Note: Descriptions are shown in the official language in which they were submitted.
DISPLAY PANEL AND METHOD OF MAKING IT
BACKGROUND OF THE INVENTION
A recently invented display panel which
comprises a dot matrix display having memory is
relatively complex and includes several support
plates, insulating layers, and electrode arrays
which must be prepared and assembled accurately.
The present invention relates to improve-
ments in the panel which simplify its preparation.
DESCRIPTION OF THE DRAWINGS
.
Fig. l is a perspective, exploded view of
a display panel embodying an embodiment of the
invention;
Fig. 2 is a sectional view through the
: : 15 panel of Fig. l along lines 2-2, with the panel
~: shown assembled;
: Fig. 3 is a sectional view of the priming
plate-glow isolator assembly of the display panel
of the invention at one stage in its manufacture;
20 ~ Fig. 4 is a view of the apparatus of Fig. 3
~: at a later stage ln:its preparation; and
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E~ig. 5 is a perspective view of a portion
of the assembly of Fig. 4 at a later stage in its
preparation.
DESCRIPT:CON OF ONE_ EME~ODIMENT OF THE INVENTION
The display panel 10 includes a gas-filled
envelope made up of an insulating base plate 20
and a glass face plate 30, which are hermetically
sealed together, as illustrated in Fig. 2, along
a closed periphery which surrounds the operating
inner portion of the panel and the various gas
cells provided therein. The base plate has a top
surface 22, in which a plurality of relatively deep
parallel longitudinal slots 40 are formed and in
each of which a scan/address anode electrode,
for example a wire S0, is seated and secured.
A plurality oE scan cathode electrodes
in the form of wires or strips 60 are seated on
the top surface of the base plate or in shallow
slots 70. The scan cathodes 60 are disposed
transverse to the scan anodes 50, and each
crossing of a scan cathode 60 and a~scan anode
40 defines a scanning cell 72 (Fig. 2). It can
be seen that the scanning cells are arrayed in
rows and columns. More specifically, the cathode
portions 61, the underlying portions of anodes
50, and the intermediate gaseous regions define
the scanning cells.
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The scan cathodes 60A, B, C, etc., form a
series of cathodes which can be energized serially in a
scanning cycle, with cathode 60A being the first cathode
energized in the scanning cycle.
A reset cathode electrode 62 is disposed in a
slot 64 in the top surface of the base plate adiacent to
the first scan cathode 60A, so that, when it is
energized, it provides excited particles for cathode
60A at the beginning of a scanning cycle to be described.
Where the reset cathode crosses each scan anode, a reset
cell is formed, and the crossing of all of the scan
anodes by the reset cathode provides a column of reset
cells. These reset cells are turned on or energized at
the beginning of each scanning cycle, and they expedite
the turn-on of the first column of scanning cells
associated with the first cathode 60A.
In the panel 10, it is desirable tha~ the
cathodes 60, or at least the portions 61 thereof which
are disposed in the scanning cells, be spaced ~uniformly
from an electrode 80 positioned above the cathodes and
described below. Thus, the cathode grooves or slots 70
must be of uniform depth. It is also desirable to
provide means for preventing the spread of cathode glow
from the operating portions 61 of the cathodes to the
intermediate portions. These conditions are satisfied
by providing insulating strips 74 between the top
surface 22 o the base plate and the cathodes 60 and
adjacent electrode plate 80, the priming plate. The
strips are aligned with the anode slots 40 and are
seat~d on the lands between these slots.
The portions of ~he panel described up ~o this
~ point comprise the base plate assembly. This is the D.C.
; portion and the scanning and addressing portion of the
panel.
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Adjacent to the base plate assembly is the
second portion of the panel which is ~ quasi A.C.
assembly; that is, it includes A.C. and D.C. features.
This portion of the panel includes an electrode in the
form of a thin metal plate 80 having an array of rows
and columns of relatively small apertures 92, each
overlying one of the scanning cells. The plate 80 is
positioned close to cathodes 60 and may be seated on
insulating sheet 74. Electrode plate 80 includes a
terminal 88 for making electrical connection thereto.
Adjacent to plate 80, and preferably in
contact with the upper surface thereof, is an apertured
plate or layer 86 having rows and columns of apertures
94 which are considerably larger than apertures 92. The
apertures 94 comprise the display cells of panel 10.
The sheet 86 may be of insulating ma~erial, as shown in
Fig~ 2, or it may be o~ metal, and, if it is of metal,
the plates 80 and 86 may be made in one piece, if
desired and if feasible.
The quasi A.C. assembly also includes a face
plate a~sembly which comprises face plate 30 and a
large-area transparent conductive electrode 100 on ~he
inner surface of the plate 30, together with a narrow
conductor 110 of silver or the like which outlines and
reinforces the electrode layer 100 to increase its
conductivity. The conductor 110 includes a portion 114,
to which external connection can be made. The large-area
electrode 100 overlies the entire array of display cells
94 in plate 86. An insulating coating 120 of glass or
the like covers electrode 100, and, if desired, a
dielectric layer 132 of magnesiu~ oxide, thorium oxide,
or the like is coated on layer 120.
In panel 10, the apertures 94 in plate 86
comprise display cells,~and, as can be seen in Fig. 2,
~5 each display cell has one end wall 134 formed by a
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portion of insulating layer 132, and an opposite end
wall 136 formed by a portion of the top surface of
plate 80. To provide cell uniformity and to minimiz~
cathode sputtering~ a coating of the material of layer
132 should also be provided on the base or lower wall
136 of each display cell 949 such as the layer 133
shown in Fig. 2.
Panel L0 has a keep-alive arrangement which
ircludes an A.C. electrode 140 in the form of a linear
conductive film or layer of opaque metal, such as
silver, provided on the inner surface of the face plate
30 adjacent to one edge of the transparent conductive
electrode 100. The A.C. keep-alive electrode 140 is
positioned so that it is in optimum operative relation
with the column of reset cells and reset cathode 62,
to which it supplies excited particles. The A.C. keep-
alive electrode 140 is covered by the insulating layers
120 and 132. The plate 86 is provided with a slot 142
and plate 80 is provided with a column of holes 150,
the slot 142 overlying and being aligned with the
column of holes 150, and both lie b~neath and are
aligned wi~h the A.C. electrode 140. The slot 142 in
the plate 86 is narrower than the opaque A.C. electrode
140 so that a viewer, looking through face plate 30,
cannot see any glow which is present in slot 142 and
holes 150. Electrode 140 operates with plate 80 to
produce glow discharge between them and produce excited
particles in slot 142 and holes 150. These excited
particles are available to the reset cathode 62 and
assist the firing of the column of reset cells.
The gas fllli.ng in panel 10 is preferably a
Penning gas mixture of, for example, neon and a small
percentage of xenon, at a pressure of about 400 Torr.
When the panel has been constructed and evacuated, the
3S gas filling is introduced through a tubulation 24
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secured to base plate 20 (Fig. 2)~ or a non-tubulated
construction can be employed~
In making the panel 10,. the ~ase plate
assembly, including plate 20 and the anodes 50
and cathodes 60, is prepared in any suitable manner,
for example, as described in U.S. Patent No. 4,352,040
of Nicholas C. Andreadakis. According to the embodi-
ment, the assembly of priming plate 80, glow iso~
lator plate 86, and insulating strips 74 is prepared
as a subassembly as follows. The metal plate 80
having holes 92 and 150 formed therein is coated on
its top surface with a thin layer of glass or
other etchable dielec~ric material such as Corning
7575* glass. A similar layer 170 is provided on
its bottom surface. Both dielectric layers 160
and 170 are coated with layers 180 and 190 o~ a
suitable photoresist.
The bottom photoresist layer 190 is then
exposed and developed to provide non-removable
strip-like regions ~00 which extend along the
photoresist layer between the rows of holes 92
and will ultimately form strips 74. The top
photoresist layer 1~0 is exposed and developed
to provide a pattern of regions which, when the
layer is later etched, will form the apertures
or cells 94. The assembly thus described is
then treated with a suitable acid to etch layers
170 and 180 at the same time to provide ~he
strips 74 and the layer of cells 94, as shown
in Fig. 4. This subassembly is then joined
with.the base plate assembl~ and the ~ace plate
- assembly described above, as illustrated in
dash lines in Fig. 4, and the parts are sealed
together and processed to form the completed
panel.
The operation of the panel 10 is not
set forth in detail herein. However, a brief
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description of the panel operation is as follows: With
the keep-alive electrodes generating excited particles~
and with operating potential applied to the scan anodes
50, the reset cathode 62 is energized to fire the column
of reset cells, and then the scan cathodes 60 are
energized sequentially to carry out a scanning operation
in the lower portion of the panel. At the same time,
with sustaining pulses applied between the electrodes ~0
and 100, as each column of scan cells is energized,
information or display signals are applied to the proper
scan anodes 50 to cause glow to develop in the
associated display cells 94 where it is sustained by
the sustaining pulses. When all of the colu~ns of scan
cells have been energized and the appropriate associated
display cells have been energized, a sustained and
visible message is present in the upper display portion
of the panel.
