US3659133A

US3659133A - In-line type triple electron gun assembly

Info

Publication number: US3659133A
Application number: US80635A
Authority: US
Inventors: Asahide Tsuneta; Yasuo Ohta; Makoto Ikegaki; Shinichi Sawagata; Fumiyuki Sato
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1969-10-15
Filing date: 1970-10-14
Publication date: 1972-04-25
Anticipated expiration: 1989-04-25

Abstract

An in-line type triple electron gun assembly wherein there is provided a central electron gun member; there are disposed on both sides of the central electron gun member in the same plane a pair of electron gun members whose axis defines a prescribed angle of inclination to that of the central electron gun member; the first and second grid electrodes of each of the paired electron gun members consist of a substantially triangular plate electrode; the plate electrodes of each of the three electron gun members have an effective surface intersecting the axis of said each member at right angles; and each plate electrode is perforated with an electron beam hole coaxial with the axis of the electron gun member.

Description

United States Patent Tsuneta et al.

[151 3,659,133 [451 Apr. 25, 1972 IN-LINE TYPE TRIPLE ELECTRON GUN ASSEMBLY Inventors: Asahide Tsuneta, Kawasaki; Yasuo Ohta; Makoto lkegaki, both of Saitama-ken; Shinichi Sawagata, Tokyo; Fumlyukl Sato, Yokohama, all of Japan Assignee: Tokyo Shibaura Electric Co., Ltd.,

Kawasaki-shi, Japan Filed: Oct. 14, 1970 Appl. No.: 80,635

Foreign Application Priority Data Oct. 15, 1969 Japan ..44/81855 Oct. 22, 1969 Japan..... ...44/9977l Nov. 17, 1969 Japan ..44/108295 U.S. Cl ..3l3/70, 313/77 Field of Search ..3 1 3/70, 69, 77

[56] References Cited UNITED STATES PATENTS 3,396,297 8/1968 Burdick ..3 13/70 a Primary Examiner-John Kominski Attorney-Flynn & Frishauf 57 ABSTRACT An in-line type triple electron gun assembly wherein there is provided a central electron gun member; there are disposed on both sides of the central electron gun member in the same plane a pair of electron gun members whose axis defines a prescribed angle of inclination to that of the central electron gun member; the first and second grid electrodes of each of the paired electron gun members consist of a substantially triangular plate electrode; the plate electrodes of each of the three electron gun members have an effective surface intersecting the axis of said each member at right angles; and each plate electrode is perforated with an electron beam hole coaxial with the axis of the electron gun member.

8 Claims, 19 Drawing Figures PATENTEDAPR 2 5 we SHEET 30F 4 FIG. 11

PIC-3.13

PATENTEDAPMS 1972 3,659,133

sum u [if 4 IN-LINE TYPE TRIPLE ELECTRON GUN ASSEMBLY BACKGROUND OF THE INVENTION The present invention relates to a triple electron gun assembly, and more particularly to an in-line type triple electro gun assembly.

The conventional in-line type triple electron gun assembly for a color television cathode ray tube consists of three elec tron gun members positioned in a prescribed relationship, each of which comprises a first cylindrical, grid electrode containing a cathode electrode and second to fifth cylindrical grid electrodes juxtaposed coaxially with the first grid electrode at a prescribed space therefrom. The electron gun assembly is constructed by arranging two electron gun members on both sides of the central electron gun member in the same plane at an angle of inclination (about 1 01 minute) to the axis of the central gun member, all the gun members being integrally set in position by support members. However, the prior art in-line type electron gun assembly constructed as described above using cylindrical grid electrodes fails to meet the demand to render the assembly more compact, increase the angle of deflection of electron beams and decrease power consumption. The reason is that to reduce power requirement for said deflection, the sensitivity of deflection should be elevated and, to this end, the neck portion of a color television cathode ray tube should be made as narrow as possible and, further to render the gun assembly compact with the angle of deflection enlarged, it is necessary angularly to broaden or flatten the funnel portion of the cathode ray tube thereby to contract the length of the tube as a whole. However, where it is attempted angularly to broaden said funnel portion, for example, to 110 to 114, the gun members on both sides of the central gun member should have their axis inclined to that of the latter about 2 10 minutes, or twice that which is required in the case of the deflection angle (85 to 90) defined by the funnel portion of the conventional cathode ray tube. Accordingly, the first grid electrode of the side gun members would extend outward and this part of the gun assembly would'have a larger maximum diameter than the inner diameter of the neck portion of the cathode ray tube, making it impossible to-insert the gun assembly into the neck portion. To avoid such difficulties, it would be considered only necessary to contract the'entire size of the electron gun assembly using grid electrodes having a smaller outer diameter. However, the reduced outer diameter of the third, fourth and fifth grid electrodes of the electron gun member should most likely cause an electron lens to present aberration and an electron gun assembly as a whole to be degraded in quality.

SUMMARY OF THE INVENTION The object of the present invention is to provide an in-line type triple electron gun assembly capable of minimizing the occurrence of aberration in an electron lens and being fitted into a compact cathode ray tube whose funnel portion defines a broad angle, characterized in that of three electron gun members juxtaposed in the same plane, at least the two on both sides of the central one have first and second grid electrodes formed in substantially triangular plates to prevent them from extending outward, thereby permitting the entire electron gun assembly to be easily inserted into the narrowed neck portion of the cathode ray tube.

BRIEF EXPLANATION OF THE DRAWINGS FIG. 1 is a fragmental sectional view of an electron gun assembly according to an embodiment of the present invention;

FIG. 2 is a sectional view on line lIII of FIG. 1;

FIG. 3 is an enlarged pictorial view of the first grid electrode ofFIGS. land 2;

FIGS. 4 and 5 are pictorial views of other modifications of the first grid electrode of FIG. 3;

FIG. 6 illustrates another modification of the first grid electrode used in the central gun member of FIGS.1 and 2;

FIG. 7 is a fragmental plan view of an electron gun assembly according to another embodiment of the invention;

FIG. 8 is a sectional view on line XIIIXIII of FIG. 7; FIG. 9 is a sectional view on line IX-IX of FIG. 7;

FIG. 10 is a pictorial view of the first grid electrode of FIG.

FIG. 11 is a pictorial view of the three electrodes of FIG. 7;

FIG. 12 is a plan view, partly in section, of an electron gun assembly according to still another embodiment of the invention;

FIG. 13 is a sectional view on line XIII-XIII of FIG. 12;

FIG. 14 is a sectional view on line XIV-XIV of FIG. 12; and

FIGS. 15 to 19 are pictorial views of the parts used in the embodiment of FIG. 12.

DETAILED DESCRIPTION OF THE INVENTION There will be first described the left side electron gun member 10 of FIG. 1. To the small diameter section of a first support member 1 is coaxially fixed a cylindrical cathode 2. The first support member I has a flange 1a formed at the end of the large diameter section. There is further provided a second support member 3 having an effective surface 3b perforated with a bore 3a so as to allow the large diameter section of the first support member 1 to pass therethrough and a fusion surface 30 substantially perpendicular to said effective surface 3b. The first support member 1 is inserted through the aforesaid bore 3a and welded to the second support member 3 at the flange la. There is provided a first grid electrode 4 at some space from the end face of the cathode 2 disposed on that side of the first support member 1 on which there is formed the flange la. The first grid electrode 4 has, as illustrated in FIGS. 2 and 3, a substantially triangular effective surface 4a and a tab member 4b which is formed by bending a strip integrally formed with the base portion of the triangular effective surface at an angle of to said surface (or more exactly 87 50 minutes, where the axis Xa-Xa of the left hand gun member is inclined 2 10 minutes to the axis X-X of the central gun member of FIG. 1, said tab member 4b equally extending in opposite directions from the base side of the triangular effective surface. At a prescribed point on a line I drawn from the center of the base side of the triangular effective surface 4a constituting part of the tab member 412 to the apex 6 of the triangle is formed a bore 5 to allow electron beams to pass therethroughlf the bore 5 is disposed near the apex 6, it will be advantageous from the standpoint of reducing the size of the first grid electrode 4.- Bothends of the tab member 4 constitute first fixing parts 7 to which there are fixed support rods 8 made of glass. In FIG. 1 a support rod in the left side is not shown. In the fixing part 7 is constructed a notch 9 to effect firm fusion. Ahead of the effective surface 4a of the first grid electrode 4, namely, in the travelling direction of electron beams is positioned a second grid'electrode 12 of the same shape as the first grid electrode 4, with the effective surface 12a of the second grid electrode 12 closely facing that of the first grid electrode 4. Further ahead of the second grid electrode 12 are arranged in turn third, fourth and fifth

cylindrical electrodes

13, 14 and 15, which have respective second fixing parts. Thus is constructed each side electron gun member 10.

There is provided another side electron gun member 16 of the same construction as the first mentioned gun member 10 on the opposite side of the central gun member 11 which has a somewhat different construction from that of said

side gun members

10 and 16. The axis Xb-Xb of said another gun member 16 is inclined about 2 I0 minutes to the axis of the central gun member 11 like the axis Xa-Xa of the first mentioned side gun member 10. The central gun member 11 assumes the same shape as that included in the conventional electron gun assembly, namely, contains first to fifth cylindrical electrodes l7, 18, I9, 20 and 21- coaxially juxtaposed in turn on the axis X-X. The three

gun members

10, 11 and 16 are linearly arranged in the same plane including line I. The

side gun members

10 and 16 are so arranged that the axes Xa-Xa and Xb-Xb thereof define a prescribed angle 0 (about 2 10 minutes in the embodiment of the present invention) with the axis XX of the central gun member, with the electron beam outlet ends of the side gunmembers l and 16 inwardly inclined. The three

gun members

10, 11 and 16 are fixed to the aforementioned four support rods 8 by means of the first and second fusion parts to finish an in-line type electron gun assembly 23.

In the electron gun assembly 23 of the present invention constructed as described above, the

side gun members

10 and 16 and first and

second grid electrodes

4 and 12 do not extend outward, enabling the electron gun assembly to be easily fitted into a cathode ray tube whose neck portion 24 has the same inner diameter as the conventional cathode ray tube whose funnel portion is deflected 85, even though the side gun members included in said assembly may be inclined through such an angleas permits the assembly to be used with a cathode ray tube whose funnel portion is deflected through a broad angle, for example 1 10.

The different potentials of. the second and

third grid electrodes

12 and 13 cause an electric field to be generated across them. Since, however, the second grid electrode 12 is made in plate form, the equipotential curve of the electric field created across these

electrodes

12 and 13 partly assumes a relatively level shape, enabling them to be reduced in size and preventing electron beams passing through them from being unnecessarily focused, so that the resulting electron gun assembly 23 can display extremely good properties. The plate-like formation of the second grid electrode 12 prevents the occurrence of discharge across the

electrodes

12 and 13 having different potentials, as is the case with the cylindrical electrodes of the prior art gun assembly which are provided at one end with a projection so as to assure good electrical connection therebetween. Unlike a cylindrical electrode, the plate-like electrode of the present invention permitsan electron beam hole to be positioned at a relatively free point on its surface. Further, the inclination of the axes XaXa and Xb-Xb of the

side gun members

10 and 16 to the axis XX of the central gun member ll may be freely chosen by varying the angle 0,,

at which the triangular effective surface of the first grid electrode 4 is bent with respect to the plane of the tab section 4b as illustrated in FIG.'3.

FIG. 4 shows another modification of the first grid electrode according to the presentinvention. Onthe base side of the triangular effective surface of a first grid electrode are formed two beads 31 bulging inside thereof for mechanical reinforcement. With each of the two oblique sides of a triangular effective surface 300 is integrally formed near the apex 32 a strip 2 to 3 mm. wide so as to constitute a floating electric field shielding plate 33. This shielding plate33 is used to prevent the intrusion of a floating electric field from outside of the neck portion of a cathode ray tube.

FIG. 5 illustrates still another modification of the first grid electrode according to the present invention. The electrode has a shielding plate 34 formed over the apex 32 of the triangular effective surface which is disposed closest to the neck portion of the cathode ray tube. This modification can more effectively shut off the intrusion of a floating electric field from outside than the electrode of FIG. 4.

The first grid electrode of the central gun member 1 1 shown in FIGS. 1 and 2 was described as having a cylindrical shape. As illustrated in FIG. 6, however, said electrode may, of course, be made into a plate form having an electron beam hole 27 bored at the center of its effective surface 26 and a fixing part formed at four corners.

FIGS. 7 to 11 jointly indicate an electron gun assembly according to another embodiment of the present invention. Referring to FIG. 7, a cathode electrode 40 made into a cylindrical form with a small diameter is fixed at one end to a first support member 41 assuming a cylindrical funnel form. There is also provided a second support member 42 having the end part of its funnel section formed into an L-shape and a relatively large bore perforated in its top surface. The first support member 41 is inserted into the bore and securely set in place by welding the flange formed at the top end of said first support member 41 to the bottom plane of the second support member 42. The second support member 42 has an effective surface 42a (a cathode fixing surface) and fixing portion 42b and is formed into an L-shape as described above. A first grid electrode 43 closely adjacent to thecathode 40 has an effective surface assuming a substantially triangular form illustrated in FIGS. 9 and 10 as viewed from the front. A strip integrally formed with the base side of the triangular effective surface is bent at an angle of approximately 88 with respect to said surface to constitute a tab section 44. The tab section 44 extends in opposite directions from the base side of the triangular effective surface 46 for an equal prescribed length to constitute fixing parts 44a. In the fixing part 44a is formed a notch so as to effect firm fixing. The effective surface 46 of the first grid electrode 43 has a through hole 45 to allow electron beams to pass therethrough. Said electron beam hole 45 may be formed at any point on a central line 1 extending from the base side of the triangle, namely, that side on which the tab section 44 is formed to the apex thereof. However, the formation of the electron beam hole 45 near the apex is more advantageous from the standpoint of reducing the size of the electrode. In the effective surface of the first grid electrode 43 is formed a groove about 2 mm. deep and 4 mm. wide along the central line 1, thereby defining a facing plane 46b. Ahead of the first grid electrode 43 constructed as described above, namely, in the travelling direction of electron beams, is disposed a second grid electrode 47 having almost the same shape and size as the first grid electrode 43 in such a manner that the effective plane 474 and the facing plane 47b of the second grid electrode 47 face the facing plane 46b and the effective surface 46a of the first grid electrode 43. The cathode, first'and

second grid electrodes

40, 43 and 47 each having the aforementioned construction are assembled into a triple electrode section 48. Further ahead of the second grid electrode are arranged in turn third, fourth and

fifth grid electrodes

49, 50 and 51, thus finishing a side electron gun member 52. This side electron gun member 52 is positioned, as shown in FIG. 7, on both sidesof a central electron gun member 53. The central electron gun member 53 has first to

fifth grid electrodes

55, 54, 49, 50 and 51 coaxially arranged in turn as in that of the conventional electron gun assembly. The first and second

electron gun members

52 and 53 totalling three units are arranged in the same plane with the central electron gun member 53 interposed between two side electron gun members 52 in such a manner that the axes XaXa and Xb-Xb of the two side electron gun members 52 are inclined at a prescribed angle 0 or about 2 10 minutes in this embodiment with respect to the axis XX of the central gun member 53. The three

gun members

52 and 53 are securely set in place by fitting the fixing parts 44a and support bands 155 to the side walls of four support rods 154, a left side support rod is not shown in FIG. 7 (see FIG. 8), thereby finishing an in-line type triple electron gun assembly 60.

The procedure of setting up the electron gun assembly 60 consists first assembling the central electron gun member 53. The first to

fifth grid electrodes

55, 54, 49, 50 and 51 constituting the central gun member 53 are jointly fitted to a jig (not shown), and the support plates 56 attached to the side walls of the respective electrodes are fixed to the support rods 57 made of insulating material thereby preliminarily to set up the central electron gun member 53. This gun member 53 is placed at the center and on both sides thereof are disposed the two remaining electron gun members 52 at a prescribed angle of inclination to the axis of the central gun member 53, thereby constituting the in-line triple electron gun assembly 60. In reference to FIGS. 8 and 9, on both sides of the central electrode are positioned substantially triangular grid electrodes. With the base side of the triangle there is integrally formed a strip which is bent so asto constitute a tab section. Said tab section extends along the central electrode. The side grid electrodes are fixed to four support rods 154, in such a manner that the entire triple electrode section 48 assumes an apparently butterfly shape. The

side plate electrodes

43 and 47 present a stepped shape by being provided with a groove. Each of the mutually facing

planes

46b and 47b of the

plate electrodes

43 and 47 has an electron beam hole 45 perforated through the bottom thereof. There is introduced an electric field across said mutually facing

planes

46b and 47b suitably to vary the equipotential curve. This contributes to the elevation of the properties of the resulting electron gun assembly and further favorably shuts off the intrusion of a floating field from outside.

Further, the side gun members and 16 are made compact to enable the diameter of the central electron gun member 11 to be enlarged by that extent, thus providing an electron gun assembly which can perform a far better focusing action.

FIGS. 12 to 19 represent an in-line type triple electron gun assembly according to still another embodiment. A small diameter cylindrical cathode electrode70 is fixed to a first support member 71 assuming a cylindrical funnel shape at one end. There is further provided a second support member 72 having the end of its funnel portion formed into an L-shape and a relatively large bore perforated in its top surface (see FIG. 17). The first support member 71 is inserted into said bore and fixed to the second support member 72 by welding the flange formed at the top end of the first support member 71 to the bottom side of the second support member 72. The

second support member 72 consists, as illustrated in FIG. 17,

of an effective surface 72a (cathode fixing surface) assuming a substantially triangular form as viewed from the front and a tab section formed by bending a strip integrally formed with the base side of the triangle about 90 to said effective surface 72a. Both ends of the tab section 72b constitute a fixing part. Thus the second support member 72 as a whole assumes an L- shape. Closely adjacent to the top plane of the cathode electrode 70 is disposed a first grid electrode 73, whose effective surface 73a assumes a substantially triangular shape shown in FIG. 18 as viewed from the front and is constructed substantially in the same manner as the aforementioned second support member 72. With the base side of the triangular plane of the first grid electrode 73 is integrally formed a strip which is bent at an angle of about 88 to said triangular plane to constitute a tab section 73d.

The tab section 73d linearly extends in opposite directions for a prescribed length from the base side to constitute two fixing parts 730. In each fixing part 73c is formed a notch so as to effect firm fixing. In the effective surface 73a of the first grid electrode 73 is formed a recess 73e. The bottom side of the recess 73e is bored with an electron beam hole 73f. Said electron beam hole 73f is positioned near the apex of the triangular surface on a line extending from the center of the tab section 73d to said apex. When there is set up an electron gun assembly, said electron beam hole 73f is so designed as to be brought to the outside of each gun member. Ahead of the first grid electrode 73 is positioned a second grid electrode 74 having an effective surface assuming almost the same form as that of the first grid electrode 73 and also an electron beam hole or recess formed in said effective surface. In this case the effective surface of the second grid electrode 74 is made to face that of the first grid electrode, and the fixing parts 740 of the second grid electrode 74 which are formed at both extended ends of the tab section 74d are fixed to a support member in an opposite direction to those of the first grid electrode 73, that is, in the travelling direction of electron beams. Further, the tab section 74d of the second grid electrode 74 is bent at a broader angle (about 92) than in the first grid electrode 73 and the apex portion of the triangular effective surface 74a of the second grid electrode 74 is also turned toward the outside of a gun member to face that of the first grid electrode 73, thereby to cause the electron beam hole 74f to be aligned with that of the latter. Thus is constructed a triple electrode section comprising the cathode electrode 70, first plate-like grid electrode 73 and second grid electrode 74. Further ahead of the second grid electrode 74 are arranged third, fourth and

fifth grid electrodes

49, 50 and 51 with the axis thereof aligned with the electron beam holes of the first and

second grid electrodes

73 and 74, thereby finishing side electron gun members 77.

In an electron gun member 78 disposed at the center of a triple electron gun assembly, a cathode electrode 70 like that of the side gun member 77 is fixed to a first cathode support 71. The flange of the cathode electrode 70 is fixed to the fixing plane 91 of a third support member assuming a substantially I-I-shape illustrated in FIG. 19 as viewed from the front. The third support member 90 has two strips integrally formed with the respective ends of the fixing plane 91 which are bent in the same direction at an angle of approximately 90 to the fixing plane 91, thereby constituting a tab section 92 and fixing parts 93. There are provided first and

second grid electrodes

94 and 95, each of which has, as shown in FIG. 16, an I- shaped plate 96 provided at the center with a recess 97 perpendicularly projecting outward, said recess 97 being bored at the center with an electron beam hole 98. Two opposite laterally extending sides of the I-shaped plate 97 are bent alike in an opposite direction to that in which said recess 97 projects. The first and second grid electrodes 94 and are so arranged as to cause the projecting recesses to abut against each other. Further ahead of the second grid electrode 95 are disposed in turn third, fourth and

fifth grid electrodes

100, 101 and 102 so as to conform their axis to that of the first and second grid electrodes 94'and 95. These third to

fifth grid electrodes

100, 101 and 102 are coaxially set in advance and supported by a first support rod 103 made of insulating material through a support strip 104 fixed to the side walls of the electrodes (FIG. 13). These electrodes have a slightly smaller diameter than the cylindrical electrodes used in the first electron gun member 77. The third electron gun member 79 constructed exactly like the first electron gun member 77 comprises a cathode and first to fifth grid electrodes. The three

electron gun members

77, 78 and 79 are positioned in the same plane in such a manner that the axes XaXa and Xb-Xb of the

side gun members

77 and 79 are inclined 2 10 minutes to the axis XX of the central gun member 78. The three electron gun members77, 78 and 79 are all fixed to four second support rods 85 (FIG. 12 does not show a left side second support rod) disposed along the axis of each gun member through a support member provided on the side wall thereof. In this case, the inclination of the

side gun members

77 and 79 to the central gun member 78 is defined by a first locating element 75 shown in FIG. 15 rather tightly engaging the small diameter portion of the third grid electrode as well as by a second locating element 76 positioned this side of the cathode. Thus is set up an in-line type electron gun assembly. The first locating element 75 has a larger diameter than the second locating element 76 so as to cause the

side gun members

77 and 79 to be inclined to the central one at the aforementioned angle. The first locating element 75 consists ofa plate member 80 shown in FIG. 15, the plate 80 being perforated at the center with a bore through which to insert an electrode. Two opposite arcuate sides of the plate 80 constitute electrode contact faces 82 (which are contacted by the side walls of the adjacent gun members when there is set up a triple electron gun assembly). Further, both ends of each of said two arcuate faces are extended to form four fixing parts 83. The aforementioned three electron gun members are assembled using an exclusive assembling jig.

According to the present invention, the electrodes or electron lenses of the central gun member have a small diameter, reducing the width of the resulting gun assembly as a whole. The narrowed neck portion of the cathode ray tube permits a deflection coil attached thereto to be contracted in size. Further due to excellent deflection sensitivity, the present electron gun assembly requires less power for deflection. In this case, the electron lens system of the central gun member has slightly smaller focusing power than that of the other gun members. If, however, the central gun member is used as a unit, for example, to take care of a green color, said defect will not become visibly prominent, thus preventing quality deterioration. The first locating element 75 fixed to the small diameter portion of the third grid electrode 49 and the second locating element 76 positioned this side of the cathode 40 jointly define an exact angle of inclination of the two side gun members, providing an electron gun assembly having excellent proerties. The first and second locating elements are firmly fixed to the second support rod 85 made of insulating material to constitute the key part of an electron gun assembly. If, therefore, the second locating element 96 is used in fixing the leg portion of a heater inserted into the cathode 40 so as to concurrently act as a support element for said heater to move together with the electron gun assembly (with the conventional electron gun assembly, the heater is supported by an inner conductor embedded in the stem, so that the heater and gun system vibrate separately, leading to the occurrence of contaminated images), thus completely eliminating the appearance of such defective images. Further, the recess formed in the first and second .grid electrodes shut off the intrusion of an unnecessary magnetic field, thereby preventing the scattering of electron beams.

What we claim is:

1. An in-line type triple electron gun assembly comprising a first electron gun member consisting of a cathode electrode and at least first to fifth grid electrodes arranged in turn ahead of the cathode electrode in the axial direction of said gun member, at least said third to fifth grid electrodes being cylindrical electrodes; second and third electron gun members positioned on both sides of the first electron gun member in the same plane with their axes inclined to that of the latter at a prescribed angle, said second and third electron gun members each containing first and second grid electrodes having a substantially triangular effective surface and a first fixing part integrally formed therewith substantially at right angles and third to fifth cylindrical electrodes having a second fixing part; and a plurality of support rods made of insulating material which are arranged outside of the electrodes of the first to third electron gun members so as to fix said electron gun members in a prescribed positional relationship through said first and second fixing parts.

2. The electron gun assembly according to claim l wherein the cathode electrode of the second and third gun members is supported by a funnel shaped support member fixed to a plate support member disposed opposite to the first grid electrode.

3. The electron gun assembly according to claim 1 wherein the first and second plate grid electrodes included in each of the second and third electron gun members have at least one bead formed on the triangular effective surface and a shielding plate fitted to both oblique sides of said triangular effective surface.

4. The electron gun assembly according to claim 3 wherein the the triangular effective surface has a curved shielding plate mounted over the apex.

5. The electron gun assembly according to claim 1 wherein the first and second grid electrodes of the first electron gun member are disc grid electrodes having a plurality of fixing parts projecting from the periphery.

6. The electron gun assembly according to claim 1 wherein the first and second grid electrodes each have a projection formed on the effective surface, said projections exactly facing each other.

7 The electron gun assembly according to claim 1 wherein the first electron gun member consists of cylindrical electrodes having a smaller diameter than the third to fifth cylindrical grid electrodes of the second and third electron gun members. 1

8. The electron gun assembly according to claim 7 wherein the first and second grid electrodes of the first electron gun member each have a square effective surface provided with a projection at the center and fixing parts integrally formed with said effective surface substantially at right angles, said projections being so disposed as exactly to face each other.

Claims

2. The electron gun assembly according to claim 1 wherein the cathode electrode of the second and third gun members is supported by a funnel shaped support member fixed to a plate support member disposed opposite to the first grid electrode.

7. The electron gun assembly according to claim 1 wherein the first electron gun member consists of cylindrical electrodes having a smaller diameter than the third to fifth cylindrical grid electrodes of the second and third electron gun members.