Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2000-05-12
2003-10-07
Patel, Nishmeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S584000
Reexamination Certificate
active
06630788
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flat display device, and ore particularly to a plasma display panel.
2. Background of the Related Art
Generally, a plasma display panel and a liquid crystal display (LCD) have lately attracted considerable attention as the most practical next generation display of flat panel displays. In particular, the plasma display panel has higher luminance and a wider visible angle than the LCD. For this reason, the plasma display panel is widely used as a thin type large display such as an outdoor advertising tower, a wall TV and a theater display.
FIG. 1
a
shows a structure of a related art plasma display panel of three-electrode area discharge type. As shown in
FIG. 1
a
, the plasma display panel of three-electrode area discharge type includes an upper substrate
10
and a lower substrate
20
which are bonded opposite to each other.
FIG. 1
b
shows a sectional structure of the plasma display panel of
FIG. 1
a
, in which the lower substrate
20
is rotated by 90°.
The upper substrate
10
includes scan electrodes
16
and
16
′, sustain electrodes
17
and
17
′, a dielectric layer
11
, and a passivation film
12
. The scan electrodes
16
and
16
′are formed in parallel to the sustain electrodes
17
and
17
′. The dielectric layer
11
is deposited on the scan electrodes
16
and
16
′ and the sustain electrodes
17
and
17
′.
The lower substrate
20
includes an address electrode
22
, a dielectric film
21
formed on an entire surface of the substrate including the address electrode
22
, an isolation wall
23
formed on the dielectric film
21
between the address electrodes, and a phosphor
24
formed on surfaces of the isolation wall
23
in each discharge cell and the dielectric film
21
. Inert gases such as He and Xe are mixed in a space between the upper substrate
10
and the lower substrate
20
at a pressure of 300 to 700 Torr. The space is used as a discharge area.
The scan electrodes
16
and
16
′ and the sustain electrodes
17
and
17
′ include transparent electrodes
16
and
17
and bus electrodes
16
′ and
17
′ of metal so as to increase optical transmitivity of each discharge cell, as shown in
FIGS. 2
a
and
2
b
.
FIG. 2
a
is a plane view of the sustain electrodes
17
and
17
′ and the scan electrodes
16
and
16
′ and
FIG. 2
b
is a sectional view thereof.
A discharge voltage from an externally provided driving integrated circuit (IC) is applied to the bus electrodes
16
′ and
17
′. The discharge voltage applied to the bus electrodes
16
′ and
17
′ is applied to the transparent electrodes
16
and
17
to generate discharge between the adjacent transparent electrodes
16
and
17
. The transparent electrodes
16
and
17
have an overall width of about 300 &mgr;m and are made of indium oxide or tin oxide. The bus electrodes
16
′ and
17
′ are formed of either three-layered thin film of Cr—Cu—Cr, or Ag. At this time, the bus electrodes
16
′ and
17
′ have a line width of ⅓ of a line width of the transparent electrodes
16
and
17
.
The operation of the aforementioned AC plasma display panel of three-electrode area discharge type will be described with reference to
FIGS. 3
a
to
3
d.
If a driving voltage is applied between the address electrodes and the scan electrodes, opposite discharge occurs between the address electrodes and the scan electrodes, as shown in
FIG. 3
a
. For this reason, some electrons discharged from the inert gas in the discharge cell come into collision with a surface of the passivation film, as shown in
FIG. 3
b
. The collision of the electrons secondarily discharges electrons from the surface of the passivation film. The secondarily discharged electrons come into collision with a plasma gas to diffuse the discharge. If the opposite discharge between the address electrodes and the scan electrodes ends, wall charges having opposite polarities occur on the surface of the passivation film on the respective address electrodes and the scan electrodes, as shown in
FIG. 3
c.
If the discharge voltages having opposite polarities are continuously applied to the scan electrodes and the sustain electrodes and at the same time the driving voltage applied to the address electrodes is cut off, area discharge occurs in a discharge area on the surfaces of the dielectric layer and the passivation film due to potential difference between the scan electrodes and the sustain electrodes, as shown in
FIG. 3
d
. The electrons in the discharge cell come into collision with the inert gas in the discharge cell due to the opposite discharge and the area discharge. As a result, the inert gas in the discharge cell is excited, and ultraviolet rays having a wavelength of 147 nm occur in the discharge cell. The ultraviolet rays come into collision with the phosphors surrounding the address electrodes and the isolation wall so that the plasma display panel is operated.
The process for fabricating the plasma display panel will be described.
As shown in
FIG. 4
a
, an upper substrate and a lower substrate are respectively formed. As shown in
FIG. 4
b
, the upper substrate and the lower substrate are bonded to each other and sealed along their edges. As shown in
FIG. 4
c
, an exhaust pipe
50
is provided in the sealed substrate to exhaust air of the discharge space where the upper substrate and the lower substrate bonded to each other, so that the inert gas is implanted.
Afterwards, initial discharge is generated in the discharge cell where the inert gas is implanted, and aging process is performed to continuously discharge the discharge cell until the plasma display panel is stably operated. Tip off process is then performed to remove the exhaust pipe. Thus, the plasma display panel is completed.
To perform the aging process, an aging voltage is applied to each discharge cell. At this time, the aging voltage is higher than a normal operating voltage by 50V to 200V. Also, the greater the size of the panel is, the higher the aging voltage is.
Furthermore, as shown in
FIG. 5
, the aging voltage is varied depending on three phosphors of red, green and blue respectively formed in the discharge cell. Particularly, the aging voltage is the highest in the green phosphor. Thus, it is probably that insulation of the dielectric is destroyed.
The aging voltage showing red color, the aging voltage showing green color, and the aging voltage showing blue color are respectively different. Particularly, since the aging voltage showing white color is higher than the aging voltage showing the other colors, a proper voltage area for red, green, blue and white in a module becomes narrow. That is to say, if the same discharge voltage is applied to all the discharge cells, emitting time of the discharge cell having the green phosphor is later than emitting time the other discharge cells having the other colored phosphors. Accordingly, although the other phosphors are emitted, the green phosphor may not be emitted. Thus, the aging voltage showing white color should have the higher potential than that showing green color.
As described above, the related art plasma display panel has several problems.
The high aging voltage destroys insulation between the electrodes. This results in that the panel cannot be used. Also, since the redundancy of the operating voltage in the module is small, the module may be operated in error.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a plasma display panel that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a plasma display panel in which an aging voltage of a green cell having the highest aging voltage is lowered to prevent insulation of a dielectric from being destroyed, and deviation of the operating range of each discharge cell is reduced to increase redundancy of the operating voltag
Berck Ken A
Fleshner & Kim LLP
LG Electronics Inc.
Patel Nishmeshkumar D.
LandOfFree
Plasma display panel does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Plasma display panel, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Plasma display panel will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3141115