CA1042059A - Cathode ray tube for displaying coloured pictures - Google Patents
Cathode ray tube for displaying coloured picturesInfo
- Publication number
- CA1042059A CA1042059A CA231,143A CA231143A CA1042059A CA 1042059 A CA1042059 A CA 1042059A CA 231143 A CA231143 A CA 231143A CA 1042059 A CA1042059 A CA 1042059A
- Authority
- CA
- Canada
- Prior art keywords
- ray tube
- cathode ray
- selection means
- display screen
- conductors
- 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
- H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
- H01J29/80—Arrangements for controlling the ray or beam after passing the main deflection system, e.g. for post-acceleration or post-concentration, for colour switching
- H01J29/81—Arrangements for controlling the ray or beam after passing the main deflection system, e.g. for post-acceleration or post-concentration, for colour switching using shadow masks
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J31/00—Cathode ray tubes; Electron beam tubes
- H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
- H01J31/10—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes
- H01J31/20—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes for displaying images or patterns in two or more colours
- H01J31/201—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes for displaying images or patterns in two or more colours using a colour-selection electrode
- H01J31/203—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes for displaying images or patterns in two or more colours using a colour-selection electrode with more than one electron beam
Landscapes
- Electrodes For Cathode-Ray Tubes (AREA)
- Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
Abstract
ABSTRACT:
A post-focusing type cathode ray tube for displaying coloured pictures. A quadrupole lens is formed in each aperture of the colour selection means.
The defocusing direction of the quadrupole lenses is parallel to the phosphor strips of the display screen.
A post-focusing type cathode ray tube for displaying coloured pictures. A quadrupole lens is formed in each aperture of the colour selection means.
The defocusing direction of the quadrupole lenses is parallel to the phosphor strips of the display screen.
Description
PHN. 7638.
. ~.
The invention relates to a cathode ray tube for displaying coloured pictures and comprising in an evacuated envelope means to generate a number of electr~n beams, a display screen oomprising a large number of regions luminescing in different colours, and colour selections means comprising a large numbeL
of apertures which assign each electnon beam to luminescent regions of one colour, which oolour selec-tion means comprise electrodes to form an electr~n lens in each aperture.
Such a post-focusing cathode ray tube is -kn~wn from the I~Lited States patent specification 3,398,309 which issued on August 20, 1968 to The Rauland Corp. m e object of post-focusing is to increase the brightness of the displayed picture by increasing the transmission of the colour selection means. In tubes without post-focusing a very large part, for example, 80 to 85%, of the electrons is intercepted by the so- -called shadow mask. By using pos -focusing the apertures in the colour selection means can be enlarged since as a result of the focusing in the apertures the electron spots on the screen are considerably smaller ~han the apertures so that nevertheless sufficient landing tolerance exists.
The electron lens which is formed in the apertures of the shadow mask of the known tube is of the -. ~
PHN. 7638.
lU~ 3 : ~
uniFotential type as a result of which a rather large voltage difference is required between the electrcdes which constitute the lens.
Another post-focusing tube is described in the Uhited States patent specification 2,728,024 which issued on Dece~ber 20, 1955 to Radio Corporation of America. In this tube the electron beams pass successively through tw~ flat grids consisting of parallel conductors. m e conductors belonging to different grids extend at right angles to each other.
The result of this is that the electron beams are suc-- oe ssively focused by two electron-optical cylinder lenses which are rotated 90 with respect to each other. By the combined action of the tw~ lenses the !' electron beams are focused in one ~;rection and defocused in a direction at right angles thereto.
A drawback of this known tube is also that a rather large voltage difference is necessary for the focusing. In addition, both grids do not form a mechani-cal unit so that the vibration of the grid wires presents great problems. In addition it is necessary for the dis-~- play screen to be flat.
.~: , .
It is the object of the invention to pro-vide a cathode ray tube for displaying coloured pictures of the kind mentioned in the prea~ble which does not ;
exhibit the said drawbacks. For that purpose, a quad-rupole lens is formed in each aperture of the colour selection means. Quadrupole lenses are relatively very str~ng since the electric field extends at right ''' ' . ,,~
' ~. . .
PHN. 7638.
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angles to the electron path, so that much lower voltages will suffice. m at a quadrupolelens focuses in one direction and defocuses in a direction at right angles thereto is no objection in principle if all the quadrupoles have the same orientation. m erefore, the luminescent regions of the display screen have the shape of substantially parallel strips the longitudinal direction of which is substantially parallel to the defocusing direction of the quadr~pole lenses.
In a suitable ~mbodiment of a tube according to the invention the colour selections means are formed by a grid consisting of two sets of parallel conductors which cross each other or are interwoven, said conductors being electrically insulated from and mechanically connected to each other at the crossings, the oonductors of each set being electrically connected together.
In another suitable enbcdiment of the invention the colour selection means are formed by a metal plate which comprises said apertures and conductive strips between the rows of apertures, said strips being electrically connected together and insulated from the plate.
Voltages from an external voltage source may b~e applied to the electrodes which constitute the quadrupole lenses.
It is also possible to electrically connect to the display screen those electrodes conveying the highest positive potential of the electrodes which oonstitute the - quadrupole lenses, and not to connect the electrcdes conveying t~e lcwest positive potential to an external voltage sour oe Z0~9 and to cause them to be charged by the electran beams.
m e invention will be described in greater detail with reference to the accompanying drawing, of which Figure 1 shcws a cathode ray tube for displaying coloured pictures according to the invention , Figure 2 serves to elucidate the principle of the invention, Figure 3 shows a first embodiment according to the invention, ~ -Figure 4 shows a second ~mbodiment according to the invention, Figure 5 shows measured results, and -; Figure 6, which is on the same page as Fig. 3, shows a third entoiimest according to the invention.
.
` 15 The tube shown ln Figure l comprises a glass envelope l, means 2 to generate threP electron beams 3, 4 and 5, a display screen 6, colour selection means 7 and -, :
deflection coils 8. The electron beams 3, 4 and 5 are gen-erated in one plate, the plane of the drawing of Figure 1, , ~;
and are deflected on the display screen 6 by means of the deflection coils 8. The display screen 6 comprises a large ; nu~ber of phosphor strips which lumines oe in red, green and blue, respoctively, and the longitudinal direction of which . . .
is at right angles to the plane of the drawing of Figure 1.
During normal operation of the tube the phosphor strips are vertical and Figure l hence represents a horizontal ; sectional view of the tube. m e colour selection means 7 which will be described in greater detail with reference to Figures 3, 4 and 7 comprise a large number of apertures 9 which are shown diagrammatically only in '...................................................................... . .
; A 5 -. ., , ~
PHN. 7638.
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Figure 1. m e three electron beams 3, 4 and 5 pass through the apertures 9 at a small angle with each other and consequently each impinge only on phosphor strips of one colour. The apertures 9 in the colour selection means 7 are thus very accurately positioned relative to the phosphor strips of the display screen 6.
In the presently generally used shadcw mask tube the electron beams 3, 4 and 5 are not focused upon passing through the apertures 9. In the already mentioned United States patent specification 3,398,309, unipotential lenses for focusing the electron beams are formed in the apertures 9. It has also been suggested to use post-focusing by means of a potential differen oe between the colour selection means 7 and the display screen 6, in which, however, much hindrance is experienoed frQm secondary electrons.
According to the invention a quadrupole lens is fonmed in each aperture. Figure 2 shcws such a quadrupole lens diagra~matically. A part of the colour selection means 7 and one of the apertures 9 is shown.
The potential variation along the edge of the aperture 9 is denoted +, -, +, -, in such manner that a quadrupole field is fo~med. The electron beam which passes through the aperture 9 is focused in the horizontally shcwn plane and is defocused in the vertically shcwn plane as a result of which the electron spot 10 is formed if the display screen is exactly in the horizontal focal point.
~U~ 5~3 PHN. 7638.
As will be described in greater detail, it is recom-mendable to focus not exactly on the display screen 6 as a result of which a slightly wider electron spot is obtained. It is only of secondary influence of the focusing when the electron beam passes ~ -thr w gh the aperture 9 at a small angle; as a result of this the aolour æ lection of the three electron beams 3, 4 and 5 takes pla oe in a manner quite analogous to that a much larger number of electrons impinge upon the display screen 6 and a brighter picture is formed.
The defocusing in the vertical direction need be no drawback if phosphor strips are used which are parallel to the longitudinal direction of the spot 10. Colour selection means aomprising a large number of quadrupole lenses have been realized in three manners. -In Figure 3 the colour selection means 7 ~-comprise two sets of parallel aonductors crossing each other. Of the first set the horizontally shown conductors 11 and 12 æe shown. Of the second set the vertically shown conductors 13 and 14 are shown. ~he aonductors 11, ;
12, 13 and 14 determine one of the apertures 9 and are insulated from each other by means of insulation material 15. m e three phosphor strips belonging to the aperture 9 are shown on the display screen 6 and are denoted by R (red), G (green) and B (blue). Only a few rays of the central electron beam 4 are shown in the Figure which form electr~n spot 10 on the phosphor strip G. The horizontal .. . -. ~ , .
.
~ Z~ PHN. 7638.
` conductors, including 11 and 12, are connected together and are at a higher potential than the vertical oonductors, including 13 and 14, oonnected together, as a result of which the quadrupole lens shown diagrammatically in Figure 2 is formed in each aperture 9.
Figure 4 shows a slightly varied em~odlment of the oolour selection means 7 in which interwoven horizontal and vertical conductors are used. A few horizontal conductors are designated 16, 17 and 18 and a few vertical oonductors are designated 19, 20 and 21.
The conductors are insulated from each other by means of insulation material 22.
m e colour selection means shown in - Figures 3 and 4 are manufactured as follows. Two sets of iran wires (the wires are preferably ferro-magnetic in connection with the screening of the earth's magnetic field) which are provided with glass insulation are pressed against each other in the desired manner in a mould or are interWDVen (Figure 4). m e assembly is then heated so that the wires with the glass insulation fuse together without, however, maXing electric contact with each other. The glass insulation is then remDved from the wire, with the ex oe ption of the crossings, so as to avoid undesired charging of the glass. ~his latter may be carried out by means of jets of pcwder frcm both sides in which the insulation of the crossing is in the shadow of the conductors or by spraying an etchant ... .. . ~ ~. - , , .
PHN. 7638.
21~
which reaches the insulation of the crossings with greater difficulty than elsewhere.
m e following results are reached in colour selection means shown in Figure 4 assenbled in a display tube and having conductors of a diameter of ~- -0.24 mm and a mutual pitch of 0.80 mm as a result of -which the transmission of the colour selection means is approx~mately 50 %. With a potential of the display screen 6 of 25 kV and a potential of the horizontal conductors of 24.55 kV and of the vertical conductors -of 25.45 kV, the focal distance of the quadrupole lenses is 18.0 mm in the centre of the display screen with incidence at right angles and 12.7 mm with an incidence of 37 in the corners of the display screen. The distan oe between the colour selection means 7 and the display screen 6 is 15 mm in the centre and 10 mm at the edge so that the focal point of the quadrupole lenses everywhere lies just slightly beyond the display - screen. As a result of this it is prevented that a so-called focal ring is visible on the display screen.
me electron spots in the centre of the display screen -; are 0.10 mm wide and in the oorner 0.09 mm wide. A
suitable width of the phosphor strips R, G and B then is 0.13 mm. m e remainder of the surface of the display screen may or may not ~e covered with a light-absorbing , material.
Fig~re 5 shows a few measured results :, :
.
- . . . -, . . .
- ~ . . ..
PHN. 7638.
~)4;~0~3 obtained with a configuration as shown in Figure 4 in a special measuring tube. In this case the diameter of the conductors was 0.2 mm and the pitch was on an average 1.2 mm. m e x-direction is parallel to a horizontal line on the display screen. m e light output in arbitrary units is plotted in the y-direction and is - measured by means of a very small aperture in a diaphragm which scans the display screen in the x-direction and a photomultiplier which receives the light which passes through the small aperture and converts it into an electric signal. m e measurements have been carried out at 0 Volt to 2000 Volts voltage difference between the horizontal and the vertical conductors, in steps of 250 Volts. m e very strong focusing at 2000 Volts is clearly visible in Figure 5.
` At 0 Volt only the vertical conductors produce shadcw - on the display screen and a uniformly illuminated spot is present behind each aperture 9. From the very steep Pdges of the measured curves the very small influence appears of secondary electrons which in the kncwn tube with post-focusing form a hazy edge (hals) around the light spots.
A third embodUm~nt of the colour selection means 7 is shown in Figure 6. In this case it oonsists of an iron plate 23 which has apertures 9 and a large number of vertical conductive strips tw~ of which are shown between the apertures 9 and are designated 24 and .. ,~.
.- :
' ::
, -PHN. 7638.
0~
25. The conductive strips are insulated from the iron plate by means of insulation material 26. m e plate 23 has a thickness of 0.15 mm. The insulation material 26, a glass layer, has a thickness of 0.06 mm. m e conductive strips consist of vapour-deposited aluninium and have a thickness of 0.0005 mm. m e apertures 9 are 0.56 x 0.56 mm and their pitch is 0.8 mm so that the transmission of the colour selection means is approximately 50 ~.
With a æ tential of the display screen 6 of 25 kV, a potential of the plate 23 of likewise 25 kV and a potential of the conductive strips 24 and 25 of 23.4 kV, the focal distan oe of the quadrupole lenses is 18 mm ~ -in the case of normal incidence in the oe ntre of the display screen and 12.7 mm in the case of inciden oe at 37 at the edge of the display screen. m e distance between the display screen 6 and the colour selection ~--~ means 7 is 15 mm in the centre of the display screen and 10 mm at the edge. m e electron spots in the centre -of the display screen are 0.10 mm wide and 0.09 mm in the corners and no focal ring is visible on the display screen. m e width of the phosphorstrips R, G and B is 0.13 mm. me remainder of the display screen may or may not be provided with a light-absorbing material.
The disp~lay screen 6 and the plate 23 are -connected electrically and re oe ive their voltage of 25 kV
from an external voltage source. m e voltage of 23,4 kV
which is app~lied to the conductive strips 24 and 25 may ' .
' :
., . ~.
-' :
,';:
PHN. 7638.
0~9 also originate fr~m an external voltage source. It is also possible not to connect the conductive strips to an external voltage source, but to cause them to be changed by the electron beams. Due to the charging with the electron beams, the quadrupole field is gradually formed in the apertures 9, as a result of the focusing effect of which the strips 24 and 25 will be hit by the electron beams to an even decreasing extent. m e final condition is stable and independent of the beam current because only very little current is necessary to maintain the potential of the strips 24 and 25.
A display screen for a tube according to the invention can be manufactured with a kncwn exposure method in which the colour selection means are reproduced on a -photo-sensitive layer on a window portion of the tube. In connection with the large transmission of the colour selection means according to the invention, the exposure method used should be suitable to reproduce the apertures 9 in a strongly narrcwed n~nner. An exposure method suitable for this purpose uses two or re light sources at some distan oe f m m each other. Of course, a tube according to the invention is also excellently suitable for so-called electronic exposure in which the sensitive layer on the window portion is "exposed" by means of an electr~n beam.
.,.. ,1 ~.
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. , .
' ~
.
. ~.
The invention relates to a cathode ray tube for displaying coloured pictures and comprising in an evacuated envelope means to generate a number of electr~n beams, a display screen oomprising a large number of regions luminescing in different colours, and colour selections means comprising a large numbeL
of apertures which assign each electnon beam to luminescent regions of one colour, which oolour selec-tion means comprise electrodes to form an electr~n lens in each aperture.
Such a post-focusing cathode ray tube is -kn~wn from the I~Lited States patent specification 3,398,309 which issued on August 20, 1968 to The Rauland Corp. m e object of post-focusing is to increase the brightness of the displayed picture by increasing the transmission of the colour selection means. In tubes without post-focusing a very large part, for example, 80 to 85%, of the electrons is intercepted by the so- -called shadow mask. By using pos -focusing the apertures in the colour selection means can be enlarged since as a result of the focusing in the apertures the electron spots on the screen are considerably smaller ~han the apertures so that nevertheless sufficient landing tolerance exists.
The electron lens which is formed in the apertures of the shadow mask of the known tube is of the -. ~
PHN. 7638.
lU~ 3 : ~
uniFotential type as a result of which a rather large voltage difference is required between the electrcdes which constitute the lens.
Another post-focusing tube is described in the Uhited States patent specification 2,728,024 which issued on Dece~ber 20, 1955 to Radio Corporation of America. In this tube the electron beams pass successively through tw~ flat grids consisting of parallel conductors. m e conductors belonging to different grids extend at right angles to each other.
The result of this is that the electron beams are suc-- oe ssively focused by two electron-optical cylinder lenses which are rotated 90 with respect to each other. By the combined action of the tw~ lenses the !' electron beams are focused in one ~;rection and defocused in a direction at right angles thereto.
A drawback of this known tube is also that a rather large voltage difference is necessary for the focusing. In addition, both grids do not form a mechani-cal unit so that the vibration of the grid wires presents great problems. In addition it is necessary for the dis-~- play screen to be flat.
.~: , .
It is the object of the invention to pro-vide a cathode ray tube for displaying coloured pictures of the kind mentioned in the prea~ble which does not ;
exhibit the said drawbacks. For that purpose, a quad-rupole lens is formed in each aperture of the colour selection means. Quadrupole lenses are relatively very str~ng since the electric field extends at right ''' ' . ,,~
' ~. . .
PHN. 7638.
~14;~0~;~
angles to the electron path, so that much lower voltages will suffice. m at a quadrupolelens focuses in one direction and defocuses in a direction at right angles thereto is no objection in principle if all the quadrupoles have the same orientation. m erefore, the luminescent regions of the display screen have the shape of substantially parallel strips the longitudinal direction of which is substantially parallel to the defocusing direction of the quadr~pole lenses.
In a suitable ~mbodiment of a tube according to the invention the colour selections means are formed by a grid consisting of two sets of parallel conductors which cross each other or are interwoven, said conductors being electrically insulated from and mechanically connected to each other at the crossings, the oonductors of each set being electrically connected together.
In another suitable enbcdiment of the invention the colour selection means are formed by a metal plate which comprises said apertures and conductive strips between the rows of apertures, said strips being electrically connected together and insulated from the plate.
Voltages from an external voltage source may b~e applied to the electrodes which constitute the quadrupole lenses.
It is also possible to electrically connect to the display screen those electrodes conveying the highest positive potential of the electrodes which oonstitute the - quadrupole lenses, and not to connect the electrcdes conveying t~e lcwest positive potential to an external voltage sour oe Z0~9 and to cause them to be charged by the electran beams.
m e invention will be described in greater detail with reference to the accompanying drawing, of which Figure 1 shcws a cathode ray tube for displaying coloured pictures according to the invention , Figure 2 serves to elucidate the principle of the invention, Figure 3 shows a first embodiment according to the invention, ~ -Figure 4 shows a second ~mbodiment according to the invention, Figure 5 shows measured results, and -; Figure 6, which is on the same page as Fig. 3, shows a third entoiimest according to the invention.
.
` 15 The tube shown ln Figure l comprises a glass envelope l, means 2 to generate threP electron beams 3, 4 and 5, a display screen 6, colour selection means 7 and -, :
deflection coils 8. The electron beams 3, 4 and 5 are gen-erated in one plate, the plane of the drawing of Figure 1, , ~;
and are deflected on the display screen 6 by means of the deflection coils 8. The display screen 6 comprises a large ; nu~ber of phosphor strips which lumines oe in red, green and blue, respoctively, and the longitudinal direction of which . . .
is at right angles to the plane of the drawing of Figure 1.
During normal operation of the tube the phosphor strips are vertical and Figure l hence represents a horizontal ; sectional view of the tube. m e colour selection means 7 which will be described in greater detail with reference to Figures 3, 4 and 7 comprise a large number of apertures 9 which are shown diagrammatically only in '...................................................................... . .
; A 5 -. ., , ~
PHN. 7638.
~a~
Figure 1. m e three electron beams 3, 4 and 5 pass through the apertures 9 at a small angle with each other and consequently each impinge only on phosphor strips of one colour. The apertures 9 in the colour selection means 7 are thus very accurately positioned relative to the phosphor strips of the display screen 6.
In the presently generally used shadcw mask tube the electron beams 3, 4 and 5 are not focused upon passing through the apertures 9. In the already mentioned United States patent specification 3,398,309, unipotential lenses for focusing the electron beams are formed in the apertures 9. It has also been suggested to use post-focusing by means of a potential differen oe between the colour selection means 7 and the display screen 6, in which, however, much hindrance is experienoed frQm secondary electrons.
According to the invention a quadrupole lens is fonmed in each aperture. Figure 2 shcws such a quadrupole lens diagra~matically. A part of the colour selection means 7 and one of the apertures 9 is shown.
The potential variation along the edge of the aperture 9 is denoted +, -, +, -, in such manner that a quadrupole field is fo~med. The electron beam which passes through the aperture 9 is focused in the horizontally shcwn plane and is defocused in the vertically shcwn plane as a result of which the electron spot 10 is formed if the display screen is exactly in the horizontal focal point.
~U~ 5~3 PHN. 7638.
As will be described in greater detail, it is recom-mendable to focus not exactly on the display screen 6 as a result of which a slightly wider electron spot is obtained. It is only of secondary influence of the focusing when the electron beam passes ~ -thr w gh the aperture 9 at a small angle; as a result of this the aolour æ lection of the three electron beams 3, 4 and 5 takes pla oe in a manner quite analogous to that a much larger number of electrons impinge upon the display screen 6 and a brighter picture is formed.
The defocusing in the vertical direction need be no drawback if phosphor strips are used which are parallel to the longitudinal direction of the spot 10. Colour selection means aomprising a large number of quadrupole lenses have been realized in three manners. -In Figure 3 the colour selection means 7 ~-comprise two sets of parallel aonductors crossing each other. Of the first set the horizontally shown conductors 11 and 12 æe shown. Of the second set the vertically shown conductors 13 and 14 are shown. ~he aonductors 11, ;
12, 13 and 14 determine one of the apertures 9 and are insulated from each other by means of insulation material 15. m e three phosphor strips belonging to the aperture 9 are shown on the display screen 6 and are denoted by R (red), G (green) and B (blue). Only a few rays of the central electron beam 4 are shown in the Figure which form electr~n spot 10 on the phosphor strip G. The horizontal .. . -. ~ , .
.
~ Z~ PHN. 7638.
` conductors, including 11 and 12, are connected together and are at a higher potential than the vertical oonductors, including 13 and 14, oonnected together, as a result of which the quadrupole lens shown diagrammatically in Figure 2 is formed in each aperture 9.
Figure 4 shows a slightly varied em~odlment of the oolour selection means 7 in which interwoven horizontal and vertical conductors are used. A few horizontal conductors are designated 16, 17 and 18 and a few vertical oonductors are designated 19, 20 and 21.
The conductors are insulated from each other by means of insulation material 22.
m e colour selection means shown in - Figures 3 and 4 are manufactured as follows. Two sets of iran wires (the wires are preferably ferro-magnetic in connection with the screening of the earth's magnetic field) which are provided with glass insulation are pressed against each other in the desired manner in a mould or are interWDVen (Figure 4). m e assembly is then heated so that the wires with the glass insulation fuse together without, however, maXing electric contact with each other. The glass insulation is then remDved from the wire, with the ex oe ption of the crossings, so as to avoid undesired charging of the glass. ~his latter may be carried out by means of jets of pcwder frcm both sides in which the insulation of the crossing is in the shadow of the conductors or by spraying an etchant ... .. . ~ ~. - , , .
PHN. 7638.
21~
which reaches the insulation of the crossings with greater difficulty than elsewhere.
m e following results are reached in colour selection means shown in Figure 4 assenbled in a display tube and having conductors of a diameter of ~- -0.24 mm and a mutual pitch of 0.80 mm as a result of -which the transmission of the colour selection means is approx~mately 50 %. With a potential of the display screen 6 of 25 kV and a potential of the horizontal conductors of 24.55 kV and of the vertical conductors -of 25.45 kV, the focal distance of the quadrupole lenses is 18.0 mm in the centre of the display screen with incidence at right angles and 12.7 mm with an incidence of 37 in the corners of the display screen. The distan oe between the colour selection means 7 and the display screen 6 is 15 mm in the centre and 10 mm at the edge so that the focal point of the quadrupole lenses everywhere lies just slightly beyond the display - screen. As a result of this it is prevented that a so-called focal ring is visible on the display screen.
me electron spots in the centre of the display screen -; are 0.10 mm wide and in the oorner 0.09 mm wide. A
suitable width of the phosphor strips R, G and B then is 0.13 mm. m e remainder of the surface of the display screen may or may not ~e covered with a light-absorbing , material.
Fig~re 5 shows a few measured results :, :
.
- . . . -, . . .
- ~ . . ..
PHN. 7638.
~)4;~0~3 obtained with a configuration as shown in Figure 4 in a special measuring tube. In this case the diameter of the conductors was 0.2 mm and the pitch was on an average 1.2 mm. m e x-direction is parallel to a horizontal line on the display screen. m e light output in arbitrary units is plotted in the y-direction and is - measured by means of a very small aperture in a diaphragm which scans the display screen in the x-direction and a photomultiplier which receives the light which passes through the small aperture and converts it into an electric signal. m e measurements have been carried out at 0 Volt to 2000 Volts voltage difference between the horizontal and the vertical conductors, in steps of 250 Volts. m e very strong focusing at 2000 Volts is clearly visible in Figure 5.
` At 0 Volt only the vertical conductors produce shadcw - on the display screen and a uniformly illuminated spot is present behind each aperture 9. From the very steep Pdges of the measured curves the very small influence appears of secondary electrons which in the kncwn tube with post-focusing form a hazy edge (hals) around the light spots.
A third embodUm~nt of the colour selection means 7 is shown in Figure 6. In this case it oonsists of an iron plate 23 which has apertures 9 and a large number of vertical conductive strips tw~ of which are shown between the apertures 9 and are designated 24 and .. ,~.
.- :
' ::
, -PHN. 7638.
0~
25. The conductive strips are insulated from the iron plate by means of insulation material 26. m e plate 23 has a thickness of 0.15 mm. The insulation material 26, a glass layer, has a thickness of 0.06 mm. m e conductive strips consist of vapour-deposited aluninium and have a thickness of 0.0005 mm. m e apertures 9 are 0.56 x 0.56 mm and their pitch is 0.8 mm so that the transmission of the colour selection means is approximately 50 ~.
With a æ tential of the display screen 6 of 25 kV, a potential of the plate 23 of likewise 25 kV and a potential of the conductive strips 24 and 25 of 23.4 kV, the focal distan oe of the quadrupole lenses is 18 mm ~ -in the case of normal incidence in the oe ntre of the display screen and 12.7 mm in the case of inciden oe at 37 at the edge of the display screen. m e distance between the display screen 6 and the colour selection ~--~ means 7 is 15 mm in the centre of the display screen and 10 mm at the edge. m e electron spots in the centre -of the display screen are 0.10 mm wide and 0.09 mm in the corners and no focal ring is visible on the display screen. m e width of the phosphorstrips R, G and B is 0.13 mm. me remainder of the display screen may or may not be provided with a light-absorbing material.
The disp~lay screen 6 and the plate 23 are -connected electrically and re oe ive their voltage of 25 kV
from an external voltage source. m e voltage of 23,4 kV
which is app~lied to the conductive strips 24 and 25 may ' .
' :
., . ~.
-' :
,';:
PHN. 7638.
0~9 also originate fr~m an external voltage source. It is also possible not to connect the conductive strips to an external voltage source, but to cause them to be changed by the electron beams. Due to the charging with the electron beams, the quadrupole field is gradually formed in the apertures 9, as a result of the focusing effect of which the strips 24 and 25 will be hit by the electron beams to an even decreasing extent. m e final condition is stable and independent of the beam current because only very little current is necessary to maintain the potential of the strips 24 and 25.
A display screen for a tube according to the invention can be manufactured with a kncwn exposure method in which the colour selection means are reproduced on a -photo-sensitive layer on a window portion of the tube. In connection with the large transmission of the colour selection means according to the invention, the exposure method used should be suitable to reproduce the apertures 9 in a strongly narrcwed n~nner. An exposure method suitable for this purpose uses two or re light sources at some distan oe f m m each other. Of course, a tube according to the invention is also excellently suitable for so-called electronic exposure in which the sensitive layer on the window portion is "exposed" by means of an electr~n beam.
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Claims (7)
1. A cathode ray tube for displaying coloured pictures and comprising in an evacuated envelope means to generate a number of electron beams, a display screen com-prising a large number of regions luminescing in different colours, and colour selection means comprising a large number of apertures which assign each electron beam to luminescent regions of one colour, which colour selection means comprise electrodes to which voltages are applied to form an electron lens in each aperture, characterized in that said colour selection means and said electrodes form one unitary construction and that a quadrupole lens is formed in each aperture.
2. A cathode ray tube as claimed in Claim 1, characterized in that the luminescent regions of the display screen have the form of substantially parallel strips the longitudinal direction of which is substan-tially parallel to the defocussing direction of the quadrupole lenses.
3. A cathode ray tube as claimed in Claim 1, characterized in that the colour selection means are formed by a grid consisting of two sets of parallel conductors which cross each other, said conductors being electrically insulated from and mechanically con-nected to each other at the crossings and the conductors of each set being electrically connected together.
4. A cathode ray tube as claimed in Claim 3, characterized in that both sets of conductors are interwoven.
5. A cathode ray tube as claimed in Claim 1 or 2, characterized in that the colour selection means are formed by a metal plate which comprises the said apertures and conductive strips between the rows of apertures, said strips being electrically connected together and being insulated from the plate.
6. A cathode ray tube as claimed in Claim 1, characterized in that voltages from an external source are applied to the electrodes which constitute the quad-rupole lenses.
7. A cathode ray tube as claimed in Claim 1, characterized in that of the electrodes which constitute the quadrupole lenses, those electrodes conveying the highest positive potential are electrically connected to the display screen and the electrodes conveying the lowest positive potential are not connected to an exter-nal voltage source and are charged by the electron beams.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7409642A NL167798C (en) | 1974-07-17 | 1974-07-17 | ELECTRON BEAM FOR DISPLAYING COLORED IMAGES. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1042059A true CA1042059A (en) | 1978-11-07 |
Family
ID=19821774
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA231,143A Expired CA1042059A (en) | 1974-07-17 | 1975-07-09 | Cathode ray tube for displaying coloured pictures |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS5524652B2 (en) |
| AT (1) | AT341012B (en) |
| AU (1) | AU500139B2 (en) |
| BE (1) | BE831393A (en) |
| BR (1) | BR7504445A (en) |
| CA (1) | CA1042059A (en) |
| ES (1) | ES439433A1 (en) |
| FR (1) | FR2279220A1 (en) |
| GB (1) | GB1496949A (en) |
| IT (1) | IT1036237B (en) |
| NL (1) | NL167798C (en) |
| SE (1) | SE398414B (en) |
| ZA (1) | ZA754032B (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL7600422A (en) * | 1976-01-16 | 1977-07-19 | Philips Nv | ELECTRICAL DISCHARGE DEVICE. |
| NL7600417A (en) * | 1976-01-16 | 1977-07-19 | Philips Nv | METHOD OF MANUFACTURING A CATHODE RAY TUBE FOR DISPLAYING COLORED IMAGES. |
| NL7600418A (en) * | 1976-01-16 | 1977-07-19 | Philips Nv | METHOD FOR MANUFACTURING A COLOR IMAGE TUBE, COLOR IMAGE TUBE MADE IN ACCORDANCE WITH THE METHOD AND DEVICE FOR PERFORMING THE METHOD. |
| NL7600419A (en) * | 1976-01-16 | 1977-07-19 | Philips Nv | COLOR IMAGE TUBE AND METHOD OF MANUFACTURE THEREOF. |
| NL7704130A (en) * | 1977-04-15 | 1978-10-17 | Philips Nv | COLOR IMAGE TUBE. |
| NL7711773A (en) * | 1977-10-27 | 1979-05-02 | Philips Nv | COLOR IMAGE TUBE AND METHOD FOR THE MANUFACTURE OF SUCH COLOR IMAGE TUBE. |
| NL7806868A (en) * | 1978-06-27 | 1980-01-02 | Philips Nv | METHOD FOR MANUFACTURING ELECTRODE SYSTEMS AND SO MADE ELECTRODE SYSTEMS |
| US4316126A (en) * | 1979-11-23 | 1982-02-16 | Rca Corporation | Color television picture tube with color-selection structure and method of operation thereof |
| US4350922A (en) * | 1980-06-20 | 1982-09-21 | Rca Corporation | Multicolor cathode-ray tube with quadrupolar focusing color-selection structure |
| US4311944A (en) * | 1980-06-27 | 1982-01-19 | Rca Corporation | CRT With dipolar deflection and quadrupolar-focusing color-selection structure |
| US6919673B2 (en) | 2001-01-30 | 2005-07-19 | Kabushiki Kaisha Toshiba | Color cathode ray tube and method of manufacturing the same |
-
1974
- 1974-07-17 NL NL7409642A patent/NL167798C/en not_active IP Right Cessation
-
1975
- 1975-06-24 ZA ZA4032A patent/ZA754032B/en unknown
- 1975-07-09 CA CA231,143A patent/CA1042059A/en not_active Expired
- 1975-07-14 AU AU83006/75A patent/AU500139B2/en not_active Expired
- 1975-07-14 SE SE7508010A patent/SE398414B/en not_active IP Right Cessation
- 1975-07-14 IT IT68833/75A patent/IT1036237B/en active
- 1975-07-14 AT AT540575A patent/AT341012B/en not_active IP Right Cessation
- 1975-07-14 GB GB29413/75A patent/GB1496949A/en not_active Expired
- 1975-07-14 BR BR7504445A patent/BR7504445A/en unknown
- 1975-07-15 BE BE158321A patent/BE831393A/en not_active IP Right Cessation
- 1975-07-15 ES ES439433A patent/ES439433A1/en not_active Expired
- 1975-07-15 JP JP8662075A patent/JPS5524652B2/ja not_active Expired
- 1975-07-16 FR FR7522220A patent/FR2279220A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| ATA540575A (en) | 1977-05-15 |
| NL7409642A (en) | 1976-01-20 |
| SE398414B (en) | 1977-12-19 |
| NL167798C (en) | 1982-01-18 |
| BR7504445A (en) | 1977-02-15 |
| AU8300675A (en) | 1977-01-20 |
| FR2279220A1 (en) | 1976-02-13 |
| GB1496949A (en) | 1978-01-05 |
| BE831393A (en) | 1976-01-15 |
| AT341012B (en) | 1978-01-10 |
| JPS5524652B2 (en) | 1980-06-30 |
| NL167798B (en) | 1981-08-17 |
| DE2529697B2 (en) | 1977-03-17 |
| JPS5134663A (en) | 1976-03-24 |
| IT1036237B (en) | 1979-10-30 |
| AU500139B2 (en) | 1979-05-10 |
| ZA754032B (en) | 1977-01-26 |
| ES439433A1 (en) | 1977-02-01 |
| SE7508010L (en) | 1976-01-19 |
| FR2279220B1 (en) | 1979-07-27 |
| DE2529697A1 (en) | 1976-01-29 |
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