Barrier rib structure for plasma display panel

Details Barrier rib structure for plasma display panel Barrier rib structure for plasma display panel

2002-03-27

2004-04-13

Patel, Vip (Department: 2879)

Electric lamp and discharge devices

With gas or vapor

Three or more electrode discharge device

C313S582000, C313S495000, C313S587000, C313S292000

Reexamination Certificate

active

06720732

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a plasma display panel (PDP), and more particularly to a barrier rib structure for preventing error discharge and improving luminescence efficiency.
BACKGROUND OF THE INVENTION
Plasma display panels (PDP) can be divided into two types, the direct current (DC) type and the alternating current (AC) type, according to their electrical driving mode. In
FIG. 1
, which illustrates a conventional AC-type PDP, glass plates
11
,
12
undergo several manufacturing steps in which many functional layers are formed thereon and are then combined together by sealing the periphery of the glass plates
11
,
12
. A mixed gas with a predetermined ratio is then introduced into the discharge units between the glass plates
11
,
12
.
In
FIG. 1
, a plurality of parallel transparent electrodes
111
and bus electrodes
112
, a dielectric layer
113
and a protective layer
114
are sequentially formed on the glass plate
11
, hereinafter referred to as front plate
11
. Similarly, a plurality of parallel address electrodes
121
, a plurality of parallel barrier ribs
122
, a fluorescencer
123
and a dielectric layer
124
are formed on the glass plate
12
, hereinafter referred to as back plate
12
. One transparent electrode
111
on the front plate
11
and one address electrode
121
on the back plate
12
, transparent electrode
111
and address electrode
121
being perpendicularly crossed, compose a discharge unit. When a voltage is applied to a specific discharge unit, gas discharge occurs at the discharge unit between the dielectric layers
113
and
124
to induce emission of a colored visible light from the fluorescencer
123
.
FIG. 2
is a schematic, cross-sectional view corresponding to FIG.
1
. In a conventional AC-type PDP
10
, referring to
FIGS. 1 and 2
simultaneously, a plurality of parallel-arranged transparent electrodes
111
are formed on the front plate
11
. Each of the transparent electrodes
111
correspondingly has a bus electrode
112
to reduce linear resistance of the transparent electrodes
111
. In one discharge unit
13
, a three-electrode structure, including an X electrode and an Y electrode of the transparent electrode
111
on the front plate
11
and an address electrode
121
on the back plate
12
, is generally employed. When a voltage is applied to the above three electrodes of a specific discharge unit
13
to induce discharge, the mixed gas in the discharge unit
13
glows ultraviolet (UV) rays to light the fluorescencer
123
inside the discharge unit
13
. The fluorescencer
123
then emits a visible light, such as a red (R), green (G) or blue (B) light. An image is thus produced by scanning the discharge unit array.
In the conventional AC-type PDP
10
, the barrier ribs
122
are arranged in parallel strips on the back plate
12
. The address electrode
121
between two adjacent barrier ribs
122
is disposed inside the dielectric layer
124
. In the structure, the fluorescencer
123
can only be coated on the sidewalls of the barrier ribs
122
and the top surface of the dielectric layer
124
, so that only three planes are utilized. In each discharge unit
13
, the fluorescencer
123
is coated on a small surface area, so that a low luminescence efficiency is obtained in the conventional PDP
10
.
Since an erroneous discharge may occur in a non-discharge unit
13
a
, illustrated in
FIG. 3
, of the conventional AC-type PDP
10
, the distance d between two adjacent discharge units
13
must be increased to prevent the same. Although a larger non-discharge unit
13
a
prevents erroneous discharge, discharge units
13
are then relatively contracted, i.e. have a reduced opening ratio, and luminescence efficiency is thus decreased. Conversely, a smaller non-discharge unit
13
a
provides larger discharge units
13
, but erroneous discharge then readily occurs, so that neighboring discharge units
13
are affected during operation.
In addition, no isolation is provided between the discharge region A and non-discharge region B and erroneous discharge thus readily occurs in the non-discharge region B. A conventional method for solving the erroneous discharge issue in non-discharge region B is to perform an additional treatment of forming black strips to shade a light produced in the non-discharge region B. The contrast of the conventional PDP
10
is therefore increased, but further manufacture cost is incurred.
To solve the foregoing described problems, several different kinds of barrier rib structure have been developed by PDP designers and manufacturers. For example, Pioneer Company provides a Waffle structure having sealed latticed barrier ribs. The fluorescencer can be coated on the five planes of each discharge unit, i.e. front, back, left, right and bottom planes, thereby improving luminescence efficiency by increasing the fluorescencer coating area. At the same time, each discharge unit becomes a closed space and this effectively prevents erroneous discharge in non-discharge units. Unfortunately, the closed discharge units result in greater difficulties when vacuuming and refilling gas during the manufacturing processes.
SUMMARY OF THE INVENTION
According to the above descriptions, for the barrier rib structure of a conventional PDP, many drawbacks occur; for example, the structure is prone to erroneous discharge, the luminescence efficiency is low, or the structure is hard to vacuum. Therefore, the present invention provides a barrier rib structure for a plasma display panel (PDP) that can resolve above problems.
It is an object of the present invention to provide a barrier rib structure where a plurality of nodes composed of two side-expanded trapezoid bulges are designed in non-discharge regions of barrier ribs to form small gas channels between the nodes. The small gas channels can inhibit unsuitable discharges in non-discharge regions during gas discharging to prevent erroneous discharge. Moreover, by controlling erroneous discharge, the margin of driving voltage can be increased, so that the yield of products can be improved. Furthermore, the small gas channels in non-discharge regions are helpful to gas purging and refilling during manufacture of a PDP device.
It is another object of the present invention to provide a barrier rib structure where a plurality of nodes composed of two side-expanded trapezoid bulges are designed in non-discharge regions of barrier ribs. The error discharge problem can be effectively prevented, so that the area of non-discharge regions can be diminished to increase the area of discharge regions. Therefore, the opening ratio can be increased, and the luminescence efficiency can be improved. The trapezoid bulges of the present invention add four tilted planes at the corners of each discharge unit. Accordingly, the fluorescencer coating area of each discharge unit is increased, and thus the luminescence efficiency is improved.
It is a yet another object of the present invention to provide a barrier rib structure that forms an almost closed discharge space to constrict energy in the discharge space as well as gas discharge, and this structure is helpful in utilizing gas discharge energy. Furthermore, the corners of the discharge space are designed as inclined planes or arced planes that improve uniform reception of ultraviolet rays by the fluorescencer to increase luminescence from the fluorescencer.
It is a further object of the present invention to provide a barrier rib structure that further comprises an isolation wall adjacent to a purge hole. The isolation wall is perpendicular to the gas channels to stop the gas from flowing straight into the purge hole, so that local disturbed gas flow can be minimized to prevent damage to the barrier ribs adjacent to the purge hole.
In one aspect, the present invention provides a barrier rib structure on a back substrate for a plasma display panel. The structure at least comprises a plurality of barrier ribs. Each barrier rib has a plurality of nodes in series composed of two side-expanded trapezoid bulges. The barr

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