Electric lamp or space discharge component or device manufacturi – Process – With start up – flashing or aging
Reexamination Certificate
2001-02-12
2003-12-23
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With start up, flashing or aging
C445S040000
Reexamination Certificate
active
06666738
ABSTRACT:
INDUSTRIAL FIELD OF USE
The present invention relates to a manufacturing method for a plasma display panel used to display images on computer monitors, televisions and the like.
RELATED ART
The following is an explanation of a display panel in the related art with reference to the drawings.
FIG. 21
is a simplified cross sectional of an alternating current (AC) plasma display panel (hereafter referred to as a PDP).
In
FIG. 21
, discharge electrodes
211
are formed on a front glass plate
210
. These are then covered by a layer of dielectric glass
212
and a protective dielectric layer
213
, composed of magnesium oxide (MgO). A description of this technique may be found in Japanese Laid-Open Patent No. 5-342991.
Address electrodes
221
are formed on a rear glass plate
220
, and covered by a visible light reflective layer
222
and partitions
223
. A phosphor layer
224
is placed on top of this. Spaces
230
are discharge spaces which enclose a discharge gas. Three types of phosphors, for producing the colors red, green and blue, are arranged in order in the phosphor layer
224
to produce a color display. The phosphors in layer
224
are excited by short-wave ultra-violet rays generated by electric discharge on a wavelength of 147 nm for example, and emit visible light.
The phosphors that make up the phosphor layer
224
are generally produced using these compounds:
Blue phosphor:
BaMgAl
10
O
17
: Eu
Green phosphor:
Zn
2
SiO
4
: Mn or BaAl
12
O
19
: Mn
Red phosphor:
Y
2
O
3
: Eu or (Y
x
Gd
1−x
) BO
3
: Eu
The following is an explanation of a PDP manufacturing method in the related art.
Firstly, discharge electrodes are formed on a front glass plate, and a dielectric layer made from dielectric glass is formed to cover the discharge electrodes. A protective layer made from MgO is formed on top of the dielectric layer. Next, address electrodes are formed on a back glass plate, and a visible light reflective layer made from dielectric glass formed on top of this. Then glass partitions are produced on top of this at fixed intervals.
A phosphor layer is formed by alternately introducing phosphor pastes for the red, green and blue phosphors produced as above into the spaces between the partitions. Next this phosphor layer is baked at a temperature of around 500° C. to eliminate resin and similar substances from the paste (Phosphor Baking Process).
After the phosphor layer has been baked, a glass frit for sealing the front and back plates together is applied to the edge of the back glass plate, and then pre-baking is performed at around 350° C. to eliminate resin and the like from the glass frit (Sealing Process, Pre-baking Process).
After this, the front glass plate, formed from the discharge electrodes, the dielectric glass layer and the protective layer, and the back glass plate are placed together with the partitions sandwiched between them and the display electrodes and address electrodes at right angles. The panel is then heated at around 450° C. to seal the edges of the plates together with glass frit (Sealing Process).
After this, the inside of the panel is evacuated by heating it to a certain temperature of around 350° C. (Evacuation Process) and a discharge gas is introduced at a certain pressure once this process is completed.
A panel manufactured using the above processes exhibits great variations in luminescence and discharge characteristics during the initial stage of ignition. Accordingly, luminescence and discharge characteristics need to be stabilized by ensuring that the manufactured panel discharges electricity only during a certain time period. This process is known as the aging process.
However, in the PDP manufacturing process used in the related art, a particular problem is posed by the fact that the aging process for stabilizing the luminescence and discharge characteristics actually causes a deterioration in the luminescence characteristics.
One reason for this is the deterioration in the phosphors used. Thee compound BaMgAl
10
O
17
:Eu used as a blue phosphor is particularly prone to deterioration during the aging process, resulting in a decrease in luminous intensity and a deterioration in luminescent chromaticity.
DISCLOSURE OF THE INVENTION
In view of the above problems, the object of the present invention is to provide a PDP that may undergo the necessary aging process with minimal phosphor deterioration, and that has a comparatively high luminous efficiency as well as high-quality color reproduction.
In order to achieve the above object, a PDP manufacturing process is performed in the following way. First, a front plate and a back plate, on at least one of which discharge electrodes have been arranged and on at least one of whose inner surfaces a phosphor layer has been formed are sealed together so that an inner space is formed between them. Then an aging process in which a required discharge voltage is applied to the discharge electrodes is performed. The aging process includes an introducing process in which a discharge gas with a partial steam pressure of 15 Torr or less is newly introduced into the inner space from the outside and an evacuating process, in which discharge gas is evacuated from the inner space. By performing the introducing process together with the evacuating process, discharge gas can be circulated continuously or intermittently through the inner space, while a required discharge voltage is applied to the discharge electrodes, thereby enabling discharge to be produced.
Furthermore, a PDP manufacturing process may be performed in the following way. First, a front plate and a back plate, on at least one of discharge electrodes have been arranged and on at least one of whose inner surfaces a phosphor layer has been formed are sealed together so that an inner space is formed between them. Then an aging process in which a required discharge voltage is applied to the discharge electrodes is performed. The aging process includes an introducing process in which a discharge gas with a partial steam pressure of 15 Torr or less is newly introduced into the inner space from the outside and an evacuating process, in which discharge gas is evacuated from the inner space. The discharge generated when a required discharge voltage is applied to the discharge electrodes is divided into a plurality of discharge periods. By performing the introducing and evacuating processes in the intervals between discharge periods, discharge gas can be circulated through the inner space.
Here, the introducing process introduces gas via a first air vent formed in the panel, and the evacuating process evacuates gas via a second air vent formed in the panel.
Consequently, the PDP subject to the aging process has the following structure. A plurality of discharge spaces are formed by arranging a plurality of partitions to divide up the inner space between the front plate and the back plate and a sealing glass layer for sealing the panel is included between the perimeters of the front plate and the back plate. Then a first space connected to the discharge spaces formed by the plurality of partitions is formed between first ends of the plurality of partitions and the sealing glass layer, and a second space connected to the discharge spaces is formed between second ends of the plurality of partitions and the sealing glass layer. The first air vent forms a connection with the first space and the second air vent with the second space. Then this structure is subject to an aging process in which the discharge gas is circulated through the discharge space. This is achieved by performing the introducing process by introducing the discharge gas into the first space via the first air vent, and the evacuating process by evacuating the discharge gas from the second space via the second air vent.
The PDP subjected to the aging process further includes a structure in which a minimum distance between partition ends of the plurality of partitions, excluding at least a partition furthest from the first air vent, and the sealing glass layer bordering the first space is
Aoki Masaki
Kado Hiroyuki
Ohtani Mitsuhiro
Matsushita Electric - Industrial Co., Ltd.
Ramsey Kenneth J.
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