US2373950A

US2373950A - Electronic tube

Info

Publication number: US2373950A
Application number: US451800A
Authority: US
Inventors: William W Eitel; Jack A Mccullough
Original assignee: Eitel Mccullough Inc
Current assignee: Varian Medical Systems Inc
Priority date: 1942-07-21
Filing date: 1942-07-21
Publication date: 1945-04-17
Anticipated expiration: 1962-04-17

Description

April 17, 1945. i w. EI"I:E L ET AL ELECTRONIC, TUBE Filed July 21, 1942 2 Sheets-Sheet 1 H L6 5% m5 wmw mMm m4 L w a Y B THEIR ATTORNEY April 1945- w. w. EITEL ET AL 7 2,373,950 ELECTRONIC TUBE Filed July 21, 1942 2 Sheets-Sheet 2 u mmrm'n INVE NTOR5 v WILL/AM W. E/TEL UACK A.MCULLOU6H MEJ THEIR ATTORNEY Patented Apr. 17, 1945 "UNITE-D STATES PATENT oi-Flo ELECTRONIC TUBE William W. Eitel, San Bruno, and Jack A.

McCullough, Millbrae, Calif., assignors to Eitel- McCullough, Inc., San Bruno, Calif., a corporav tion of California Application July 21, 1942, Serial No. 451,800

3'Claims. (or. 250-275) going, are set forth in the following description of our invention. It is to be understood that we do not limit ourselves to this disclosure of species of our invention, as we may adopt variant em-' bodiments thereof within the scope of the claims.

Referring to the drawings: Figure l is a perspective view of a tube embodying the improvements of our invention; and

Figure 2 is a side view of the same, partly in section and partly in elevation.

In terms of broad inclusion, our tube comprises an envelope enclosing a plurality of electrodes and having leads therefore sealed to the envelope. A shield is disposed transversely of the envelope between its stem end and the electrodes, which shield is supported on certain of the electrode leads. The envelope preferably contains a plurality of operative units, each including a cathode and grid and plate, and the shield is preferably supported on the. grid leads.

In greater detail, and referring to the drawings,

our tube comprises an envelope of glass or the like having a cylindrical body with an enlarged portion 2 and a reduced portion 3. portion is joined to a neck 4 at a shoulder forming a flat ledge 6 between these parts. A reentrant stem 1 projects inwardly from the lower end of neck 4. The tube is fitted with a suitable base 8 carrying prongs 9. I

Within the envelope are arranged a plurality of operative units, say four triode units, each including a filamentary cathode ll, grid l2 and a capped plate I3. These units are disposed about parallel axes and are equally spaced about the axis of the envelope. The plate electrodes are unitarily supported by a bracket 14 on a common plate lead l6 extending thru the top of the envelope at seal ll. Cathodes ll each have a pair of leads 18, all sealed to stem 1'; these leads being connected to prongs 9 so that two of the filaments are connected in parallel to a pair of The latter 1 the prongs and the other two filaments in parallel to the other two prongs.

Grids H are separately supported on the upper .ends of leads 2! by brackets 22. These grid leads extend longitudinally of the envelope and are equally spaced about the tube axis in alignment with the electrodes. The lower ends of leads 2| project thru ledge 6 of the envelope at seals 23, and are Welded to lips 24 on a common external terminal ring 26 cemented to the envelope at the shoulder. A projection 21 on the ring provides a terminal button.

We also provide improved means in the envelope for shielding stem 1 and grid lead seals 23 against heat and electron bombardment from the electrodes.

lead seals, at which points the glass is strained and particularly prone to crack under excessive heating. V

This difiiculty is overcome in our tube by means of a circular shield 28, preferably of nickel, disposed transversely of the envelope between the stem and the electrodes. Apertures 29 in the shield provide free passage forthe cathode leads. The shield is supported on grid leads 2| by means of tabs 3| welded to the leads.

In order to give full protection to the stem and seals, shield 28 is substantially co-extensive with the cross-sectional area of the envelope; the shield periphery terminating adjacent the annular side wall of the envelope. The shield is preferably cup-shaped with its side flange. 33 extending upwardly alongside the inner surface of the glass Wall. In a tube of the particular type illustrated, the envelope sections are fused together at a seal 34 in reduced portion 3. Our

shield 28 thus also protects this seal from heat originating at the electrodes.

We claim:

1. An electronic tube comprising an envelope having a stem, a cathode and. gridelectrode in the envelope, leads for the cathode sealed tothe stem, a grid lead supporting the grid and sealed.

to the envelope intermediate the ends of the envelope, and a shield mounted on the grid lead and interposed between the electrodesand said stem.

2. An electronic tube comprising anenvelope having a stem at one end thereof, a plurality of A serious problem in thermionic tubes is to prevent leaks from developing at the mediate the ends thereof, and a shield mounted on the grid supporting means and disposed transversely of said axis between the electrodes and said stem, said shield covering the ends of all of said groups of electrodes.

3. An electronic tube comprising an envelope, electrodes extending longitudinally of the envelope, means supporting the electrodes in the envelope, and a shield interposed between the electrodes and an end of the envelope, said shield extending transversely of said electrodes and being substantially co-extensive with that crosssectional area of the envelope with the peripheral edge of the shield spaced from the envelope side wall.

WILIIAM W. EITEL.

JACK A McCULLOUGI-I.