Gas discharge panel

Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device

Reexamination Certificate

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Details

C315S169100

Reexamination Certificate

active

06707259

ABSTRACT:

TECHNICAL FIELD
The present invention relates to gas discharge panels such as plasma display panels and the like.
BACKGROUND ART
Plasma display panels (PDPs) are one of the various types of plasma display apparatuses. Given their relative suitability for thin, large-screen applications, PDPs are currently attracting attention as the possible displays of the future, and 60-inch class models are already available on the market.
FIG. 42
is a partial perspective view showing a main structure of a known surface-discharge AC-type PDP. In
FIG. 42
, a thickness of the PDP is in the z direction and the panel surface of the PDP lies parallel to the xy plane. The PDP includes a front panel
20
and a back panel
26
arranged so that the main surfaces of each panel face each other.
A front panel glass
21
forms a substrate of front panel
20
. Plural pairs of display electrodes
22
and
23
(i.e. scan electrode
22
and sustain electrode
23
) extending in the x direction are arranged on a main surface of front panel glass
21
so as to enable a surface discharge to be conducted between the electrodes
22
and
23
in each pair. The electrodes
22
and
23
can be formed, for example, from a mixture of Ag and glass.
Each scan electrode
22
is electrically independent with respect to its power supply. In contrast, each sustain electrode
23
is connected to the same power supply. A dielectric layer
24
and a protective layer
25
, both of which are formed from an insulating material, are coated in the stated order over the surface of front panel glass
21
on which the pairs of display electrodes are arranged.
A back panel glass
27
forms a substrate of back panel
26
. A plurality of address electrodes
28
extending in the y direction is arranged in a stripe-pattern on a main surface of back panel glass
27
, and a predetermined space is provided between adjacent address electrodes. The address electrodes may be formed from a mixture of Ag and glass.
A dielectric layer
29
formed from an insulating material is coated over the surface of back panel glass
27
on which address electrodes
28
are arranged. Barrier ribs
30
are provided between adjacent address electrodes
28
on dielectric layer
29
. Phosphor layers
31
,
32
, and
33
corresponding to the colors red (R), green (G) and blue (B) are formed between adjacent barrier ribs
30
, the phosphor layers being formed on the barrier rib walls and over the dielectric layer
29
between adjacent barrier ribs.
Front panel
20
and back panel
26
as described above are arranged to face each other such that address electrodes
28
extend in an orthogonal direction to display electrodes
22
and
23
.
Front panel
20
and back panel
26
are sealed together around their respective peripheries using a sealing material such as frit glass, and a vacuum is created within the space enclosed therebetween.
In should be noted that only one of each of electrodes
22
,
23
and
28
has been shown in
FIG. 42
for ease of description. The known PDP as described here actually includes a plurality of each of these electrodes.
A discharge gas (enclosed gas) that includes Xe is enclosed at a predetermined pressure (approx. 40 kPa to 66.5 kPa in conventional PDPS) within the sealed space between the front and back panels.
A discharge space
38
is thus formed in the space defined between dielectric layer
24
of front panel
20
, phosphor layers
31
-
33
of back panel
26
, and adjacent barrier ribs
30
interposed therebetween Furthermore, a plurality of cells (not depicted in
FIG. 42
) used in image display is provided in discharge space
38
, each cell being formed in the region where a single address electrode
28
extends across a single pair of display electrodes
22
and
23
.
FIG. 43
shows the matrix of the PDP formed by the plural pairs of display electrodes
22
,
23
(N line) and the plurality of address electrodes
28
(M columns).
When the PDP is driven, a discharge is initiated between address electrode
28
and either display electrode
22
or
23
in each of the cells. Ultraviolet light (Xe resonance line; wave length approx. 147 nm) having short wavelengths is generated as a result of a discharge that. then occurs between display electrodes
22
and
23
in each pair, the generated ultraviolet light striking phosphor layers
31
to
33
and exciting them to emit visible light. Image display is achieved as a result.
The following is a detailed description of a prior art method for driving the known PDP with reference to
FIGS. 44 and 45
.
FIG. 44
is a conceptual block diagram showing an image display apparatus (PDP display apparatus) using the known PDP.
FIG. 45
shows exemplary drive waveforms applied to each of the electrodes in the PDP.
As shown in
FIG. 44
, in order to drive the PDP, the PDP display apparatus includes the following elements: a frame memory
10
, an output processing circuit
11
, an address electrode drive apparatus
12
, a sustain electrode drive apparatus
13
, and a scan electrode drive apparatus
14
. Each of electrodes
22
,
23
and
28
are connected to scan electrode drive apparatus
14
, sustain electrode drive apparatus
13
, and address electrode drive apparatus
12
, respectively. Elements
12
,
13
and
14
are connected to output processing circuit
11
.
When the PDP is driven, image information inputted into the PDP display apparatus from an external source is initially stored in frame memory
10
, and then based on timing information, the image information is transferred from frame memory
10
to output processing circuit
11
. Then, based on the image information and the timing information, output processing circuit
11
becomes operational. Output processing circuit
11
outputs instructions to the elements
12
,
13
and
14
, and applies pulse voltages to each of electrodes
22
,
23
and
28
, thereby conducting the image display.
As shown in
FIG. 45
, when the PDP is driven, a setup pulse is applied to scan electrodes
22
, initializing a wall charge within each of the cells. Next, a scan pulse and a write pulse are applied respectively to scan electrode
22
and sustain electrode
23
positioned at the top of the screen (i.e. in the y direction), thus initiating a write discharge. As a result of the write discharge, wall charge is stored on the surface of dielectric layer
24
in each of the cells corresponding to the electrodes
22
and
23
that have been applied with the pulses.
Continuing on, a scan pulse and a write pulse are then applied respectively to scan electrode
22
and sustain electrode
23
in the line second from the top of the screen, and wall charge is stored on dielectric layer
24
in each of the cells corresponding to the electrodes
22
and
23
in the stated line. One screen of latent image is thus written by repeating this process for all display electrodes
22
and
23
forming the display surface.
Next, a sustain discharge is conducted by grounding address electrodes
28
and applying sustain pulses alternately to scan electrodes
22
and sustain electrodes
23
. A discharge is generated in the cells storing wall charge on dielectric layer
24
when the potential of the surface of layer
24
increases above the discharge initiating voltage in the respective cells. The sustain discharge is maintained in the cells applied with the write pulse for the duration that the sustain pulses are applied (i.e. sustain period). Erase pulses, each of short duration, are then applied so as to weaken the discharge and eliminate the wall charge, thereby serving to erase the latent image.
In television image display according to the NTSC standard, one image is composed of 60 fields per second. Primarily, a PDP is only capable of expressing the two states of “on” and “off.” Thus, in order to display the intermediate color gradations, a method is adopted according to which the “on” periods of each of the colors red (R), green (G) and blue (B) are timeshared and one field is divided into a plurality of subfields. The intermediate color gradations can thus be expressed d

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