Note: Descriptions are shown in the official language in which they were submitted.
; 1(~8~6~3
l The present invention relates to a flat display
device including means for scanning an electron beam over the
i~ .
; image screen thereof, and particularly to such a device
including a guide structure for confining and guiding the
beam and for selectively extracting the beam from the guide.
Cathodoluminescent display devices which are
presently used commercially, such as the display devices for
television, generally include a neck and funnel extending
perpendicularly from the screen and are thus relatively deep
in the dimension perpendicular to the screen.
It has long been a desire to reduce the depth or
thickness of such display devices to provide a substantially
flat display device. As shown in U. S. Patent No. 2,928,014,
issued March 8, 1960 to W. R. Aiken et al., one structure
which has been proposed involves a guided beam approach and
comprises a thin box-like envelope with one of the large
surfaces thereof constituting a faceplate on which a phosphor
screen is disposed. An electron gun is provided at one side
of the screen, generally at one corner, and is arranged so as
to direct a beam of electrons across the device in a path
substantially parallel to the screen. Deflection elements
are provided to selectively deflect the beam onto successive
points of the screen to achieve the desired scanning thereof.
The deflection elements are generally in the form of metal
film electrodes coated on the back surface and on the sides
; of the tube.
In using the guided beam approach, a problem has
arisen in making flat display tubes having large area screens,
such as screens which are about 75 cm by 100 cm. For such
large size devices, some type of internal support structure is
- -2- _
RCA 67,646A
iU~8~
required to prevent the evacuated envelope from collapsing.
In a device having an internal support structure the
confinement and guiding of the electron beam is more critical
than in a device which has no such supporting structure,
because of the need to prevent the supporting structure from
interfering with the proper scanning of the beam along the
screen. Also, in the guided beam flat display devices of the
type shown in U. S. Patent No. 2,928,01~, high voltages have
been needed to deflect the electron beam. It would be
desirable to have such a display device which operates at
lower voltages and still achieves satisfactory confinement and
guidance of the beam.
A flat picture display device in accordance with
this invention includes an evacuated envelope having a front
wall and a phosphor screen along the inner surface of the
front wall. In the device is means for generating one or more
beams of electrons and directing each beam in a path generally
parallel to and across the front wall. Means are disposed
along the beam path for causing the beam to travel in a
substantially undulating path, but permitting the beam to be
deflected out of the path toward the phosphor screen at
various selected points along the path. Means are along the
beam path for laterally confining the electrons to a
relatively narrow beam.
In the drawings:
FIGURE l is a perspective view, partially cut away,
of a flat display device including a beam guide.
FIGURES 2a and 2b are schematic views of one form
of the beam guide of FIGURE 1, illustrating its operation.
FIGURES 3a, 3b and 3c are schematic views of another
:
RCA 67,646A
1088613
1 form of the beam guide of FIGURE 1, illustrating its
operation.
FIGURE 4 is a transverse sectional view of a
portion of the display device of FIGURE 1, looking down the
channels in the device and showing one form of the beam guide
thereof.
FIGURE 5 is a sectional view similar to FIGURE 4,
showing a modified form of the beam guide of FIGURE 4.
FIGURE 6 is a sectional view similar to FIGURE 4,
showing a third form of beam guide which can be used in a
flat display device.
FIGURE 7 is a sectional perspective view showing a
fourth form of beam guide which can be used in a flat display
device.
FIGURES 8-13 are transverse sectional views similar
to FIGURE 4 and of a different form of a beam guide which can
be used in the display device of FIGURE 1.
Referring to FIGURE 1, a flat display device
including a beam guide 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 and a rectangular back wall 20 in
spaced parallel relation with the front wall 18. The front
` 25 wall 18 and back wall 20 are connected by side walls 22. The
front wall 18 and back wall 20 are dimensioned to correspond
with the size of the viewing screen desired, e.g., about 75
cm by 100 cm, and are spaced apart typically about 2.5 to 7.5
cm.
3 A plurality of spaced, substantially parallel,
.
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RCA 67,646A
10~ 13
1 vertically extending support walls 24 are secured between the
; front wall 18 and the back wall 20. The support walls 24
provide the internal support for the evacuated envelope 12
against external atmospheric pressure, and divide the display
section 14 into a plurality of vertically extending channels
26. In each of the channels 26 iS a beam guide. On the
- inner surface of the front wall 18 is a phosphor screen 28.
;~ The gun section 16 iS an extension of the display
section 14 and extends along one set of adjacent ends of the
channels 26. The gun section may be of any shape suitable to
enclose the particular gun structure contained therein, and
may be of any well-known construction suitable for selectively
directing a beam of electrons along each of the channels 26.
For example, the gun structure may comprise a plurality of
individual guns, one being mounted at one end of each of the
channels 26, for directing separate beams of electrons along
each of the channels.
Alternatively, the gun structure may be a single
gun at one end of the gun section 16 and directing an electron
beam across the ends of the channels 26, with deflection
electrodes being provided along the gun section 16 for
selectively deflecting the electron beam into each of the
channels 26. One such gun structure is shown in the
aforementioned U. S. Patent No. 2,928,014.
Another type of gun structure which can be used
includes 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 this type is described in U. S. Patent No.
2,858,464, issued October 28, 1958 to W. L. Roberts.
. .
RCA 67,646A
108~613
1 A terminal 27 extends through a side wall 22 of the
envelope 12. The terminal 27 includes a plurality of
terminal wires by which the gun structure and other parts of
the display within the envelope 12 can be electrically
connected to suitable operating circuitry and power source(s)
outside of the envelope 12.
The beam guide disposed in each of the channels 26
utilizes the technique of slalom focusing described in the
article: "Slalom Focusing", by J. S. Cook et al.,
10 Proceedings of the IRE, Vol. 45, November 1957, pages 1517-
1522. Slalom focusing, as there described, makes use of a
plurality of spaced, parallel wires or rods arranged in a
common plane midway between two parallel plates. The wires
or rods are charged positively with respect to the plates.
The electrostatic field thereby created is such that when a
beam of electrons is directed into the space between the
plates along the plane of the rods or wires, the beam will
weave an undulating path through the array of rods or wires.
While such a structure pxovides for confining the beam along
its intended path, it does not provide for extraction of the
beam from the structure at selected points, as is required
for the present invention.
Referring to FIGURE 2a, there is shown schematically
one form of the beam guide, generally designated as 29, which
can be used in the display device 10 to provide focusing and
selective deflection of the electron beam. The beam guide 29
comprises a first set of spaced, parallel wires 30 arranged
in a common plane between a ground plane 32 and a second set
of spaced, parallel wires 34 arranged in a common plane
3 parallel to the ground plane 32. The first set of wires 30
,
,
~: .
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1(~88613
1 is posltioned closer to the ground plane 32 than to the
second set of wires 34. The second set of wires 34 contains
the same number of wires as contained in the first set of
wires 30, and each of the wires 34 is directly over and
parallel to a different one of the wires 30. In the operation
of this form of the beam guide, a potential +VO, which is
; positive with respect to the ground plane 32, is applied to
each of the wires 30 of the first set; and an equal but
negative potential -V0 is applied to each of the wires 34 of
the second set. This creates a zero volt plane, indicated by
the dashed line 36, between the two sets of wires and parallel
to the ground plane 32. Thus, as in the article of Cook et
al., a beam of electrons directed into the beam guide will
follow an undulating path weaving itself through the first
set of wires 30 as indicated by the arrow-headed line 38.
As shown in FIGURE 2b, to extract the electron beam
from the beam guide 29, a wire 30a of the first set of wires
30 is switched to a low DC potential, VD, which is less than
+VO; and the corresponding wire 34a of the second set of wires
34 is switched to a positive DC potential, VE. This changes
the electrostatic field so that the beam is deflected away
from the ground plane 32 and out of the beam guide 29 between
two wires of the second set of wires 34, as shown by the line
38a. Thus, by switching the potentials applied to the
various pairs of adjacent wires of the two sets of wires 30
and 34, the electron beam can be deflected out of the beam
guide 29 at selected points along the beam guide.
Referring to FIGURE 3a, another form of the beam
guide which can be used in the display device lO is generally
3 designated as 40. The beam guide 40, like the beam guide 29
-7-
. ~ , ,
.
.
RCA 67,646A
1(~88613
1 shown in FIGURE 2a, includes a first set of spaced, parallel
wires 42 arranged in a plane between a ground plane 44 and a
second set of spaced, parallel wires 46 lying in a common
plane parallel to the ground plane 44. However, in the beam
guide 40, the number of wires 46 in the second set is greater
than the number of wires 42 in the first set, and the first
set of wires 42 is positioned midway between the ground plane
44 and the second set of wires 46.
In the operation of the beam guide 40, each of the
wires 42 of the first set is at a potential +VO which is
positive with respect to the ground plane 44 and both the
ground plane 44 and the second set of wires 46 are at zero
; potential. This creates an electrostatic field such that
when an electron beam is directed into the beam guide, the
electron beam will follow an undulating path through the
array of the first set of wires 42 as indicated by the arrow-
headed line 48.
To extract the electron beam from the beam guide 40,
two adjacent wires 46a and 46b of the second set of wires 46
are switched to a positive DC potential VE which is
approximately equal to +VO, as indicated in FIGURE 3b. This
; causes the electron beam to be deflected toward the second set
of wires 46. The beam passes between the two positively
charged wires 46a and 46b as indicated by the line 48a in
FIGURE 3b and out of the beam guide 40. Thus, by switching
various pairs of adjacent wires of the second set of wires 46
to a positive potential, the electron beam can be deflected
out of the beam guide 40 at selected points along the beam
guide.
FIGURE 3c illustrates an alternate manner of
'
--~ RCA 67,646A
~088613
1 operating the beam guide 40 to selectively extract the
electron beam. In this manner of operation, one of the wires
42a of the first set is switched to a negative voltage -VE,
which is not as negative as -VO~ This changes the
electrostatic field applied to the electron beam so as to
deflect the beam toward the second set of wires 46. The
electron beam then passes out of the beam guide 40 between
two of the wires 46a and 46c of the second set of wires 46,
as indicated by the solid line 48b. If the one wire 42a of
the first set is switched to a potential more negative than
-VE, the electrostatic force applied to the beam causes the
beam to deflect further away from the wire 42a. This will
cause the electron beam to pass out of the beam guide 40
between two different wires 46a and 46b of the second set, as
indicated by the dashed line 48c. Therefore, by varying the
magnitude of the negative potential applied to the wires 42
of the first set, the electron beam can be deflected by
different amounts to extract the beam from the beam guide 40
at various selected positions between different parts of
adjacent wires 46 which are positioned between adjacent wires
42 of the first set of wires. Thus, this manner of operating
the beam guide 40 permits extracting the electron beam at a
greater number of positions than can be achieved with the beam
guide 29 of FIGURE 2 or the manner of operation shown in
FIGURE 3b.
Referring to FIGURE 4, there is shown a section of
the beam guide 40 of FIGURE 3 in the display device lO. Since
the electron beam must pass along each of the channels 26, the
beam guide must also include means for laterally confining the -~
beam in the channel 26 in a direction parallel to the wires 42
_g_
: -
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lC~88613
~ ,
I to prevent the support walls 24 from interfering with the flow
: of the electron beam. In each of the channels 26 of the
display device 10, the ground plane 44 of the beam guide is a
film of an electrically conductive metal on the inner surface
: 5 of the back wall 20 of the envelope 12. The wires 42 of the
first set of wires extend through and are supported by the
support walls 24, with each of the wires 42 extending across
all of the channels 26. The wires 42 are in spaced relation
along the length of the channels 26, and are all in a common
plane parallel to the back wall 20. The wires 46 of the
- second set of wires also extend through and are supported by
the support walls 24, with each of the wires 46 extending
across all of the channels 26. The wires 46 are in spaced
, relation along the length of the channels 26, and are in a
15 common plane between the first set of wires 42 and the front
. wall 18. In each of the channels 26, a first pair of metal
? film lateral confinement electrodes 50 is on the support wall
24 between the ground plane 44 and the first set of wires 42.
The first pair of lateral confinement electrodes 50 extends
20 to the ground plane 44 so as to be electrically connected
thereto, but is spaced from the first set of wires 42. A
second pair of metal film lateral confinement electrodes 52
is on the support walls 24 between the first set of wires 42
and the second set of wires 46. The second pair of lateral
: 25 confinement electrodes 52 is spaced from both sets of wires
42 and 46. Both the electrodes 50 and 52 are continuous
strips extending the entire length of the channels.
In the operation of the display device 10, each of
the second set of wires 46, the ground planes 44, the first
30 pair of lateral confinement electro~es 50 and the second pair
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RCA 67, 646A
~0~8613
1 of lateral confinement electrodes 52 is at zero potential,
and each of the first set of wires 42 is at a potential ~VO
which is positive with respect to the ground planes 44. Thus,
the electron beam directed along each of the channels 26 from
the gun section 16 of the device 10 will follow an undulating
path through the array of the first set of wires 42 as
previously described with regard to the beam guide 40 shown
in FIGURE 3. The electric fields created between the wires
42 and the lateral confinement electrodes 50 and 52 apply
electrostatic forces to the electrons of the electron beam in
the direction indicated by the arrows 54 in FIGURE 4, so as
to force the electrons toward the central portion of the
channel 26. This confines the beam to the central portion of
the channel 26 and thereby prevents the support walls 24 from
interfering with the beam. By making the potential applied
to two adjacent wires 46 of the second set of wires more .
positive, as shown and described with regard to FIGURE 3b; or
by switching ~ne of the wires 42 of the first set to a
negative potential, as shown and described with regard to
FIGURE 3c; the electron beam will be deflected away from
ground plane 44 and will pass out of the beam guide toward
the front wall 18, impinging on the phosphor screen 28 which
is at a positive potential with respect to the gun structure.
Thus, a confined electron beam can be provided along each of
25 the channels 26, and the beam can be deflected toward the : :
phosphor screen 28 at various selected points along the length :
of the channels 26. By providing an electron beam or electron
beams along the channels 26 and by varying the points of
deflection of the beams, horizontal and vertical scanning of
the phosphor screen 28 can be achieved to provide a display
~ _~ RCA 67,646A
10~8613
l on the front wall 18 of the display device lO.
A specific example of a beam guide 40 can use wires
42 and 46 which are 0.15 mm in diameter. The wires 42 of the
first set of wires can be spaced apart a distance of 1.5 mm,
and the wires 46 of the second set of wires can be spaced
apart a distance of 0.5 mm. The second set of wires 46 can
be spaced from the ground plane 44 a distance of 1.5 mm. With
the second set of wires 46, the ground plane 44 and the
confinement electrodes being at zero potential, the first set
10 of wires 42 being at a potential of +300 volts and the cathode
of the gun structure being at -30 volts, an electron beam
directed into the guide 40 will follow an undulating path
through the array of the first set of wires 42. The beam can
be extracted from the beam guide 40 by either switching two
adjacent wires 46 of the second set of wires to a potential of
approximately +300 volts or by switching one of the first set
of wires 42 to a potential of approximately -lO0 volts.
Referring to FIGURE 5, there is shown a beam guide
55 which is a modified form of the beam guide 40 of FIGURE 4.
The beam guide 55 in each of the channels 26 is the same as
that shown in FIGURE 4 except that only the first set of
lateral confinement electrodes 50 are provided on the support
walls 24. In the operation of this form of the beam guide,
the forces created by the electric fields between the first
set of wires 42 and the lateral confinement electrodes 50 and
ground plane 44, which forces confine the electron beam to the
center portion of the channel 26, are applied to the electron
beam only during the time that the electron beam passes
between the first set of wires 42 and the ground plane 44, as
indicated by the arrows 56. However, since these confinement
RCA 67,646A
1~8t~613
1 forces are being applied to the electron beam during about one
half of the length of its travel along the channel 26, they
are sufficient to maintain the electron beam away from the
support walls 24.
Referring to FIGURE 6, a modification of the display
device of the present invention is generally designated as
110. Display device 110 is of a structure similar to the
display device 10 shown in FIGURE 1, except that the inner
surface of the back wall 120 has a plurality of parallel
grooves 121 therein of arcuate, e. g., semicircular, cross
section. The support walls 124, which are secured between
the front wall 118 and the back wall 120, are positioned
along the ridges between the grooves 121 so that each of the
grooves extends along a separate one of the channels 126.
The first set of wires 142 extends through the support walls
124 at the junction of the support walls 124 and the back
wall 120. rletal film ground ~lanes 144 are disposed on the
surfaces of the grooves 121, so that each of the ground
planes 144 is substantially U-shaped with ends spaced from
the first set of wires 142. The second set of wires 146
extends through the support walls 124 between the first set
of wires 142 and the front wall 118. A phosphor screen 128 is
on the inner surface of the front wall 118.
The display device 110 operates in the same manner
as previously described with regard to the display device 10
shown in ~IGURE 4. However, the electric fields created
between the U-shaped ground planes 144 and the wires 142
create electrostatic forces as indicated by the arrows 158,
so that when the electron beam passes between the first set -~
of wires 142 and the ground plane 144 the beam is confined to
.:
:
-~ RCA 67,646A
613
1 the central portion of the channel 126. Thus, the ground
plane 144 also serves as the lateral confinement electrodes
so that laterally confining forces are applied to the electron
beam during about one half of its length of travel along the
channel 126, in a manner similar to that of the form of the
beam guide shown in FIGURE 5, but without the need for
confinement electrodes on the support walls 124.
. Referring to FIGURE 7, a display device having
another form of beam guide is generally designated as 210.
10 The display device 210 includes front and back walls 218 and
220, respectively, and spaced support walls 224 extending
between the front and back walls and forming a plurality of
~ channels 226. A first metal ground plate 266 is disposed on
the inner surface of the back wall 220. The first ground
plate 266 has a plurality of spaced, substantially parallel
grooves 268 in its surface facing the front wall 218. Each of
the grooves 268 is arcuate, e.g., semicircular, in cross
section and extends in the same direction as the channels 226
between the support walls 224. Elongated spacer rods 270 of
an electrical insulating material, such as glass, are in
spaced ones of the grooves 268 with at least one groove 268
being between each pair of adjacent spacer rods 270. The
spacer rods 270 are of a diameter slightly greater than the
depth of the grooves 268, so that the spacer rods project -
slightly out of the grooves 268. A set of spaced, parallel
wires 242 extend across and engage the spacer rods 270. Since
the spacer rods 270 project beyond the grooves 268, the wires
242 are spaced from the first ground plate 266.
A second metal ground plate 272 is parallel to the
first metal ground plate 266, but on the side of the set of
-14-
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lU88613
1 wires 242 toward the front wall 218. The second ground plate
272 has a plurality of spaced, parallel grooves 274 in its
surface facing the first ground plate 266. The grooves 274
are arcuate, e.g., semicircular, in cross section and mutually
coextensive in length, and face corresponding grooves 268 in
the first ground plate 266. Elongated spacer rods 276 of an
electrical insulating material, such as glass, are disposed
in the grooves 274 which mate with the grooves 268 containing
the spacer rods 270. The spacer rods 276 are of a diameter
slightly greater than the depth of the grooves 274 so as to
project slightly out of the grooves 274. The spacer rods 276
engage the set of wires 242 so as to space the second ground
plate 272 from the wires 242.
The second ground plate 272 has a plurality of
openings 278 therethrough. The openings are arranged in
aligned rows along the bottoms of the grooves 274. Each of
the openings 278 is elongated along the length of the grooves
274 and is positioned in a space between the wires 242. The
support walls 224 extend between the front wall 218 and the
second ground plate 272, and are positioned along the grooves
of the ground plate which contain the spacer rods 270 and 276,
so as to provide mechanical support between the front wall
218 and the back wall 220. Although the display device 210 is
shown having three pairs of mating grooves 268 and 274 along
- 2S each of the channels 226 between the support walls 224, the
support walls 224 can be either closer together or further
apart to provide any desired number of the mating grooves
along each of the channels. The grooves 268 and 274 can be
rectangular instead of arcuate and serve their intended
3 purpose. Also, the ground plates 266 and 272 can be flat
.: :
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1 metal plates with a plurality of spaced, parallel projections
or ribs extending from the surface of the plates to form, in
essence, the equivalent of the grooves. A phosphor screen 228
is on the inner surface of the front wall 218 in each of the
channels 226.
In the operation of the display device 210, the
ground plates 266 and 272 are each at zero potential, and the
wires 242 are at a positive potential. Thus, an electron beam
which is directed into each pair of mating grooves 268 and 274
will follow an undulating path along the array of the wires
242. The grooves 268 and 274 create an electrostatic field
which confines the beam to substantially the center line of
the grooves in the manner described with regard to the beam
guide shown in FIGURE 6, but with the lateral confinement
forces being applied along the entire undulating path of the
beam. By switching selected ones of the wires 242 to a
negative potential, the electron beam will be deflected
toward the second ground plate 272 and will pass out of the
beam guide through one of the openings 278 in the manner
described with regard to the manner of operation shown in
FIGURE 3c. Since the openings 278 are elongated, by varying
the magnitude of the potential applied to the respective wires
242, the angle of deflection can be varied so that the
electron beam will impinge on the phosphor screen 228 at
various points.
Referring to FIGURE 8 there is shown another
modification of the focusing guide, in accordance with the
present invention. The focusing guide includes a first set of
wires 342 between first and second ground planes 344 and 346.
The first ground plane 344 comprises a plurality of spaced,
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10886~3
1 parallel, metal film strips on the inner surface of the back
wall 320 and extending longitudinally along the channel. Each
of the metal strips extends along a separate beam path.
; Between the metal strips of the first ground plane 344 are
lateral confinement electrodes 350. The lateral confinement
electrodes 350 are metal films on the inner surface of the
back wall 320 and extending longitudinally along the channels
between and spaced from the metal film strips of the first
ground plane 344. The second ground plane 346 is a wire mesh
10 extending across the first set of wires 342 substantially ~-
parallel to the back wall 320. The second ground plate 346
can alternatively be either a second set of wires as shown in
FIGURES 4, 5, and 6, or a metal plate having holes there-
through such as shown in FIGURE 7.
In the operation of the focusing guide, the first
set of wires 342 is at a potential which is positive with
respect to the first and second ground planes 344 and 346.
Thus, an electron beam directed into the focusing guide at
each of the metal strips of the first ground plane 344 will
follow an undulating path through the array of the first set
of wires 342 as previously described. The lateral confinement
electrodes 350 are each ata potential slightly less than the
potential applied to the first ground plane 344. The
potential difference between the lateral confinement
25 electrodes 350 and the first ground plane 344 creates
electrostatic force fields as indicated by the arrows 354
which laterally confine the electrons in the beam as the beam
travels longitudinally along the metal strip of the first -
ground plane 344.
Referring to FIGURE 9 there is shown another form of
RCA 6 7 , 6 4 6A
,
l()W613
. .
the focusing guide, in accordance with the present invention.
The focusing guide includes a first set of spaced, parallel,
coplanar wires 442 extending transversely across the channels
between first and second ground plane members 444 and 446.
The first ground plane member 444 is a metal film on the inner
surface of the back wall 420. The second ground plane member
446 may be a wire mesh extending transversely across and
longitudinally along the channels; a plurality of spaced,
parallel, coplaner wires extending transversely across the
channels such as shown in FIGURES 4, 5 and 6; or a plurality
of spaced, parallel, coplanar wires extending longitudinally
along the channels. Lateral confinement electrodes 450 extend
along the second ground plane member 446 longitudinally of the
channels and on opposite sides of the beam paths. The metal
confinement electrodes 450 are wires which are greater in
diameter than the diameter of the wires of the second ground
plane member 446 so that the metal confinement electrodes 450
project from the second ground plane member 446 toward the
first set of wires 442.
In the operation of the focusing guide, the first
set of wires 442 is at a potential more positive than the
first and second ground plane members 444 and 446. As
previously described, an electron beam directed along the
channel will thus follow an undulating path through the array
of the first set of wires 442. The lateral confinement
electrodes 450 are at the same potential as the second ground
plane member 446. Since the lateral confinement electrodes
450 project beyond the second ground plane member 446
electrostatic forces are created between the lateral
3 confinement electrodes 450 and the first set of wires 442 as
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1 indicated by the arrows 454 which laterally confine the
electrons to the beam as the beam passes along the channel.
Referring to FIGURE lO there is shown still another
modification of the focusing guide in accordance with the
present invention. The focusing guide includes a first set of
spaced, parallel, coplanar wires 542 extending transversely ~-~
across the channel between first and second ground plane
members 544 and 546. The first ground plane member 544 is a
metal film on the inner surface of the back wall 520. The
second ground plane member 546 comprises a plurality of
parallel, coplanar wires extending longitudinally along the
channel and spaced transversely across the channel. Lateral
confinement electrodes 550 extend longitudinally along the
channels on opposite sides of the beam paths. The lateral
15 confinement electrodes 550 are wires which are coplanar with -
the second ground plane member 546 and extend between but are
spaced from the wires of the second ground plane member.
In the operation of the focusing guide, the first ~ -
set of wires 542 is at a potential greater than that on the
first and second ground plane members 544 and 546. Thus, a
beam of electrons directed into the focusing guide will follow
an undulating path through the array of the first set of wires
542. The lateral confinement electrodes 550 are at a
potential slightly less than that of the second ground plane
member 546. This creates electrostatic forces as indicated by
the arrows 554 which laterally confine the electrons in the
beam as the beam passes along the focusing guide. This
focusing guide is simi]ar in structure and operation to the
focusing guide shown in FIGURE 8, except that the lateral
confinement electrodes are along the second ground plane
i
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RCA 67,646A
1~8~6~3
member rather than the first ground plane member, so that the
lateral confinement forces are applied to the beam as it
passes between the first set of wires and the second ground
plane member rather than as the beam passes between the first
set of wires and the first ground plane member.
Referring to FIGURE 11 there is shown still another
form of the focusing guide in accordance with the present
invention. The focusing guide includes a first set of spaced,
parallel coplanar wires 642 extending transversely across the
channel between a first ground plane member 644 and a second
set of wires 646 which serve to form the same function as a
second ground plane member. The first ground plane member 644
is a metal film on the inner surface of the back wall 620.
The second set of wires 646 include a plurality of parallel,
coplanar wires extending longitudinally along the channel and
spaced transversely across the channel. The wires 646 are
positioned along opposite sides of the path of the beam of
electrons along the channel. A metal grid 648 extends
transversely across the channel between the second set of
20 wires 646 and the phosphor screen 628 on the inner surface of
the front wall 618. The metal grid 648 may be a film on the
phosphor screen 628. However, if the metal grid 648 is spaced
from the phosphor screen the metal grid should have a
plurality of openings therethrough to allow the electron
beams to pass therethrough to the phosphor screen.
In the operation of the focusing guide, the first
set of wires 642 is at a potential positive with respect to
the first ground plane member 644 and the second set of wires
646. The potential applied to the second set of wires 646 is
such that the force field created between the second set of
-20-
--~ RCA 67,646A
~0~8613
1 wires 646 and the first set of wires 642 is equivalent to that
which would be achieved by a ground plane member so that a
beam of electrons directed into the focusing guide will follow
an undulating path through the array of the first set of wires
642. A potential is applied to the metal grid 648 which is
highly positive with respect to the potential applied to the
second set of wires 646. The potential difference between
the second set of wires 646 and each of the first set of wires
642 and the grid plate 648 creates electrostatic force fields
as indicated by the arrows 654 which laterally confine the
electrons in the beam as the beam passes along the focusing
guide.
In the focusing guide shown in FIGURES 5, 6, 8, 9,
10 and 11 lateral confinement of the electrons in the beam is
achieved during only one half of each cycle of the beam
through the focusing guide. In the focusing guide shown in
FIGURES 5, 6 and 8 the lateral confinement is achieved only as
the beam passes between the first set of wires and the first
ground plane, whereas in the focusing guide shown in FIGURES
9, 10 and 11 the lateral confinement is achieved only as the
beam passes between the first set of wires and the second
ground plane. Lateral confinement can be achieved during the
entire cycle of the beam, i.e., on both sides of the first set
of wires, by combining these various types of focusing guides.
For example, in the focusing guide shown in FIGURE 12, the
focusing guide shown in FIGURE 8 is combined with the focusing
guide shown in FIGURE 11. This results in a first ground
plane number 744 which comprises a plurality of spaced,
parallel, metal film strips on the inner surface of the back
wall 720 and extending longitudinally along the channel with
RCA 67,646A
lV88613
1 lateral confinement electrodes 750 on the inner surface of the
back wall 720 between the ground plane number strips; and a
second ground plane and lateral confinement means provided by
a plurality of spaced, parallel wires 746 extending
longitudinally along the channel and a grid plate 748 between
the wires 746 and the front wall 718 of the display envelope.
As previously described with regard to EIGURES 8 and 11, the
: lateral confinement electrodes 750 provide lateral confinement
of the electrons in the beam as the beam passes between the
first set of wires 742 and the first ground plane 744, and the
wires 746 provide lateral confinement of the electrons as the
beam passes between the first set of wires 742 and the wires
746.
In the focusing guide shown in FIGURE 13, the
lateral confinement means shown in FIGURE 11 is used on both
sides of the first set of wires 842. On the inner surface of
the back wall 820 is a metal film grid 844 and between the
metal grid 844 and the first set of wires 842 is a second set
of wires 845. The second set of wires 845 extend
longitudinally along the channel and are in spaced, parallel
relation transversely of the channel with the wires being
positioned at opposite sides of the beam paths. A metal grid
848 is between the first set of wires 842 and the front wall
818 of the display envelope, and a third set of wires 846 is
between the first set of wires 842 and the grid 848. The
third set of wires 846 extend longitudinally along the channel
with each of the wires 846 extending along a separate one of
the wires 845. In the operation of the focusing guide, the
first set of wires 842 is at a potential positive with respect
to each of the second set of wires 845 and the third set of
-22-
CA 67,646A
,~
1~8~6~3
1 wires 846, and each of the grids 844 and 848 is at a potential
substantially more positive than that on the second set of
wires 845 and third set of wires 846, respectively. The
relative potentials applied to the wires 842 and 845 create an
electrostatic field between the first set of wires 842 and
each of the second set of wires 845 and third set of wires 846
which causes an electron beam injected into the focusing guide -
to follow an undulating path through the array of the first
set of wires. As previously described with regard to FIGURE
ll, the potential difference between the second set of wires
845 and the grid 844 and the third set of wires 846 and the
grid 848 creates electrostatic force fields which laterally
; confine the electrons to the beam as the beam passes along the
focusing guide.
Thus, there is provided by the present invention a
flat display device, in which beam guides which utililze
slalom focusing are provided in channels in an evacuated
envelope, to guide beams along the channels. The beam guides
have means for laterally confining the electrons in the beam
as the beam passes along the guides, to maintain the cross
sectional dimension of the beam. The beam guides also include
means for deflecting the beam at various points along the
length of the channel toward the phosphor screen of the
display device.
