US3085172A

US3085172A - Cathode ray tube gun assembly

Info

Publication number: US3085172A
Application number: US798720A
Authority: US
Inventors: Wendell O Smith
Original assignee: Corning Glass Works
Current assignee: Corning Glass Works
Priority date: 1959-03-11
Filing date: 1959-03-11
Publication date: 1963-04-09
Anticipated expiration: 1980-04-09

Description

April 9, 1963 w. 0. SMITH CATHODE RAY TUBE GUN ASSEMBLY Filed March 11. 1959 zoi INVENTOR. Men 0544 0. 6M/ 71/ United States Patent 3,%5,l72 CATHUDE RAY TUBE GUN ASElEWBLY Wendell 0. Smith, Corning, NY assign-or to Qorning Glass Worlrs, Qorning, N511, a corporation of New York Filed Mar. 11, 1959, 3am No. 793,724? 2 tilaims. (6i. 313-32) The present invention relates to cathode ray tubes and more particularly to an improvement in the electron gun structures therefor.

Although many different electrode configurations have been devised heretofore to provide electrostatic focusing for the electron beams in cathode ray or other charged particle tubes, the various elements of the guns thereof have customarily been made structurally unitary by means of longitudinally plane surfaced insulating rods, com posed of glass or the like, extending along two opposite sides of the assembled and properly spaced electrodes attached thereto by means of studs projecting from such electrodes into the rods.

In the continuing effort to improve the efhciency of such guns their dimensions and the diameter of the tube necks enclosing them have been reduced from time to time.

Since in use of the tube, at least one of the gun elements is at high voltage potential while others are at ground or relatively low potential, a substantial number of such guns fail because of high voltage leakage and arcing along the relatively short paths along their rod surfaces.

In the older electron guns the enclosing tubes were of relatively large diameter and length compared to present day requirements. This permitted a liberal spacing of the respective gun elements with respect to one another along their supporting rods and, accordingly, gun failure from such causes as improper spacing of the respective elements from one another, surface contamination of the rods, or from the use of excessive test voltages rarely resulted.

ln the modern electron guns the enclosing tubes have been materially reduced both in diameter and length, thus making it necessary to reduce the size and spacing of the gun elements and of their support rods to such an extent that failure from one or another of the foregoing causes frequently occurs.

One known structure, devised with a view to reduce tube failures from the foregoing causes, supports those electrodes at or near ground potential between one pair of such rods and those at high and intermediate potentials between a second pair of such rods radially removed from the first pair 90. Such a structural arrangement, while helpful, is complicated by the use of four rather than but two electrode support rods.

According to the invention rods having plain surfaces are replaced with rods shaped or surface figured to impart to them a greatly increased surface length, as by giving them a surface that is non-planar parallel to their longitudinal axes, thus giving them surface resistances therealong comparable to and even greater than those employed in the hereinbefore referred to older types of guns. Such a structure greatly reduces the danger of gun failure resulting from high voltage leakage and arcing along the rod surfaces without complicating it by use of two pairs of rods, but nevertheless is equally applicable to the latter form of structure to further improve it.

For a better understanding of the invention reference will hereinafter be made to the accompanying drawing wherein:

FIG. 1 is an enlarged vertical elevation of an electron gun constructed according to the invention and having the tube envelope broken away.

FIG. 2 is a greatly enlarged vertical elevation of gun electrode assembly sectioned to the right of centerline.

Referring in detail to the drawing, there is illustrated the neck 2 and base i of a cathode ray tube, the enlarged bulb and screen supporting face of which are not shown. Supported within the neck 2 is an electron gun of the type commonly known as a straight gun. This electron gun comprises a cathode grid assembly 6, a second grid 3, an anode it}, a focusing ring 12 and an accel rating anode 14.

The

respective gun elements

6, 3, 1d, 12, and 14 are made structurally unitary by spot welding to two opposite sides of each of such elements the closed ends of U-shaped studs, such as 2% and 22, and by embedding their free ends into rods 24 and '25 of dielectric material, such as glass or the like.

According to the invention the rods 24 and 2-5, instead of, as in conventional past practice, having their exterior surfaces extending in planes parallel to their longitudinal axes, are provided along their lengths with undulating or transversely ribbed surfaces 353-, thereby greatly elongating their surface length. Such rods, accordingly, have surface resistances between the respective gun elements comparable to or greater than those employed in the older forms of electron guns.

Obviously, the character of configuration given to the rods to suitably increase the leakage paths between the respective electrode elements may take any of a great variety of forms without departing from the spirit of the invention.

What is claimed is:

1. An electron gun comprising a cathode element for emitting electrons along an electron beam path, an electron creating and focusing structure comprising in order along said beam from said cathode element, a first grid element, a second grid element, an anode element, a focusing electrode element, and an accelerating anode element arranged in the order named, and two rods of dielectric material rigidly supportnig said elements therebetween along their length in predetermined juxtaposed spaced relation with respect to one another, said rods being of a length which is substantially no greater than the distance between the regions of their connections with the first grid element and with the accelerating element respectively having surfaces figured to afford maximum leakage paths over their surfaces between respec tive ones of said elements.

2. in an electron gun providing electrostatic focusing for the electron beams in cathode ray and other charged particle tubes having a plurality of gun elements made substantially unitary by being rigidly supported in suitably spaced relation between rods of rigid dielectric material, the improvement which comprises use of rods straight throughout their lengths having surfaces that are non-planar parallel to their axes to increase the length of the surface paths between points of attachment of the respective elements thereto.

the

References (fed in the file of this patent UNITED STATES PATENTS 2,460,201 Trump Jan. 25, 1949 2,578,908 Turner Dec. 18, 1951 2,810,851 Johnson Oct. 22, 1957 2,836,788 Atlee May 27, 1958 2,927,233 Barnett Mar. 1, 1960 FOREIGN PATENTS 740,263 Great Britain Nov. 9, 1955

Claims

1. AN ELECTRON GUN COMPRISING A CATHODE ELEMENT FOR EMITTING ELECTRONS ALONG AN ELECTRON BEAM PATH, AN ELECTRON CREATING AND FOCUSING STRUCTURE COMPRISING IN ORDER ALONG SAID BEAM FROM SAID CATHODE ELEMENT, A FIRST GRID ELEMENT, A SECOND GRID ELEMENT, AN ANODE ELEMENT, A FOCUSING ELECTRODE ELEMENT, AND AN ACCELERATING ANODE ELEMENT ARRANGED IN THE ORDER NAMED, AND TWO RODS OF DIELECTRIC MATERIAL RIGIDLY SUPPORTING SAID ELEMENTS THEREBETWEEN ALONG THEIR LENGTH IN PREDETERMINED JUXTAPOSED SPACED RELATION WITH RESPECT TO ONE ANOTHER, SAID RODS BEING OF A LENGTH WHICH IS SUBSTANTIALLY NO GREATER THAN THE DISTANCE BETWEEN THE REGIONS OF THEIR CONNECTIONS WITH THE FIRST GRID ELEMENT AND WITH THE ACCELERATING ELEMENT RESPECTIVELY HAVING SURFACES FIGURED TO AFFORD MAXI-