US3743984A

US3743984A - Magnetic convergence device for use in an in-line type color cathode ray tube

Info

Publication number: US3743984A
Application number: US00237855A
Authority: US
Inventors: K Itaka; S Takenaka; S Goshi
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1972-03-24
Filing date: 1972-03-24
Publication date: 1973-07-03
Anticipated expiration: 1990-07-03
Also published as: GB1330827A; NL164696B; NL164696C; FR2177559B1; CH534426A; FR2177559A1; DE2215723A1; DE2215723B2; NL7204295A

Abstract

A pair of E-shaped cores are mounted radially in opposite directions on the outer surface of a neck portion of an inline type color cathode ray tube. Each of the E-shaped cores has a center leg and two side legs about which dynamic convergence coils are wound in radial arrangement relative to the neck portion so as to converge electron beams from the cathode ray tubes along the longitudinal direction of the center legs of the respective cores. First and second disc-shaped permanent magnets are rotatably mounted on a cross-piece connecting the one side ends of the respective legs, and provide adjustable static fluxes cooperating with the dynamic convergence flux by travelling through the center and side legs and across the open ends thereof.

Description

United States Patent 1191 Takenaka et al. July 3, 1973 [54] MAGNETIC CONVERGENCE DEVICE FOR 3,496,501 2/1970 Harten et al 335/2l2 USE IN AN IN-LINE TYPE COLOR CATHODE RAY TUBE Primary ExaminerGeorge Harris Arr Rob tD. Fl L 0 ard Holtz et al. [75] lnventors: Shlgeo Takenaka; Seljl Goshl; Omey fir ynn e n Kazuhlko ltaka, all of Fukaya-shi, Saitama-ken, Japan [57] ABSTRACT A pair of E-shaped cores are mounted radially in oppo- [73] Asslgnee' {okyo l gl f Electric site directions on the outer surface of a neck portion of awasa apan an inline type color cathode ray tube. Each of the E- [22] Filed; Mar. 24, 1972 shaped cores has a center leg and two side legs about which dynamic convergence coils are wound in radial [21] Appl' 237855 arrangement relative to the neck portion so as to converge electron beams from the cathode ray tubes along [52] U.S. C1. 335/212, 313/77 the ngi in l ir ion of the center legs of the re- [51] Int. Cl. H01t 1/00 speetive ore First an econd isc-shaped permanent [58] Field of Search 335/210, 212, 213; m gn s are ro atably mounted on a cross-piece con- 313/75, 76, 77 necting the one side ends of the respective legs, and provide adjustable static fluxes cooperating with the [56] References Cited dynamic convergence flux by travelling through the UNITED STATES PATENTS center and side legs and across the open ends thereof.

3,305,807 2/1967 Ashley et al. 335/210 11 Claims, 8 Drawing Figures 43 a \36G 42; Q9 M 22x32 251112 1250 l23o\ 3 8 33 3410 320 2 Sheets-Sheet 1 FIG.

Patented July 3, 1973 FIG. 2

FIG. 3

Patent ed July 3, 1973 '2 Sheets-Sheet 2 Q 9 M m E: II

FIG.

FIG. 7

FIG. 8

MAGNETIC CONVERGENCE DEVICE FOR USE IN AN IN-LINE TYPE COLOR CATHODE RAY TUBE This invention relates to a magnetic convergence device for converging the multiple electron beams of an in-line type color cathode ray tube and more particularly to a magneticconvergence device having an improved static magnetic convergence means cooperating with a dynamic convergence means.

An in-line type color cathode ray tube has recently come into use as a color cathode ray tube. The in-line type. tube generally has three electron guns arranged in linear relationship, and the electron beams emitted from the guns are directed to a fluorescent screen through the neck portion keeping the in-line arrangement of said electron guns. Among these beams, the center beam is usually for a green color and the two side beams are respectively for red and blue colors. To provide a clear and proper color picture over the entire area of the fluorescent screen, it is necessary for the three electron beams convergently to impinge on a given small area of the fluorescent screen. For this purpose, a dynamic convergence means and a static convergence means cooperating therewith are generally provided on the outer surface of the neck portion in connectqon with the red and blue color electron beams. Further, the red and blue color electron beams should be deflected all over the fluorescent screen so as to obtain a good beam convergence, but any of the conventional convergence devices has failed to effect proper deflection.

Accordingly, it is an object of this invention to provide a magnetic convergence device for use in an inline type color cathode ray tube capable of adjusting the convergence of multiple electron beams accurately and uniformly.

i SUMMARY OF THE INVENTION In accordance with this invention, the abovementioned object can be achieved by providing a magnetic convergence device for use in an in-line tupe color cathode ray tube comprising a pair of E-shaped cores, each of said cores having a center leg, two side legs and a cross-piece connecting the ends of said center and said legs; a nonmagnetic frame having a tubular member for mounting said E-shaped cores radially in facing relationship on the outer surface of the neck portion of said cathode ray tube; dynamic convergence coils wound about said legs for generating a dynamic convergence flux therethrough; two disc-shaped permanent magnets for creating an adjustable static flux cooperating with said dynamic convergence flux by travelling through said legs and across the open ends thereof; and means'for rotatably mounting said permanent magnets on said cross-piece of at least one of said E-shaped cores.

The present invention can be more fully understood from the following detailed description when taken in connection with the accompanying drawings, in which:

FIG. 1 is a front view of a magnetic convergence device according to an embodiment of this invention;

FIG. 2 is a side view, partly in section, along line 22 of FIG. 1;

FIG. 3 is a schematic front view of the magnetic convergence device of FIG. 1, presenting the operation thereof;

FIG. 4 shows a modification of the convergence adjusting mechanism of thedevice of FIG. 1;

FIGS. 5 to 7 show other modifications of the static convergence adjusting mechanism of the device of FIG. 1; and

FIG. 8 is a fractional schematic front view of another embodiment of the invention.

Referring to FIGS. 1 and 2 of the accompanying drawings, a mounting frame 10 is made of a nonmagnetic material, preferably a plastic material. The mounting frame 10 has a tubular member 11 fitted around the outer surface of the neck portion 12 of an in-line type color cathode ray tube. The three

electron beams

13, 14 and 15 representing red, green and blue colors of the color cathode ray tube are aligned in line with one another and separated by

magnetic shield plates

16 and 17 so as to prevent interaction between the magnetic fields applied to the respective electron 13 to 15. The beams, in particular the beams 13 and 15, are therefore independently adjustable and their convergence is controlled by magnetic assemblies 18 and 19. The assemblies 18 and 19 are positioned external to the neck portion 12 of the cathode ray tube and adjacent to the internal

magnetic shield plates

16 and 17. The assemblies 18 and 19 create a flux for deflecting the respective beams 13 and 15. Each assembly, for example, assembly 18 comprises a dynamic electromagnet 20 and two disc-shaped

permanent magnets

21 and 22. Since each assembly is identical in structure, description of the parts of the assembly 18 will suffice and is applicable to those of the other assembly 19 which are designated by the same numerals having a letter a suffixed thereto.

The dynamic electromaget 20 has an E-shaped iron core prepared by powder metallurgy and consisting of a center leg 23, two

side legs

24 and 25 and a crosspiece, the cross-piece being divided into a portion 26 connected to the center leg 23 and two other portions 27 and 28 connected to the

side legs

24 and 25. Further, said cross--piece has magnetic gaps formed by nonmagnetic

adhesive spacers

29 and 30 disposed in the boundaries of the adjacent ones of the aforesaid three portions 26, 27 and 28.

Coils

31 and 32 are wound about the

side legs

24 and 25 to create an alternting flux by alternating current passing therethrough in addition to the static fluxes of

permanent magnets

21 and 22.

Each dynamic electromagnet 20 is secured between side shoulders 33 longitudinally of the subject magnetic convergence device with the innermost ends of the

side legs

24 and 25 tightly fitted to the inside of the top shoulders 34 so as to prevent the electromagnet 20 from unduly approaching the neck portion, that is, to allow a presecribed space therebetween.

The aforementioned shoulders 33 and 34 are formed on the frame 10 so as to support the

side legs

24 and 25 and also fit the innermost ends of the legs 23 to 25 around the outer surface of the neck portion 12.

Between the dynamic electromagnet 20 and the end wall 36 of the frame 10 are provided

permanent magnets

21 and 22 respectively supported by rotatable supporting members comprised of

rods

39 and 40 and adjusting

wheels

41 and 42. The

rods

39 and 40 have projections 37 fitted into perforations 38 provided in the wall 36 of the frame 10. Between the adjusting

wheels

41 and 42 and

permanent magnets

21 and 22, there are wound

compression coil springs

43 and 44 around the

rods

39 and 40 to press the

permanent magnets

21 and 22 against the crosspie'ce of the dynamic eleetromagnet 20. The

permanent magnets

21 and 22 have bores 45 rectangular in cross section to allow the passage therethrough of the top portions of the rods 39 and 4h having a rectangular cross section similar to that of the bores 45. Thus the permanent magnets 2R and 22 are normally pressed against the dynamic electromagnet 20, and, when rotated by manually turning the adjusting

wheels

41 and 22, can adjust the direction in which there is created a static flux therefrom. The

permanent magnets

21 and 22 are respectively so positioned as to bridge the boundaries defined by the central portion 26 of the cross-piece 28 with the adjacent portions 2'7 and 28. The height of the side portions of the frame lltll gradually decreases toward the end wall 36 to facilitate the manual rotation of adjusting wheels 41 and &2.

There will now be described by reference to FIG. 3 the operation of the magnetic convergence device shown in FIGS. l and 2. When the permanent magnet 21 generates a flux in the same direction, that is, the same polarity arrangement NS as the permanent magnet 22 as shown in the left side of FIG. 3, then the resultant compound flux F mainly passes through the paired

side legs

24 and 25 by travelling across a space defined between their mutually facing open ends, causing the red color electron beam 13 to be deflected in the direction indicated by the arrow I or II. The deflecting direction I or II of the red color electron beam 113 is determined by the directions in which the compound flux F and said beam 13 are travelling. For example, when the compound flux F takes a course shown by the arrow and the red color electron beam 13 is assumed to pass from the under to the upper surface of the drawing sheet, then said beam 13 will be deflected in the direction of the arrow I. And if the beam 13 travels conversely from the upper to the under surface thereof, then the beam 13 will be deflected in the direction of the arrow II.

On the other hand, when the

permanent magnets

21 and 22 create fluxes in opposite polarity arrangements, for example, of SN-NS as shown in the right side of FIG. 3, then the resultant compound flux Fa passes through the center leg 23a and is thereafter divided into two portions flowing from the open end of the center leg 23a to the open ends of the side legs 2 1a and 250. Further when the

permanent magnets

21 and 22 create fluxes in different opposite polarity arrangements from the previous case, that is, NS-SN, then the compound flux Fa travels conversely from the open ends of the side legs 24a and 25a to the open end of the center leg 23a. Accordingly, the blue color electron beam is deflected by the compound flux Fa in the direction shown by the arrow III or IV. The deflecting J direction of said beam 15 is determined similarly in accordance with the directions in which the compound flux Fa and the blue color electron beam l5 are travelling.

The peripheral portions of the adjusting wheels QR and 42 of FIG. 1 are separated as viewed in the crosswise direction of the magnetic convergence device but overlap each other as viewed in the lengthwise direction of said device. However as illustrated in FIG. 4, to facilitate the manual rotation of the

wheels

41 and 42, they may be so disposed as to have the peripheral portions thereof separated as viewed in the crosswise direction of the magnetic convergence device but prevented from overlapping each other as viewed in the lengthwise dirction thereof as in the previous case.

FIGS. 5 to '7 show the modifications of the static convergence adjusting mechanism of the magnetic convergence device of FIG. I. The static convergence adjusting mechanism of FIG. 5 comprises a supporting rod fixed to the end wall 36, the free end of the rod 50 rotatably supporting the permanent magnet 21!) by being received in a bore 51 provided therein, and a compression coil spring 52 for resiliently pressing the magnet Zlb against the cross-piece of the electromagnet 20.

The static convergence adjusting mechanism of FIG. 6 comprises a compression coil spring 53 stretched between the end wall 36 and permanent magnet 21 for resiliently pressing the magnet 21 against the cross-piece of the electromagnet 20 so as to permit the rotation of said magnet 2ll.

The static convergence adjusting mechanism of FIG. 7 comprises a hook-shaped leaf spring 54, the curved portion thereof engaging the surface of the magnet 21 so as to permit its rotation and the straight portion thereof being secured to the end wall 36.

In another embodiment of the invention of FIG. 8, an integrally formed E-shaped core 55 has

side legs

56 and 57, a center leg 58 and a cross-piece 59 connecting the ends of the legs 56 to 58. Dynamic coils 60, 61 and 62 are wound about the respective legs 56 to 58. The other elements of the embodiment of FIG. 8 are operated in the same manner as those of FIG. 1 and description thereof is omitted.

The foreggoing description relates to the case where the three legs had such lengths as permitted their close abutment against the periphery of the neck portion of the color cathode ray tube, with their end faces varied accordingly.

However, this invention is also applicable even where the center and paired side legs constituting the E- shaped core have substantially the same length and cross section.

What we claim is:

II. A magnetic convergence device for use in an inline type color cathode ray tube comprising:

a pair of E-shpaed cores, each having a center leg, two side legs and a cross-piece connecting the ends of said center and side legs;

a non-magnetic frame having a tubular member so as to mount said cores radially in facing relationship on the outer surface of the neck portion of said cathode ray tube;

dynamic convergence coils wound about said legs so as to generate a dynamic convergence flux therethrough;

at least two disc-shaped permanent magnets for creating an adjustable static flux cooperating with said dynamic convergence flux by traveling through said legs and across the open ends thereof; and

means for rotatably mounting two of said permanent magnets on the cross-piece of at least one of said E-shaped cores such that said permanent magnets are both rotatable relative to said at least one core.

2. A magnetic convergence device as claimed in claim ll wherein each of said E-shaped cores has a cross-piece separated into first, second and third divisions respectively connected to said center and side legs with first and second magnetic gaps provided between the adjacent ones of said divisions; and said permanent magnets are so positioned as to bridge the magnetic gaps.

3. A magnetic convergence device as claimed in claim 1 wherein said means for rotatably supporting the permanent magnets has two supporting members, each of which is pivotally mounted on said frame and has an adjusting wheel, a rod member with a rectangular head, each of said magnets having a rectangular bore for slidably receiving said rectangular head, and a spring member for resiliently pressing said magnet against said cross-piece.

4. A magnetic convergence device as claimed in claim 3 wherein the first and second adjusting wheels included in said two supporting members are positioned at different distances from the end wall of the frame.

5. A magnetic converence device as claimed in claim 4 wherein the peripheral portions of the first and second adjusting wheels overlap each other as viewed in the lengthwise direction of the convergence device.

6. A magnetic convergence device as claimed in claim 4 wherein said first and second adjusting wheels are so disposed as to prevent their peripheral portions from overlapping each other as viewed in the lengthwise direction of the convergence device.

7. A magnetic convergence device as claimed in claim 1 wherein said means for rotatably supporting the permanent magnets include supporting rods secured to said frame, said magnets having bores for rotatably receiving the free end of said supporting rods and spring members for resiliently pressing said magnets against said cross-piece.

8. A magnetic convergence device as claimed in claim 1 wherein said means for rotatably supporting the permanent magnets include spring members stretched between said frame and permanent magnets for resiliently pressing said magnets against said cross-piece.

9. A magnetic convergence device as claimed in claim 8 wherein said spring member is a compression coil spring.

10. A magnetic convergence device as claimed in claim 8 wherein said spring member is a hook-shaped leaf spring, the curved portion thereof engaging the surface of said magnets and the straight portion being secured to said frame.

11. A magnetic convergence device as claimed in claim 1 comprising four disc-shaped permanent magnets, and wherein said means for rotatably mounting said magnets includes means for rotatably mounting two of said permanent magnets on respective crosspieces of each of said E-shaped cores.

Claims

1. A magnetic convergence device for use in an in-line type color cathode ray tube comprising: a pair of E-shpaed cores, each having a center leg, two side legs and a cross-piece connecting the ends of said center and side legs; a non-magnetic frame having a tubular member so as to mount said cores radially in facing relationship on the outer surface of the neck portion of said cathode ray tube; dynamic convergence coils wound about said legs so as to generate a dynamic convergence flux therethrough; at least two disc-shaped permanent magnets for creating an adjustable static flux cooperating with said dynamic convergence flux by traveling through said legs and across the open ends thereof; and means for rotatably mounting two of said permanent magnets on the cross-piece of at least one of said E-shaped cores such that said permanent magnets are both rotatable relative to said at least one core.

2. A magnetic convergence device as claimed in claim 1 wherein each of said E-shaped cores has a cross-piece separated into first, second and third divisions respectively connected to said center and side legs with first and second magnetic gaps provided between the adjacent ones of said divisions; and said permanent magnets are so positioned as to bridge the magnetic gaps.

11. A magnetic convergence device as claimed in claim 1 comprising four disc-shaped permanent magnets, and wherein said means for rotatably mounting said magnets includes means for rotatably mounting two of said permanent magnets on respective cross-pieces of each of said E-shaped cores.