Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
1999-02-23
2003-06-10
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S584000, C313S586000, C313S587000
Reexamination Certificate
active
06577061
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display device and a plasma display panel, especially suitable for an image display with a high color temperature.
2. Description of the Background Art
FIG. 29
is a block diagram of a plasma display device disclosed for example in U.S. Pat. No. 5,661,500. In
FIG. 29
, the reference numeral
100
designates a plasma display device;
1
is a plasma display panel (hereinafter referred to as “PDP”) including display electrodes EX and EY (hereinafter referred to as “X electrode EX” and “Y electrode EY”) that induce display discharge in a space therebetween, and address electrodes (hereinafter referred to as “A electrode”);
110
is a scan control unit;
120
is an A/D converter (hereinafter referred to as “A/D”) converting input signals from analog to digital;
130
is a frame memory storing the output of the A/D
120
;
141
is an X-electrode driving circuit for supplying a driving signal to the X electrodes EX of the PDP
1
;
142
is a Y-electrode driving circuit for supplying a driving signal to the Y electrodes EY of the PDP
1
;
143
is an A-electrode driving circuit for supplying a driving signal to the A electrodes of the PDP
1
;
2
is a driving control system comprising the X-electrode driving circuit
141
, the Y-electrode driving circuit
142
, and the A-electrode driving circuit
143
.
We will now describe a method for driving the plasma display device
100
.
FIGS. 30A through 30E
are timing charts showing an example of waveforms of applied voltages during one subfield according to a subfield gradation technique, disclosed for example in Japanese Patent Laid-open No. 7-160218A.
In
FIGS. 30A through 30E
, n
1
is a scan pulse; n
2
is an address pulse; n
3
is a sustain pulse; and n
4
is a priming pulse (full writing pulse).
One subfield is divided into: (1) a reset period to erase wall charges; (2) an address period to store wall charges in cells that emit lights for display; and (3) a sustain discharge period to induce sustain discharge in the cells where the wall charges are stored during the address period, to produce light emissions for display.
In the reset period, the full writing pulse n
4
is applied to the sustain electrode EX to induce discharge in all cells. The full writing pulse n
4
may also be referred to as “priming pulse”. At the falling edge of the full writing pulse n
4
, self-erase discharge is induced in all the cells to erase wall charges.
In the address period, the scan pulse n
1
is sequentially applied to the Y electrodes EY
1
to EYn, and the address pulse n
2
is applied to the A electrodes
22
j
. This induces address discharge in cells to be lightened for display during the display period, and wall charges are stored in the surface of a protective layer
18
of those cells.
In the sustain discharge period, the sustain pulse n
3
is alternately applied to the Y electrodes EYi (i=1 to n) and the X electrode EX to induce sustain discharge only in the cells where the address discharge occurs.
FIG. 31
a perspective view showing the structure of a conventional PDP
1
disclosed for example in U.S. Pat. No. 5,661,500. In
FIG. 31
, the reference number
11
designates a front or first substrate;
17
is a dielectric layer covering the X electrode EX and the Y electrode EY which will be described later;
18
is a protective layer formed for example of MgO and covering the surface of the dielectric layer
17
;
22
is the A electrode;
21
is a rear or second surface;
28
is an uninterrupted phosphor stripe formed along the A electrode
22
;
29
is a barrier rib provided on the side of the second substrate
21
;
30
is a discharge space;
41
is a strip transparent conductive film (hereinafter referred to as “transparent electrode”) which is formed of a tin oxide layer, etc. and disposed in parallel with each other at given intervals (discharge gap) to form the X electrode EX and the Y electrode EY; and
42
is a strip metal film (hereinafter referred to as “metal electrode”) formed of a multilayer film such as Cr—Cu—Cr or Cr—Al—Cr to supplement conductivity of the transparent electrode
41
. Each of the X electrode EX and the Y electrode EY is composed of the transparent electrode
41
and the additional metal electrode
42
. The reference character EG designates a pixel, which is, in the case of color display devices, composed of unit luminescent areas EU emitting lights of a plurality of colors. The reference character S designates a display surface.
Next, we will describe operation of the conventional plasma display device. The plasma display device
100
comprises the PDP
1
and the driving control system
2
for driving the PDP
1
, electrically connected to the PDP
1
via a flexible printed wiring board. In the driving control system
2
, an analog input signal is converted into a digital form by the A/D
120
; the digital output from the A/D
120
is stored in the frame memory
130
as a digital image signal; and according to the digital image signal, the output of the scan control unit
110
is supplied to the X-electrode driving circuit
141
, the Y-electrode driving circuit
142
, and the A-electrode driving circuit
143
to drive the PDP
1
.
The PDP
1
is a surface discharge type PDP with a three electrode structure having a pair of display electrodes, namely X electrode EX and Y electrode EY, and the A electrode which correspond to the unit luminescent area EU. Both the X electrode EX and the Y electrode EY are composed of the transparent electrode
41
and the metal electrode
42
and disposed on a surface of the first substrate
11
on the side of the display surface S. On the second substrate
21
, the barrier ribs
29
are provided, defining the height of the discharge space
30
. The discharge space
30
is sectioned by the unit luminescent areas EU along an extending direction of the X and Y electrodes EX and EY (hereinafter referred to as “first direction”).
Between the parallel barrier ribs
29
, an A electrode of a given width is disposed by printing and firing a pattern of a silver paste; and a phosphor stripe
28
is provided to cover side walls of the barrier ribs
29
and the second substrate
21
including the surface of the A electrode
22
. The pixel EG is almost in the shape of a square, composed of three unit luminescent areas EU(
28
R), EU(
28
G), EU(
28
B) (generically referred to as “unit luminescent area EU”) which are approximately similar rectangles in shape and correspond to the emitted colors: red (R), green (G), and blue (B), respectively. That is, the unit luminescent area EU of each emitted color in the pixel EG is about the same in width in the first direction D
1
, constituting one third the width of the pixel in the first direction D
1
.
To prevent deterioration in contrast of the screen due to incident extraneous lights from the first substrate
11
of the PDP
1
, a black low melting point glass (black stripe) may be provided between the pair of the X electrode EX and the Y electrode EY on the first substrate
11
.
FIG. 32
is a schematic diagram showing an arrangement of phosphors viewed from the display surface S. As shown in
FIG. 32
, a pixel EG is basically composed of the unit luminescent areas EU with a red phosphor
28
R, a green phosphor
28
G, and a blue phosphor
28
B (each alphabet designates the emitted color and the aforementioned phosphor
28
is a generic name for these three phosphors) corresponding to three primary colors: red (R), green (G), and blue (B), respectively. Color reproduction is thus made by additive mixing of color lights emitted from the unit luminescent areas EU corresponding to the three primary colors. For instance, the red phosphor
28
R is formed of (Y, Gd) BO
3
:EU
3+
; the green phosphor
28
G of Zn
2
SiO
4
:Mn; and the blue phosphor
28
B of BaMgAl
14
O
23
:Eu
2+
.
The composition of materials of the phosphors is selected so that a mixture of the three colors becomes white (somewhat reddish white) when light emissions (excitation) from
Nagai Takayoshi
Nagano Shinichiro
Saikatsu Takeo
Sano Ko
Uchiumi Toyohiro
Mitsubishi Denki & Kabushiki Kaisha
Patel Ashok
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