US3529195A

US3529195A - Electron gun electrode mounting arrangement

Info

Publication number: US3529195A
Application number: US695080A
Authority: US
Inventors: Frederick G Oess
Original assignee: Hughes Aircraft Co
Current assignee: Raytheon Co
Priority date: 1968-01-02
Filing date: 1968-01-02
Publication date: 1970-09-15
Anticipated expiration: 1987-09-15

Description

Sept. 15, 1910 F. #5. OESS 3,529,195

ELECTRON :GUN ELECTRODE MOUNTING ARRANGEMENT Filed Jan. 2, 1968 2 Sheets-Sheet l m zwae Ram/ck 6 05:5,

QL FB 4770 04 F. G. OESS Sept. 15, 1970 ELECTRON GUN ELECTRODE MOUNTING ARRANGEMENT 2 Sheets-Sheet Filed Jan. 2, 1968 M I z United States Patent US. Cl. 313-82 7 Claims ABSTRACT OF THE DISCLOSURE An electron gun cylinder is deformed to provide a press fit and abutment means for an insulative G1 electrode mounting and dimpled to oflFer spot-weld mounting for a G2 electrode. The G2 electrode includes bosses which abut against the G1 electrode insulative mounting to axially secure the G1 electrode.

BACKGROUND OF THE INVENTION Electron guns have many service applications, a typical example of which is a cathode ray tube. Basic gun construction usually involves an electron producing cathode aligned with several control electrodes, one of which is usually called the G1 electrode, Which is mounted immediately adjacent the electron producing surface of the cathode. The G1 electrode is provided with an aperture aligned with the forwardly facing cathode surface to accommodate passage of the electron beam. Characteristically, the G1 electrode is controllably electrically biased and used to modulate the electron beam from a full oif condition to maximum allowable electron flow condition (generally zero bias). A second electrode is usually positioned forwardly of the G1 electrode and may be called the G2 or accelerating electrode. It is also provided with an aperture to accommodate passage of the electron beam and may be electrically biased to produce electron beam acceleration. The best electron gun operation requires precise alignment of the beam passing aperturesin the G1 and G2 electrodes with respect to the gun axis.

However, the cathode produces electrons as a result of the application of heat, an electrical heating element being provided internally of the cathode for this purpose. Due to heating, radiation levels are produced which may create component operating temperatures up to 850 C. This extreme temperature variation, that is, from normal room temperature up to 850 C., occurs each time the electron gun is placed in operation. Thermal expansion and contraction of the various components in response to temperature variation makes it extremely difficult to maintain proper aperture alignment. In addition, the electron guns may be subject to vibration and other physical shock which also tends to destroy the noted aperture align ment. Experience has shown that these factors have, in fact, adversely affected the in situs operation of many prior art electron gun structures.

SUMMARY OF THE INVENTION Accordingly, it is the primary object of the invention to provide a novel mode of structurally mounting control electrodes in a support cylinder in a manner to achieve aperture alignment. Experience has shown that these factors have, in fact, adversely affected the in situs operation of many prior art electron gun structures.

It is a further object of the invention to provide a mounting for electrode components of an electron gun particularly adapted to maintain the physical relation of the electrode components even under the noted severe environmental conditions.

It is a specific object of the invention to provide an interference pressure mounting between a control electrode and its supporting cylinder.

These and other features and advantages of the invention will become apparent in the course of the following description and from an examination of the related drawings, wherein:

FIG. 1 is a side elevational detail view of a supporting cylinder used in the disclosed electron gun;

FIGS. 2 and 3 are a fragmentary side elevational sectional view and end elevational view, respectively, of the supporting cylinder shown in FIG. 1;

FIG. 3A is a fragmentary transverse sectional view of a typical supporting cylinder and diagrammatically illustrates a preferred mode of cylinder fabrication;

FIG. 4 is a transerse sectional view of a support cylinder illustrating the G1 electrode in assembled position;

FIG. 5 is an end elevational view of the structure shown in FIG. 4;

FIG. 6 is a vertical sectional view of the support cylinder with the G1 and G2 electrodes assembled thereto; and

FIGS. 7 and 8 are detailed views of a G2 aperture cup.

Describing the invention in detail and directing attention to the drawings, an electron gun supporting cylinder is shown in detail in FIG. 1 and indicated by the numeral 10. In a preferred form the cylinder 10 is of uniform diameter having an internal passage 12 to carry the electrode structure. A typical cylinder, to be approximately one-half inch in inner diameter and which may be flared at its upper end, as at 14 if desired.

Referring to FIG. 2, and as an initial manufacturing step, the cylinder 10 is first subjected to a dye operation which partially shears the cylinder wall and forms a plurality of

annular shelves

16, 16. Any number of shelves 16 may be provided; however, in a tube of the size indicated three shelves angularly spaced at degrees have been found satisfactory. In addition to shelves 16 a peripheral wall of the tube 10 is provided with a plurality of

indentations

18, 18, again preferably formed with an angular spacing of 120 degrees when the cylinder is of the size described.

Considering FIGS. 2, 3 and 3A, a preferred mode of forming the indentations 18 Will now be described. To prevent undesired distortion of the wall of the support cylinder 10 during forming, it is preferred that the indentations always be formed on a radius which approximates the radius of the cylinder per so, as is shown in FIG. 1. With the typical cylinder described above, that is, one having a one-half inch diameter, indentations 18 are therefore formed on a radius of approximately one-quarter of an inch. For example, and directing attention to FIGS. 2 and 3, the indentations there shown are oblong in form paralleling the axis of the cylinder 10 and formed on the

radii

20, 22 and 24. The depth of each indentation 18 should be related to the outer diameter of the subsequently assembled G1 electrode to produce the fit as hereafter described.

Directing attention to FIG. 3A, a fragmentary partially diagrammatic transverse section of the tube 10, which will be seen at each indentation 18, is initially formed to a radius R which equals the normal internal radius of the cylinder 10 prior to assembly of the control electrode.

FIGS. 4 and 5 show the support cylinder 10 and G1 electrode, here indicated generally at 26, in the assembled relation. A preferred depth of each indentation 18 may be twice the normal radial clearance between the internal diameter of the cylinder 10 and the external diameter of the G1 assembly 26, plus about three thousandths of an inch. This provides the proper press fit for the assembly 26 in the cylinder 10 and minimizes distortion and internal cylinder stress.

After completion of the indentation operation 18 the G1 electrode 26 is press fitted into the passage 12 of cylinder 10 until the electrode 26 engages the shelves 16 and is in three point pressure fit with the dimples 18 as shown in FIGS. 4 and 5. This interference fit described provides firm support for the G1 electrode 26. As shown in FIG. 3A, primary points of pressure support are thus provided at 19, 19 and secondary contact is provided at points 21, 21. Under heating the cylinder 10 can expand and still provide support at points 19.

Shown in FIG. 7 is a typical cup shape G2 in vertical transverse section. The G2 electrode comprises cylindrical wall 30, end wall 32 and beam aperture 34 formed centrally thereof. A plurality of bosses 36, for example 3, may be formed peripherally around the outer edge of wall 32, the purpose of which will be hereinafter explained.

:Returning to FIGS. 4 and 5, it will be noted that after assembly of the G1 electrode 26 to the cylinder 10 the peripheral wall of the cylinder is dimpled as at 38, 3 8 in an area immediately above the G1 electrode 26. As shown in FIG. 6, the cup-shaped G2 electrode 30 may be telescopically positioned within the passage 12 of the cylinder 10. Thus, the perture of the G1 electrode and the aperture of the G2 electrode are in alignment with respect to the gun axis. The bosses 36 engage the upper ceramic surface of the G1 electrode assembly providing a radial passage 40 between the upper surface of the G1 assembly and the lower Wall 32 of the G2 electrode to accommodate the passage of gas therebetween. This radial passage aids in de-gassing a cathode ray tube.

After positioning of the G2 electrode 30 within the cylinder 10, as shown in FIG. 6, the dimples 38 formed in the cylinder 10 walls, as shown in FIG. 4, may be spotwelded to the outer diameter of the G2 electrode 30, providing both secure mounting therefor. The G2 electrode also axially positions the G1 electrode.

Both the novel electrode structure, as well as the methd of manuacture, are well designed to limit minimum induced stresses, both in the assembled electrodes and in the supporting cylinder thereby inhibiting component distortion and subsequent misalignment when the gun is in its operational situs.

The invention is shown by way of illustration and not limitation and may be subject to various modifications, all Within the scope of the appended claims.

What is claimed is:

1. In an electrode arrangement for an electron gun, the combination of an outer metal supporting cylinder,

abutment means disposed internally of the cylinder, said cylinder having its wall formed with deformations directed radially inwardly,

a first electrode having an outer insulating element engaging said abutment means disposed within the cylinder, said insulating element additionally being in pressure contact with said deformations.

'2. An electrode arrangement for an electron gun according to claim 1, and including a second electrode mounted in the cylinder adjacent said first electrode on the side thereof opposite from said abutment means.

3. An electrode arrangement for an electron gun according to claim 2, wherein said second electrode is Welded to the cylinder wall.

4. An electrode arrangement for an electron gun according to claim 3, and including bosses on one electrode and engaging the other electrode to provide spacing between the electrodes.

5. An electrode arrangement for an electron gun according to claim 4 wherein said abutment means comprises distortions in the Wall of said supporting cylinder.

6. An electrode arrangement for an electron gun according to claim 5, wherein said supporting cylinder additionally has dimples formed inwardly in the wall thereof to provide points of weld connection between said cylinder and said second electrode.

7. An electrode arrangement for an electron gun according to claim 1, wherein said support cylinder is partially sheared at no less than three continuous portions along a single circumference therea'bout and said cylinder wall indented radially inwards on a common side of said circumference thereby to form said abutment means.

References Cited UNITED STATES PATENTS 1,901,176 3/1933 Lawson 313-356 X 2,212,144 8/1940 Beers 313356 X 2,509,763 5/1950 Degier 313-82 2,667,598 1/1954 Linder 313-85 X 2,810,851 10/1957 Johnson 313-82 3,008,064- 11/1961 Niklas ct al. 313-82 3,188,506 6/1965 Rome 313284 X 3,210,145 10/1965 Fyler 313-283 X 3,320,457 5/1967 Burdick et al. 313-82 3,441,786 4/1969 Clayton 313-85 X JOHN HUCKERT, Primary Examiner A. J. JAMES, Assistant Examiner -U.S. Cl. X.R.