Note: Descriptions are shown in the official language in which they were submitted.
I'('A -/ r~
S~4;3
The presellt invent~on relates to a flat panel
display and method of operatlng the same, and particularly to
a display in which line scanninc3 of the entire display screen
is achieved with a minimum number of deflection electrodes.
There is known a flat panel cathodo-
luminescent display device which includes an evacuated
envelope having a display section which includes a plurality
of parallel channels extending along rectangular front and
back walls. A gun section extends across one end of the
channels and includes gun structure which will direct one or
more electron beams along each of the channels. In each of
the channels is a beam guide which confines the electrons in
each beam and guides each beam along the channel. The beam
guides also include electrodes which are used to selectlvely
deflect the beams out of the guides toward a phosphor screen
on the inner surface of the ront wall.
At each point that the electron beams are deflected
out of the beam guides toward the phosphor screen, the beams
impinge on the phosphor screen to provide a line scan of the
phosphor screen in one direction across the display section,
e.g., the horizontal direction. By sequentially switching the
deflection of the beams along the deflection electrodes a
scanning of the phosphor screen is achieved in a direction
orthogonal to the above stated direction, e.g., the vertical
direction. The combination of these two scans provides a
complete raster scanning of the phosphor screen. In a
standard TV display device in the United States there are
about 500 vertical scan points. Thus, there would be
3 required in the above display device about 500 deflection
-2-
RC~ 7(),')3l
~0~544;~
1 electrodes to achieve the needed number of vertical scan
points. In order to se4uentially switch the 500 deflection
electrodes they must be connectecl to some type o~ switchin~J
mechanism which is either insicle or outside the envelope of
the display device. Th:LS results in either a complex
mechanism inside the envelope or a large number of terminals
extending through the envelope to be connected to the
switching mechanism outside the envelope.
In accordance with the invention, a display device
includes an evacuated envelope having a fron-t wall, a phosphor
screen extending across the inner surface of the front wall,
means for generating at least one beam of electrons and
directing the beam along a path substantially parallel to the
front wall, and a focusing guide extending along substantially
the entire length of the beam path for applying electrostatic
forces to the electrons of the beam for confining the electrons
to the beam. The display device also includes means for
selectively deflecting the beam toward the front wall at
spaced points along the beam path so that the beam impinges
the phosphor screen at a first series of spaced points, and
means for selectively deflecting the beam toward the front
wall at each of the spaced points along the beam path so that
the beam impinges the phosphor screen at a second series
of spaced points with each of said second points being
interlaced between two of the first points.
In the drawing:
FIGURE 1 is a perspective view, partially cut away,
of one form of a flat display device according to the
present invention.
FIGURE 2 is a longi-tudinal sectional view taken
.' , . .
1'(`~ 7!), ~
~8544.3
I along a portion of olle o the channcls of the display device
of FIGURE 1.
FIGURE 3 is a sectional view similar to FIGUR~ 2
showing another form of a display device according to the
present invention.
Referring to FIGURE 1, one form of a flat display
device according to the present invention is generally
designated as 10. The display device 10 comprises an
evacuated envelope 12, typically of glass, having a display
section 14 and an electron gun section 16. The display
section 14 includes a rectangular front wall 18 which supports
the viewing screen, and a rectangular back wall 20 in spaced,
parallel relation with the front wall 18. The front wall
15 18 and back wall 20 are connected by side walls 22. The
front wall 18 and back wall 20 are dimensioned to provide
the size of the viewing screen desired, e.g., 75 by 100
centimeters, and are spaced apart about 2.5 to 7.5 centimeters.
A plurality of spaced, parallel support walls 24
are secured between the front wall 18 and the back wall 20
and extend from the gun section 16 to the opposite side wall
22. The support walls 24 provide the desired internal
support for the evacuated envelope 12 against external
atmospheric pressure,and divide the display section 14 into
a plurality of channels 26. On the inner surface of the
front wall 18 is a phosphor screen 28. The phosphor screen
28 may be of any well known type presently being used in
cathode ray tubes, e.g., black and white or color television
display tubes. A metal film electrode 30 is provided on the
phosphor screen 28.
R(A 7(),9`~1
~()85~;3
1 The gun section 16 is an extention of the display
section 14 and extends along one ~et of adjacent ends of the
channels 26. The c3un section may be of any shape suitahle to
enclose the particular gun structure contained therein. The
electron gun structure contained in the gun section 16 may
be of any well known construction sui-table for selectively
directing beams of electrons along each of the channels 26.
For example, the gun structure may comprise a plurality of
individual guns mounted at the end of the channels 26 for
directing separate beams of electrons along the channels.
Alternatively, the gun structure may include a line cathode
extending along the gun section 16 across the ends of the
channels 26 and adapted to selectively direct individual
beams of electrons along the channels. A gun structure of
the line type is described in U. S. Patent No. 2,858,464,
issued October 28, 1958 to W. L. Roberts.
In each of the channels 26 are focusing guides for
confining electrons directed into the channel into a beam,
which travels a path along the channel. Each guide also
includes means for deflecting its beam out of the guide and
toward the phosphor screen 28 at various points along the
length of the channel 26.
Referring to FIGURE 2, there is shown one form of
a focusing guide which can be used in the channels 26.
The focusing guide includes spaced, parallel first
and second metal grid plates 32 and 36 which
~ 7(),'~
l~Sf.~
I extend transvers~ly across the channel 26 with the first
grld p:late 32 bein(l adjacent to but spaced from the back
wall 20. The metal grid p:La'-es 32 and 36 extend
longitudinally the full length of the channel 2h. The grid
plates 32 and 36 have a plurality of spaced, rectangular
openings 34 and 38 therethrough. The openings 34 and 38 are
arranged in rows both longitudinally along and transversely
across the channel 26 and each of the openings 34 is co-
axially aligned with the opening 38. A plurality of spaced,
parallel conductors 40 are Oil the inner surface of the back
wall 20 and extend transversely across the channel 26. The
conductors 40 are strips of an electrically conductive
material, such as a metal coated on the back wall 20. Each
of the conductors 40 extends directly behind a transverse
row of the openings 34 in the first grid plate 32.
A focusing grid plate 42 extends transversely across
the channel 26 between the second grid plate 36 of the
focusing guide and the front wall 18. An acceleration grid
plate 44 extends transversely across the channel 26 between
the focusing grid plate 42 and the fro.nt wall 18. The
focusing grid plate 42 and the acceleration grld plate 44
are in spaced, parallel relation and extend the full length
of the channel 26. The focusing grid plate 42 and the
acceleration grid plate 44 each have a plurality of spaced,
rectangular openings 46 and 48 respectively therethrough.
The openings 46 and 48 are arranged in rows both
longitudinally along and transversely across the channel 26,
with each of the openings 48 in the acceleration grid plate
44 being co-axially aligned with one of the openings 46 in
the focusing grid plate 42. The longitudinal rows of the
~ 7~),'J3l
I openings 46 and 48 are aligned with the longitudinal rows of
the openings 34 and 38. However, the transverse rows of the
openings 46 and 48 are offset from the transverse rows of
the openings 34 and 38 so that each of the openings 46 and
48 overlays two of the openings 34 and 38.
In a typical display device of the construction
shown in FIGURE 2, the conductors 40 are each of a width,
i.e., dimension longitudinally along the channel 26, of
about 2.5 mm. The first grid plate 32 of the focusing guide
10 is spaced from the conductors 40 about 0.50 mm and the
second grid plate 36 is spaced from the first grid plate 32
about 0.76 mm. The openings 34 and 38 in the grid plates 32
and 36 respectively are rectangular and each have a dimension ,
transversely of the channel 26 of about 3.30 mm and a
dimension longitudinally of the channel 26 of about 2.0 mm.
The openings in each of the qrid plates are spaced apart
transversely of the channel 26 about 1.78 mm and
longitudinally of the channel 26 about 1.0 mm. The focusing
grid plate 42 is spaced from the second grid plate 36 of the
20 focusing guide about 3.18 mm. The acceleration grid plate 44
is spaced from the focusing grid plate 42 about 2.79 mm and
is spaced from the front wall 18 about 6.78 cm. The
openings 46 and 48 in the focusing grid plate 42 and
acceleration grid plate 44,respectively,are rectangular and
~5 have a dimension longitudinally of the channel 26 of about
2.54 mm and a dimension transversely of the channel 26
approximately equal to that dimension of the openings 34 and
38.
In the operation of the display device 10 having the
focusing guide shown in FIGURE 2, a relatively high positive
--7--
~C~ 70,931
16)ff5~;3
1 potential, typically about 300 volts, is applied to each of
the conductors 40; ~nd a low positive potential, typically
about 40 volts, is applied to each of the first and second
grid plates 32 and 36. A positive potential of about 1000
volts is applied to the focusing grid plate 42, and a potential
of about 8000 volts is applied to each of the acceleration
grid plate 44 and the metal film 30 on the phosphor screen
28.
Beams of electrons 50 are directed into the focusing
guides between the first grid plate 32 and the second grid
plate 36, with each beam 50 extending along a substantially
straight line path along a separate longitudinal row of the
openings in the grid plates. The potential differences
between the first grid plate 32 of the focusing guide and
the conductors 40, and between the second grid plate
36 of the focusing guide and the focusing grid 42, create
electrostatic force fields which confine the electrons in
the beam along the entire length of the path of the beam
through the focusing guide.
To extract the electron beam 50 from the focusing
guide, the potential applied to a conductor 40 is switched to
a negative voltage. When the electron beam reaches this
conductor, the beam will bend away from the negative potential
conductor 40 and pass through an adjacent opening 38 in the
first grid plate 36 to pass out of the beam guide. The
electron beam will then pass through an adjacent opening 46
in the focusing grid plate 42 which will result in a focusing
of the beam because of the potential applied to the focusing
grid plate 42. The electron beam will then be accelerated
- 30
-- 8
I'(`A 7 !), ') ~ I
S4~3
1 toward the phos~ or s(reen 28 by the high potential applied
to the acceleratio~ rid ~la~e 44. The beam will pass
through an adjacent o~enin(J 48 in the acceleration grid plate
44 and will finally im~inge on the phosphor screen 28.
It has been found that the electron beam 50 can be
extracted from the focusing beam guide at different angles by
applying different negative potentials to the conductor 40.
For example, referring to FIGURE 2, if a negative potential
of one magnitude, for example, -100 volts, is applied to the
conductor 40, the electron beam 50 will be extracted from the
beam guide at one angle, indicated by the beam path 50a, to
impinge on the phosphor screen 28 at one point. However, if
the potential applied to the conductor 40 is more negative,
for example -200 volts, the electron beam 50 will be
extracted at a greater angle to follow a path such as
indicated as 50b and will impinge on the phosphor screen 28
at a different point. Thus, at each of the conductors 40,
the electron beam 50 may be extracted from the focusing
beam guide at different angles,to impinge on the phosphor
In a preferred manner of operation of the display
device 10, the conductor 40 closest to the side wall 22
directly opposite the gun section 16, i.e., the top-most
conductor in FIGURE 1 or left-most-conductor in FIGURE 2,
is first switched to a negative potential. Thus all of the
~S beams 50 in all of the channels 26 will be deflected at a
point close to that side wall 22 to pass out of their
respective guides and impinge on the phosphor screen 28 to
provide a line scan of the phosphor screen. The alternate
conductors 40 are then switched to the negative potential in
sequence along the entire length
~ 7 n, ~ ~3l
S443
1 of the channels so that the Deams are extracted from their
guides at various points along the length oE the guides to
provide a line-by-line scan of the phosphor screen 28. This
sequence of switching the potentials applied to the conduc-
tors 40 is then repeated but with the conductors 40 beingswitched to a second negative potential different from that
of the first negative potential. This deflects the beams
out of their guides at each of the same points along the
guides as the first set of deflections but at a different
angle so that the beams will impinge on the phosphor screen
28 at a second set of points which are between the first set
of points of impingement. This provides a second set of
line scans of the phosphor screen 28 between the first set
of line scans. By carrying out the switching at the proper
speed and by modulating the various beams in the gun
section 16 during each line scan, a visual display can be
provided on the phosphor screen 28 which can be viewed
through the front wall 18 of the envelope 12. This manner
of operation provides a field interlace which has the
advantage that it is compatable with the conventional field
interlace system presently used in television display.
Referring to FIGURE 3, another form of a display
device according to the present invention is generally
designated as 100. The display device 100 is similar in
construction to the display device 10 shown in FIGURE 1 in that
it includes a display section and an electron gun section with
the display section having rectangular front and back walls
118 and 120 in spaced, parallel relation. The front and
back walls 118 and 120 are connected by side walls. A plurality
of spaced, parallel support walls are secured between the
--10--
~ A 7r)~931
i~85~43~
1 front wall 118 and back wall 120 and extend from the gun
section to the opposite side wall and divide the display
section into a plurality of channels 126. A phosphor screen
128 is on the inner surface of the front wall 118,and a metal
film electrode 130 is on the phosphor screen 128. In each
of the channels 126 are focusing guides for confining
electrons directed into the channel into a beam, which beam
travels a path along the channel. The display device 100
differs from the device 10 shown in FIGURES 1 and 2 in that
10 the spacing between the front wall 118 and back wall 120 is
less in the display device 100 than in the display device 10,
and in the construction of the focusing guides in the
channels.
The
focusing guide includes a plurality of spaced, parallel wires
52 extending transversely across the channels 126. The wires
52 are in a common plane which is spaced from and parallel
to the back wall 120. A metal ground plane plate 54 extends
transversely across the channels 126 spaced from and
parallel to the wires 52 and between the wires 52 and the
front wall 118. The ground plane plate 54 has a plurality
of openings 56 therethrough which are arranged in rows
longitudinally along and transversely across the channel 126.
The transverse rows of the openings 56 are positioned between
adjacent wires 52 with the openings 56 being longitudinally
spaced so as to be positioned between alternate pairs of the
wires 52. A plurality of spaced, parallel conductors 58 are
--11--
~S~43 RCA 70,93l
1 on the inner surface of the back wall 120 and extend
transversely across the channels 126. Each of the conductors
58 extends along a separate ~ransverse row of the openings
56 in the ground plane plate 54.
In the operation of the display device 100, a
positive potential is applied to each of the wires 52,and
zero potential is applied to each of the conductors 58 and
the ground plane plate 54. Electron beams 150 are directed
into the focusing guides between the ground plane plate 54
1O and the back wall 120,with each beam 150 being along a
separate longitudinal row of the opening 56 in the ground
plane plate 54. The potential difference between the
wires 52 and the conductors 58 and the ground plane plate
54 creates electrostatic fields which will cause the
electron beams 150 to follow an undulating path along
the array of the wires 52, so as to guide the electron
beams along the length of the channels 126.
By switching the potential applied to each of the
conductors 58 to a negative potential, the electrostatic
forces applied to the beam as it passes between the switch
conductor and the adjacent wire 52 will cause the beam to be
deflected out of its undulating path away from the negative
potential conductor. The deflected beam will then pass
through an adjacent opening 56 in the ground plane plate 54
and will impinge on the phosphor screen 128. As previously
described with regard to the display device 10, the beam can
be deflected out of the focusing guide at different angles
by using different negative potentials on the conductors 58.
Thus, if a relatively low negative potential, e.g. -100 volts,
5~3 ~c A 7(), 9 31
I is applied to a conductor 58, the beam 150 wilL be deflected
at a relatively low ancJle to follow a first path 150a and
impinge on the phosphor screen 128 at a first point. ~lowever,
if a higher negative potential, e.g., -200 volts,is applied to
the conductor 58, the beam will be deflected at a greater
angle to follow a path 150b and impinge on the phosphor
screen 128 at a second point. Thus, by switching the
conductors 58 in sequence to a first negative potentia~ the
beams in the channels 126 can be deflected at various points
along the channels to achieve a scanning of the phosphor
screen 128 along a first set of lines; and then by switching
the conductors 58 in sequence to a second negative potential,
the beams can be deflected at the various points along the
channel to achieve a scanning of the phosphor screen along a
second set of lines interlaced with the first set of lines.
Although the deflection of the electron beam 150
in the display device 100 has been described as being
accomplished by applying a negative potential to a conductor
58, the
deflection can alternatively be achieved by changing the
potential applied to a wire 52 to a negative potential. This
will cause the beam 150 to be deflected out of the guide at
a point just prior to the wire 52 having the negative
potential applied thereto. The angle at which the beam 150
will be deflected will depend on the particular potential
applied to the wire 80, so that the beam can be deflected at
different angles to impinge on the phosphor screen 128 at
different points by applying different negative potential to
the wire 52. If the beam 150 is to be deflected out of the
focusing guide by means of applying negative potential to the
-13-
~ 7(),93l
lC)~S~IL4;~
I wires 52, the conductor 58 on the inner section of the back
wall 120 can be a single layer of metal over the entire
surface of the back wall 120 rather than individual strips.
Although the display device 10 is shown in
FIGURE 2 as having a focusing guide of the type which includes
two plates between which the electron beams flow, the
display device 10 can alternatively use the type of focusing
guide shown in FIGURE 3 which includes a set of wires between
a ground plane plate and the conductor. Likewise the display
device 100 can alternatively use the type of focusing guide
shown in FIGURE 2.
Thus, there is provided a
display device in which a plurality of individual beams of
electrons are individually guided along substantially parallel
paths substantially parallel to a phosphor screen. The
beams are simultaneously deflected out of these paths toward
the phosphor screen at a plurality of points along the paths
to achieve a pluraiity of line scans of the phosphor screen.
The deflection of the beams is achieved by a deflection
potential in the beam guide, the magnitude of which controls
the angle of deflection and thus the point on the phosphor
screen that the beams will impinge upon. In accordance with
the present invention,the beams are deflected at each point
by at least two different deflection potentials so that at
least two different line scans ofthephosphorscreenresult at
each point of deflection of the electron beams. The
scanning of the entire phosphor screen can be achieved by
first deflecting the electron beams at each of the points in
sequence at one deflection potential to achieve one set of
line scans,and then deflecting the electron beams at each of
1~3~443
1 the points in sequence at the second deflection potential to
achieve a second set of line scans which are interlaced with
the line scans of the first set.
The present invention has the advantage that since
two or more line scans of the phosphor screen can be
obtained at each deflection point of the electron beams,there
is required fewer deflection points, one half or less
than was previously required with this type of flat
panel display. Also, in the focusing guide shown in FIGURE
2, the openings 34 and 38 in the grid plates 32 and 36 can be
made larger with fewer openings per unit length of the focusing
guide required. ln the focusing guide shown in FIGURE 3,
the openings 56 in the ground plane plate 54 can be larger
with fewer openings per unit len~th of the focusing guide,
and the wires 52 can be spread further apart with fewer wires
per unit length of the focusing guide. This greatly
simplifies the structure of the display device in that it
greatly reduces the number of deflection electrodes needed,
thus reducing the number of terminals which would extend
through the envelope and simplifying the switching mechanism
for achieving the scanning. Also, the structure of the
focusing guide is simplified since there are fewer openings
in the grid or ground plane
plates and fewer wires. Also, since a factor affecting the
focusing action of the focusing guides is the size of the
openings in the grid plates in one of the guides and the
spacing of the wires in the other guide, reducing the number
of these openings or wires reduces the possible inconsistancies
in the size or spacing so that the consistancy of the
3 focusing action is improved. Also, the larger the openings
~ 3 l~c~ 7(),93l,
l in the grid pl,ates or the greater the spacing between the
wires, the less effect minor tolerance errors will having on
the focusing action. Hence, using the method of the present
invention allows for use of improved focusing guides. ~lso,
in the display device which includes a focusing grid plate
between the beam guide and the phosphor screen, the openings
in the focusing grid plate can be larger so as to reduce
lens aberations and achieve improved focusing. Although the
display device has been described as having two different
potentials applied to each deflection electrode to achieve
two different line scans at each deflection point, it is
possible to apply three or more different deflection
potentials at each deflection point to achieve three or more
different line scans on each point.
-16-
