Plasma display unit with number of simultaneously...

Details Plasma display unit with number of simultaneously... Plasma display unit with number of simultaneously...

1999-12-23

2002-06-25

Shalwala, Bipin (Department: 2673)

Computer graphics processing and selective visual display system

Plural physical display element control system

Display elements arranged in matrix

C345S067000, C345S068000, C345S096000, C345S209000, C313S581000, C313S584000, C315S169100, C315S169400

Reexamination Certificate

active

06411268

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display unit, and more particularly to an AC-discharge, memory-type plasma display unit.
2. Description of the Related Art
Plasma display units emit visible light to energize pixels by producing an electric discharge in a rare gas such as of Ne or Xe to generate ultraviolet radiation for exciting phosphors to emit visible light. The plasma display units display images in the form of a dot matrix, and are drawing attention as flat display units capable of emitting-light with high luminance.
CRTs (Cathode-Ray Tubes), which are a typical image display unit, have an appreciable depth that increases as the screen size increases. However, the depth of a plasma display unit does not increase even if its screen size increases.
LCD (Liquid Crystal Display) units have individual display cells, and their yield sharply drops when their screen size increases. However, the yield of plasma display units is not greatly reduced when their screen size increases because display cells are provided by points of intersection of vertical and horizontal electrodes.
Plasma display units include DC-discharge and AC-discharge types. The AC-discharge plasma display units have a dielectric protective film over the electrodes which are therefore not exposed to a discharge space. Consequently, the AC-discharge plasma display units have a much longer service life than the DC-discharge plasma display units whose electrodes are exposed.
The AC-discharge plasma display units are divided into refresh-type and memory-type plasma display units depending on how they are energized. The memory-type plasma display units produce wall charges using the dielectric on the electrodes, and generate an electric discharge by giving and receiving such wall charges.
More specifically, when a number of display cells in the display panel of a memory-type plasma display unit are successively scanned, wall charges are written in only those display cells which are to emit light according to image data. After the writing of the wall charges is completed, sustaining pulses are repeatedly applied to all the display cells, enabling only the display cells in which the wall charges are written to generate an electric discharge to emit light.
In such a memory-type plasma display unit, it is difficult to control the luminance of light by controlling the intensity of the electric discharge. Therefore, it is the general practice to control the number of times that a sustaining pulse is applied per display cell for thereby changing the visually perceived luminance to express gradations.
The AC-discharge plasma display units include surface-discharge AC-discharge plasma display units which have surface-discharge electrode pairs of scanning and sustaining electrodes placed in a plane, and facing-discharge AC-discharge plasma display units which produce an electric discharge between facing substrates. The surface-discharge AC-discharge plasma display units are expected as large-size, full-color flat display units because it is easier to develop electrostatic capacitance for forming wall charges, a memory margin is wider, phosphors are less degraded, and the emission efficiency is better.
One conventional AC-discharge, memory-type, surface-discharge plasma display unit will be described below with reference to
FIGS. 1 through 3
of the accompanying drawings. For illustrative purposes, it is assumed that scanning and sustaining electrodes extend in a row direction, and data electrodes extend in a column direction.
As shown in
FIG. 1
, a plasma display unit
1
comprises a display panel
2
and a drive circuit
3
. The display panel
2
has various electrodes connected to the drive circuit
3
.
The display panel
2
includes a front transparent insulating substrate
15
and a rear insulating substrate
16
. On the inner surface of the front transparent insulating substrate
15
, there are disposed m surface-discharge electrodes pairs
10
comprising parallel scanning and sustaining electrodes
11
,
12
as row electrodes parallel to the row direction and juxtaposed in the column direction.
On the inner surface of the rear insulating substrate
16
, there are disposed n data electrodes
14
as column electrodes parallel to the column direction and juxtaposed in the row direction. A discharge space
13
filled with a rare gas including Xe is defined in the gap between the insulating substrates
15
,
16
.
Since the scanning and sustaining electrodes
11
,
12
are positioned in front of light spots, they are usually made of an electrically conductive material that is highly light transmissive, such as ITO (Indium Tin Oxide). However, the material is not electrically conductive enough, so narrow trace electrodes
17
,
18
of metal are placed on the scanning and sustaining electrodes
11
,
12
. A dielectric layer
19
and a protective layer
20
are successively placed on the trace electrodes
17
,
18
. The scanning and sustaining electrodes
11
,
12
confront the discharge space
13
through the trace electrodes
17
,
18
, the dielectric layer
19
, and the protective layer
20
.
A dielectric layer
22
is disposed on the data electrodes
14
on the inner surface of the rear insulating substrate
16
. Partitions
21
for blocking the propagation of electric discharges and spacing the insulating substrates
15
,
16
from each other are disposed on the dielectric layer
22
and positioned between the data electrodes
14
. A phosphor layer
23
is positioned on the surface of the dielectric,layer
22
and sides of adjacent two of the partitions
21
.
The m surface-discharge electrodes pairs
10
and the n data electrodes
14
cross each other with the discharge space
13
interposed therebetween, providing m×n points of intersection successively arranged in the row and column directions as display cells
24
that serve as pixels for individually emitting light.
As shown in
FIG. 1
, the m scanning electrodes
11
have left ends connected respectively to m scanning wires
25
, to which in scanning drivers
26
are individually connected. The m sustaining electrodes
12
have right ends connected in common to a single sustaining wire
27
, to which a single sustaining driver
28
is connected.
To the n data electrodes
14
, there are connected n data drivers
29
, respectively. The above drives
26
,
28
,
29
jointly make up the drive circuit
3
.
The AC-discharge, surface-discharge plasma display unit
1
is capable of displaying a desired image in the form of a dot matrix by individually controlling the m×n display cells
24
for light emission. A process of energizing the plasma display unit
1
will be described below with reference to FIG.
3
.
In
FIG. 3
, “Wu” represent sustaining pulses applied from the single sustaining driver
28
in common to the m sustaining electrodes
12
, “Ws
1
-Wsm” scanning pulses applied from the m scanning drivers
26
individually to the m scanning electrodes
11
, and “Wd” data pulses applied from the n data drivers
29
individually to the n data electrodes
14
with respect to those display cells
24
in which wall charges are to be written.
In a priming period A, preliminary discharge pulses Pp
1
, Pp
2
are applied respectively to all the sustaining electrodes
12
and all the scanning electrodes
11
, generating active particles and wall charges in the discharge space
13
. Then, preliminary discharge erasing pulses Ppe are applied to the scanning electrodes
11
to erase excessive wall charges, developing a condition for stably writing wall charges.
In a scanning period B, the m scanning drivers
26
applies base pulses Pbw uniformly and also scanning pulses Pw at successively shifted times to the m scanning electrodes
11
. In synchronism with these times, the n data drivers
29
apply data pulses Pd to certain data electrodes
14
which correspond to an image to be displayed.
Those display cells
24
where a pulse voltage in excess of a discharge threshold is applied to the scanning and data ele

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