CA1075541A - Method and apparatus for lining a cathode ray tube with an electrically conductive coating having a sharply defined boundary - Google Patents
Method and apparatus for lining a cathode ray tube with an electrically conductive coating having a sharply defined boundaryInfo
- Publication number
- CA1075541A CA1075541A CA260,322A CA260322A CA1075541A CA 1075541 A CA1075541 A CA 1075541A CA 260322 A CA260322 A CA 260322A CA 1075541 A CA1075541 A CA 1075541A
- Authority
- CA
- Canada
- Prior art keywords
- neck
- conductive material
- line
- pipe
- bulb
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
- H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
- B05B1/26—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means with means for mechanically breaking-up or deflecting the jet after discharge, e.g. with fixed deflectors; Breaking-up the discharged liquid or other fluent material by impinging jets
- B05B1/262—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means with means for mechanically breaking-up or deflecting the jet after discharge, e.g. with fixed deflectors; Breaking-up the discharged liquid or other fluent material by impinging jets with fixed deflectors
- B05B1/265—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means with means for mechanically breaking-up or deflecting the jet after discharge, e.g. with fixed deflectors; Breaking-up the discharged liquid or other fluent material by impinging jets with fixed deflectors the liquid or other fluent material being symmetrically deflected about the axis of the nozzle
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2209/00—Apparatus and processes for manufacture of discharge tubes
- H01J2209/01—Generalised techniques
- H01J2209/012—Coating
- H01J2209/015—Machines therefor
Abstract
ABSTRACT
In a method of manufacturing a cathode ray tube an electrically conductive coating is provided on an inner surface of the tube. The boundary of said conduc-tive coating in the neck of the tube is obtained by wetting the part of the surface of the tube not to be covered with a liquid removing the conductive material from the place where said boundary should be formed and then cleaning said wetted surface by rinsing.
In a method of manufacturing a cathode ray tube an electrically conductive coating is provided on an inner surface of the tube. The boundary of said conduc-tive coating in the neck of the tube is obtained by wetting the part of the surface of the tube not to be covered with a liquid removing the conductive material from the place where said boundary should be formed and then cleaning said wetted surface by rinsing.
Description
p ~ '> 1~
1~75541 131~`. ji I
"Making a cathode ray tube"
.
The invention relates to a method of manu~ac-~ turing a cathode ray tube in ~hich an electrically - conductive coating is provided on a part of the inner - surface of the tube and has a sharp boundary with respect to the non-covered part of the surface.
The invention furthermore relates to a device for carrying out said method, as well as to a tube obtained accoding to said met~od.
Various methods are known for providing an electrically conductive layer on the inner surface of a cathode ray tube~ for example a television display tube. Starting from a suspension of electrically conductive particles in a suitabl carrier llquid, the conductive layer may be provided by spr~ying, pouringj dipping or brushing and then be subjected to a thermal hardening treatment so as to obtain a hard layer. In general such a layer is provided on the inner wall of the cone and a part of the neck of the tube. A problem involved is to obtain a re~dily defined boundary of the conductive layer with respect to the uncovered part of the surface. Conductive particles remaining on what should be the uncovered ~
part of the surface is a dra~back, when during opera- -^
tion of the tube the conductive coating has applied to it a potential of a few tens of kilovolts because electric flashovers may occur, ~etween said conductive layer and these unwanted conductive particles United States Patent Specification 2,6g7,59~
discloses a method of internally coating a cathode rav ~0 tube with a conductive suspension, in which the boundary p ~
1~75541 30 ~ ~ ~7~
.`
of the layer is obtailled b~ placing a rul!l)er stopper in the neclc of the tuhc-. Tlle part of the tllbe above the stopper is filled through a pipe inser-ted through an apert~re in the stopper wi-th the conductive sus-pension up to a ccrtain level and is therl drained.
After drying the conductive coating remaining on the tube wall the stopper is removed from the neck of the tube. However, this method-has the drawback that after removing the stopper a thick slightly milled ribbed edge remains. This edge easily crumbles away when in assembling an electron gun in the neck of the tube, the usual centering and contact springs secured to said gun are slid over said edge. Such crumbled-aT~ay par-ticles may remain in the tube and cause short circuit between the electrodes. Furthermore, when the conduc-; tive coating conveys a high potential, undesired sput-tering phenomena may occur at the milled boundary of the conductive coating. Another drawback of the known method is that the conductive suspension also remains on the rubber stopper so that upon removing said stop-per the non-covered part of the tube is easily conta-minated and has still to be cleaned.
According to the invention, after providing the conductive coating, the desired boundary thereof is obtained by wetting the part of the surface not to be covered with a liquid which removes the conductive material from the place where said boundary should be formed and then cleaning said wettted surface by rinsing.
l`he boundary of the conductive layer has been formed to show a smooth edge which does not crumble away when an electron gun is inserted into the neck of the tube and which does not exhibit inadmissible sputtering phenomena 1~7~5~1 30 ~ 91~
wllerl the conductive layer con~cys a l1i~h pote~1tial.
Furthermore, the method suitable for mechanisatioll.
The composition of the liquid with which the ;
conductive material is removed from the wall of the tube depends upon the composition o~ the conductive layer. Furthermore, where the layer is deposited from a suspension the liquid for removing a dried layer, will generally have a composition differing from that for removing a layer which has not yet dried. A layer which has not yet dried can usually be removed more simply than a dried layer. In providing the conductive coating it is suitable to start from a suspension of electrically conductive particles in a suitable carrier liquid at least a part of the surface of the tube is covered with a layer of the said suspension the part of the s~rface not to be covered is kept wet from the place ~here the boundary of the coating should be formed, while the remaining part of the coating is dried and the part of the surface not to be covered is finally rinsed clean. Preferably the removal of the coating and the rinsing of the part of the surface of the tube not to`be co~ered are carried out in one operation.
In another embodiment the part of the surface not to be covered is wlped clean by means of a wiplng member at least at the area where the boundary of the conductive coating should beformed. Preferably) the w~ping member performs a rotary movement about an axis parallel to the longitudinal axis of the tube with a continuous supply of rinsing liquid.
It is to be noted that the above mentioned United States Patent Specification also starts from a suspen-sion for providing the conductive coating. It is also :
1(:i 7~4~
30-6~ 7G
stated that hlrirlg drying t~le susl-ensioil, conden~ation of ~vater val~our occur~s on the wall of th~ neck of the tllbe so that when the stopper is relrloved a clean surface would be left. EIowcver, the already-mentioned drawbac~s remain because the boundary of the conductive coating is determined by the stopper itself while the formed quantity of condensation is insufficient to obtain a clean surface when the stopper is removed.
The method according to the invention can be performed efficaciously with a device which comprises ; means to support a cathode ray tube and furthermore comprises a nozzle mounted on a liquid duct, said nozzle being movable axially in t,he neck of the tube and having means for guiding a t~et of liquid emerging ~ 15 from the nozzle in a directionwhich encloses an acute ; angle with the said axial direction in suci~L manner that, measured in a plane through the axis of the tube, the jet of llquid encloses an obtuse angle with -the surface of the neck of thel tube to be cleaned.
The outflow aperture in the nozzle is preferably rotationally symmetric so that a substanti;illy rota-tionally symmetric distribution of the quantity of liquid ~lowing out of the aperture is obtained. Such a distribution can also be obtained when the nozzle is arranged so as to be rotata~le about an axis paral-lel to the above-mentioned axial direction. In a par-ticularly favou~able embodiment of the device the nozzle comprises at least one wiper blade the edge of which, with a relative rotation of the nozzle with respect to the neck of the tuhc, covers the wall Or the nec~ of the tube over a pre-scribed length.
Emb'odiments of the invention will now be des-~, - -- - - - - .
1075~4~ 30~ 76 cribed by ~ay of e~alllple with rel`crerlce to the accom-panying diagrammatic drawings in whicll Figure~s 1a, lb and 1c sho~ thrce~successive stages of a method embodying the invention, ~igure 2 illustrates another embodiment, Figure 3 shows a detail of a nozzle for provi-ding a conductive suspension on the inner surface of a cathode ray tube, ~igure 4 shows in detail a nozzle for cleaning the part of the surface of the neck of the tube not to be covered, and Figure 5 illustrates another method of providing a conductive suspension on the inner surface of a catbode ray tube.
In Figure 1a a glass cone 1 of a tube is coated internally with a conductive material consisting of an aqueous alkali metal silicate solution in which small quantities of an organic binder and a conductive powde~
are incorporated. Such a suspension comprises, for example, 10-207' by weight of graphite powder as the con-ductive material, approximately 20% by weight of water- ;
,~
glass consisting (~f a 20% solution of K20 and SiO2 in the rat o 1, 3.5, approximately 170 of an organic binder, for example polyvinylpyrrolidon and approxi- -mately 607~ by weight of water. The suspension flo~s from a container 2 through a pipe 3 which discharges on the inner surface 10 of the cone 1 and hits said surface at approximately 1 cm below the edge 4 of the cone. The pipe 3 is moved along the edge of the cone 1 until the inner surface 10 is covered every~here with a uniformly thick layer of the suspension. Instead of movln~ the pipe 3, it is alternatively possible to ' ~
.. . .
.
I'ill\,.~`;l~'l ~.6)7 55 4~ 3 () ~ ) 7 6 rotate th~ cone 1 about i.ts ll)ngitlldi.~la1y a~is, the outflo~i aperture of the pipe being al~ays kept at a fi,~ed distance from the edge 4-of the cone. The excess suspension flows through the necl; 5 of.the cone 1 into a reservoir 6 and is pumped by means of a pump 8 bacl;
into the container 2 through a return duct 7. The level of the suspension in the container 2 is further main-: tained through a duct 9. In the phase of the method illustrated in Figure 1b the cone 1 is placed with its neck 5 downwards in a reservoir 12 for example water, filled with liquid 11, so tha-t the liquid level 15 in the neck,of the tube is at the place where the boundary of the conductive coating needs to be formed.
The wet suspension 13 with the exception of the part which is present below the liquid level 15 is dried by means of a nwnber of infrared lamps 14 or by a flow of warm air. The liquid 11 prevents the suspension from adhering to the immersed part cf the neck 5 and the liquid level 15 thus determ;.nes the boundary between a dried conductive layer adhering to the wall of the tube and a wet layer not adhering to the ~all of the tube. In the subsequent phase illustrated i.n ~igure 1c a nozzle 17 mounted on a l~iquid duct 16 is lnserted axially into the neck 5 of the tube. Deionised water is supplied through the duct 16 and is directed to the wall of the neck 5 by the nozæle 17 so that the non-dried part of the conductive coating of the part of the wall of the.tube not to be covered is rinsed.
In this manner a readily defined smooth boundary of the conductive coating on the wall of the neclc 5 of the tube is obtained.
Several modifications of the method described ~07~54~ 30~ G
.
w;th rcfererce to l~igurcs la, 1h and 1c are ~)ossible.
For e~ample, after providing the conducti~-~ suspension, the whole layer may also be dried and then, in analog~
witll the phase illustratc-d in Figure lb, thc tube may be placed in a liquid-filled reservoir. In this case it probably will not suffice to use normal water for removing the layer from the part of the tube surface not to be coated, and amore aggressive liquid, for example, dilute HF acid provably, will ha~e to be used.
In another method embodying the invention and illustrated in Figures 2 and 3 a conductive stet suspen-sion of the above-mentioned composition is supplied through a duct 20 as described with reference to Figure 1a. A nozzle 21 of which Figure 3 is an axial sec-tional view, is mounted at the open end of the duct 20. The nozzle consists of a pipe 22 which nas an axial outflow aperture 23, and also has lateral outflow apertures 24 distributed regul~rly around its circum-ference. The outflow direction of the lateral aper-tures is determined by a collar 25 and a collar 26 ; having conical surfaces 27 and 28~ respectlvely.
- Suitably, the conical surfaces make an angle of 30with the centre line of the pipe 22, the pipe has an internal diameter of 10 mm, the outflow aperture 23 has a diameter of 5 mm and each lateral outflow aper-` ture has a diameter of 1.5 mm and is located at a distance of 10 mm abo~e the aperture 23.
In operation, the nozzle 21 is place~ against the inner wall of the cone 30 with the collar 25 being pressed against the wall of the cone and the ~butment 29 secured to the nozzle bearing on the edge 31 of the : ~8-1~3755 30-fi- 1 ~)7~
cone. The ccne 30 ;s supported ~y follr supportiIlg mcrll-bers 32 two of wllich are shown. The supporting members are secured to a base plate not shown in the dra~ing and are capable of rotating about an axis coinciding with the axis of the tube. During this rotatlon the suspension is supplied through the duct 20, the edge 31 of the cone being drawn past the nozzle 21. The greater part of the supplied quantity of suspension leaves the nozzle through the aperture 23 while a smal-ler part leaves the nozzle through the lateral aper-tures ?4. The point of contact of the collar 25 with the wall of the cone determines the boundary 33 of the conductive coating, so that the edge 31 of the cone is not covered with the suspension. In a manner ana-logous to ~ig. 1a the excessive suspension can be pumped back throug~ a return duct to a buffer reservoir.
T~e next pilase in the method relates to ob-taining a boundary of the conductive coating in the neck 34 of the tube. For that purpose, a nozzle 36 mounted on a liquid duct 35 is insert-ed axially into the neck 34 of the tube. The nozæle 36 which i3 shown r on an enlarged scale in ~igure 4, consists of a pipe 37 at one end of which is fixed to a circular flange 38 having a diameter of for example 25 mm. A dished second flange 39 is secured to the flange 38 by three bolts 40 spared 120 apart, a space of approximately
1~75541 131~`. ji I
"Making a cathode ray tube"
.
The invention relates to a method of manu~ac-~ turing a cathode ray tube in ~hich an electrically - conductive coating is provided on a part of the inner - surface of the tube and has a sharp boundary with respect to the non-covered part of the surface.
The invention furthermore relates to a device for carrying out said method, as well as to a tube obtained accoding to said met~od.
Various methods are known for providing an electrically conductive layer on the inner surface of a cathode ray tube~ for example a television display tube. Starting from a suspension of electrically conductive particles in a suitabl carrier llquid, the conductive layer may be provided by spr~ying, pouringj dipping or brushing and then be subjected to a thermal hardening treatment so as to obtain a hard layer. In general such a layer is provided on the inner wall of the cone and a part of the neck of the tube. A problem involved is to obtain a re~dily defined boundary of the conductive layer with respect to the uncovered part of the surface. Conductive particles remaining on what should be the uncovered ~
part of the surface is a dra~back, when during opera- -^
tion of the tube the conductive coating has applied to it a potential of a few tens of kilovolts because electric flashovers may occur, ~etween said conductive layer and these unwanted conductive particles United States Patent Specification 2,6g7,59~
discloses a method of internally coating a cathode rav ~0 tube with a conductive suspension, in which the boundary p ~
1~75541 30 ~ ~ ~7~
.`
of the layer is obtailled b~ placing a rul!l)er stopper in the neclc of the tuhc-. Tlle part of the tllbe above the stopper is filled through a pipe inser-ted through an apert~re in the stopper wi-th the conductive sus-pension up to a ccrtain level and is therl drained.
After drying the conductive coating remaining on the tube wall the stopper is removed from the neck of the tube. However, this method-has the drawback that after removing the stopper a thick slightly milled ribbed edge remains. This edge easily crumbles away when in assembling an electron gun in the neck of the tube, the usual centering and contact springs secured to said gun are slid over said edge. Such crumbled-aT~ay par-ticles may remain in the tube and cause short circuit between the electrodes. Furthermore, when the conduc-; tive coating conveys a high potential, undesired sput-tering phenomena may occur at the milled boundary of the conductive coating. Another drawback of the known method is that the conductive suspension also remains on the rubber stopper so that upon removing said stop-per the non-covered part of the tube is easily conta-minated and has still to be cleaned.
According to the invention, after providing the conductive coating, the desired boundary thereof is obtained by wetting the part of the surface not to be covered with a liquid which removes the conductive material from the place where said boundary should be formed and then cleaning said wettted surface by rinsing.
l`he boundary of the conductive layer has been formed to show a smooth edge which does not crumble away when an electron gun is inserted into the neck of the tube and which does not exhibit inadmissible sputtering phenomena 1~7~5~1 30 ~ 91~
wllerl the conductive layer con~cys a l1i~h pote~1tial.
Furthermore, the method suitable for mechanisatioll.
The composition of the liquid with which the ;
conductive material is removed from the wall of the tube depends upon the composition o~ the conductive layer. Furthermore, where the layer is deposited from a suspension the liquid for removing a dried layer, will generally have a composition differing from that for removing a layer which has not yet dried. A layer which has not yet dried can usually be removed more simply than a dried layer. In providing the conductive coating it is suitable to start from a suspension of electrically conductive particles in a suitable carrier liquid at least a part of the surface of the tube is covered with a layer of the said suspension the part of the s~rface not to be covered is kept wet from the place ~here the boundary of the coating should be formed, while the remaining part of the coating is dried and the part of the surface not to be covered is finally rinsed clean. Preferably the removal of the coating and the rinsing of the part of the surface of the tube not to`be co~ered are carried out in one operation.
In another embodiment the part of the surface not to be covered is wlped clean by means of a wiplng member at least at the area where the boundary of the conductive coating should beformed. Preferably) the w~ping member performs a rotary movement about an axis parallel to the longitudinal axis of the tube with a continuous supply of rinsing liquid.
It is to be noted that the above mentioned United States Patent Specification also starts from a suspen-sion for providing the conductive coating. It is also :
1(:i 7~4~
30-6~ 7G
stated that hlrirlg drying t~le susl-ensioil, conden~ation of ~vater val~our occur~s on the wall of th~ neck of the tllbe so that when the stopper is relrloved a clean surface would be left. EIowcver, the already-mentioned drawbac~s remain because the boundary of the conductive coating is determined by the stopper itself while the formed quantity of condensation is insufficient to obtain a clean surface when the stopper is removed.
The method according to the invention can be performed efficaciously with a device which comprises ; means to support a cathode ray tube and furthermore comprises a nozzle mounted on a liquid duct, said nozzle being movable axially in t,he neck of the tube and having means for guiding a t~et of liquid emerging ~ 15 from the nozzle in a directionwhich encloses an acute ; angle with the said axial direction in suci~L manner that, measured in a plane through the axis of the tube, the jet of llquid encloses an obtuse angle with -the surface of the neck of thel tube to be cleaned.
The outflow aperture in the nozzle is preferably rotationally symmetric so that a substanti;illy rota-tionally symmetric distribution of the quantity of liquid ~lowing out of the aperture is obtained. Such a distribution can also be obtained when the nozzle is arranged so as to be rotata~le about an axis paral-lel to the above-mentioned axial direction. In a par-ticularly favou~able embodiment of the device the nozzle comprises at least one wiper blade the edge of which, with a relative rotation of the nozzle with respect to the neck of the tuhc, covers the wall Or the nec~ of the tube over a pre-scribed length.
Emb'odiments of the invention will now be des-~, - -- - - - - .
1075~4~ 30~ 76 cribed by ~ay of e~alllple with rel`crerlce to the accom-panying diagrammatic drawings in whicll Figure~s 1a, lb and 1c sho~ thrce~successive stages of a method embodying the invention, ~igure 2 illustrates another embodiment, Figure 3 shows a detail of a nozzle for provi-ding a conductive suspension on the inner surface of a cathode ray tube, ~igure 4 shows in detail a nozzle for cleaning the part of the surface of the neck of the tube not to be covered, and Figure 5 illustrates another method of providing a conductive suspension on the inner surface of a catbode ray tube.
In Figure 1a a glass cone 1 of a tube is coated internally with a conductive material consisting of an aqueous alkali metal silicate solution in which small quantities of an organic binder and a conductive powde~
are incorporated. Such a suspension comprises, for example, 10-207' by weight of graphite powder as the con-ductive material, approximately 20% by weight of water- ;
,~
glass consisting (~f a 20% solution of K20 and SiO2 in the rat o 1, 3.5, approximately 170 of an organic binder, for example polyvinylpyrrolidon and approxi- -mately 607~ by weight of water. The suspension flo~s from a container 2 through a pipe 3 which discharges on the inner surface 10 of the cone 1 and hits said surface at approximately 1 cm below the edge 4 of the cone. The pipe 3 is moved along the edge of the cone 1 until the inner surface 10 is covered every~here with a uniformly thick layer of the suspension. Instead of movln~ the pipe 3, it is alternatively possible to ' ~
.. . .
.
I'ill\,.~`;l~'l ~.6)7 55 4~ 3 () ~ ) 7 6 rotate th~ cone 1 about i.ts ll)ngitlldi.~la1y a~is, the outflo~i aperture of the pipe being al~ays kept at a fi,~ed distance from the edge 4-of the cone. The excess suspension flows through the necl; 5 of.the cone 1 into a reservoir 6 and is pumped by means of a pump 8 bacl;
into the container 2 through a return duct 7. The level of the suspension in the container 2 is further main-: tained through a duct 9. In the phase of the method illustrated in Figure 1b the cone 1 is placed with its neck 5 downwards in a reservoir 12 for example water, filled with liquid 11, so tha-t the liquid level 15 in the neck,of the tube is at the place where the boundary of the conductive coating needs to be formed.
The wet suspension 13 with the exception of the part which is present below the liquid level 15 is dried by means of a nwnber of infrared lamps 14 or by a flow of warm air. The liquid 11 prevents the suspension from adhering to the immersed part cf the neck 5 and the liquid level 15 thus determ;.nes the boundary between a dried conductive layer adhering to the wall of the tube and a wet layer not adhering to the ~all of the tube. In the subsequent phase illustrated i.n ~igure 1c a nozzle 17 mounted on a l~iquid duct 16 is lnserted axially into the neck 5 of the tube. Deionised water is supplied through the duct 16 and is directed to the wall of the neck 5 by the nozæle 17 so that the non-dried part of the conductive coating of the part of the wall of the.tube not to be covered is rinsed.
In this manner a readily defined smooth boundary of the conductive coating on the wall of the neclc 5 of the tube is obtained.
Several modifications of the method described ~07~54~ 30~ G
.
w;th rcfererce to l~igurcs la, 1h and 1c are ~)ossible.
For e~ample, after providing the conducti~-~ suspension, the whole layer may also be dried and then, in analog~
witll the phase illustratc-d in Figure lb, thc tube may be placed in a liquid-filled reservoir. In this case it probably will not suffice to use normal water for removing the layer from the part of the tube surface not to be coated, and amore aggressive liquid, for example, dilute HF acid provably, will ha~e to be used.
In another method embodying the invention and illustrated in Figures 2 and 3 a conductive stet suspen-sion of the above-mentioned composition is supplied through a duct 20 as described with reference to Figure 1a. A nozzle 21 of which Figure 3 is an axial sec-tional view, is mounted at the open end of the duct 20. The nozzle consists of a pipe 22 which nas an axial outflow aperture 23, and also has lateral outflow apertures 24 distributed regul~rly around its circum-ference. The outflow direction of the lateral aper-tures is determined by a collar 25 and a collar 26 ; having conical surfaces 27 and 28~ respectlvely.
- Suitably, the conical surfaces make an angle of 30with the centre line of the pipe 22, the pipe has an internal diameter of 10 mm, the outflow aperture 23 has a diameter of 5 mm and each lateral outflow aper-` ture has a diameter of 1.5 mm and is located at a distance of 10 mm abo~e the aperture 23.
In operation, the nozzle 21 is place~ against the inner wall of the cone 30 with the collar 25 being pressed against the wall of the cone and the ~butment 29 secured to the nozzle bearing on the edge 31 of the : ~8-1~3755 30-fi- 1 ~)7~
cone. The ccne 30 ;s supported ~y follr supportiIlg mcrll-bers 32 two of wllich are shown. The supporting members are secured to a base plate not shown in the dra~ing and are capable of rotating about an axis coinciding with the axis of the tube. During this rotatlon the suspension is supplied through the duct 20, the edge 31 of the cone being drawn past the nozzle 21. The greater part of the supplied quantity of suspension leaves the nozzle through the aperture 23 while a smal-ler part leaves the nozzle through the lateral aper-tures ?4. The point of contact of the collar 25 with the wall of the cone determines the boundary 33 of the conductive coating, so that the edge 31 of the cone is not covered with the suspension. In a manner ana-logous to ~ig. 1a the excessive suspension can be pumped back throug~ a return duct to a buffer reservoir.
T~e next pilase in the method relates to ob-taining a boundary of the conductive coating in the neck 34 of the tube. For that purpose, a nozzle 36 mounted on a liquid duct 35 is insert-ed axially into the neck 34 of the tube. The nozæle 36 which i3 shown r on an enlarged scale in ~igure 4, consists of a pipe 37 at one end of which is fixed to a circular flange 38 having a diameter of for example 25 mm. A dished second flange 39 is secured to the flange 38 by three bolts 40 spared 120 apart, a space of approximately
2 mm being left between the flanges. Suitably, the flange 3 has a diameter of 27 mm and can be moved in the neck 34 of the tube ~ith a play of 1 mm. The flanges 38 and 3 have conical surfaces 41 and 42, respectively, which enclose an angle of, for example 57 with the centre longitudinal axis of the pipe 37 and determine ~ 75~41 ~o-~- 19~
tllC outflow d:irectioll of the lic~ id fLo~ g out oI` the no~7.1e. With .3llch an arrarlgemont a jet o:f li.-luid converging from the nozzle makes an acllte angle . th the central lon.gitudinal axis of the pipe 37 in such a manner that measured in a plane to l.rhich thi~ a~is is normal, the jet of liquid makes an obtuse an~le with the surfaee of the neck 34 of the tube. After the nozzle has been inserted in the neck of the tube in th.e desired place, the coating on the inner wall is dried by spraying warm water, at for example 60C, against the outer wall of the cone from an annular nozzle 43.
If desired, drying may be accelerated by irradiating the inner wall of the cone by means of infrared lamps.
Simultaneously with the drying operation, the part of the wall of the neck which is not to be covered is rinsed with a qua~tity of deionised water of 1 litre per minute supplied through the duct 35. The nozzle 36 rotates at a speed of one revolution per second about its longitudinal centre line ~nd the neck of the tube is wiped clean by means of two rubber wipers ~4 secured to the shaft 37. ~fhe boundary 45 o* the conducti~e ~ coating is formed at the position where the ~et of water flowing out of the nozzle impinges upon the wall of the neck of the tube. In order to prevent a column : 25 of water from forming between the wall of the tube and the flange 39 by capillary action, the flange 39 at . its circumference has a thickness of at most 1 mm andpreferably less than 0.5 mm. The drawback of such a ;~ water column actually is that a poorly adhering coatiIlg : 30 remains there dueto the low water circulation wh~ile the adhering constituents are washed out of the SllS-pension.
1075541 P~ 2~1 30-6-l'J76 The two em~odinlents so far descri~ed concern that ~-ind of process in which the cone is provided ~ith a conductive layer before being united ~ith the face place of the tube such metllods are suitable for Manu-facturing a colour television display tube bccause the faceplate and the cone can be connected together only after providing the internal conductive coating. How-ever, the invention is also applicable when the conduc-tive coating is provided after the faceplate and the cone have been connected together, for example, in the manufacture of a black-and-white display tube and an embodiment using this technique will now be described with reference to Figure 5.
A glass envelope consisting of a cone 51 sealed to a faceplate 50 is placed in a reservoir 54 with the - neck 52 of the tu~s do~wards~ the reservoir containing a conductive suspension 53. The air is pumped out of the enve ope through a duct 55 causing the level of the suspension in the envelope to~rise. When the level reaches the open end of the duct 55 a cock 56 in the duc* is closed. The duct 55 is then detached from the pump af*er which t~-e cock 56 is opened and air is admittGd to the envelope and the level of the suspension in the enve-lope falls to its original height the envelope may then be removed from the reservoir 54. The conductive layer left on the neck of the tube can be removed as required in a manner analogous to that described with reference to Figure 2.
-11 - .
tllC outflow d:irectioll of the lic~ id fLo~ g out oI` the no~7.1e. With .3llch an arrarlgemont a jet o:f li.-luid converging from the nozzle makes an acllte angle . th the central lon.gitudinal axis of the pipe 37 in such a manner that measured in a plane to l.rhich thi~ a~is is normal, the jet of liquid makes an obtuse an~le with the surfaee of the neck 34 of the tube. After the nozzle has been inserted in the neck of the tube in th.e desired place, the coating on the inner wall is dried by spraying warm water, at for example 60C, against the outer wall of the cone from an annular nozzle 43.
If desired, drying may be accelerated by irradiating the inner wall of the cone by means of infrared lamps.
Simultaneously with the drying operation, the part of the wall of the neck which is not to be covered is rinsed with a qua~tity of deionised water of 1 litre per minute supplied through the duct 35. The nozzle 36 rotates at a speed of one revolution per second about its longitudinal centre line ~nd the neck of the tube is wiped clean by means of two rubber wipers ~4 secured to the shaft 37. ~fhe boundary 45 o* the conducti~e ~ coating is formed at the position where the ~et of water flowing out of the nozzle impinges upon the wall of the neck of the tube. In order to prevent a column : 25 of water from forming between the wall of the tube and the flange 39 by capillary action, the flange 39 at . its circumference has a thickness of at most 1 mm andpreferably less than 0.5 mm. The drawback of such a ;~ water column actually is that a poorly adhering coatiIlg : 30 remains there dueto the low water circulation wh~ile the adhering constituents are washed out of the SllS-pension.
1075541 P~ 2~1 30-6-l'J76 The two em~odinlents so far descri~ed concern that ~-ind of process in which the cone is provided ~ith a conductive layer before being united ~ith the face place of the tube such metllods are suitable for Manu-facturing a colour television display tube bccause the faceplate and the cone can be connected together only after providing the internal conductive coating. How-ever, the invention is also applicable when the conduc-tive coating is provided after the faceplate and the cone have been connected together, for example, in the manufacture of a black-and-white display tube and an embodiment using this technique will now be described with reference to Figure 5.
A glass envelope consisting of a cone 51 sealed to a faceplate 50 is placed in a reservoir 54 with the - neck 52 of the tu~s do~wards~ the reservoir containing a conductive suspension 53. The air is pumped out of the enve ope through a duct 55 causing the level of the suspension in the envelope to~rise. When the level reaches the open end of the duct 55 a cock 56 in the duc* is closed. The duct 55 is then detached from the pump af*er which t~-e cock 56 is opened and air is admittGd to the envelope and the level of the suspension in the enve-lope falls to its original height the envelope may then be removed from the reservoir 54. The conductive layer left on the neck of the tube can be removed as required in a manner analogous to that described with reference to Figure 2.
-11 - .
Claims (30)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for coating with an electrically conductive material the inner surface of a cathode ray tube bulb having a funnel portion with a cylindrical neck, said method comprising the steps of supporting the bulb with the neck downward, covering the inner surface of the bulb with a carrier liquid containing said conductive material, allowing said carrier liquid to drain downwardly and leave a residue of said conductive material on said inner surface of said bulb, drying said residue of said conductive material sufficiently to prevent said conductive material on the inner surface of said neck from flowing downwardly, and directing a stream of rinsing liquid along a circum-ferential line extending about the inner surface of said cylindrical neck, said rinsing liquid being directly outwardly and downwardly at an acute angle to the axis of said neck to strike the inner surface of said neck at an obtuse angle directed away from the coated surface area above said line to rinse away said conductive material from the inner surface of said neck below said line and leave a coating of said conductive material with a sharply defined smooth edge on the inner surface of said neck above said line.
2. The method of claim 1 comprising the step of wiping said internal wall surface of said neck below said line simultaneously with said step of directing said rinsing liquid.
3. The method of claim 1 wherein said rinsing liquid is directed rotationally against said inner surface of said neck to obtain uniform rinsing along said line and therebelow.
4. The method of claim 1 wherein said step of drying includes the step of spraying warm water on the external surface of said funnel portion to dry the coating on the internal wall surface thereof.
5. The method of claim 1 wherein said step of drying includes the step of heating the wall surface of said funnel portion with infrared radiation to dry said coating on the internal wall surface thereof.
6. The method of claim 1 in which said rinsing liquid is deionized water.
7. The method of claim 1 comprising immersing the neck end of said funnel portion in liquid up to the location of said line while said drying step is being accomplished; and thereafter carrying out said rinsing step.
8. The method of claim 1 comprising drying the residue of said electrically conductive material above and below said line thereafter submerging said neck end of said funnel portion up to the location of said line in a reservoir of liquid capable of remov-ing said electrically conductive material up to said location of said line; thereafter removing said neck from said reservoir and carrying out said rinsing step.
9. The method of claim 8 in which the liquid in said reservoir is dilute hydrofluoric acid.
10. A method for applying a band of electrically con-ductive coating to the inner surface of a cathode ray tube bulb having a funnel portion with an enlarged end and a cylindrical neck, said method comprising the steps of supporting the bulb with the neck downward, covering with a carrier liquid containing a con-ductive material the inner surface of said bulb up to a first line located near said enlarged end and extending about the inner sur-face of said funnel portion, allowing said carrier liquid to drain downwardly leaving a coating of said conductive material on said inner surface of said bulb below said first line with a smooth first edge adjacent said enlarged end, drying said coating of said conductive material sufficiently to prevent said conductive material on the inner surface of said neck from flowing downwardly, and directing a stream of rinsing liquid along a second line extending about said inner surface of said cylindrical neck, said rinsing liquid being directed outwardly and downwardly at an acute angle to the axis of the cylindrical neck to strike the inner surface of said neck at an obtuse angle directed away from the coated surface area above said second line to rinse away said conductive material from the inner surface of said neck below said second line and leave behind a coating of said conductive material with a second sharply defined smooth edge on the inner surface of said neck above said second line.
11. The method of claim 10 wherein said enlarged end of said funnel portion is open and comprising the step of directing said carrier liquid outwardly, and downwardly from an origin of said liquid within said open enlarged end to strike said internal surface only at and below said first line and allowing said carrier liquid to drain downwardly therefrom to define said first smooth edge.
12. The method of claim 11 comprising the steps of establishing relative movement of said origin of said liquid and said funnel portion to form said first smooth edge entirely around said open end; and maintaining said origin at a sub-stantially fixed distance from said internal surface while said relative movement completes said first smooth edge.
13. The method of claim 12 comprising directing said carrier liquid at said internal surface a substantially fixed distance from the edge of said enlarged end.
14. The method of claim 10 wherein the step of drying includes directing a stream of warm water over the external surface of said funnel portion.
15. The method of claim 14 wherein the step of drying includes directing infrared radiation at the inner surface of said funnel portion simultaneously with directing said stream of warm water at said external surface.
16. The method according to claim 10 wherein the enlarged end of the funnel portion is covered by a faceplate sealed airtight to said enlarged end, the step of covering with said carrier liquid in-cludes immersing the end of said neck in a quantity of said carrier liquid containing the conductive material, removing air from said funnel portion to draw said carrier liquid with the conductive material in said funnel portion up to the location of said first line, and said step of allowing said liquid to drain includes readmitting air to said funnel portion to allow the carrier liquid and the conductive material to flow out of said funnel portion while leaving a residue of said conductive material on said internal wall surface from said first line downward into said neck and removing said bulb structure from said quantity of carrier liquid.
17. A method for coating with an electrically conductive material the inner surface of a cathode ray tube bulb having a funnel portion with a cylindrical neck, said method comprising the steps of supporting the bulb with the neck downward, covering the inner surface of the bulb with a carrier liquid containing said conductive material, allowing said carrier liquid to drain downwardly and leave a residue of said conductive material on said inner surface of said bulb, drying said residue of said conductive material sufficiently to prevent said conductive material on the inner surface of said neck from flowing downwardly, directing a stream of rinsing liquid along a circumferen-tial line extending about said inner surface of said cylindrical neck, said rinsing liquid being directed outwardly and downwardly at an acute angle to the axis of the cylindrical neck to strike the inner surface of said neck at an obtuse angle directed away from the coated surface area above said line to rinse away said conductive material from the inner surface of said neck below said line and leave a coating of said conductive material with a sharply defined smooth edge on the inner surface of said neck above said line, and wiping the inner surface of said neck below said line simultaneously with said step of directing said rinsing liquid.
18. An apparatus for producing a sharp boundary in a coating applied to the inner surface of a cathode ray tube bulb having a conical portion and a generally cylindrical neck, said apparatus comprising means for supporting the tube bulb with the neck downward, and a pipe having a nozzle for supplying liquid for washing the coating from the inner surface of the bulb, said pipe and nozzle being insertable in and being arranged for axial movement relative to the neck of said tube, said nozzle including guide means for directing the liquid emerging from said pipe downwardly at an acute angle to the axis of said pipe to form a downwardly directly stream of liquid which strikes the inner surface of said neck along a circumferential line extending about said inner surface of said neck and thereby wash away coating material from the inner surface of said neck below said line and leave a coating with a sharply defined smooth edge on the interior of said bulb above said line.
19. The apparatus according to claim 18, wherein said guide means includes a transverse member spaced from and extending from the end of said pipe and having a down-turned perimeter configured to direct the liquid emerging from the pipe downwardly at said acute angle.
20. The apparatus according to claim 18, wherein said transverse member is a dish-shaped disk with a diameter less than the inner diameter of said neck.
21. The apparatus of claim 18 comprising spacer means attached to said nozzle and said transverse member to support said transverse member at a predetermined distance from the end of said pipe.
22. The apparatus of claim 20 in which said disk has a thickness at its perimeter of not substantially more than 1 mm.
23. The apparatus of claim 20 comprising rotary means supporting said nozzle to rotate said nozzle on its longitudinal axis.
24. The apparatus of claim 23 comprising wiper blade means attached to said pipe below the end thereof to wipe the inner cylindrical surface of said neck as said pipe rotates.
25. An apparatus for forming a sharply-defined boundary of a coating of conductive material on the inner surface of a funnel-shaped portion of a cathode ray tube bulb, said funnel-shaped portion having an enlarged open end and a constricted neck end spaced from said enlarged end along a bulb axis, said device comprising a nozzle and pipe having a longitudinal axis substantially parallel to said bulb axis but offset therefrom;
guide means to emit a carrier liquid containing said conductive material in a jet emanating outwardly and downwardly from said nozzle at an angle with respect to said longitudinal axis;
and means to move said nozzle and pipe relative to said funnel-shaped portion while keeping said axes substantially parallel and said guide means substantially at a constant distance from the inner surface of said funnel-shaped portion to direct said jet of carrier liquid at an acute angle with respect to the longitudinal axis of said nozzle and pipe to strike the inner wall of said funnel-shaped portion only at and below a pre-determined distance below the edge of said enlarged end to pro-duce said sharply-defined boundary, said conductive material remaining as a residue on said inner surface from said boundary down into said neck end of said funnel-shaped portion.
guide means to emit a carrier liquid containing said conductive material in a jet emanating outwardly and downwardly from said nozzle at an angle with respect to said longitudinal axis;
and means to move said nozzle and pipe relative to said funnel-shaped portion while keeping said axes substantially parallel and said guide means substantially at a constant distance from the inner surface of said funnel-shaped portion to direct said jet of carrier liquid at an acute angle with respect to the longitudinal axis of said nozzle and pipe to strike the inner wall of said funnel-shaped portion only at and below a pre-determined distance below the edge of said enlarged end to pro-duce said sharply-defined boundary, said conductive material remaining as a residue on said inner surface from said boundary down into said neck end of said funnel-shaped portion.
26. The device of claim 25 in which said nozzle comprises a partial restriction at the end of said pipe and said guide means comprises a plurality of apertures in said pipe substantially equidistant from the end thereof to direct some of said carrier liquid outwardly and downwardly at said acute angle.
27. The apparatus of claim 26 comprising a sleeve fitting over said pipe above said apertures and extending downwardly but spaced outwardly from said pipe below said apertures.
28. The apparatus of claim 27 in which the inner surface of the lower end of said sleeve flares outwardly at an angle of approximately 30° relative to said longi-tudinal axis.
29. The apparatus of claim 25 comprising a flange on said pipe to engage the edge of the enlarged end of said funnel-shaped portion to maintain the end of said pipe a fixed distance below said edge during relative movement between said nozzle and pipe and said funnel-shaped portion
30. The apparatus of claim 25 comprising a second nozzle and pipe extending upwardly into said neck end and having a second longitudinal axis parallel to said bulb axis; and second guide means directing a jet of rinsing liquid at a second acute angle relative to the neck end of said second longitudinal axis to strike the inner wall of said portion at and below a predetermined location at said neck end to rinse said conductive material off the inner surface of said neck end below said predetermined location to produce a second sharply-defined smooth boundary of said coating.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7510274A NL7510274A (en) | 1975-09-01 | 1975-09-01 | PROCEDURE FOR MANUFACTURE OF A CATHODE NOZZLE TUBE WITH AN INTERNAL CONDUCTIVE COVER, DEVICE FOR PERFORMING THE METHOD AND TUBE OBTAINED ACCORDING TO THIS PROCESS. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1075541A true CA1075541A (en) | 1980-04-15 |
Family
ID=19824388
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA260,322A Expired CA1075541A (en) | 1975-09-01 | 1976-09-01 | Method and apparatus for lining a cathode ray tube with an electrically conductive coating having a sharply defined boundary |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US4151312A (en) |
| JP (1) | JPS604541B2 (en) |
| BE (1) | BE845678A (en) |
| CA (1) | CA1075541A (en) |
| DE (1) | DE2637754C3 (en) |
| FR (1) | FR2322445A1 (en) |
| GB (1) | GB1552801A (en) |
| IT (1) | IT1071423B (en) |
| NL (1) | NL7510274A (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2382762A1 (en) * | 1978-01-20 | 1978-09-29 | Sony Corp | CRT interior coating system - operates using automatic masking of selected zones of tube inside surface |
| DE2903735A1 (en) * | 1979-02-01 | 1980-08-07 | Standard Elektrik Lorenz Ag | Conductive cathode ray tube layer - applied after coating bare areas with lacquer film |
| JPS58184235A (en) * | 1982-04-21 | 1983-10-27 | Hitachi Ltd | Manufacture of cathode-ray tube |
| DE3511211A1 (en) * | 1985-03-28 | 1986-10-09 | Standard Elektrik Lorenz Ag, 7000 Stuttgart | COLOR IMAGE TUBES WITH AN INNER CONDUCTIVE LAYER AND METHOD FOR PRODUCING THE COLOR IMAGE TUBES |
| JPS61180132U (en) * | 1985-04-27 | 1986-11-10 | ||
| JPS61198240U (en) * | 1985-05-24 | 1986-12-11 | ||
| JPH01274867A (en) * | 1988-04-27 | 1989-11-02 | Toshiba Corp | Method and device for coating |
| KR930007123B1 (en) * | 1991-04-15 | 1993-07-30 | 주식회사 금성사 | Method of painting a graphite of crt |
| US5418349A (en) * | 1993-06-04 | 1995-05-23 | Xerox Corporation | Process for reducing thickness of a polymeric photoconductive coating on a photoreceptor with laser |
| US5403627A (en) * | 1993-06-04 | 1995-04-04 | Xerox Corporation | Process and apparatus for treating a photoreceptor coating |
| US5766489A (en) * | 1993-09-13 | 1998-06-16 | Pts Gesellschaft Fuer Physikalisch-Technische Studien Jena Mbh | Process and arrangement for continously carrying out photoreactions in a liquid phase |
| US5467789A (en) * | 1994-01-24 | 1995-11-21 | Sony Electronics Inc. | System for removal of phosphor from CRT panels |
| TW480543B (en) | 2000-06-16 | 2002-03-21 | Koninkl Philips Electronics Nv | Method of manufacturing a CRT |
| DE10154402B4 (en) * | 2001-10-10 | 2008-08-07 | Schott Ag | Process for internally reflecting glass tubes, in particular for solar collectors |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1988469A (en) * | 1931-06-30 | 1935-01-22 | Rca Corp | Cathode ray apparatus |
| US2695593A (en) * | 1952-05-14 | 1954-11-30 | Sylvania Electric Prod | Apparatus for applying conductive coating |
| US2692209A (en) * | 1953-04-29 | 1954-10-19 | Gen Electric | Bulb coating process |
| US2763233A (en) * | 1953-11-25 | 1956-09-18 | Gen Electric | Automatic machine for coating cathode ray tube bulbs |
| DE1077794B (en) * | 1958-09-20 | 1960-03-17 | Telefunken Gmbh | Piston washing machine for washing the inside of the pistons of electric discharge tubes, especially picture tubes |
| US2987415A (en) * | 1960-07-21 | 1961-06-06 | Gen Electric | Method of filming cathode ray tubes |
| US3315638A (en) * | 1965-03-29 | 1967-04-25 | Rauland Corp | Masking device |
| US3326224A (en) * | 1965-09-29 | 1967-06-20 | Sylvania Electric Prod | Coating removal device |
| NL6808721A (en) * | 1968-06-21 | 1969-12-23 | ||
| US3759735A (en) * | 1970-09-11 | 1973-09-18 | Zenith Radio Corp | Panel method for cleaning the sealing land of a cathode ray tube faceplate |
| DE2123740C3 (en) * | 1971-05-13 | 1981-02-19 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | Method for producing a light-absorbing layer |
| US3868264A (en) * | 1973-03-21 | 1975-02-25 | Corning Glass Works | Method of applying light diffusing coating to interior of incandescent lamp envelope |
-
1975
- 1975-09-01 NL NL7510274A patent/NL7510274A/en not_active Application Discontinuation
-
1976
- 1976-08-21 DE DE2637754A patent/DE2637754C3/en not_active Expired
- 1976-08-24 US US05/717,371 patent/US4151312A/en not_active Expired - Lifetime
- 1976-08-27 GB GB35728/76A patent/GB1552801A/en not_active Expired
- 1976-08-27 IT IT69104/76A patent/IT1071423B/en active
- 1976-08-28 JP JP51102217A patent/JPS604541B2/en not_active Expired
- 1976-08-30 BE BE170213A patent/BE845678A/en unknown
- 1976-09-01 FR FR7626411A patent/FR2322445A1/en active Granted
- 1976-09-01 CA CA260,322A patent/CA1075541A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2637754A1 (en) | 1977-03-03 |
| FR2322445A1 (en) | 1977-03-25 |
| BE845678A (en) | 1977-02-28 |
| NL7510274A (en) | 1977-03-03 |
| IT1071423B (en) | 1985-04-10 |
| DE2637754B2 (en) | 1980-05-08 |
| JPS5230155A (en) | 1977-03-07 |
| US4151312A (en) | 1979-04-24 |
| JPS604541B2 (en) | 1985-02-05 |
| FR2322445B1 (en) | 1980-05-16 |
| DE2637754C3 (en) | 1984-08-23 |
| GB1552801A (en) | 1979-09-19 |
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