U.S. patent number 3,571,897 [Application Number 04/858,214] was granted by the patent office on 1971-03-23 for apparatus for making a color screen for cathode-ray tubes.
This patent grant is currently assigned to Hughes Aircraft Company. Invention is credited to Hans W. Heil.
United States Patent |
3,571,897 |
Heil |
March 23, 1971 |
**Please see images for:
( Certificate of Correction ) ** |
APPARATUS FOR MAKING A COLOR SCREEN FOR CATHODE-RAY TUBES
Abstract
Apparatus for forming phosphor patterns on the faceplate of a
cathode-ray tube, including means for electrically charging
phosphor powder, means for forming the charged phosphor powder into
a stream, and means for scanning the faceplate with the charged
phosphor powder stream.
Inventors: |
Heil; Hans W. (Malibu, CA) |
Assignee: |
Hughes Aircraft Company (Culver
City, CA)
|
Family
ID: |
27076594 |
Appl.
No.: |
04/858,214 |
Filed: |
June 4, 1969 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
575129 |
Aug 25, 1966 |
3479711 |
Nov 25, 1969 |
|
|
Current U.S.
Class: |
445/73; 118/50.1;
118/622; 118/624; 118/636; 118/640; 445/52; 445/58 |
Current CPC
Class: |
H01J
9/2277 (20130101); H01J 9/2276 (20130101); H01J
9/2275 (20130101) |
Current International
Class: |
H01J
9/227 (20060101); H01j 009/06 () |
Field of
Search: |
;118/50.1,622,624,636,640 ;29/25.19,25.2 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Campbell; John F.
Assistant Examiner: Lazarus; Richard Bernard
Parent Case Text
This application is a division of application Ser. No. 575,129, now
U.S. Pat. No. 3,479,711, filed Aug. 25, 1966 for "Method and
Apparatus for Producing a Color Kinescope and Blank Unit Therefor."
Claims
I claim:
1. Apparatus for depositing color phosphor particles on the viewing
panel of a kinescope in a desired geometry comprising: a source of
color phosphor particles; means for electrically charging said
particles; means for forming and accelerating said particles into a
beam; means for supporting a color kinescope tube with the viewing
panel thereof transverse to the path of said accelerated particles;
means for establishing a vacuum adjacent said viewing panel and
around the path of said particles; and means for effecting
relatively movement between said particle beam and said viewing
panel of the tube to deposit said particles in the desired geometry
on said viewing panel.
2. The apparatus according to claim 1 wherein said charging means
and said accelerating means are mounted in an evacuable chamber;
and means for coupling at least a portion of said tube to said
chamber.
3. The apparatus according to claim 1 including means for effecting
relative shifting movement between said particle charging and
accelerating means on the one hand and said kinescope tube on the
other hand so as to align said particle beam substantially with the
effective color centers of the different phosphor colors.
4. The apparatus according to claim 1 including electrostatic
deflection plates disposed in opposed relation about the effective
color centers of said phosphor colors; and means for varying the
deflection potentials on said plates to scan the particle beam
across the surface of said viewing panel, with the effective
deflection points for the particle beam substantially coinciding
with said effective color centers.
5. The apparatus according to claim 1 including means mounting said
tube for universal swiveling movement relative to said particle
beam to scan the beam over said panel surface.
6. The apparatus according to claim 1 including a source of supply
for each of the different color phosphor particles; means for
shifting said sources into alignment with said particle charging
means; and means for individually controlling the discharge of
particles from said sources.
7. The apparatus according to claim 6 including means for bodily
shifting said tube to substantially align the effective color
centers therein for the different colors with said particle
beam.
8. The apparatus according to claim 5 including means for
supplying, charging, and accelerating phosphor particles for each
color phosphor, and means supporting said last-mentioned means
within the tube from the plane of the effective color centers for
the universal movement to be gravity-biased to a vertical position
regardless of the angle assumed by the tube.
9. The apparatus according to claim 8 in which the exits of said
particle supplying, charging, and accelerating means are spaced
substantially in alignment with the effective color centers of said
tube.
10. The apparatus according to claim 9 in which said particle
supplying, charging, and accelerating means individual to each
color are suspended individually from points coincident with the
effective color centers of said tube.
Description
This invention relates to color cathode-ray tubes or kinescopes,
such as used in color television receivers, of the type employing
color light-producing phosphors disposed in a repetitive or mosaic
design and which in combination with a mask member permits the
selection of the color phosphors to be impacted by a scanning
cathode ray or electron beam.
More particularly, the present invention relates to a color
cathode-ray tube in which the front end of the tube, including the
faceplate or viewing panel, the outwardly flared envelope or funnel
portion of the tube, and the mask are permanently sealed together
into a unit prior to the printing or depositing of the color
phosphors on the viewing screen, and to a method and apparatus for
depositing the color phosphors in the desired pattern on the
viewing panel or screen without requiring disassembly of the tube
faceplate or viewing screen, the funnel portion and mask unit.
Color cathode-ray tubes or color kinescopes, particularly as
utilized in color television receivers, include an image screen
made up of a large number of phosphor groups of the colors red,
blue and green in the form of lines or dots of subelemental image
dimensions disposed on a glass substrate comprising the front
viewing panel or faceplate of the tube. One kind of color kinescope
has an image screen consisting of a large number of vertically or
horizontally disposed strips or lines of different colored phosphor
materials arranged in a sequence which may vary with the number of
cathode-ray guns used in the tube and with the widths of the
different color phosphor lines. For example, in a three-gun
kinescope the color phosphors may be formed in lines of equal width
(10 mils wide, for example) in a repetitive sequence of:
red-blue-green-red-blue-green...; in a single-gun kinescope one of
the color phosphors, for example green, may be formed in lines only
half the width but at twice the frequency of the other two color
phosphors for use with a voltage switched mask or grid member to
produce the desired focusing and deflecting of the electron beam.
In this latter arrangement, the exampled green color phosphor lines
can be 10 mils wide and the red and blue phosphor lines 20 mils
wide and the arrangement of lines be a repetition of:
green-red-green-blue-greeen-red....
In another type of color kinescope the color phosphors are disposed
in an array of triangularly disposed dots or triads of equal
diameters, for example 10 mils. In this kinescope three guns are
generally used to generate three electron beams and the mask in
such a tube may comprise a unipotential perforated plate having
perforations equal in number to the number of triads of dots in the
viewing screen.
For the strip or line disposition of the color phosphors the mask
on the gun side of the viewing screen is usually in the form of a
grid of wires parallel to the phosphor lines. The grid wires are
maintained at a unipotential for the three-gun kinescope; in a
single-gun kinescope alternate wires are connected together and
insulated from the wires therebetween to permit voltage switching
for directing the electron beam.
In all types of color kinescopes the different color-producing
phosphor areas must be correctly and precisely arranged on the
image-viewing screen in order to achieve color purity without
distortion or color contamination when impacted by the scanning
electron beam. The ability of such color tubes to produce a true
color image thus depends to a large extent upon the achievement of
the correct size and proper geometric location of the different
color-producing phosphor materials with respect to the path of scan
of an electron beam or beams serving to selectively energize the
different phosphor areas.
At the present time there are two main methods utilized for laying
down or printing the different color-producing phosphor areas on
the image or viewing screen. In one method the back of the
faceplate panel of the tube is coated with a layer of a
light-sensitive lacquer, resin or the like which desirably is
partially conductive as by having a conductive filler incorporated
therein. Light patterns corresponding to the desired color phosphor
patterns are them employed to selectively or differently sensitize
the desired areas of the viewing screen lacquer so that the
different color-producing phosphor materials may be laid down in
the desired pattern in accordance with the respective sensitization
of given areas. This method requires several temporary assembly and
disassembly operations of the viewing screen and the mask member.
Final indexing of the mask with respect to the phosphor areas is
difficult and time consuming, requires extensive production
facilities, and is a major source for rejects in the production
process.
The second method presently utilized for printing the different
color-producing phosphor areas on the viewing screen uses an
electron beam sensitive coating for the gun side of the front panel
of the tube and sensitizes different areas of the viewing screen
coating to different extents by electron beams from an electron gun
or guns similar to those to be permanently incorporated in the
tube. Thereafter, with several covering, settling and washing
steps, the different color phosphors are deposited on the viewing
screen in the desired geometrical arrangement. In this method also,
the front panel or viewing screen and mask must be temporarily
assembled, disassembled and reassembled in exact registry, and the
deposition steps involved are lengthy, complicated and
expensive.
The temporary assembly and disassembly required in both these
methods of deposition not only makes the exact indexing of the
mask, whether wire grid or perforated plate, with the image screen
a difficult and critical task but also the assembly and disassembly
requires repetitive evacuation of the tube envelope. These methods
further require that a smoothing film or coating, usually of
polymerized material, be deposited on the back face of the
deposited color phosphors before the formation of a conventional
metal (aluminum) surface thereon.
In the color cathode-ray or television tube according to the
present invention, the front panel or faceplate, the mask member
and the funnel portion of the tube are permanently assembled
together as a unit prior to the deposition of the color phosphors
on the image screen or faceplate. In one example, a wire grid mask
can have the individual wires thereof directly sealed into the tube
wall and this front end assembly can be completed by the glass
manufacturer. The phosphor screen printing and aluminizing
operations are performed by the tube manufacturer without the
necessity of disassembling the front panel and the grid, thus
eliminating the difficulty of indexing the mask with the color
phosphor geometry and further eliminating some of the evacuating
operations.
Such a unit front assembly tube is possible because of the method
of depositing the color phosphors and the apparatus therefor,
according to the present invention. In the process of the
invention, the surface of the viewing panel or fireplace is coated
with a tacky substance which is at least slightly conductive and
the different color phosphors are deposited thereon at exactly
those positions where the electrons, which cause the color
phosphors to luminesce, strike under normal tube operating
conditions. To effect this, the individual phosphor particles are
charged, accelerated and made to follow a trajectory in the
evacuated tube identical to the one the electrons themselves
follow. This is possible because the trajectory of a charged
particle in an electric field is independent of the magnitude of
the charge-to-mass ratio thereof.
In one method of depositing the phosphor particles according to the
present invention, an electrostatic deflection system is used to
cause the phosphor particle beam to scan the viewing panel or
screen. It is not necessary to focus the particle beam; a flooding
source at the position of the color center, which is the point of
effective deflection, may be used. This method of description is
particularly suitable for tubes employing focusing masks in order
to direction-select the colors. Deposition of the color phosphor
particles may be either parallel strips or triad dots with wire
grid or perforated plate masks, respectively.
As will be described in detail hereinafter, instead of employing an
electrostatic deflection system for scanning the phosphor particle
beam and to distribute it across the viewing panel, the tube itself
can be pivoted or swiveled substantially about the color center,
while the particle beam remains stationary. In this manner, all
areas of the viewing panel may be brought beneath the particle
beam.
Although the particle trajectory is substantially independent of
the charge-to-mass ratio, Z/M, the influence of gravitational
force, if Z/M is too small, and the danger of changing the state of
charge on the particle during flight, if the charge is too high,
set practical limits to the value of Z/M which should be used. With
Z expressing the charge on the particle in coulombs C and M the
weight of the particle in kilograms kg., a value of 0.01 C kg..sup.
.sup.-1 is indicated as a practical lower limit for the
charge-to-mass ratio. With a negatively charged particles, the
charge is deleteriously changed by field emission when the electric
field at the surface is above 10.sup.8 volts per meter, which
represents a practical upper limit for negatively charged particles
and corresponds to a charge density of approximately 10.sup..sup.-2
coulombs per square meter for particle sizes of 2.sup..sup.-10
microns. This corresponds roughly to a Z/M of 1 C kg..sup..sup.-1
for the upper limit.
A positive sign of charge is preferred for the phosphor particles
to be deposited on the screen since the positive charge is not as
readily lost by thermionic, field or photo emission. The upper
limit for the field and Z/M ratio of positively charged particles
can be one or two orders of magnitude higher than for negatively
charged particles. The sign of charge to be placed on the phosphor
particles in the apparatus to be hereinafter described can be
readily regulated by the electron energy of operation since it
determines the secondary emission yield at the particle surface.
Thus, the cathode potential for charging the particles is
controlled so that secondary emission at the surface may be higher
than unity if positively charged particles are desired, and less
than unity if negatively charged particles are desired.
The charged phosphor particles are accelerated and pass in the
evacuated tube through the color center of the particular color
phosphor to be deposited. The beam of particles is either deflected
between electrostatic plates, the potential across which is varied
to secure universal swinging of the particle beam across the
viewing panel, or the particle beam remains stationary and the tube
and panel are bodily swiveled relative to the beam to effect the
desired deposition. By deflection and focusing at the tube mask,
the particles are placed in the desired geometrical position for
each color phosphor on the image screen, as will be apparent
hereinafter from the various apparatus embodiments and methods
herein specifically illustrated and described.
An object of the present invention is the provision of a new and
improved color kinescope in which the front end of the tube
including the viewing panel, the funnel portion thereof and the
mask are permanently joined together as a unit prior to the
deposition of the color phosphors on the viewing panel.
Another object of this invention is to provide a new and improved
article of manufacture comprising a viewing panel or faceplate, a
tube funnel and mask as a permanently assembled unit without a
phosphor image screen for incorporation and use in a color
kinescope.
Another object of this invention is to provide a new and improved
method of depositing color phosphors on the viewing panel of a
color kinescope in which the individual phosphor particles are
electrically charged, accelerated and made to follow trajectories
onto the viewing panel substantially similar to the ones followed
by the electrons in the normal operation of the kinescope.
A further object of this invention is to provide a new and improved
method of depositing color phosphors on the viewing screen of a
color kinescope in which the individual phosphor particles are
electrically charged, accelerated and given flight trajectories
substantially coincident with the ones the electrons follow in the
normal operation of the kinescope, and in which the particle beam
is scanned across the surface of the viewing panel by deflection
between electrostatic plates, the voltage across which is caused to
vary.
A still further object of the present invention is to provide a new
and improved method of depositing color phosphors on the viewing
panel of a color kinescope in which the phosphor particles are
electrically charged, accelerated and caused to follow flight
trajectories substantially coincident with the ones the electrons
follow in normal kinescope operation, and in which a tube body
portion is pivoted relative to a fixed position particle beam
whereby the particles are deposited in the proper geometric pattern
over and on the surface of the viewing panel.
Another object of this invention is the provision of new and
improved apparatus for depositing color phosphors in a desired
geometric pattern in a color kinescope by which the color phosphors
are charged, accelerated and caused to follow trajectories in the
tube substantially coincident with the trajectories the electrons
follow in the normal operation of the kinescope, the particles
being received and retained in a tacky, at least slightly
conductive (electrically) film on the surface of the viewing
panel.
Yet another object of the present invention is to provide an
apparatus in accordance with immediately preceding object including
an electrostatic deflection system disposed at the color centers of
the tube for scanning the particle beam over the viewing panel.
Yet another object of the present invention is to provide an
apparatus alternative to the immediately preceding apparatus in
which the scanning of the particle beam is effected by bodily
pivoting or swiveling the tube relative to the particle beam.
These and other objects and features of the invention will be
readily apparent to those skilled in the art from the following
specification and the appended drawings in which:
FIG. 1 is a partially diagrammatic representation of an apparatus
according to the present invention in which a beam of charged and
accelerated phosphor particles is electrostatically deflected and
which includes optional means for shifting the particle delivery
elements into alignment with the different positions of the color
centers of a multigun kinescope;
FIG. 2 is a greatly enlarged representation of the viewing panel
showing the tacky film and phosphor particles deposited thereon
prior to aluminizing of the phosphor image screen;
FIG. 3 is a view similar to FIG. 2 after aluminizing of the image
screen;
FIG. 4 is a composite diagrammatic representation of the paths into
which the charged phosphor particles may be focused and deflected
by a switched wire grid of a single-gun kinescope;
FIG. 5 is a greatly enlarged view of the focusing and deflecting of
one-color charged phosphor particles onto the image screen for one
relative voltage switching of the wire grid of a single-gun
kinescope;
FIG. 6 is a view similar to FIG. 5 showing the focusing of the
charged phosphor particles of a different color with a unipotential
grid;
FIG. 7 is a view similar to FIGS. 5 and 6 but showing the focusing
and deflection of the third color phosphor particles with grid wire
potential differences opposite to those of FIG. 5;
FIG. 8 is a view showing focusing of the particles of one of the
color phosphors from the middle color center of a three-gun
kinescope;
FIG. 9 is a view similar to FIG. 8 showing, greatly exaggerated,
the focusing of particles of a second color from a side color
center of a three-gun kinescope;
FIG. 10 is a view similar to FIGS. 8 and 9 but showing, greatly
exaggerated, the focusing of the particles of a third color from
the color center at the side opposite to that of FIG. 9;
FIG. 11 is a diagrammatic representation of a color kinescope
employing a triad dot image screen mosaic with a perforated shadow
mask and three-gun electron beam sources;
FIG. 12 is a diagrammatic representation of a single-gun color
kinescope employing a switching wire grid and a phosphor strip or
line configuration;
FIG. 13 is a diagrammatic representation of an apparatus similar to
FIG. 1 but in which the particle delivery system may remain
stationary while the tube is shifted to align the color centers
with the axis of the particle beam in the case of a three-gun
kinescope. This FIG. also illustrates shifting of the containers
for the different color phosphors into alignment with the particle
delivery system;
FIG. 14 shows a gimbal mounting for a color kinescope tube by which
the viewing panel is moved relative to a stationary phosphor
particle beam;
FIG. 15 is an enlarged, sectional view showing gimbal mounting of
the phosphor charging, accelerating and delivery systems within the
tube of FIG. 14;
FIG. 16 is a transverse, sectional view on the line 16-16 of FIG.
15;
FIG. 17 is an enlarged view of the phosphor supply and charging
portion of FIG. 15;
FIG. 18 is a schematic representation of an alternate mounting for
the phosphor charging, accelerating and delivery systems for the
swiveling kinescope tube of FIG. 14.
Referring to the embodiment of the present invention shown in FIG.
1, there is provided a cabinet 21 having a sealable cover 22 and a
vacuum pump 23 by which the cabinet enclosure may be evacuated. The
bottom 20 of cabinet 21 has an opening 24 therein in which there is
disposed a sealing ring 25 adapted for receiving the small end of
the funnel portion 26 of a kinescope tube 27 in airtight
relationship. The tube 27 is exteriorly supported on a base 35
which may be adjustable with respect to the cabinet 21.
The funnel portion 26, the faceplate or viewing panel 28, and the
wire grid mask 29 of the tube 27 are permanently joined together as
a unit precluding disassembly of the elements thereof. As
previously stated, in the case of the wire grid mask shown in FIG.
1, the individual wires may be individually sealed into the tube
wall. In the case of a three-gun tube the wires of the grid 29 will
be electrically connected together so as to be at the same
potential. In the case of the single-gun tube, alternate wires are
electrically connected together by base conductors 31 and 32 so
that separate voltages may be switched to the alternate wires of
the grid mask 29, as desired. For this purpose, separate insulated
leads 33 and 34 may be brought into the tube, as shown in FIG. 1. A
universal tube unit may be provided initially as per the
arrangement of FIG. 1, the unit may be converted for use as a
three-gun tube at any time merely by connecting the leads 33 and 34
together to a single potential source. The inside surface of the
funnel portion 26 may be rendered conductive as by aluminizing as
shown at 37 to duplicate operating conditions within the tube
during the processing thereof according to the invention.
The inside surface of the faceplate or viewing panel 28 may be
provided with a coating or film 38 which is initially tacky. The
material of the film 38 should also be slightly conductive. A
suitable material for this purpose is polyvinyl alcohol. A terminal
39 is connected to the coating 38 and may be optionally connected
as well to the aluminum coating 37 on the funnel portion 26.
Alternatively, the aluminum lining 37 on the funnel may be
insulated from the faceplate coating 38 where the funnel conductive
coating 37 is to be connected at grid or other potential. An
ammeter at 41 may be provided for measuring the rate of deposition
of the phosphor particles and if of integrating type will indicate
the total amount deposited.
Rigidly mounted in the cabinet 21 are rails 42 within which are
rollers 43 carried by and supporting a panel 44, shown in phantom
in FIG. 1. A reversing motor 45 is stationarily mounted in the
cabinet to drive, through conventional speed reduction means, a
gear 46 meshing with a rack 47 mounted on the panel 44. A reversing
switch 50 controls rotation of motor 45 to cause the panel 44 to
move slowly between the center position shown in FIG. 1 and
opposite side positions engaging the stops 48 and 49. The panel 44
carries a continuous feed belt 51 mounted between a pair of pulleys
52 and 53 and driven through a flexible drive by a motor 54 having
a manual control switch at 55.
Aligned with feed belt 51 are containers 56, 57, and 58
individually serving as hoppers for the particles of the three
color phosphors red, blue, and green. The containers 56--58 are
supported at 61 on the bottom of the cover 22 and are provided with
sealing covers 59 at the exterior of the cabinet and vent openings
60 interiorly thereof. At the bottom of each container is a valve
62 controlled by a common rod 63 having accurately spaced valve
openings therethrough whereby the valves 62 may be individually
opened or all closed to individually control the feed of the color
phosphor particles. An exterior knob 64 controls the position of
the valving rod 63. A vibrator 65 may be connected on the end of
the rod 63 to insure regular feeding of the phosphor particles
through the valves.
Rigidly secured on the panel 44 is a particle charging box 66 of
conducting material having a top entrance opening 67 disposed
beneath the feeding end of the belt 51. A sidewall of the charging
box 66 is open at 68 to pass the terminals 69 of a hot wire cathode
71 fed from an electrical control and supply cabinet 72. The bottom
wall of the charging box 66 has an opening 73 aligned with the
opening 67 and beneath the charging box 66 is a three-electrode
acceleration system formed of conducting plates 74 and 75 and a
conducting tube shield 76 depending from the plate 75 and
electrically connected thereto. Openings through the plates 74 and
75 index with the openings 67 and 73 and the axis of the tube 76,
all the openings being substantially of the same size, for example
of the order of 3 millimeters. From the tubular shield 76 depend
insulating arms 77, four in number to support the four oppositely
facing or orthogonally disposed electrostatic deflection plates 78
which are disposed around color centers 79, 80, and 81,
representing the effective deflection points for the electron
beams.
The box 66 may, by way of example, be at substantially ground
potential or slightly above ground potential of the order of +10 to
+50 volts. The cathode 71 may have an exemplary potential of -3 kv.
Assuming positively charged phosphor particles, the plate 74 may
be, by way of example, at +50 volts, and the plate 75 and shield
tube 76 at a potential of -20 kv. The potential applied to the
conductive tacky film 38 may also be of the order of -20 kv. and
the unipotential or average potential applied to the grid 29 of the
order of -6 kv. For switching the alternate wires of the single-gun
grid, their potentials may be made more or less negative than the
average by about 0.5 kv., between -5.5 kv. and 6.5 kv. The size of
the phosphor particles to be deposited is not critical but should
be quite small, for example of the order of 2--10 microns.
In the case of the single-gun kinescope, only the central color
center 80 need be utilized and in this case the panel 44 remains in
the central position shown in FIG. 1 during deposition of all three
color phosphors. Focusing and deflection of the different color
phosphor particles may be effected by switching the potential of
the alternate conductors of the grid 29, as will be explained
hereinafter. In the case of the three-gun kinescope, three color
centers 79, 80, and 81 are utilized and may be arranged either in a
straight line at right angles to the stripes of a stripe phosphor
color geometry or at the points of an equilateral triangle
corresponding to the drop hole locations of FIG. 16, in which case
FIG. 1 represents their projected positions. Triangularly arranged
guns may be used with either the strip or triad dot color phosphor
geometry as is well known in the art.
The voltages applied to the deflection plates 78 deflect the beam
of charged particles and are varied to scan the beam across the
surface of the faceplate 28 so that the color phosphors are
deposited entirely thereover to form a phosphor viewing screen. The
maximum voltage should produce just sufficient deflection to cause
the particle stream to reach the edges of the panel and the rate of
change of the voltage should be relatively slow compared to the
rate of scan of an electron beam. The speed of scan and the rate of
feed of the particles will determine the rate of deposition in the
image screen.
The method of operation of the apparatus of FIG. 1 will now be
described. The unitary front end tube blank having the funnel,
faceplate, and grid permanently sealed together as a unit has the
inner surface of the funnel portion 26 aluminized as at 37 and the
inner surface of the panel 28 coated at 38 with a tacky, at least
slightly conductive, material such as polyvinyl alcohol or the
like. The neck of the tube is inserted through the opening 24 by
adjustment of the base support 35 and the tube is hermetically
sealed to the cabinet by means of the ring 25. The cabinet is
evacuated by the pump 23 and the proper voltages applied to the
elements of the tube and apparatus of the exemplary values
previously given.
To secure a positive charge on the phosphor particles, a current
density of substantially the order of 2 Am.sup..sup.-2 may be
desirable for a dwell time of the particles in the charging box 66
of the order of 50 milliseconds. This dwell time, T, depends on the
depth of fall of the particles before entering the box and the
height of the box between its upper and lower walls. The particles
exit the opening 73 in an essentially slow fall, charged condition,
are accelerated by the three-electrode system 74--76, and are
attracted to the tacky coating 38 by means of the negative
potential thereon.
In operating the apparatus of FIG. 1, the valve regulating knob 64
will be turned to open the proper valve 62 to secure the desired
flow of phosphor particles and the vibrator 65 will be operated to
maintain a substantially constant flow. The motor 54 is energized
to drive the belt 51 and the phosphor particles dropping from the
opened valve 62 are fed on the belt 51 through the opening 67 into
the box 66 where they are charged positively by secondary emission
due to bombardment thereof by electrons from cathode 71. The
particles are then accelerated by the accelerating electrode system
74--76 to pass through the color center 80, in the position shown
in FIG. 1, and thence onto the tacky coating 38. The particle beam
need not be focused but can flood the tacky surface with a diameter
thereat of the order of one-half inch to 4 inches. The particle
beam will be scanned across the surface of the viewing panel by
suitably varying the voltage applied to the deflection plates 78,
the particles thereby deflecting effectively at what will be the
color center of the finished tube.
The operation for a single-gun kinescope employing voltage
switching at the grid wires is illustrated in FIGS. 5--7 for a
segment near the center of the viewing panel. FIG. 5 illustrates
the deposition of red phosphor particles between grid wires 29A,
29B, 29A--onto the tacky coating 38 on the glass substrate or
faceplate 28. The wires 29A and 29B are 2--3 mils in diameter and
are spaced on centers 30 mils apart. The wires 29A are switched to
a potential of -5.5 kv. while the wires 29B are switched to a
potential of -6.5 kv. Since the wires 29B are negative with respect
to the wires 29A, deflection and focusing of the positive charge
particles is achieved as shown in FIG. 5. It will, of course, be
understood that in the event negatively charged particles are used,
the signs of all the voltage values given for the screen, grid and
accelerating electrodes of the particle gun will be reversed. The
charged particles in FIG. 5 are indicated at 82 arriving in the
direction of the arrows 83 at slightly different angles of approach
to the plane of the grid depending on the distance displaced from
the center of the tube. Under the grid voltage condition of FIG. 5,
the positive particles will be focused and deflected more from the
grid conductors 29A and will be deposited on the tacky coating 38
to form a region of deposit constituting a 20-mil strip 84, for
example.
The rate of deposition of the particles can be measured by a simple
ammeter 41 since the rate of charge deposition in coulombs per
second is, by definition, amperes. An integrating ammeter or
coulombmeter will indicate the total charge deposited and therefore
the total amount of phosphor particles which have reached the tacky
material. From this the depth of deposit of the color phosphor may
be determined and regulated. Alternatively, the deposited phosphor
may be luminesced by an electron beam and the brightness measured
by a photocell at the exterior of the tube to indicate the amount
of phosphor deposited.
When the desired amount of the red phosphor has been uniformly
deposited in strips 84 in the tacky coating 38, the supply of the
red phosphor particles is cut off by the valve 62 therefor by means
of the knob 64. In the case of the single-gun kinescope, for which
the phosphor depositions are illustrated in FIGS. 4--7, the panel
44 remains in the central position shown in FIG. 1 and all of the
different color phosphor particles pass through the common color
center 80. The knob 64 is now manipulated to open the valve 62 for
the green phosphor particles and the conductors 29A, 29B are
connected together to a common potential of -6 kv., as shown in
FIG. 6. The positively charged green particles at 85 approach from
the same directions 83 and are focused by the unipotential wires
29A, 29B into positions at opposite sides of the red strips 84, the
green strips 86 being of 10 mils width, for example.
When the desired amount of green phosphor particles has been
uniformly deposited to form the strips 86, the knob 64 closed the
valve 62. The wires 29A, 29B are then switched to the reversed
potential of FIG. 5; that is, the wires 29A are now maintained more
negative (i.e., at -6.5 kv.) and the wires 29B are maintained less
negative (i.e., -5.5 kv.). The valve 62 for the blue phosphor
particles is now opened which are indicated at 87 in FIG. 7 as
again approaching in the direction of the arrows 83 and being both
focused and deflected to be deposited in 20-mil strips 88 to
complete the image screen geometry. When the desired amount of blue
particles has been deposited, the tube 27 can be removed from the
cabinet 21 for further processing.
The composite view of FIG. 4 is made up from the individual
deposits of FIGS. 5, 6, and 7 and does not therefore represent an
actual operating condition since the phosphors will be individually
deposited, and focused and deflected by the voltages on the grid
wires individually into the positions indicated.
FIG. 2 shows, in a greatly enlarged view, the color phosphor
particles deposited in the tacky coating 38 upon the panel
substrate 28. Since the phosphor particles impact the coating 38
with considerable energy, they penetrate therein and the initial
thickness of the coating 38 is such that at the termination of the
phosphor deposit there is a thin film of the coating at 89 covering
the phosphor particles, which film serves as a relatively smooth
continuous base to receive an aluminum coating 91 evaporatively
deposited thereon by known aluminizing techniques. After
aluminizing the tacky material 38 may be removed by baking to leave
the color phosphors in their geometric pattern between the thin
aluminum film 91 and the viewing panel or faceplate 28 as an image
screen to luminesce upon the impact of electrons thereon.
FIGS. 8--10 illustrate the deposition of the different color
phosphors for a three-gun kinescope. In this type of kinescope all
of the wires of the grid mask 29 are maintained at the same
potential of -6 kv. in the example given. FIG. 8, therefore, takes
the same configuration as FIG. 6 when the panel 44 is in the
position shown in FIG. 1 and the charged and accelerated blue
phosphor particles pass through the central actual or projected
color center 80. Blue phosphor particles are shown as being
deposited at 87 in FIG. 8 and are focused into 10-mil strips 95,
for example. The positions which the strips assume relative to the
grid wires will, of course, vary with the angles of approach of the
particles, indicated by the arrows 83 in FIG. 8 as being adjacent a
central portion of the screen.
With the deposition of the blue phosphor particles completed, their
supply is terminated at the appropriate valve 62 and the motor 50
is energized to shift the panel 44 to the left, as viewed in FIG.
1. Upon engaging the stop 48, the panel 44 is positioned so that
the axis of the particle path through the openings 67, 73, etc.
passes through the color center 79 which corresponds in position to
that of the green color gun of a three-gun kinescope. FIG. 9 shows
the green particles 85 approaching the wires of the grid 29 from a
greatly exaggerated approach angle indicated by the arrows 92. The
shifting between the color centers, a distance ordinarily of about
1 centimeter, produces at the grid mark a difference of angle of
approach between the arrows 83 and 92 of substantially
2.degree.--3.degree.. The particles 85 are now focused into a 10
mil green strip 93 alongside the blue strip 95.
At the termination of the deposit of the green phosphor particles,
their supply is cut off and the motor 45 is energized to shift the
panel 44 to the right, as viewed in FIG. 1, until it engages stop
49 so that the axis of the particle beam now passes through the
color center 81 corresponding to that of the red gun of the
three-gun tube. The supply of red particles is now initiated and
they approach the wires of the grid 29, in the screen portion under
consideration, at a reverse angle of 2.degree.--3.degree., shown
greatly exaggerated by the arrows 94 in FIG. 10. The red particles
82 are focused into 10-mil strips 97 between the blue and green
strips.
The structure of FIG. 1 and the description of operation of FIGS.
8--10 apply equally to three-gun tubes whether the guns are in a
straight line at right angles to the wires of the grid 29, or
arranged at the tips of an equilateral triangle having a base at
right angles to the wires of the grid. In the case of aligned guns,
the axis of the particle beam is aligned with the color center. In
the triangular gun grouping, the beam axis is aligned with the
projection of the color center parallel to the grid wires. In the
latter case, the offset of the axis of the particle beam and the
color centers in the direction parallel to the wires of the grid is
immaterial since it has no effect on the correct geometry of the
strips.
FIG. 11 shows a three-gun kinescope using a triad dot geometry and
a perforated mask while FIG. 12 shows a single-gun kinescope with a
strip phosphor geometry and a wire grid. A three-gun electron
source arranged either aligned or triangularly may be used in the
geometry and grid configuration of FIG. 12 but only the triangular,
three-gun arrangement is usable in the triad dot and apertured mask
kinescope of FIG. 11. It will be understood that with a single-gun
source in FIG. 12 alternate wires of the grid mask must be
insulated to permit voltage switching for both focusing and
deflection of the electron beam. In all cases of a three-gun
electron beam source the masks are at unipotential. In the gun of
FIG. 11, the funnel lining has been given a separate terminal which
may be connected either to the screen or to the mask, it being
required that whichever connection is used for the phosphor
particle deposit must also be used in the normal operation of the
tube. In the tube of FIG. 12, the aluminized screen and the
aluminum lining for the funnel have been shown permanently
connected within the tube. Either physical arrangement may be
utilized in either tube.
FIG. 13 illustrates an alternate apparatus according to the present
invention for carrying out the method in the tube of the invention.
This apparatus also employs electrostatic deflection of the
particle beam to scan the surface of the viewing panel. The
charging box 66 and the particle guns 74--76 are stationarily
mounted in this embodiment within a cabinet 96 having a shiftable
cover portion 97 and a shiftable bottom portion 98. The sealing
ring 25 for the kinescope tube 27 is mounted in the shiftable
bottom portion 98 and the base support 35 for the tube is mounted
to shift therewith, by means not shown, in the direction transverse
to the wires of the grid 29. The color centers of their projections
are located as before at 79, 80, and 81 and in the apparatus of
FIG. 13 the axis of the particle beam is aligned with the various
color centers by shifting the tube 27 bodily with respect to the
stationary charging and accelerating structure.
FIG. 13 also illustrates another arrangement for the phosphor
containers, here shown at 99, 100, and 101 mounted on the portion
97 of the cabinet cover and shiftable therewith to align the proper
feeding funnel 103 with the opening 67 into the charging box 66.
The phosphor containers have the same valve and vibrator feed
controlled by an exterior knob 102. The other elements shown in
FIG. 13 are as previously described for FIG. 1 except that the
funnel lining 37 is insulated from the tacky conducting coating 38
and is given a separate terminal lead 104 so that it may be
connected as desired. The cabinet 96 and tube 27 are again
evacuated by the vacuum pump 23. The method of depositing the color
phosphors with the apparatus of FIG. 13 is exactly the same as that
described for FIG. 1, with the appropriate change in the steps by
which the phosphors are fed to the opening 67 and the tube color
centers are aligned with the axis of the phosphor particle beam
rather than the reverse.
While both FIGS. 1 and 13 show kinescope 27 having wire grid masks
and the methods of operation have been described with respect to
such a wire grid mask, these structures and the method of operation
illustrated in FIGS. 8--10 are equally usable with the kinescope of
FIG. 11 employing the triangularly arranged three-gun source, a
triad dot color mosaic, and a perforated mask. The particles of
each color phosphor will be deposited through the apertures in the
mask onto the proper geometric location of the dots of the
particular color being deposited, the particles being focused by
the unipotential mask in accordance with the angular approach of
the particles thereto. The charged particles will again take
exactly the same trajectory onto the tacky, conductive coating 38
as is taken by the electrons in the normal operation of the
tube.
With the aluminizing of the image screen as shown in FIG. 2 to
prevent shadowing by the mask, whether grid or perforated plate,
several sources of aluminum vapor may be utilized spaced apart to
insure that all areas of the image screen are covered.
FIGS. 14--18 illustrate, more or less diagrammatically, structures
according to present invention usable to effect relative scan
between the phosphor particle beam and the viewing panel without
deflecting the particle beam by the electrostatic plates. In these
embodiments, relative movement between the beam and the viewing
panel is secured by bodily pivoting or swiveling the kinescope tube
in a gimbal for universal movement and at the same time mounting
the phosphor particle sources and guns within the tube for
universal swiveling the swiveling point being coincident with the
color centers.
The embodiments as specifically illustrated in FIGS. 14--18 are for
three-gun kinescopes with either the parallel strip or triad dot
geometric configuration of the color phosphors, as described
hereinbefore. They may be adapted to produce screens for single-gun
kinescopes with only simple modifications, as will be explained
hereinafter.
As shown in FIG. 14, the color kinescope tube 27 is mounted by an
external strap 111 to the inner ring 112 of a gimbal mounting 113,
the inner ring 112 being pivoted about an axis 114 in an
intermediate ring 115 which is in turn pivoted about an axis 116,
at right angles to the axis 114, in an outer stationary ring 117.
The neck 118 of the kinescope tube 27 is connected by a vacuum
coupling 119 and flexible tubing to a vacuum pump such as that
shown at 23 in the previous embodiment. An electrical cable 120
leads through the coupling to the electrical leads within the
tube.
With the tube 27 fixedly mounted in the inner ring 112 of the
gimbal mounting 113, the color centers are offset from the center
of swivel, as shown in FIG. 16, but since there is only a small
swiveling angle and the offset error involves the cosine of this
small angle, the actual error in position and angle of approach
becomes so small as to be negligible. For more precise location of
the axis of the particle beam so that it may pass through the color
center, an arrangement such as diagrammatically illustrated in FIG.
18 may be used.
Referring now to FIGS. 15--17, the three color phosphors are
mounted in three segmental hoppers 121, 122, and 123 having
particle delivering openings 121A, 122A, and 123A leading
downwardly therefrom and located at the tips of an equilateral
triangle in coincidence with the color centers of triangularly
located guns for a three-gun kinescope. In each of the hopper
openings there is a pin 124 which substantially closes the opening
from the hopper to prevent feed of the phosphor particles therefrom
unless the pin 124 for that particular hopper is vibrated by a
vibrator 125, individually controlled by its electric coil 126 so
that only that phosphor will feed from a hopper 121--123 which has
the vibrator 125 for its pin 124 energized.
Each opening 121A--123A leads into a charging box 127 conforming in
function to the charging box 66 previously described and having
therein a hot cathode wire 128 conforming to the cathode wire 71.
The charging boxes 127 and cathode wires 128 are duplicated for
each of the hoppers 121--123. Beneath the hoppers are mounted
accelerating plates 129 and 131 insulated from the charging box and
from each other, conforming in function to the plates 74 and 75 of
the previously described embodiment and carrying similar
accelerating potentials relative to the box potential. The bottoms
of the charging boxes 127 and the plates 129 and 131 have openings
therethrough aligning vertically with the holes 121A--123A in the
hoppers and with the color centers.
The hoppers 121--123, the charging boxes, and the accelerating
plates are all mounted in a gimbal ring 132 of insulating material
pivoted at 133 in a second gimbal ring 134 which is in turn pivoted
at 135 in a pair of straps 136 integral with a sleeve 137 suspended
in the neck 118 of the kinescope tube 27 in any convenient
mechanical manner, as from the coupling 119. A heavy pendulum ring
138 is suspended from the gimbal ring 132, as by legs 139, and the
pendulum ring 138 functions in conjunction with the gimbal mounting
to maintain the phosphor supplying, charging, and accelerating
systems erect despite swiveling of the kinescope tube 27. The
method of depositing the color phosphors using the apparatus of
FIGS. 14--13 is substantially the same as that described in
connection with FIGS. 8--10, the vibrators 125 being successively
energized to deposit the respective color phosphor particles in
succession in the geometric pattern for the image screen provided
for by the type of mask used in the tube. The coating 38 and mask
have the exemplary potentials previously given and swiveling of the
tube 27 and its viewing panel relative to the particle beam
distributes the particles in the geometric pattern controlled by
the mask over the panel surface in the coating 38. The swiveling
provides a method of relative scan between the particle beam and
the screen or panel without the necessity of electrostatically
deflecting the particle stream.
Referring to FIG. 18, the mounting therein shown provides for
precise alignment of the axes of the particle beams with the color
centers during swiveling of the tube which may be mounted as in
FIG. 14. A sleeve 141 suspended from the coupling 119 extends
through the neck 118 of the tube and provides three suspension
points 142 at exactly the location of the color centers in the
finished kinescope. Suspended as pendulum weights by the cables 143
or the like from each suspension point 142 are particle supply
units 144. Each unit 144 includes a hopper 145 like the hoppers
121--123 and including a similar vibrating pin feed controlled by a
vibrator 146. A charging box 147 is located beneath each hopper and
contains a particle charging cathode 148. Acceleration of the
charged particles may be effected by an accelerating electrode
system 149--151 like the accelerating system 74--76 of FIG. 1. In
this embodiment, as the tube 27 is swiveled the phosphor particle
units 144 will stay in vertical alignment with the suspension
points and color centers 142. The particle focusing is the same as
previously described.
Since the hopper delivery openings 121A--123A are offset from the
axis of the tube 27, none of them has the same geometry with
respect to the tube as the color center of a single gun tube so
that the embodiments of FIGS. 14--18 may not be used for a
single-gun kinescope without modifications which are, however, a
simple and readily made. For example, the opening for phosphor
delivery is made coincident with the axis of the tube at the color
center thereof. In this arrangement only a single central hole need
be provided for the plates 129, 131 of FIGS. 15--17 and a single
central charging box 127 may be provided, as in FIGS. 1 and 13. The
hoppers 121--123 for the three color phosphors may then be made
shiftable relative to the changing box to index there outlets
successively therewith. Alternatively, all three hoppers for the
different color phosphors may be arranged in line with this line
being parallel to the phosphor stripes. The fact that the color
centers may be offset in this variation is of no effect on the
location of the phosphor stripes.
Other features of the apparatus of FIGS. 1 and 13 which are not
peculiar to the use of electrostatic deflection, such as the
covering film 89 and aluminizing 91 of FIGS. 2 and 3, the
measurement of the charge deposit or the brilliance of the
deposited phosphor, etc. are equally adaptable to the tube
swiveling modifications of FIGS. 14--18 and are to be considered
incorporated therein although not specifically illustrated.
While certain preferred embodiments, methods, and products have
been specifically disclosed and described herein, it is understood
that the invention is not limited thereto as many variations in
each will be apparent to those skilled in the art and the invention
is to be given its broadest interpretation within the terms of the
following claims.
* * * * *