CA1043412A - Deflection coil device for cathode ray tube - Google Patents
Deflection coil device for cathode ray tubeInfo
- Publication number
- CA1043412A CA1043412A CA286,212A CA286212A CA1043412A CA 1043412 A CA1043412 A CA 1043412A CA 286212 A CA286212 A CA 286212A CA 1043412 A CA1043412 A CA 1043412A
- Authority
- CA
- Canada
- Prior art keywords
- tube
- supporting
- cage
- coil device
- deflection coil
- 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
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- Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
Abstract
ABSTRACT
In picture display tubes having deflection angles of 110° and more the conical central part near the transition to the neck has a substantially flat variation perpendicular to the tube axis. As a result of this an accurate positioning of the deflection device on the display tube is seriously hampered. this problem is solved by centering members which are present on the conical central part and which cooperate in a self-centring manner with centring members forming part of the supporting cage of the deflection device.
The position of the deflection device in the axial direction is ac-curately fixed by abutment members forming part of the supporting cage in co-operation with abutment surfaces forming part of the envelope of the tube.
In picture display tubes having deflection angles of 110° and more the conical central part near the transition to the neck has a substantially flat variation perpendicular to the tube axis. As a result of this an accurate positioning of the deflection device on the display tube is seriously hampered. this problem is solved by centering members which are present on the conical central part and which cooperate in a self-centring manner with centring members forming part of the supporting cage of the deflection device.
The position of the deflection device in the axial direction is ac-curately fixed by abutment members forming part of the supporting cage in co-operation with abutment surfaces forming part of the envelope of the tube.
Description
~0434~Z
The invention relates to a picture display device com-prising a picture display tube having an envelope including a display screen a neck and an intermediate cone portion, means for generating at least one electron beam disposed in said neck and means disposed on said cone portion, for centering a deflection coil supporting cage with respect to the longitudinal axis of the tube.
Such a picture display device is known from the United States Patent Specification 2,354,661 which issued on August 1, 1944 to General Electric Company.
The developement of picture display tubes has of late ~ -years been considerably directed to the construction of display tubes having smaller and smaller dimensions in the axial direction.
For that purpose, the electron beam or beams generated in an el-ectrode system are deflected over an ever increasing angle. Start- --ing with a deflection angle of 70, said development has continued via a deflection angle of 90 to the nowadays usual construction having a deflection angle of 110. The problems associated with ~ --this development, however, do not only relate to the construction -of the deflection coils themselues, but also to the connection of the supporting cage thereof on the envelope of the display tube.
According 8S the deflection angle is larger, more stringent re- :quirements are imposed upon the accuracy with which the system of deflection coils can be positioned relative to the optical axis of the electrode system present within the neck of the tube. In part- -, icular in the case of colour television display tubes it is of im-portance that the central axis of the system of deflection coils :
coincides as accurately as possible with the said optical axis so as to minimize colour defects as a result of mislandings of an electron beam on the display screen. ~
, :' ~ .:' '
The invention relates to a picture display device com-prising a picture display tube having an envelope including a display screen a neck and an intermediate cone portion, means for generating at least one electron beam disposed in said neck and means disposed on said cone portion, for centering a deflection coil supporting cage with respect to the longitudinal axis of the tube.
Such a picture display device is known from the United States Patent Specification 2,354,661 which issued on August 1, 1944 to General Electric Company.
The developement of picture display tubes has of late ~ -years been considerably directed to the construction of display tubes having smaller and smaller dimensions in the axial direction.
For that purpose, the electron beam or beams generated in an el-ectrode system are deflected over an ever increasing angle. Start- --ing with a deflection angle of 70, said development has continued via a deflection angle of 90 to the nowadays usual construction having a deflection angle of 110. The problems associated with ~ --this development, however, do not only relate to the construction -of the deflection coils themselues, but also to the connection of the supporting cage thereof on the envelope of the display tube.
According 8S the deflection angle is larger, more stringent re- :quirements are imposed upon the accuracy with which the system of deflection coils can be positioned relative to the optical axis of the electrode system present within the neck of the tube. In part- -, icular in the case of colour television display tubes it is of im-portance that the central axis of the system of deflection coils :
coincides as accurately as possible with the said optical axis so as to minimize colour defects as a result of mislandings of an electron beam on the display screen. ~
, :' ~ .:' '
- 2 - ~
. i . . "
10434~Z
In the usual connection, the supporting cage is slid over the neck of the tube until a supporting ring forming part of the supporting cage engages the conical central part. The supporting cage is clamped on the rear side on the neck of the tube by means of a clamping band.
Since in tubes having a deflection angle of 110 the conical central part near the transition to the neck has a sub-stantially flat variation at right angles to the axis of the tube, an accurate positioning of the supporting cage at the area where it engages the said conical central part is seriously hampered.
In the picture display device known from the said United States Patent Specification the cathode-ray tube describ-ed therein which otherwise has a comparatively small deflection angle shows a cylindrical part at the area of the centre of gravity of the tube around which means are provided to support --the tube during mounting thereof in a cabinet. For that purpose, the said cylindrical part has screwthread or a flange which may be moulded in the glass and on which the supporting cage of the system of deflection coils is also screwed or secured by means of bolts. Such a way of connection is not easy to control and - -hardly ensures an accurate positioning of the system of de-flection coils since for each of the members required for said --~
connection an accurate positioning and precision is required.
It is the object of the invention to provide a pic-ture display device of the type mentioned in the preamble in which the said problems are solved in a simple and efficacious - ~ -manner. -~ - -For that purpose, a picture display device according -to the invention is characterized in that the centering edge -for centring the supporting cage on the cone portion of the
. i . . "
10434~Z
In the usual connection, the supporting cage is slid over the neck of the tube until a supporting ring forming part of the supporting cage engages the conical central part. The supporting cage is clamped on the rear side on the neck of the tube by means of a clamping band.
Since in tubes having a deflection angle of 110 the conical central part near the transition to the neck has a sub-stantially flat variation at right angles to the axis of the tube, an accurate positioning of the supporting cage at the area where it engages the said conical central part is seriously hampered.
In the picture display device known from the said United States Patent Specification the cathode-ray tube describ-ed therein which otherwise has a comparatively small deflection angle shows a cylindrical part at the area of the centre of gravity of the tube around which means are provided to support --the tube during mounting thereof in a cabinet. For that purpose, the said cylindrical part has screwthread or a flange which may be moulded in the glass and on which the supporting cage of the system of deflection coils is also screwed or secured by means of bolts. Such a way of connection is not easy to control and - -hardly ensures an accurate positioning of the system of de-flection coils since for each of the members required for said --~
connection an accurate positioning and precision is required.
It is the object of the invention to provide a pic-ture display device of the type mentioned in the preamble in which the said problems are solved in a simple and efficacious - ~ -manner. -~ - -For that purpose, a picture display device according -to the invention is characterized in that the centering edge -for centring the supporting cage on the cone portion of the
- 3 -- ,, , , , , , , , , , : ,; ,, , ~043~Z
tube has a centering surface which is conical relative to the longitudinal axis of the tube and which cooperates with centr-ing members forming part of the supporting cage. Because of the self-centering effect of the conical surface of the center-ing edge of the invention, the invention ensures a readily de-fined and very accurate position of the supporting cage on the envelope o1` a picture display tube. The manner of securing is very reproducible and is excellently suitable for use in picture display devices for colour television. As already noted, an ac-curate position of the system of deflection coils is an indis-pensable requirement in this application.
According to the invention, the said centring edge may be interrupted so that a number of centring cams are ob-tained.
Preferably the cone portion of the tube has an axial abutment for the supporting cage disposed in a plane perpendicular to the longitudinal axis of the tube. Such an axial abutment -may have the form of an abutment edge or a number of abutment ~ -cams cooperating with abutment members present on the supporting -cage. According to the invention, the said axial abutment pre-ferably consists of an end face which bounds the centring edge - - --on the side facing the neck of the tube. ~- -According to a further embodiment of the invention the supporting cage comprises on its side facing the display screen -~
a supporting edge which forms a polygon in cross-section. The ;
centres of the sides of the polygon in cooperation with a con-ical centring edge on the envelope deviate resiliently in the radial direction until the abutment members of the supporting cage bear on the axial abutment disposed on the tube. ;~
In another embodiment of the invention the supporting , , ~ . .
lV43412 edge of the supporting cage has centring cams on the inside of the supporting edge facing the longitudinal axis of the tubes. -At least in case of a circular cylindrical supporting edge, according to the invention said supporting edge has incisions which extend in the axial direction on either side of said centring cams so as to obtain the said resilient action.
According to a further embodiment of the invention said centring cams may form one assembly with the above-mention-ed abutment members of the supporting cage.
The invention is partlcularly suitable when used in a picture display device for colour television the picture dis-play tube of which comprises an electrode system which generates three electron beams which are present substantially in one plane.
In such a system, as is known, means for a dynamic convergence of the electron beams may be omitted. A condition in that case is, however, that the system of deflection coils for the said three beams is very accurately positioned relative to the el-ectron optical axis so as to compensate for the lack of electric correction means. -It is to be noted that it is known to use in such a picture display tube for the connection of the deflection device ~-a ring which is cemented to the conical central part (see I.E.E.E.
Transactions on Broadcast and Television Receivers, 1972, Volume BTR-18, Nr. 3, pp. 193-200). Said ring has projections which project with ample play through recesses provided in the sup-porting cage. After providing the deflection device in the de-s~red position, the recesses are filled with a thermoplastic mat-erial and the deflection device is permanently secured to the tube. In this case there is no question of a self-centring ring.
Such a manner of connectlon presents problems in a possible re-., .
1~43412 pair of the tube while readjustment of the deflection device can be carried out with difficulty only.
The invention will be described in greater detail with reference to a drawing, in which Figure 1 is a partial cross-sectional view of an embod-iment according to the invention, Figure 2 is a perspective view of the deflection device shown in Figure 1, Figure 3 shows an embodiment of a clrcular cylindrical supporting edge, and Figure 4 shows another embodiment of a supporting edge in cooperation with a non-conical centring edge.
The device shown in Figure 1 consists inter alia of a colour television display tube 1, the envelope of which is formed by a display screen 2, a cone portion 3 and a neck 4. An electrode system 5, shown diagrammatically, for generating three electron beams located ;n one plane is present in the neck 4. Said beams on their way to the display screen 2 are deflected by a magnetic -field generated by a deflection device 5 secured to the tube.
For that purpose, said deflection device comprises a system of deflection coils which is secured on an inner cage 7 of a synthetic material and which consists of a number of deflection coils 8 and an annular core 9 which are shown diagrammatically in the Figure.
The inner cage 7 has studs 10 which project through holes 11 in the supporting cage 12 of synthetic material. The holes 11 are elongated in the axial direction. The studs 10 also project through holes 13 which are elongated in the radial direction and are provided in the closing plates 14 (see Figure 2). So ~-relative to the supporting cage 12, the inner cage 7 can be moved along its longitud~nal direction and be rotated thereabout.
10434~Z
By tightening the wingnuts 15, the inner cage is secured relative to the supporting cage.
As is obvious from Figure 2, the supporting cage has a hexagonal supporting ring 16 of which the centres of the sides which are denoted by 17 cooperate with a conical centring edge 18.
Said centring edge is bounded externally by a curved centring sur-face 19 and an end face 20 which is present in a plane perpendic-ular to the tube axis. Curved surface and end face intersect each other at an angle of 110. (This angle is not critical but is preferably chosen to be between 100 and 130). The end face 20 forms an axial abutment for the supporting cage 12, namely for -a number of abutment members 22 thereof. (Although six abutment members are shown, said three are already sufficient).
Upon assembling, the deflection device 6 is slid over ~ -the tube neck 4 until the centres of the sides of the hexagonal supporting edge 16 which are denoted by 17 bear on the curved ~-centring surface 19. The side of the deflection device re-mote from the display screen is centred on the neck of the tube by means of a gu;de 24 which forms part of the supporting cage. -The side of the deflection device facing the display screen is now centred by moving the supporting edge further in the direction of ~-~
the display screen. The centres 17 of the sides of the supporting edge 16 are slightly forced outwardly radially by the curved centr-ing surface 19, as is denoted by 21. In this stage of the assembly, ;~
the deflection device is accurately centred relative to the tube -axis by the self-centring action of the curved surface 19. The position in the axial direction is fully established by the abut-ment members 22 in cooperation with the end face 20 of the centr- -ing edge 18. The clamping band 23 provided around the guide 24 is now tightened so that the deflection device 6 is accurately centred on the display tube 1.
10~34~2 F;gures 3 and 4 show two embodiments in the case in which the centring edge present on the cone portion of the tube is not conical. In Figure 3 the circular cylindrical supporting edge 30 has centring cams 34 with centring surfaces 31 present on a conical surface relative to the tube axis. On either side of the cams 34 the supporting edge 30 has incisions 32 which extend in the axial direction and which permit of a deviation of the cams 34 in the radial direction. The abut- -ment members 33 are shown individually but, as shown in Figure 4, they may also form one assembly with the centring cams. The centring cams 41 cooperate with the non-conical centring edge 44 and have centring surfaces 44 and abutment faces 42. The -supporting edge 40 in cross-section may be either a polygon or a circle.
In the axial direction the position of the supporting cage is fully determined by a centring edge (18, 44) forming one : -assembly with the conical central part. Said centring edge may serve as a common reference both during the positioning of the system of deflection coils and that of, for example, the electrode ~ -system in the neck of the tube. Such a common reference increases - ~--the accuracy in the positioning of the components mutually.
. . .
tube has a centering surface which is conical relative to the longitudinal axis of the tube and which cooperates with centr-ing members forming part of the supporting cage. Because of the self-centering effect of the conical surface of the center-ing edge of the invention, the invention ensures a readily de-fined and very accurate position of the supporting cage on the envelope o1` a picture display tube. The manner of securing is very reproducible and is excellently suitable for use in picture display devices for colour television. As already noted, an ac-curate position of the system of deflection coils is an indis-pensable requirement in this application.
According to the invention, the said centring edge may be interrupted so that a number of centring cams are ob-tained.
Preferably the cone portion of the tube has an axial abutment for the supporting cage disposed in a plane perpendicular to the longitudinal axis of the tube. Such an axial abutment -may have the form of an abutment edge or a number of abutment ~ -cams cooperating with abutment members present on the supporting -cage. According to the invention, the said axial abutment pre-ferably consists of an end face which bounds the centring edge - - --on the side facing the neck of the tube. ~- -According to a further embodiment of the invention the supporting cage comprises on its side facing the display screen -~
a supporting edge which forms a polygon in cross-section. The ;
centres of the sides of the polygon in cooperation with a con-ical centring edge on the envelope deviate resiliently in the radial direction until the abutment members of the supporting cage bear on the axial abutment disposed on the tube. ;~
In another embodiment of the invention the supporting , , ~ . .
lV43412 edge of the supporting cage has centring cams on the inside of the supporting edge facing the longitudinal axis of the tubes. -At least in case of a circular cylindrical supporting edge, according to the invention said supporting edge has incisions which extend in the axial direction on either side of said centring cams so as to obtain the said resilient action.
According to a further embodiment of the invention said centring cams may form one assembly with the above-mention-ed abutment members of the supporting cage.
The invention is partlcularly suitable when used in a picture display device for colour television the picture dis-play tube of which comprises an electrode system which generates three electron beams which are present substantially in one plane.
In such a system, as is known, means for a dynamic convergence of the electron beams may be omitted. A condition in that case is, however, that the system of deflection coils for the said three beams is very accurately positioned relative to the el-ectron optical axis so as to compensate for the lack of electric correction means. -It is to be noted that it is known to use in such a picture display tube for the connection of the deflection device ~-a ring which is cemented to the conical central part (see I.E.E.E.
Transactions on Broadcast and Television Receivers, 1972, Volume BTR-18, Nr. 3, pp. 193-200). Said ring has projections which project with ample play through recesses provided in the sup-porting cage. After providing the deflection device in the de-s~red position, the recesses are filled with a thermoplastic mat-erial and the deflection device is permanently secured to the tube. In this case there is no question of a self-centring ring.
Such a manner of connectlon presents problems in a possible re-., .
1~43412 pair of the tube while readjustment of the deflection device can be carried out with difficulty only.
The invention will be described in greater detail with reference to a drawing, in which Figure 1 is a partial cross-sectional view of an embod-iment according to the invention, Figure 2 is a perspective view of the deflection device shown in Figure 1, Figure 3 shows an embodiment of a clrcular cylindrical supporting edge, and Figure 4 shows another embodiment of a supporting edge in cooperation with a non-conical centring edge.
The device shown in Figure 1 consists inter alia of a colour television display tube 1, the envelope of which is formed by a display screen 2, a cone portion 3 and a neck 4. An electrode system 5, shown diagrammatically, for generating three electron beams located ;n one plane is present in the neck 4. Said beams on their way to the display screen 2 are deflected by a magnetic -field generated by a deflection device 5 secured to the tube.
For that purpose, said deflection device comprises a system of deflection coils which is secured on an inner cage 7 of a synthetic material and which consists of a number of deflection coils 8 and an annular core 9 which are shown diagrammatically in the Figure.
The inner cage 7 has studs 10 which project through holes 11 in the supporting cage 12 of synthetic material. The holes 11 are elongated in the axial direction. The studs 10 also project through holes 13 which are elongated in the radial direction and are provided in the closing plates 14 (see Figure 2). So ~-relative to the supporting cage 12, the inner cage 7 can be moved along its longitud~nal direction and be rotated thereabout.
10434~Z
By tightening the wingnuts 15, the inner cage is secured relative to the supporting cage.
As is obvious from Figure 2, the supporting cage has a hexagonal supporting ring 16 of which the centres of the sides which are denoted by 17 cooperate with a conical centring edge 18.
Said centring edge is bounded externally by a curved centring sur-face 19 and an end face 20 which is present in a plane perpendic-ular to the tube axis. Curved surface and end face intersect each other at an angle of 110. (This angle is not critical but is preferably chosen to be between 100 and 130). The end face 20 forms an axial abutment for the supporting cage 12, namely for -a number of abutment members 22 thereof. (Although six abutment members are shown, said three are already sufficient).
Upon assembling, the deflection device 6 is slid over ~ -the tube neck 4 until the centres of the sides of the hexagonal supporting edge 16 which are denoted by 17 bear on the curved ~-centring surface 19. The side of the deflection device re-mote from the display screen is centred on the neck of the tube by means of a gu;de 24 which forms part of the supporting cage. -The side of the deflection device facing the display screen is now centred by moving the supporting edge further in the direction of ~-~
the display screen. The centres 17 of the sides of the supporting edge 16 are slightly forced outwardly radially by the curved centr-ing surface 19, as is denoted by 21. In this stage of the assembly, ;~
the deflection device is accurately centred relative to the tube -axis by the self-centring action of the curved surface 19. The position in the axial direction is fully established by the abut-ment members 22 in cooperation with the end face 20 of the centr- -ing edge 18. The clamping band 23 provided around the guide 24 is now tightened so that the deflection device 6 is accurately centred on the display tube 1.
10~34~2 F;gures 3 and 4 show two embodiments in the case in which the centring edge present on the cone portion of the tube is not conical. In Figure 3 the circular cylindrical supporting edge 30 has centring cams 34 with centring surfaces 31 present on a conical surface relative to the tube axis. On either side of the cams 34 the supporting edge 30 has incisions 32 which extend in the axial direction and which permit of a deviation of the cams 34 in the radial direction. The abut- -ment members 33 are shown individually but, as shown in Figure 4, they may also form one assembly with the centring cams. The centring cams 41 cooperate with the non-conical centring edge 44 and have centring surfaces 44 and abutment faces 42. The -supporting edge 40 in cross-section may be either a polygon or a circle.
In the axial direction the position of the supporting cage is fully determined by a centring edge (18, 44) forming one : -assembly with the conical central part. Said centring edge may serve as a common reference both during the positioning of the system of deflection coils and that of, for example, the electrode ~ -system in the neck of the tube. Such a common reference increases - ~--the accuracy in the positioning of the components mutually.
. . .
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A deflection coil device for a picture display tube, said device having a system of deflection cells mounted in a supporting cage having a longitudinal axis, said supporting cage having a supporting edge including radially resilient centering means for selfcentering said cage on the envelope of the tube.
2. A deflection coil device as claimed in Claim 1, wherein the supporting edge in cross-section forms a polygon.
3. A deflection coil device as claimed in Claim 1 or 2, wherein the supporting cage has abutment member means for cooperating with axial abutment means on the tube.
4. A deflection coil device as claimed in Claim 1, wherein the supporting edge has centering cams on its side facing said longitudinal axis.
5. A deflection coil device as claimed in Claim 4, wherein the supporting edge on either side of each cam has incisions which extend substantially in the axial direction.
6. A deflection coil device as claimed in Claim 4 or 5, wherein the centering cams also comprise abutment members for cooperating with axial abutment means on the tube.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7311430.A NL164154C (en) | 1973-08-20 | 1973-08-20 | IMAGE DISPLAY DEVICE. |
| CA207,136A CA1027164A (en) | 1973-08-20 | 1974-08-15 | Deflection coil support for cathode ray tube |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1043412A true CA1043412A (en) | 1978-11-28 |
Family
ID=25667662
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA286,212A Expired CA1043412A (en) | 1973-08-20 | 1977-09-07 | Deflection coil device for cathode ray tube |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1043412A (en) |
-
1977
- 1977-09-07 CA CA286,212A patent/CA1043412A/en not_active Expired
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