CA1059568A - Colour television display tube - Google Patents
Colour television display tubeInfo
- Publication number
- CA1059568A CA1059568A CA270,486A CA270486A CA1059568A CA 1059568 A CA1059568 A CA 1059568A CA 270486 A CA270486 A CA 270486A CA 1059568 A CA1059568 A CA 1059568A
- Authority
- CA
- Canada
- Prior art keywords
- resistive layer
- colour
- envelope
- display tube
- tube
- 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
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/92—Means forming part of the tube for the purpose of providing electrical connection to it
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
- H01C7/003—Thick film resistors
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
Abstract
ABSTRACT:
A colour television display tube having colour selection means which are connected electrically, via at least one metal contact spring, to a resistive layer provided intern-ally on the envelope of the tube. The contact spring is in electrical contact with said resistive layer via a contact face which is provided on the resistive layer and consists of a layer of electrically readily conductive material.
A colour television display tube having colour selection means which are connected electrically, via at least one metal contact spring, to a resistive layer provided intern-ally on the envelope of the tube. The contact spring is in electrical contact with said resistive layer via a contact face which is provided on the resistive layer and consists of a layer of electrically readily conductive material.
Description
PIJN.8~24 ~K~ r.
oG-o 1- 77 lU~35~i8 "Colour telcvision display tube".
The invention relates to a colour television display tube comprising in an evacuated envelope an electrode system for generating at least two electron beam~, a display screen consisting of a large number of regions luminescing in different colours and provided on an internal wall part of the envelope which forms the display window, an electrical resistive layer on an internal wall part of the envelope which is situated between the electrode system and the display screen, and colour selection means having a large number of apertures which assign eaeh electron beam to luminescent regions of one colour, whieh colour seleetion means are situated in the tube at a defined ;i distance from the display sereen and are eonnected electrically to the said resistive layer by means of at least one metal con-taet spring whieh presses against the part of the wall of the tube eomprising the resistive layer.
~ or generating an electron beam in a picture display tube, the electrodes of the electrode systems mounted in the tube for that purpose are often operated at very dif-. ferent voltages. Voltage differences of 20 kV between electrodes situated at short distance from each other are quite usual, in particular in display tubes for displaying coloured pictures.
With such voltage differenees, electrical flash-overs may occur between the eleetrodes and, when no special measures are taken, may be associated with currents rising very rapidly in time and reaching values of 500 A and higher. Via inductive or capacitive -~ couplings, said eurrents may seriously damage eertain eomponents, ~ - 2 - ` ~
: ., , :.' .'~ ; .
P~N.86~l~
06-o1-77 l05556~
in particular semiconductor components, in the electronic circuit of the television receiver, while the electrode system itself may also be damaged.
British Patent Specification 1,226,728 discloses a television display tube, which, in order to restrict the de-trimental results of such an electrical flash-over, has a re-sistive layer which is provided on an internal wall part of the tube envelope. ~lthough with such a resi~tive layer good results can be obtained as regards the safety of the electronic circuit of the television receiver, the use of said layer proves to pre-sent some problems in other respects. Notably problems occur which are associated with the fact that a switched-on television ~l receiver may be a source of interference for a radio receiver placed in the proximity thereof which is tuned to a transmitter ~i in the long or medium waveband. This interference is caused for a considerable part by the video signal. During operation of the display tube, the display screen is scanned with electron beams modulated according to the video signal. A part of said ;1 beams reaches the display screen via the apertures in the colour v¦ ~election means, while the part of the beams which is not passed through impinges upon the colour selection means themselves.
hs a result of this, the electrical potential of the colour selection means and the display screen fluctuates in accordance with the~amplitude of the video signal. Said fluctuations are ) transmitted as interference radiation by the display screen.
It is the object of the invention to provide a colour television display tube having an internal resistive layer, in which mea~ures are taken to reduce the above-mentioned i ~nterference radiation.
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. . ...... .. . . . . .. . -. . .... .
- ........... . . .- . .. .. ~ . ... .
- .. . .. .
.. ~ . . ~.................... .
P~IN.8621~
1059~8 For that purpose, Q colour televis-Lon display tube according to the invention, in which the colour selection means aI~e connected electrically to the internal resistive layer by means of at least ono metal contact spring which presses against the wall part of the tube having the resistive layer, is characterized in that the contact spring is cornected elec-trically to the resistive layer via a contact face provided on the resistive layer and consisting of a material having an electrical conductivity which exceeds that of the material of the resistive layer.
The invention is based on the recognition re-sulting from experiments that the interference radiation trans-mitted by the tube is smaller according as the electrical con-nection between the colour selection means and the resistive layer represents a smaller electrical resistance. In tubes having an internal resistive layer, said resistance is mainly determined ny the contact resistance between the contact spring and the resistive layer. Said contact resistance is a result of the fact that the resistive layer consists of a mixture of electrically readily conductive and electrically poorly conductive particles.
The contact resistance is the higher according as a smaller n~mber of electrically readily conductive particles of the re-sistive layer is in contact with the contact spring. By using the invention, the effective contact surface area between the ~resistive layer and the contact spring is enlarged, which re-sults in a reduction of the contact resistance. In a practical case, in which the resistive layer had a resistance of approxi- I
mately 1000 ohms par square, a contact resistance of approximately j 5000 ohms was measured without the use of the invention. After :.' :. , PHN.~624 06~01-77 ~..()595~8 providing a low-ohmic contact face on the re~istive layer, ap-proximately 5 cm2 in area, resistance approximately 25 ohms per square, the contact resistance proved to have been reduced by approximately a factor 100. All this resulte~ in a reduction of the interference radiation level by approximately 10 dB. Low-ohmic means that the electrical conductivity of the contact face i9 as large as possible and is preferably at least a factor 10 larger than that of the resistive layer. Possible tolerances in the location of a contact spring are compensated for by giving the low-ohmic contact face an area of at least 5 cm2. A contact face in the form of a strip of low-ohmic material on the resis- ;
tive layer has been found to be particularly favourable. Due to its large area, the advantage of such a strip is that a good electrical coupling is obtained between on the one hand the co-our selection means and the display screen and on the other hand the capacitor formed by the inner coating of the tube (the resistive layer) and the usual low-ohmic coating provided on the Dutside of the tube and connected to the chassis of the television receiver. In the case in which more than one contact spring is usedf the contact faces belonging to said springs form one assembly with the above-mentioned strip. Strip and con-tact faces may consist of the same low-ohmic material so that they can be provided on the wall of the tube in one operation.
The invention will now be.described in greater ' detail with reference to t,he drawing, in which:
Figure 1 is a sectional view of a colour tele~
vision display tube according to the invention, Figure 2 shows the cone of the tube shown in Figure 1 provided with an internal resistive layer, and .'. .
.
;
-: :
PIIN . 862~1 o6-o 1 - 77 l:a59S68 Figurc 3 shows a possible connection of a get~
tering de~ice in a display tube as shown in Figure 1.
The tube shown in a hori.zontal sectional view in Figure 1 comprises a glass envelope consisting of a display window 1, a cone 2 and a neck 3. Positioned in the neck 3 is an electrode system 4 comprising three electron guns for generating three electron beams 5, 6 and 7. The electron beams are gener-ated in one plane (here the plane of the drawing) and are di-rected onto a display screen 8 which is provided internally on the display window 1 and consists of a large number of phosphor strips coated with an aluminium layer and luminescing in red, green and blue and the longitudinal direction of which is normal to the plane through the electron guns (here the plano of the ;, drawing). On their way to the display screen 8, the electron beams 5, 6 and 7 are deflected over the display screen 8 by means of a number of deflection coils 9 arranged coaxially around tha tube axis and then pass through a colour selection elec-I trode 10 consisting of a metal plate having elongate apertures ¦ 11 the l ngitudinal direction of which is parallel to the phos-i phor strips of the display screen 8. The three electron beams 5, 6 and 7 pass through the apertures 11 at a small angle with each other and consequently each impinge only upon phosphor strips of one colour. The tube furthermore comprises an internal resistive layer 12 and a readily conductive layér 13 provided .
on the outside of the cone 2. The resistive layer 12 has a thickness of approximately 10 microns and consists of 1 part by weight of graphite powder, 6 to 10 parts by weight of iron oxide powder (Fe203~ and 1.5 to 3 parts by weight of an inorganic ~inder, for example potassium silicate or sodium silicate. The .`':: :` ' `
.
Pf~N.8624 10~5~8 resistive layer 12 is conn~ctod to a hugh-voltage contact 14 pro-vided in the cone of thc tube. The colour selection electrode 10 is connected to the display screen 8 by means of a number of contact springs 15. A metal screening cone 16 i9 connected on the one hand to the colour sclection electrode 10 and on the other h~nd to the resistive layer 12 by means of two contact springs 17. During operation of the tube, -the layer 12 is at an operating potential of approximately 25 kV and the layer 13 is at mass potential because it i9 connected to the chassis of the receiver. The layers 12 and 13, with the glass of the cone inbetween as a dielectric, constitute a capacitor which serves as a smoothing capacitor for the high voltage. Said capacitor discharges when an electrical flash-over occurq in the electrode system 4, for example, between the electrod~ 18 and the elec-trode 19 situated at a short distance therefrom. The value of the current pulse occurring in said discharge, however, is res-tricted by the resistive layer 12 and that mainly by the part thereof extending over the neck-cone transition and in the neck.
The resistance represented by the resistive layer in dynamic conditions, that is during the above-mentioned electrical flash-., .
; over, generally is lower than in static conditions. Static con-ditions is to be understood to mean h0rein the r0sistance de-''.~:' ' fined as the quotient of a voltage difference of a few tens of _ volts set up across the resistive layer and the current conse-quently flowing through the resistive layer. For the above-given : composition of the layer the dynamic resistance is approximately . . .
~00 ohms and the static resistance is approximately 2000 ohms.
The use of a resistive layer reduces the filter-~ ing affect of the tube with respect to the interference radiation '''- .
.' ' .
: .
'' , : ' ' ' : .
P~IN.8624 o6-o 1- 77 ~S95~
transmitt~d by it. In this connection t}~e contact resistance between the corltact sprirlgs 17 and thc resistive layer 12 proves to be Or particular importance in that sense that the quantity of interference radiation ~s smaller as said contact resistance is lower. In order to obtain a low contact resistance, a low-o~hmic contact face in the face of a strip 20 is provided on the resistive layer 12 at the area where the contact springs 17 press against the wall of the tube. Said strip 20 consists of a low-ohmic material of the composition 60-90 parts by weight of graphite and 10-40 parts bey weight of an inorganic binder, for example potassium silicate or sodium silicate. Such a ma-terial may be provided in the form of an aqueous suspension by means of a brush. Instead of this material, however, other good conductors may also be used, for example aluminium. The strip 20 has a width of approximately 5 cm and, as shown in Figure 2, :
constitutes a closed ring on the inner surface of the cone 2.
As a result of its large contact area, such a ring moreover pro-vides a good electrical coupling between on the one hand the colour selection electrode 10 and the disp~ay screen 8 and on the other hand the capacitor constituted by the resistive layer t2 and the external layer 13.
As is known, a layer of gettering material of, for example, barium, strontium, calcium or magnesium, is depo-sited on the wall of the tube after evacuating the tube so as to getter the residual gases in the tube. In the conventional display tube the holder from which said gettering material is released by heating is connected to the electrode system either directly or by means of a metal strip. This conventional con-nection method cannot be used in a display tube according to the invention beeause in that case a part of the gettering metal '' , .
' .: . . . ..... .. . . .
P~IN.8624 o6~o 1-77 ~OS9568 would be depositecl on the resistive layer 12 at the area of the neck and the neck-cone transition, so that the resistive layer i~ short-circuited. Furthermore, in th0 case of an electrical flash-over, sliding sparks may occur along the connection strip of the holder. Figure 3 shows an example of a possible connection of the getter holder in which these problems are avoided. In this example the said gettering holder 30 is connected to the high-voltage connection 14 by means of a connection strip 31.
In this manner it i8 achieved that the getter-ing material is not deposited on the neck and the neck-cone transition but on the wide part of the cone 2. Short-circuiting the resistive layer at this area improves the above-mentioned filtering effect of the tube while the dynamic resistance of the .
layer 12 is hardly influenced thereby during an electrical flash-over.
... . .
il The invention is not restrlcted to tubes having an internal metal screening cone. The invention may alternatively . be used in tubes w:ithout a metal screening cone or in tubes having an external screening cone. In those cases, for example, the contact springs 17 are directly secured to the frame of the I colour selection electrode 10 and the low-ohmic contact faces : or strip 20 are situated farther in the direction towards the display screen than is shown in Figure 1.
. , ' , ' ' ' .' , :. _ g _ .
'` ' ~ : , :
','' ~ , ' , ' : ' . `~
oG-o 1- 77 lU~35~i8 "Colour telcvision display tube".
The invention relates to a colour television display tube comprising in an evacuated envelope an electrode system for generating at least two electron beam~, a display screen consisting of a large number of regions luminescing in different colours and provided on an internal wall part of the envelope which forms the display window, an electrical resistive layer on an internal wall part of the envelope which is situated between the electrode system and the display screen, and colour selection means having a large number of apertures which assign eaeh electron beam to luminescent regions of one colour, whieh colour seleetion means are situated in the tube at a defined ;i distance from the display sereen and are eonnected electrically to the said resistive layer by means of at least one metal con-taet spring whieh presses against the part of the wall of the tube eomprising the resistive layer.
~ or generating an electron beam in a picture display tube, the electrodes of the electrode systems mounted in the tube for that purpose are often operated at very dif-. ferent voltages. Voltage differences of 20 kV between electrodes situated at short distance from each other are quite usual, in particular in display tubes for displaying coloured pictures.
With such voltage differenees, electrical flash-overs may occur between the eleetrodes and, when no special measures are taken, may be associated with currents rising very rapidly in time and reaching values of 500 A and higher. Via inductive or capacitive -~ couplings, said eurrents may seriously damage eertain eomponents, ~ - 2 - ` ~
: ., , :.' .'~ ; .
P~N.86~l~
06-o1-77 l05556~
in particular semiconductor components, in the electronic circuit of the television receiver, while the electrode system itself may also be damaged.
British Patent Specification 1,226,728 discloses a television display tube, which, in order to restrict the de-trimental results of such an electrical flash-over, has a re-sistive layer which is provided on an internal wall part of the tube envelope. ~lthough with such a resi~tive layer good results can be obtained as regards the safety of the electronic circuit of the television receiver, the use of said layer proves to pre-sent some problems in other respects. Notably problems occur which are associated with the fact that a switched-on television ~l receiver may be a source of interference for a radio receiver placed in the proximity thereof which is tuned to a transmitter ~i in the long or medium waveband. This interference is caused for a considerable part by the video signal. During operation of the display tube, the display screen is scanned with electron beams modulated according to the video signal. A part of said ;1 beams reaches the display screen via the apertures in the colour v¦ ~election means, while the part of the beams which is not passed through impinges upon the colour selection means themselves.
hs a result of this, the electrical potential of the colour selection means and the display screen fluctuates in accordance with the~amplitude of the video signal. Said fluctuations are ) transmitted as interference radiation by the display screen.
It is the object of the invention to provide a colour television display tube having an internal resistive layer, in which mea~ures are taken to reduce the above-mentioned i ~nterference radiation.
,~.,, ., :' !
. . ...... .. . . . . .. . -. . .... .
- ........... . . .- . .. .. ~ . ... .
- .. . .. .
.. ~ . . ~.................... .
P~IN.8621~
1059~8 For that purpose, Q colour televis-Lon display tube according to the invention, in which the colour selection means aI~e connected electrically to the internal resistive layer by means of at least ono metal contact spring which presses against the wall part of the tube having the resistive layer, is characterized in that the contact spring is cornected elec-trically to the resistive layer via a contact face provided on the resistive layer and consisting of a material having an electrical conductivity which exceeds that of the material of the resistive layer.
The invention is based on the recognition re-sulting from experiments that the interference radiation trans-mitted by the tube is smaller according as the electrical con-nection between the colour selection means and the resistive layer represents a smaller electrical resistance. In tubes having an internal resistive layer, said resistance is mainly determined ny the contact resistance between the contact spring and the resistive layer. Said contact resistance is a result of the fact that the resistive layer consists of a mixture of electrically readily conductive and electrically poorly conductive particles.
The contact resistance is the higher according as a smaller n~mber of electrically readily conductive particles of the re-sistive layer is in contact with the contact spring. By using the invention, the effective contact surface area between the ~resistive layer and the contact spring is enlarged, which re-sults in a reduction of the contact resistance. In a practical case, in which the resistive layer had a resistance of approxi- I
mately 1000 ohms par square, a contact resistance of approximately j 5000 ohms was measured without the use of the invention. After :.' :. , PHN.~624 06~01-77 ~..()595~8 providing a low-ohmic contact face on the re~istive layer, ap-proximately 5 cm2 in area, resistance approximately 25 ohms per square, the contact resistance proved to have been reduced by approximately a factor 100. All this resulte~ in a reduction of the interference radiation level by approximately 10 dB. Low-ohmic means that the electrical conductivity of the contact face i9 as large as possible and is preferably at least a factor 10 larger than that of the resistive layer. Possible tolerances in the location of a contact spring are compensated for by giving the low-ohmic contact face an area of at least 5 cm2. A contact face in the form of a strip of low-ohmic material on the resis- ;
tive layer has been found to be particularly favourable. Due to its large area, the advantage of such a strip is that a good electrical coupling is obtained between on the one hand the co-our selection means and the display screen and on the other hand the capacitor formed by the inner coating of the tube (the resistive layer) and the usual low-ohmic coating provided on the Dutside of the tube and connected to the chassis of the television receiver. In the case in which more than one contact spring is usedf the contact faces belonging to said springs form one assembly with the above-mentioned strip. Strip and con-tact faces may consist of the same low-ohmic material so that they can be provided on the wall of the tube in one operation.
The invention will now be.described in greater ' detail with reference to t,he drawing, in which:
Figure 1 is a sectional view of a colour tele~
vision display tube according to the invention, Figure 2 shows the cone of the tube shown in Figure 1 provided with an internal resistive layer, and .'. .
.
;
-: :
PIIN . 862~1 o6-o 1 - 77 l:a59S68 Figurc 3 shows a possible connection of a get~
tering de~ice in a display tube as shown in Figure 1.
The tube shown in a hori.zontal sectional view in Figure 1 comprises a glass envelope consisting of a display window 1, a cone 2 and a neck 3. Positioned in the neck 3 is an electrode system 4 comprising three electron guns for generating three electron beams 5, 6 and 7. The electron beams are gener-ated in one plane (here the plane of the drawing) and are di-rected onto a display screen 8 which is provided internally on the display window 1 and consists of a large number of phosphor strips coated with an aluminium layer and luminescing in red, green and blue and the longitudinal direction of which is normal to the plane through the electron guns (here the plano of the ;, drawing). On their way to the display screen 8, the electron beams 5, 6 and 7 are deflected over the display screen 8 by means of a number of deflection coils 9 arranged coaxially around tha tube axis and then pass through a colour selection elec-I trode 10 consisting of a metal plate having elongate apertures ¦ 11 the l ngitudinal direction of which is parallel to the phos-i phor strips of the display screen 8. The three electron beams 5, 6 and 7 pass through the apertures 11 at a small angle with each other and consequently each impinge only upon phosphor strips of one colour. The tube furthermore comprises an internal resistive layer 12 and a readily conductive layér 13 provided .
on the outside of the cone 2. The resistive layer 12 has a thickness of approximately 10 microns and consists of 1 part by weight of graphite powder, 6 to 10 parts by weight of iron oxide powder (Fe203~ and 1.5 to 3 parts by weight of an inorganic ~inder, for example potassium silicate or sodium silicate. The .`':: :` ' `
.
Pf~N.8624 10~5~8 resistive layer 12 is conn~ctod to a hugh-voltage contact 14 pro-vided in the cone of thc tube. The colour selection electrode 10 is connected to the display screen 8 by means of a number of contact springs 15. A metal screening cone 16 i9 connected on the one hand to the colour sclection electrode 10 and on the other h~nd to the resistive layer 12 by means of two contact springs 17. During operation of the tube, -the layer 12 is at an operating potential of approximately 25 kV and the layer 13 is at mass potential because it i9 connected to the chassis of the receiver. The layers 12 and 13, with the glass of the cone inbetween as a dielectric, constitute a capacitor which serves as a smoothing capacitor for the high voltage. Said capacitor discharges when an electrical flash-over occurq in the electrode system 4, for example, between the electrod~ 18 and the elec-trode 19 situated at a short distance therefrom. The value of the current pulse occurring in said discharge, however, is res-tricted by the resistive layer 12 and that mainly by the part thereof extending over the neck-cone transition and in the neck.
The resistance represented by the resistive layer in dynamic conditions, that is during the above-mentioned electrical flash-., .
; over, generally is lower than in static conditions. Static con-ditions is to be understood to mean h0rein the r0sistance de-''.~:' ' fined as the quotient of a voltage difference of a few tens of _ volts set up across the resistive layer and the current conse-quently flowing through the resistive layer. For the above-given : composition of the layer the dynamic resistance is approximately . . .
~00 ohms and the static resistance is approximately 2000 ohms.
The use of a resistive layer reduces the filter-~ ing affect of the tube with respect to the interference radiation '''- .
.' ' .
: .
'' , : ' ' ' : .
P~IN.8624 o6-o 1- 77 ~S95~
transmitt~d by it. In this connection t}~e contact resistance between the corltact sprirlgs 17 and thc resistive layer 12 proves to be Or particular importance in that sense that the quantity of interference radiation ~s smaller as said contact resistance is lower. In order to obtain a low contact resistance, a low-o~hmic contact face in the face of a strip 20 is provided on the resistive layer 12 at the area where the contact springs 17 press against the wall of the tube. Said strip 20 consists of a low-ohmic material of the composition 60-90 parts by weight of graphite and 10-40 parts bey weight of an inorganic binder, for example potassium silicate or sodium silicate. Such a ma-terial may be provided in the form of an aqueous suspension by means of a brush. Instead of this material, however, other good conductors may also be used, for example aluminium. The strip 20 has a width of approximately 5 cm and, as shown in Figure 2, :
constitutes a closed ring on the inner surface of the cone 2.
As a result of its large contact area, such a ring moreover pro-vides a good electrical coupling between on the one hand the colour selection electrode 10 and the disp~ay screen 8 and on the other hand the capacitor constituted by the resistive layer t2 and the external layer 13.
As is known, a layer of gettering material of, for example, barium, strontium, calcium or magnesium, is depo-sited on the wall of the tube after evacuating the tube so as to getter the residual gases in the tube. In the conventional display tube the holder from which said gettering material is released by heating is connected to the electrode system either directly or by means of a metal strip. This conventional con-nection method cannot be used in a display tube according to the invention beeause in that case a part of the gettering metal '' , .
' .: . . . ..... .. . . .
P~IN.8624 o6~o 1-77 ~OS9568 would be depositecl on the resistive layer 12 at the area of the neck and the neck-cone transition, so that the resistive layer i~ short-circuited. Furthermore, in th0 case of an electrical flash-over, sliding sparks may occur along the connection strip of the holder. Figure 3 shows an example of a possible connection of the getter holder in which these problems are avoided. In this example the said gettering holder 30 is connected to the high-voltage connection 14 by means of a connection strip 31.
In this manner it i8 achieved that the getter-ing material is not deposited on the neck and the neck-cone transition but on the wide part of the cone 2. Short-circuiting the resistive layer at this area improves the above-mentioned filtering effect of the tube while the dynamic resistance of the .
layer 12 is hardly influenced thereby during an electrical flash-over.
... . .
il The invention is not restrlcted to tubes having an internal metal screening cone. The invention may alternatively . be used in tubes w:ithout a metal screening cone or in tubes having an external screening cone. In those cases, for example, the contact springs 17 are directly secured to the frame of the I colour selection electrode 10 and the low-ohmic contact faces : or strip 20 are situated farther in the direction towards the display screen than is shown in Figure 1.
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','' ~ , ' , ' : ' . `~
Claims (6)
1. A colour television display tube comprising in an evacuated envelope an electrode system for generating at least two electron beams, a display screen consisting of a plurality of regions luminescing in different colours and provided on an internal wall part of the envelope which forms the display window, an electrically resistive layer extending on an internal wall part of the envelope between the elec-trode system and the display screen, and an apertured colour selection means for assigning each electron beam to lumines-cent regions of one colour, which colour selection means is situated in the envelope at a predetermined distance from the display screen and is coupled electrically to the display screen, at least one metal contact spring disposed between the colour selection means and the internal surface of the envelope, wherein the contact spring presses against the part of the envelope comprising the resistive layer and is connected electrically to the resistive layer via a contact face provided on the resistive layer, said contact face consisting of a material having an electrical conductivity which exceeds that of the material of the resistive layer and having an area which is greater than that between the spring and the contact face.
2. A colour television display tube as claimed in Claim 1, wherein the contact face has an area of at least 5 cm2.
3. A colour television display tube as claimed in Claim 1, wherein the contact face consists of a strip of low-ohmic (as herein defined) material.
4. A colour television display tube as claimed in Claim 3, wherein the strip constitutes a closed ring.
5. A colour television display tube as claimed in Claim 3 or 4, in which the colour selection means is coupled to the resistive layer via at least two contact springs which press resiliently against the strip of low-ohmic material provided on the resistive layer.
6. A colour television display tube as claimed in Claim 1, wherein the resistive layer comprises 1 part by weight of graphite powder, 6 to 10 parts by weight of iron oxide powder (Fe2O3) and 1.5 to 3 parts by weight of alkali-metalsilicate, and the contact face comprises 60 to 90 parts by weight of graphite and 10 to 40 parts by weight of alkali-metalsilicate.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7613806A NL7613806A (en) | 1976-12-13 | 1976-12-13 | COLOR TELEVISION PICTURE TUBE. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1059568A true CA1059568A (en) | 1979-07-31 |
Family
ID=19827368
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA270,486A Expired CA1059568A (en) | 1976-12-13 | 1977-01-26 | Colour television display tube |
Country Status (8)
| Country | Link |
|---|---|
| JP (2) | JPS5374356A (en) |
| BE (1) | BE850728A (en) |
| CA (1) | CA1059568A (en) |
| DE (1) | DE2703093C2 (en) |
| FR (1) | FR2373867A1 (en) |
| GB (1) | GB1567653A (en) |
| IT (1) | IT1077887B (en) |
| NL (1) | NL7613806A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL7712707A (en) * | 1977-11-18 | 1979-05-22 | Philips Nv | COLOR TELEVISION PICTURE TUBE. |
| US4210844A (en) * | 1978-11-20 | 1980-07-01 | Gte Sylvania Incorporated | Cathode ray tube arc suppressor coating |
| GB2180393A (en) * | 1985-09-11 | 1987-03-25 | Philips Electronic Associated | Termination arrangement for cathode ray display tube |
| NL8701031A (en) * | 1987-05-01 | 1988-12-01 | Philips Nv | CATHED BEAM TUBE. |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL6900696A (en) * | 1969-01-16 | 1970-07-20 | ||
| US3543072A (en) * | 1969-04-16 | 1970-11-24 | Sylvania Electric Prod | Color cathode ray tube with metallic contactor ribbon bonded on inside wall of tube between the high voltage terminal and the shadow mask frame |
| BE791817A (en) * | 1971-11-26 | 1973-03-16 | Rca Corp | CATHODIC RAY TUBE |
| BE794166A (en) * | 1972-01-19 | 1973-07-17 | Philips Nv | PROCESS FOR MANUFACTURING A DEVICE INCLUDING A LAYER CONSTITUTING A RESISTANCE |
| US3959686A (en) * | 1975-01-06 | 1976-05-25 | Gte Sylvania Incorporated | Cathode ray tube construction having defined processing and operational means incorporated therein |
-
1976
- 1976-12-13 NL NL7613806A patent/NL7613806A/en not_active Application Discontinuation
-
1977
- 1977-01-25 BE BE174361A patent/BE850728A/en unknown
- 1977-01-25 FR FR7701995A patent/FR2373867A1/en active Granted
- 1977-01-26 CA CA270,486A patent/CA1059568A/en not_active Expired
- 1977-01-26 DE DE19772703093 patent/DE2703093C2/en not_active Expired
- 1977-01-26 GB GB314377A patent/GB1567653A/en not_active Expired
- 1977-01-26 IT IT1967477A patent/IT1077887B/en active
- 1977-03-24 JP JP3166977A patent/JPS5374356A/en active Pending
-
1983
- 1983-08-10 JP JP12333583U patent/JPS5951439U/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| NL7613806A (en) | 1978-06-15 |
| DE2703093C2 (en) | 1986-01-23 |
| IT1077887B (en) | 1985-05-04 |
| JPS6110292Y2 (en) | 1986-04-02 |
| JPS5951439U (en) | 1984-04-04 |
| FR2373867B1 (en) | 1980-03-28 |
| JPS5374356A (en) | 1978-07-01 |
| GB1567653A (en) | 1980-05-21 |
| FR2373867A1 (en) | 1978-07-07 |
| DE2703093A1 (en) | 1978-06-15 |
| BE850728A (en) | 1977-07-25 |
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