US3643121A

US3643121A - A triple electron gun apparatus provided with convergence electrode

Info

Publication number: US3643121A
Application number: US831314A
Authority: US
Inventors: Shinichi Sawagata; Masakatsu Nakahara; Asahide Tsuneta
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1968-06-10
Filing date: 1969-06-09
Publication date: 1972-02-15
Anticipated expiration: 1989-02-15
Also published as: FR2010610A1

Abstract

A triple electron gun apparatus comprises three electron gun units, a convergence electrode for converging electron beams emitted from said units, and three insulating support bars. These bars juxtapose the units to form a triple electron gun assembly as well as securely join the convergence electrode with the triple electron gun assembly.

Description

United States Patent Sawagata et al.

[ Feb. 15, 1972 TRIPLE ELECTRON GUN APPARATUS PROVIDED WITH CONVERGENCE ELECTRODE Inventors: Shlniehi Saw-guts, Tokyo; Masaluttsu Nalmhlra; Auhide Tauncta, both of YOkOhBlflii-llhl, all of Japan Assignec: 'lokyo Shlhuura Electric Co., Ltd..

Kawasaki-shi, Japan Filed: June 9, 1969 Appl. No.: 831,314

Foreign Application Priority Data June I0, 1968 Japan ..43/39430 US. Cl ..3l3/70, 29/25.l5, 313/251 Int. Cl ..I-l0lj 29/02, I-l0lj l9/46, HOlj 9/18 [58] l leldolscarch ..3l3/70C [56] Itelcrcnces Cited UNITED STATES PATENTS 3,268,753 8/1966 Hughes ..3 l 3/70 X Primary Examiner Robert Scgal Allumey-lrving M. Wcincr 57 ABSTRACT A triple electron gun apparatus comprises three electron gun units, a convergence electrode for converging electron beams emitted from said units, and three insulating support bars These bars juxtapose the units to form a triple electron gun assembly as well as securely join the convergence electrode with the triple electron gun assembly.

5 China, 16 Drawing Figures PAIENTEUFEMS r912 3.643.121

SHEEIIOFS 22v I I8 1 1g 14 Prior Art) (Prior Art) PATENTEDFEBISIQTZ 3.643.121

swan u 0F 5 FIGIO A TRIPLE ELECTRON GUN APPARATUS PROVIDED WITII CONVERGENCE ELECTRODE The present invention relates to a triple electron gun apparatus, particularly a triple electron gun apparatus having a convergence electrode disposed ahead of a triple electron gun assembly and also to a method for manufacturing the same.

A triple electron gun apparatus generally used in a shadowmaslt-type color television picture tube comprises three electron gun units each emitting electron beams and a convergence electrode arranged in the under-mentioned relationship. Namely, the respective electron gun units are juxtaposed in such a manner that their central axes are aligned with the edges of an equilateral triangular core. Further, these electron gun units are so inclined as to cause electron beams released therefrom to intersect each other at the hole of a shadow mask disposed at a prescribed position in the aforementioned image pickup tube and integrally supported by support bars. This is formed the triple electron gun assembly. Ahead of this assembly is coaxially positioned a convergence electrode for converging electron beams. There will now be described by reference to FIGS. I and 2 the above-mentioned conventional triple electron gun apparatus and the method for manufacturing the same. Each electron gun unit I4 comprises afirst cylindrical grid electrode to including an electron beam-emitting cathode and second to fourth grid electrodes II, I2 and 13 successively disposed ahead of said first grid electrode in coaxial relationship therewith. Three such electron gun units are juxtaposed to fonn a triple electron gun assembly I5. These units are fixed in place by means of metal strips 16. each of which is welded to part of the outer circumferential wall of the respective electrodes constituting each unit. and the end of each of which is fixed to a support bar 17 made of insulating material and disposed parallel to the central axis of each unit. said support bar 17 being provided for each unit. At a prescribed position ahead of the triple electron gun assembly IS having the aforementioned arrangement is positioned a convergence electrode 18 as illustrated in FIG. 2 to form a triple electron gun apparatus. There will now be described the arrangement of said convergence electrode. This convergence electrode I8 has a cylindrical cup-shaped electrode 20. the bottom of which is perforated with three spatially arranged through holes I9 for allowing the pasage of electron beams. In the cup-shaped electrode are disposed three pairs of convergence electrode plates 21 with each of the aforesaid through holes I9 lying at the part between the paired convergence plates. and a Y-shaped shielding plate 22 which is so arranged that each group consisting of one pair of convergence electrode plates associated with each through hole 19 is separated from the other groups by the shielding plate 22. The convergence electrode 18 is fitted to the triple electron gun assembly I5 by fixing to the bottom ofthe cup-shaped elec trode 2O byweldingorother meansasupportstripZJprojectingly formed at the furthest end of the fourth grid electrode [3 of each electron gun unit [4. The weldingof said supportstripZJtothebottom ofthecup-shapedelectmdenis carried out by holding both the electron gun unit Id and cupshaped electrodebymeansofnfrginsuchamannerthatthe central axis of each electron gun unit I is aligned with the cemerofeachofthe throughholes I9ofthecup-shapedelectrode 20.

According to the prior art the convergence electrode 18 and the triple electron gun assembly I5 are separntcdly fabricated. and thereafterjoined togetherwith high precision soastomaintaintheirprescribed relationship.t.husrequiringa complicated asembling jig. Even with such jig, it is difficult to causethecentralsxisoftheconvergenceelectrode lltoaccord with that of the triple electron gun assembly I5. Moreoverthese two members I5 and I8 ofthe tripleelectron gun apparatus are only joined together by the aforesaid supportstripsfiJotlnttheyareliabletobedisplacedfmmtheit original positions during use. causing the apparatus as a whole to fail in its proper performance.

The present invention provides triple electron gun apparatus and a method for manufacturing the same. wherein the contact points of a convergence electrode member are fixed to the furthest end of each of three support bars made of insulating material used in assembling three electron gun units in prescribed relationship to each other. thereby integrally joining said convergence electrode unit with each electron gun member. The present invention enables the convergence electrode member to be fixed at once with a triple electron gun assembly by means of said three support bars. thus simplifying the method of manufacturing a triple electron gun apparatus and allowing it to have a very accurate coaxial relationship among the parts and display great durability as a whole.

This invention can be more fully understood from the following detaileddescription when taken in connection with reference to the accompanying drawings. in which:

FIGS. 1 and 2 show a triple electron gun apparatus of the prior art; FIG. I is a sectional view and FIG. 2 is a plan view of the same;

FIGS. 3 to 5 present a triple electron gun apparatus according to an embodiment of the present invention; FIG. 3 is an enlarged perspective view of particularly a convergence electrode; FIG. 4 is a plan view of said electrode and FIG. 5 is a perspective view of a triple electron gun apparatus involving said convergence electrode;

FIGS. 6 and illustrate a device for assembling the triple electron gun apparatus of FIG. 5; FIG. 6 is an elevation, with part broken away, of said asernbling device and FIG. 7 is a section of the device broken away along aline 7-7 in FIG. 6;

FIG. 8 indicates the sections of the locating bar of said assembling device and columnar support, illustrating the degree of inclination of said locating bar;

FIG. 9 is an enlarged section of the third and fourth electrodes shown in 6, as well as of spacers interposed therebetween;

FIGS. I0 to present a triple electron gun apparatus according to another embodiment of the present invention; FIG. 10 is a perspective view of the convergence electrode; FIG. I I is an enlarged sectionofthe cavity ofFIG. I0; FIG. I2 is a perspective view of the shielding electrodes of the convergence electrode member. FIG. 13 is a perspective view of a support element fitted to the first electrodes of the triple electron gun assembly; and FIG. I4 is a perspective view of the entire assembled triple electron gun apparatus; and

FIGS. 15 and 16 indicate part of the assembling device of the triple electrongun apparatus shown in FIG. 14; FIG. I5 is a section, with part broken away, of the electrodes supported by two locating bars; and FIG. I6 is a section of the joint betweenthethirdandfourthelectrodesshown in FIG. 15.

There will now bcdescribed by reference to the appended drawings a triple electron gun apparatus according to an embodiment of the present invention and a method for manufacturing the same.

FIG. 3 shows a convergen-e electrode 30 according to the present invention. It comprises a cylindrical convergence cup 31 made of nonmagnetic material such as stainles steel! three pairs of convergence electrode plates 33 made of magnetic material. part ofeach ofwhich is welded on the outer wall surface ofthe convergence cup 31. the bent portion ofeach electrode plate passing through each of three pairs of slits 32 spatiallyfomtedinthewallofsaidconvergencecupiil andthree electron beam-passing holes 34 perforated at the bottom of the convergence cup 31 in corresponding relationship to each pair of electrode plates 33. namely. at the center of the intermediate space between each pair. Referring to FIG. 4. there arefurtlterprovidedaY-shapedshieldingplate3s,soastodivide the convergence cup 31 into three equal sections. each of which involves one pair of plates 33 with each of the aforesaid electron beam-paming holes 34 lying therebetween. Further there is formed a in a manner to extend over part of the outerwall lurfaceaswelluol'theouter bottom surfaceofthe convergence cup 31 and lie half way between the adjacent groups of paired convergence plates 33. The cavity 36 has a prescribed depth and width (which are large enough to receive a support bar later welded thereto) and a flat bottom. to which are welded two metal plates 37 bent in the L-shape with their back sides abutted to each other. Thus is fonned a support element 38. The three electron beam-passing holes 34 and three cavities or support elements 38 respectively face each other in such a manner. as shown in FIGS. 3 and 4. that each of the former lies half way between the adjacent two of the latter. Therefore, when each of the support bars holding together the later described triple electron gun assembly is welded to the respective tapered support elements 38. the central axes of the three electron beam-pasing holes are made to agree with those of the three electron gun units. On the other hand. the triple electron gun assembly is formed by juxtaposing three electron gun units 44. each of which is composed of. as shown in FIG. 5. a first grid electrode 40 including a cathode (not shown) and second to fourth cylindrical grid electrodes 41. 42 and 43 successively arranged in a straight line ahead of said first grid electrode 40. The convergence electrode 30 and triple electron gun asembly 45 are joined together in a prescribed relationship to each other by three support bars 46 made of electrically insulating material which hold together the three electron gun units 44. The coupling of the convergence electrode 30 and triple electron gun assembly 45 is carried out byjoining the support bars 46 thereto. each of which is prepared from. for example. multifonn glas (which consists of powders of borosilicate glass fabricated into a prescribed form. followed by baking). in this case. each support bar 46 is joined with the convergence electrode 30 at the aforementioned support element 38 and with the triple electron gun assembly 45 by the medium of support metal strips 47. each of which is welded by the known method to the first to fourth electrodes to 13.

There will now be described a method of manufacturing a triple electron gun apparatus of the aforementioned arrangement. Let us explain first the fabrication of the convergence electrode 30. There is provided a cylindrical convergence cup 31 made of stainless steel. The wall of the cup 31 is perforated with three pairs of spatially disposed slits 32. Three pairs of convergence electrode plates 33 are welded to the outer wall surface of the convergence cup 31 with one end of each plate 33 introduced through each slit 32. That part of the bottom of the convergence cup 31 \vhich corresponds to the middle point between each pair of convergence electrode plates 33 is perforated with a through hole 34 for allowing the pasage of electron beams. The positions of these through holes 34 are, of course. so defined as to cause their centers to stand at the respective apices of an equilateral triangle. namely. to be aligned with the central axial line of each electron gun unit 44. In the metal cup 31 is formed a Y-shaped shielding plate 35 whose edges radially extend from the center of said cup 3! at a space of I". so as to divide the cup area into three equal compartments. namely. to separate one pair of convergence electrode plates 33 including a through hole 34 lying therebetween from the other such pairs Previously when the convergence cup 3! is fabricated. there is formed a cavity by pressintheangularbottomsectionofthecylindricalcup3l at which the outer circumferential wall surface and outer bottom surface of said cup 3i intersect each other andat a point lying halfway between the adjacent groups of paired electrode plates 33. These three cavities 36 are allowed to have a prescribed depth and width. To the outer bottom surface of each aivity 36 are welded two L-shaped metal plates 37 with their back sides abutted to each other to form a support element 38. The convergence electrode arranged as described above is fitted into an asernbling device 50 as shown in FIGS. 6 and 7. In the outer circumferential wall of a columnar support memberSZ fixedon the bae rnemberSl oftheassernbling device 50 are formed three grooves having a V-shaped crosseetioninsuchamannerthattheydividetheperiphery of said columnar support member 52 into three equal segconverge at the apices of an equilateral triangle. into the holes 34 of said cup 31 are inserted three locating bars 54 (only one of them is indicated and the other two are not shown). A group of electron gun electrodes 40 to 43 constituting each electron gun unit 44 is coaxially fixed in place. as shown in FIG. 6. by means of spacers 55. 56. $7. 58 and 59. The locating bar 54 consists of an electrode supporting element or stepped portion 60 and tapered portion 61. This tapered section is so positioned as to cause the central axis of the locating bar 54 to define a prescribed angle 0 with respect to that of the triple electron gun assembly. (See FIG. 8) The axis of each electron gun unit 44 is automatically regulated by fitting said tapered portion 6| into the V -shaped groove 53. The locating bar 54 holds the respective electrodes forming each electron gun unit 44 and the holes 34 of ihe cup electrode of the convergence electrode 30 coaxially and at a prescribed space. and is supported at both ends by a jig 62 for aligning each electron gun unit 44. This jig 62 is fabricated in the approximately rectangular form, and is provided at one of its projecting end portions 63 with a small protrusion 65 which fits in with a shallow hole 64 formed at the bottom end of the tapered portion 61 of the locating bar 54. and at the other projecting end portion 66 with a cylindrical through hole 67. In the through hole 67 is slidably disposed a keep bar 68 which slides therethrough in the lengthwise direction of the jig 62 so as to keep the electron gun unit 44 supported by the locating bar 54 and convergence electrode 30 pressed to each other. Further. the keep bar 68 is provided with a coil spring 69 for applying a pressing force in the axial direction of the electron gun unit 44 (as indicated by the arrow). In the through hole 67 perforated in the wall of the projecting end portion 66 of the jig 62 is formed an L-shaped groove 70 extending all along the wall of said through hole 67. On the side wall of the keep bar 68 sliding through said hole 67 is provided a slide control element 71 inserted into the groove 70. At the top end of the keep bar 68 is disposed a knob 72 by which said keep bar 68 is usually operated. The keep bar 68 which applies a pressing force by sliding is stopped when the slide control element 71 is brought to the rest point 73 of the L-shaped groove 70. On the wall of the intermediate part of the jig 62 is provided a pressing means 74 for prexing the tapered portion 61 of the locating bar 54 to the groove 53 formed in the columnar support member 52. Each of these presing means 74 has. as shown in FIG. 7. a horizontally rotatable plate 75 fitted to each of the three projecting walls of the base member 5! and a pin 76 projectingly formed on one side of said plate 75. The other side of said plate 75 is presed by a vertically rotatable keep plate 77. On part of the outer surface of said keep plate 77 is provided a grip pin 78, which isoperated to rotate the keep plate 77.

On the electrode supporting element 60 of the locating bar 54 is disposed a first electrode supporting member 79 formed of a combination of the convergence electrode 30. fourth grid electrode 43, first spacer 55. second spacer S6 and third spacer 57. as mentioned from the bottom of the ananged order. The other electrodes are coaxially held in place at a prescribed space by

other spacers

58 and 59 succesively arranged at a prescribed space from the aforementioned electrode supporting member 79. There will now be described by reference to FIG. 9 the manner in which the fourth electrode is held by the first electrode supporting member 79. This supporting member 79 is inserted between the fourth grid electrode 43 and third grid electrode 42 positioned above the convergence electrode and consists of three spacers 55. 56 and 57. Into the through hole of the middle spacer $6 is inserted the support element 60 of the locating bar 54. Part of both end spacersSSandSlisnotchedtoforrnastepped portionsoas coaxially to receive the third and

fourth grid electrodes

42 and 43 with the middle spacer $6 lying therebctween.

Afterthep'idelectrodes40to43areheldinplaceinthe aforementioned manner as shown in FIG. 6. a glass support bar 46 is thermally melted and attached to said electrodes by the medium of support strips 47 welded thereto by the known menu and the lines connecting the bottoms of said grooves 53 75 method. At the same time the support strip 38 of convergence electrode 30 and the end of said support bar 46 are welded together. This joining operation is repeated three times to cause the three electron gun units 44 and convergence electrode 30 to be integrally fixed by the support bar 46 at once. After such assembly, the second and

third spacers

58 and 59 are removed and the locating bar 54 is drawn out. Thereafter the middle spacer 56 and then both

end spacers

55 and 57 are taken out thereby to finish the fabrication of a triple electron gun apparatus.

As mentioned above, the method of the present invention permits the simultaneous bonding of the convergence electrode and triple electron gun assembly to form an electron gun apparatus, which has heretofore been deemed the most difficult problem. Accordingly, the present invention has various advantageous effects of locating both components of the triple electron gun apparatus in extremely accurate coaxial relationship, permitting an easy fabrication due to the simultaneous assembly of said both components and allowing the resultant triple electron gun apparatus to display excellent properties.

There will now be described by reference to FIGS. to 16 a triple electron gun apparatus according to another embodiment of the present invention. The same parts of this embodiment as those of the preceding one are denoted by the same numerals and explanation thereof is omitted. FIG. 10 presents a convergence electrode 30, which comprises a cylindrical convergence cup 31, three pairs of slits 32, three pairs of convergence electrode plates 33 and three electron beam-passing holes 34. In the convergence cup 31 there is formed a shielding plate or electrode 35 as later described radially extending from the center of said cup 31 at a space of 120 so as to divide the cup area into three equal compartments. There is also provided a cavity 36 in a manner to extend over part of the outer circumferential wall surface and outer bottom surface of said cup and be located half way the adjacent two groups of convergence electrode plates 33. Said cavity 36 has a prescribed depth and width which are large enough to receive a support bar later welded thereto. The

planes

80 and 81 of said cavity 36 are made flat, and at the center of these planes is formed a slit 82in a manner to extend from the plane 80 to the plane 81. On the plane 81 are set up a pair of cutout support strips 83 along said slit 82 in perpendicular relationship with respect to said plate 81 (See FIG. 11). The slit 82 has a slightly broader width than the thickness of the later described shielding plates. At part of the peripheral portion of the opening of the convergence cup 31 are formed V-shaped notches 84, which are intended to receive the aforesaid shielding plates. In the convergence cup 31 thus formed there is formed spaced shielding electrode 35. The shielding electrodes 35 are prepared by bending through an angle of 120 three metal plates 85 cut out to a prescribed size and superposing them on each other in a manner to divide the cut area into three equal portions. At a prescribed point near each end of the shielding electrode 35 there is cut out a notch 86 to form a welding strip 87. There are separately provided ear portions 88 at the top ends of the shielding electrode 35. One group 88 of ear portions engages the notches 84 formed in the top peripheral wall of the convergence cup 31. The welding strips 87 are inserted through the slits 82 formed in the aforesaid cavities in a manner to project into them, and said ear portions 88 are attached to the outer bottom surface of the convergence cup 31, if required, by welding. Thus is formed the convergence electrode 30. One of the characteristics of this embodiment is that there are provided a pair of support strips 83 and welding strips 87 on the underside of each cavity formed at the bottom of the convergence cup 31. They are welded to the later described support bar 46 at the same time in such a manner that the electron gun units mentioned below and electron beam-passing holes 34 bored in the convergence cup 31 are aligned in coaxial relationship. On the other hand, the triple electron gun assembly 45 is formed, as shown in FIG. 14, by juxtaposing three electron gun units 44 consisting of four

cylindrical grid electrodes

40, 41, 42 and 43. The grid electrodes constituting the triple electron gun assembly 45 are held in place by three support bars 46 positioned along the walls of the grid electrodes, said bars being made of electrically insulating material and having a prescribed length. To facilitate the fabrication of the triple electron gun assembly 45, there is formed a support element 90 for said assembly 45 so as to contact the underside of the respective first grid electrodes 40. This support element 90 is a fiat metal plate assuming an approximately triangular form as viewed horizontally, with the apex portions slightly curved. The curvature of these triangular apices 91 is so formed as to allow a space of 0.5 mm. between said apices and the inner wall surface of the neck portion of the glass bulb of a Braun tube into which the triple electron gun assembly is inserted. Each of the three straight edges connecting the apices 91 is provided with a pair of outwardly projecting support strips 92 having a prescribed length. The three apex portions of the support element 90 are perforated with three through holes 93 arranged in such a manner as to form an equilateral triangle whose center accords with the central axis of said support element 90. These through holes 93 are so disposed as to assume a larger triangular form than that presented by the three through holes 34 of the convergence cup 31. Accordingly, when the central axes of both triangles are made to agree with each other, the axis of each of the through holes of the support element 90 forming a larger triangle defines a prescribed angle with respect to each unit electron gun member. The support element 90 is disposed at the bottom of the triple electron gun assembly 45 in coaxial relationship therewith and fixed to the support bar 46 as an indispensable member to maintain the coaxial relationship of the convergence electrode 30 and triple electron gun assembly 45 as well as the mechanical strength of the resultant triple electron gun apparatus as a whole. Thus is formed the triple electron gun apparatus of FIG. 14.

There will now be described by reference to FIGS. 15 and 16 a part of the assembling device of the triple electron gun apparatus of FIG. 14. As partly shown in FIG. 15 in the eutaway form, the first cylindrical grid electrode 40 and second to fourth

cylindrical grid electrodes

41, 42 and 43 arranged in a straight line above said first electrode 40 are held in place by inserting therethrough a stepped locating bar 54 provided at the top with a stepped portion as explained in connection with the assembling device of FIG. 6. In this case, the respective grid electrodes are kept in coaxial relationship with said locating bar 54 by interposing therebetween a plurality of

spacers

100, 101 and 102 illustrated, for example, in FIG. 16, and also arranged at a prescribed space from each other. There is pro vided another locating bar 103 which tightly fits into each of the through holes 93 of the aforementioned support element 90 and the top end of which is provided with a hole tightly to receive the smallest diameter bottom end of the first mentioned stepped locating bar 54. Said second locating bar 103 is used in coaxially supporting the through holes 93 of the support element 90 and the respective electron gun units and also helps to cause the axes of each through hole 34 of the convergence electrode 30, the grid electrodes of each electron gun unit and each through hole 93 of the support element 90 to agree with each other. Thereafter, the support strips 47 welded to the respective grid electrodes, support strips 92 of the support element 90 and welding strips 87 of the shielding electrode 35 and paired support strips 83 of the respective cavities 36, which are all previously heated, are fixed to the softened support bars 46 made of electrically insulating material such as a glass. Such bonding operation is successively repeated three times and then the spacers and first and second locating bars 54 and 103 are removed to finish a triple electron gun apparatus.

As mentioned above, a triple electron gun apparatus according to this embodiment can be easily fabricated without using any special complicated jig, and has prominent advantages that every component can be arranged in extremely accurate coaxial relationship and a very great mechanical strength is attained. Namely, the respective parts of the triple electron gun apparatus formed in the aforementioned manner can be fixed in place at the same time using three support bars for holding together said parts and a simple jig extremely free from deviations. The axis of each unit electron gun member is allowed automatically to define a prescribed proper angle of inclination with respect to the central axis of the entire apparatus simply by inserting it into the through hole of the support element and through hole of the convergence cup. In other words, the axes of the grid electrodes of the assembled electron gun units and the electron beam-passing holes formed at the bottom of the cup of the convergence electrode member assume a full coaxial relationship. Each of the three cavities extending over part of the outer circumferential wall surface and outer bottom surface of the convergence cup is provided with a pair of support strips formed by cutting out part of one plane of each cavity and setting up said cutout portions. Said support strips of the respective cavities and the welding strips formed by causing part of the shielding elec trodes to project from the slits provided between said paired support strips are integrally fixed at the same time by the same support bar to which a plurality of grid electrodes constituting each electron gun unit are welded by means ofa support plate. Accordingly, both convergence electrode and triple electron gun assembly maintain an extremely good coaxial relationship. Moreover, at the time of welding, the support bar which bridges the bottoms of the cavities of the convergence electrode and the support strips of the support element is restricted in excessive welding by the bottoms of said cavities and the outer wall of the support element, both of which act as a sort of stopper, so that the support bar is prevented at the time of welding from pressing the electron gun support members beyond a required extent. Accordingly, the present invention also has an advantageous efi'ect of substantially eliminating axial displacement caused by unnecessary pressure applied to the grid electrodes or their thermal deformation when the support bar is welded thereto. Heretofore, the triple electron gun assembly and convergence electrode were separately fabricated and thereafter assembled together by welding or other means. Thus the prior art method was encountered with various difficult problems in connection with the use of complicated jigs required in said welding, fixing tongues or locating members. However, the present invention has eliminated such drawbacks, and permits the easy fabrication ofa triple electron gun apparatus which can offer good workability and very accurate coaxial relationship and display superb properties.

Further, as shown in FIG. 13, the support element of the triple electron gun assembly is fabricated in a substantially triangular form. lts outer dimensions are so formed as to allow a space of 0.5 mm. between the respective apices and the inner wall surface of the smallest diameter bulb neck of a color television Braun tube, so that when a triple electron gun apparatus is sealed into said neck portion there is obtained a full coaxial relationship therebetween. With the neck portion of a 19-inch or l6-inch Braun tube, it is, of course, sufi'icient to maintain the aforementioned space between the inner wall surface of said neck portion and triple electron gun apparatus placed therein in order to assure their coaxial relationship.

What we claim is:

l. A triple electron gun apparatus comprising three electron gun units, each of which has a plurality of coaxially arranged electrodes, a convergence electrode for converging electron beams emitted from the electron gun units and three support bars made of electrically insulating material, said support bars juxtaposing the electron gun units to form a triple electron gun assembly and securely joining the convergence electrode with the triple electron gun assembly.

2. The triple electron gun apparatus according to claim I wherein the convergence electrode comprises a cylindrical body having a bottom wall, said bottom wall having three openings formed therein to allow the passage of electron beams released from the respective electron gun unit, three pairs of plate electrodes disposed in the cylindrical body to conver e electron beams thus emitted, a Y-shaped shielding electro e positioned m the cyllndrical body to shield the electron beams from each other which are emitted from the respective electron gun unit, and said cylindrical body having three cavities formed in its outer bottom surface to allow the support bars to be fixed therein.

3. The triple electron gun apparatus according to claim 2 wherein the cavities have support members projectingly formed therein, and the support bar is joined to said support members.

4. The triple electron gun apparatus according to claim 2 wherein each end portion of the shielding plates is introduced through the cylindrical body to project into the cavity and the support bar is joined to said projecting portion and separate protrusions extending into the cavity.

5. The triple electron gun apparatus according to claim 1 wherein the triple electron gun assembly has one support plate stretched over the entire underside of three grid electrodes corresponding to three unit electron gun members and disposed at the rearmost end of the triple electron gun assembly.

Claims

1. A triple electron gun apparatus comprising three electron gun units, each of which has a plurality of coaxially arranged electrodes, a convergence electrode for converging electron beams emitted from the electron gun units and three support bars made of electrically insulating material, said support bars juxtaposing the electron gun units to form a triple electron gun assembly and securely joining the convergence electrode with the triple electron gun assembly.

2. The triple electron gun apparatus according to claim 1 wherein the convergence electrode comprises a cylindrical body having a bottom wall, said bottom wall having three openings formed therein to allow the passage of electron beams released from the respective electron gun unit, three pairs of plate electrodes disposed in the cylindrical body to converge electron beams thus emitted, a Y-shaped shielding electrode positioned in the cylindrical body to shield the electron beams from each other which are emitted from the respective electron gun unit, and said cylindrical body having three cavities formed in its outer bottom surface to allow the support bars to be fixed therein.