Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2000-11-20
2002-11-19
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C345S041000, C345S042000, C345S060000
Reexamination Certificate
active
06483250
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of driving a plasma display panel (hereinafter, also referred to as “PDP”), and more particularly to a technique in using a round waveform for driving the PDP to reduce an application time of the round waveform.
2. Description of the Background Art
Various studies have been made on a PDP as a thin-type television and a display monitor. Among the PDPs, there is a surface discharge AC-type PDP as one of AC-type PDPs having a memory function.
(Structure of PDP)
FIG. 17
is a perspective view showing an AC-type PDP
101
in the background art. The PDP of this structure is disclosed in Japanese Patent Application Laid Open Gazette Nos. 7-140922 and 7-287548.
The PDP
101
comprises a front glass substrate
102
as a display surface and a rear glass substrate
103
opposed to the front glass substrate
102
with a discharge space
111
sandwiched therebetween.
On a surface of the front glass substrate
102
on the side of the discharge space
111
, n strip-like electrodes
104
a
and n strip-like electrodes
105
a
which are paired respectively are extendedly formed. For convenience of illustration range, one electrode
104
a
and one electrode
105
a
are shown in FIG.
17
. The electrodes
104
a
and
105
a
which are paired with each other are arranged with a discharge gap DG interposed therebetween. The electrodes
104
a
and
105
a
work to induce a discharge. Further, a transparent electrode is used for the electrodes
104
a
and
105
a
to extract more visible light, and hereinafter the electrodes
104
a
and
105
a
are also referred to as transparent electrodes
104
a
and
105
a
. Furthermore, in some cases, the electrodes
104
a
and
105
a
are made of the same material as metal (auxiliary) electrodes (or bus electrodes)
104
b
and
105
b
as discussed later are made of On the transparent electrodes
104
a
and
105
a
, the metal (auxiliary) electrodes (or bus electrodes)
104
b
and
105
b
are formed extendedly along the transparent electrodes
104
a
and
105
a
. The metal electrodes
104
b
and
105
b
have impedance lower than those of the transparent electrodes
104
a
and
105
a
, and work to supply a current from a driving device.
In the following discussion, an electrode constituted of the transparent electrode
104
a
and the metal electrode
104
b
is referred to as a (row) electrode
104
(or X) and an electrode constituted of the transparent electrode
105
a
and the metal electrode
105
b
is referred to as a (row) electrode
105
(or Y). The row electrodes
104
and
105
(or row electrodes X and Y) which are paired with each other are also referred to as a pair of (row) electrodes
104
and
105
(or a pair of (row) electrodes X and Y). Further, in some cases, the row electrode
104
is constituted of only electrode which corresponds to the electrode
104
a
and/or the row electrode
105
is constituted of only electrode which corresponds to the electrode
105
a.
A dielectric layer
106
is formed covering the row electrodes
104
and
105
and a protection film
107
made of MgO (magnesium oxide) which is a dielectric substance is formed on a surface of the dielectric layer
106
by evaporation method and the like. The dielectric layer
106
and the protection film
107
are also generally referred to as a dielectric layer
106
A. Further, in some cases, the dielectric layer
106
A does not include the protection film
107
.
On the other hand, on a surface of the rear glass substrate
103
on the side of the discharge space
111
, m strip-like (column) electrodes
108
are so formed extendedly as to be orthogonal to (as to grade-separately intersect) the row electrodes
104
and
105
. Hereinafter, the (column) electrode
108
is also referred to as a (column) electrode W Furthermore, for convenience of illustration range, three electrodes
108
are shown in FIG.
17
.
Between the adjacent column electrodes
108
, a barrier rib
110
is formed extendedly in parallel with the column electrodes
108
. The barrier ribs
110
separate a plurality of discharge cells (discussed later) arranged along the extending direction of the row electrodes
104
and
105
from each other and the barrier ribs
110
support the PDP
101
so as not to be crushed by atmospheric pressure.
Inside a substantial U-shaped trench constituted of the adjacent barrier ribs
110
and the rear glass substrate
103
, a phosphor layer
109
is formed covering the column electrode
108
. In more detail, in the above substantial U-shaped trenches, phosphor layers
109
R,
109
G and
109
B for respective emitted light colors, red, green and blue are formed and for example, the phosphor layers
109
R,
109
G and
109
B are arranged in this order in the entire PDP
101
.
The front glass substrate
102
and the rear glass substrate
103
having the above structure are sealed with each other and the discharge space
111
between the front glass substrate
102
and the rear glass substrate
103
is filled with discharge gas such as Ne—Xe mixed gas or the He—Xe mixed gas under a pressure lower than the atmospheric pressure.
In the PDP
101
, a discharge cell or a light emitting cell is formed at a (grade-separation) intersection of the row electrodes
104
and
105
and the column electrode
108
. Specifically, three discharge cells are shown in FIG.
17
.
(Principle of Operation of PDP)
Next, a principle of display operation of the PDP
101
will be discussed. First, a voltage or a voltage pulse is applied across the row electrodes
104
and
105
to generate a discharge in the discharge space
111
. Then, by exciting the phosphor layer
109
with an ultraviolet ray generated by this discharge, the discharge cell emits light or lights up. Charged particles such as electrons and ions generated in the discharge space
111
through this discharge move in a direction of the row electrode to which a voltage having a polarity reverse to that of the charged particles is applied and are accumulated on the surface of the dielectric layer
106
A on the row electrode (referred to as “on the row electrode” hereinafter). The electric charges such as electrons and ions accumulated on the surface of the dielectric layer
106
A are referred to as “wall charges.”
Since the respective wall charges accumulated on the row electrodes
104
and
105
through the discharge form an electric field in a direction of weakening the electric field between the pair of the row electrodes
104
and
105
, the discharge quickly disappears with formation and accumulation of the wall charges. When a voltage having polarity reverse to that of the above voltage is applied to the row electrodes
104
and
105
after the discharge disappears, an electric field in which the electric field generated by the applied voltage is superimposed on the electric field generated by the wall charges is substantially applied to the discharge space
111
, i.e., a voltage in which the applied voltage is superimposed on the voltage (wall voltage) generated by the wall charges is substantially applied to the discharge space
111
. The superimposed electric field can cause a discharge again.
Specifically, once the discharge is generated, continuous discharge (sustain discharge) can be caused by a voltage (sustain voltage) lower than the applied voltage used for starting the initial discharge through the electric field generated by the wall charges. Therefore, after the discharge is once generated, by alternately applying a pulse (sustain pulse) having an amplitude of sustain voltage to the row electrodes
104
and
105
, in other words, by applying the sustain pulse across the row electrodes
104
and
105
with its polarity reversed, the discharge can be regularly sustained and continued (sustain operation).
Specifically, the discharge can be continued by continuously applying the sustain pulse until the wall charges disappear. Further, to extinguish the wall charges is referred to as “an erase operation” (or simply as “an erase”) while to form the wall c
Hashimoto Takashi
Iwata Akihiko
Nagai Takayoshi
Tsunoda Yoshikazu
Urakabe Takahiro
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tran Thuy Vinh
Wong Don
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