Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2001-06-01
2002-12-17
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169100, C313S585000, C313S584000
Reexamination Certificate
active
06495967
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to plasma display panels (PDPs) and more particularly to a structure of discharge cells between barrier walls of alternating current discharge type PDPs with improved characteristics.
BACKGROUND OF THE INVENTION
A manufacturing process of a conventional alternating current discharge type plasma display panel (PDP)
10
is shown in FIG.
1
. First, two different activation layers are formed on glass substrates
11
and
12
respectively. Then the peripheries of substrates are sealed. A mixed gas consisting of helium (He), neon (Ne), and xenon (Xe) (or argon (Ar)) having a predetermined mixing volume ratio is stored in a discharge space therein. A front substrate
11
is defined as one that faces viewers. A plurality of parallel transparent electrodes
111
, a plurality of bus electrodes
112
, a dielectric layer
13
, and a protective layer
14
are formed from the front substrate
11
inwardly. Correspondingly, from rear substrate
12
inwardly, a plurality of parallel data electrodes
121
, a dielectric layer
124
, a plurality of parallel spacer walls
122
, and a uniform phosphor layer
123
are formed. When a voltage is applied on electrodes
111
,
112
, and
121
, dielectric layers
113
and
124
will discharge to discharge cell
13
formed by adjacent barrier walls
122
. As a result, a ray having a desired color is emitted from phosphor layer
123
.
Conventionally, in PDP
10
, a plurality of parallel transparent electrodes
111
are formed on an inner surface of front substrate
11
by sputtering and photolithography. (or printing). Then a plurality of bus electrodes
112
are formed on the transparent electrodes
111
by plating (or sputtering) and photolithography. The line impedance of the transparent electrodes
111
may be reduced by the provision of bus electrodes
112
. In the following description, two adjacent transparent electrodes
111
(including bus electrodes
112
) on the front substrate
11
are represented by an X electrode and a Y electrode respectively. A triple electrode is formed by the X electrode, Y electrode and corresponding data electrode
121
on the rear substrate
12
. When a voltage is applied on the triple electrode, dielectric layers
113
and
124
will discharge to discharge cell
13
formed by adjacent spacer walls
122
. Hence, UV rays are emitted from the mixed gas stored therein. And in turn, phosphor layer
123
in discharge cell
13
is excited by the UV rays. As an end, visible light is generated by the red, green and blue phosphor layers, resulting in appearance of an image.
As shown in
FIGS. 1 and 2
, a plurality of parallel barrier walls
122
are provided on back substrate
12
. A plurality of parallel data electrodes
121
are provided on the underside of dielectric layer
124
. Barrier walls
122
and data electrodes
121
alternate, with barrier walls
122
being positioned between data electrodes
121
. A discharge cell
13
is formed between two adjacent barrier walls
122
. A phosphor layer
123
is coated on discharge cell
13
, opposite walls of barrier wall
122
, and dielectric layer
124
respectively. However, several drawbacks have been found as detailed below
(a) The coating area of phosphor layer
123
is small: In view of back substrate
12
, phosphor layer
123
is only allowed to be coated on discharge cell
13
, opposite-walls of barrier wall
122
, and dielectric layer
124
respectively. This may lower the emissivity of PDP
10
.
(b) Discharge area is small: Referring to
FIG. 3
, there is shown a sectional view of adjacent discharge cells
13
with a suitable distance D formed therebetween in the conventional alternating current type PDP
10
. Such distance D is provided for avoiding an undesired discharge. However, the provision of distance D may narrow the discharge cells
13
(i.e., opening too narrow), resulting in a lowering of emissivity. To the contrary, a small nondischarge cell may provide a large discharge space for obtaining an increased emissivity. However, this may also tend to cause undesired discharge which in turn has an adverse effect on the adjacent discharge cell.
(c) Subject to undesired discharge: Referring to
FIG. 4
, there is shown two adjacent discharge regions A and a sandwiched non-discharge region B in the conventional alternating current type PDP
10
. It is seen that there is no barrier between two adjacent discharge regions A. Hence, it is subject to undesired discharge in non-discharge region B.
(d) Additional processing required: Referring to
FIG. 5
, there is shown two adjacent discharge regions A, a sandwiched non-discharge region B, and a hatched region C. The hatched region C is where additional processing on non-discharge region is performed for blocking light emitted from non-discharge region B, thereby obtaining a strong contrast of the image shown on PDP
10
.
A number of proposals regarding the structure of the barrier wall have been submitted by PDP designers and manufacturers for solving the above drawbacks. For example, Pioneer Company (Japan) discloses a waffle-like barrier wall
622
as shown in FIG.
6
. The phosphor layer is respectively coated on the top, bottom, left, right, and
20
underside of the discharge cell. Hence, the coating area of the phosphor layers is increased, resulting in an increase in emissivity. Also, the discharge cell is enclosed for eliminating undesired discharge in their non-discharge region. However, such enclosed discharge cell may increase difficulty of vacuum and gas filling. Another design is disclosed by Fujitsu Company (Japan) wherein barrier wall
722
has a meander rib structure as shown in FIG.
7
. Such structure can increase the coating area to a maximum. However, this design suffers from several disadvantages. For example, phosphor layer printing is difficult in the process. As a result, colors tend to mix. Further, uniformity of phosphor layer printing is not obtainable. This in turn increases manufacturing cost and difficulty. Even worse, the yield is lowered. Moreover, a back substrate manufactured by such technique does not conform to the conventional front substrate. Hence, a specifically designed front substrate is required. As to drive technique, conventional drive techniques are not applicable if a complex drive technique such as ALIS is not adopted in conjunction therewith. In brief, despite achieving a maximum coating area the design proposed by Fujitsu Company is still disadvantageous due to problems associated with manufacturing process and drive technique.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide, in an alternating current discharge type plasma display panel (PDP), a plurality of parallel barrier walls formed on the top surface of a back substrate of the PDP, the barrier walls being disposed corresponding to cross-points of X electrodes and Y electrodes on a front substrate of the PDP. The structure comprising the plurality of discharge cells between the adjacent barrier walls has a smaller width corresponding to the X and Y electrodes for forming a large first space, a plurality of non-discharge cells each between the adjacent discharge cells forming a small second space that serves as a gas channel between the adjacent discharge cells, and a junction having a predetermined shape between one discharge cell and the adjacent non-discharge cell, so that energy released from a gas is discharge in the discharge cells is concentrated within the discharge cells for increasing discharge efficiency, and emissivity, for avoiding undesired gas discharge, and for achieving a smooth vacuum and gas filling during the manufacturing process of PDP.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.
REFERENCES:
patent: 5150007 (1992-09-01), Andreadakis
patent: 6373195 (2002-04-01), Whang et al.
patent: 2000011894 (2000-01-01), None
Chen Kuang-Lang
Kao Shiuh-Bin
Lee Sheng-Chi
Lin Ching-Hui
Yu Yi-Sheng
Bacon & Thomas
Chunghwa Picture Tubes Ltd.
Vu Jimmy T
Wong Don
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