip
Sughrue & Mion, PLLC
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