US2444281A - Electron tube - Google Patents

Description

June 29, 1948.

R. H. CHAMBERLIN ELECTRON TUBE Filed April 29, 1946 IN VEN TOR. file/MR0 CHA MBEEL IN ATTORNEY Patented June 29, 1948 OFFICE ELECTRON TUBE Richard H. Ghambcrlin, San Bruno, Calif., as-

signor to Eitel-McCullough, Inc., San Bruno, Calif., a corporation of California I Application April 29, 1946, Serial No. 665,690

1 Claim. (Cl. 250-275) My invention relates to electron tubes such as vacuum tubes and the like.

It is among the objects of :my invention to provide improvements in tube structure adapting the tube for higher frequency operation.

Another object is to provide a tube of the character described which is adaptablefor power tube uses. r

A further object is to provide a tube construction which facilitates assembly of the envelop parts and aligmnent of the electrodes.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of my invention. It is to be understood that I do not limit myself to this disclosure of species of my invention as I may adopt variant embodiments thereof within the scope of the claim.

Referring to the drawing, the single figure is a vertical sectional view of a tube embodying the improvements of my invention.

In terms of broad inclusion, my tube comprises upper and lower sections joined along a transverse plane, which sections include metallic ring members on opposing rims fitted together at the junction. The sections are connected together by a fused metallic bond uniting the rings. Cooperating electrodes are carried by the envelope sections, such as an anode on the upper section and a cathode and grid on the lower section. This arrangement greatly simplifies assembly of the tube, the procedure being to mount the electrodes on the envelope sections and then joining the sections by fusing the rings together. The annular member formed by the rings provides a terminal for the grid, and the anode is preferably of the external type with a portion projecting into the envelope. Such a structure provides a compact electrode arrangement with direct terminal connections, suitable for higher frequency operation.

In greater detail, and referring to the drawing, my tube has an envelope comprising an upper section 2 and a lower section 3 joined along a transverse plane indicated by the dotted line 4. These sections include metallic rings 6 and l fitted together at the junction and united by a fused metallic bond 8. In my preferred construction these rings are cup-shaped pieces having nested flanges with registered edges, which edges are fused together as by brazing or welding.

Upper section 2 preferably carries an anode 9 which is insulated from ring 6 by a vitreous wall portion 1 I of glass or the like. The anode chosen for purposes of illustration comprises a metallic body having a cylindrical recessed inner end I12 serving as the anode proper and having a finned outer end l3 serving as the anode cooler. This anode is preferably of a metal, such as copper, having good heat conductivity, and has a sealing flange l4 brazed to its intermediate portions.

Vitreous wall H of the upper sectionis sealed at one end to anode flange l4 and at the other end to ring 6. A passage l6 in anode 9 communi eating with tabulation l'l provides an exhaust duct for evacuating the envelope.

Lower section 3 preferably carries a cathode it which is insulated from ring 1 by vitreous wall portion H9. The cathode illustrated is of the indirectly heated oxide-coated type, having a cylindrical shell carrying the active coating material, and is mounted on a coaxial stem comprising an outer tubular member 2| and. an inner rod-like member 22. Vitreous portion [9 of the lower section is cup-shaped with its upper end sealed to ring I and its lower end sealed to stem member 2!. The inner stem member is carried by a metallic sleeve 23 brazed at the upper end to outer stem member 2 l, a vitreous ring or head 24 being scaled between the lower end of sleeve 23 and the inner stem member. Cathode heater 26 comprises a coil welded at one end to stem rod 21 and at the other end to the cathode shell adjacent a. heat shield 28.

Grid 29 interposed between the cathode and anode has an upper free end and a lower fixed end, the lower end being fastened to a tubular bracket 3! having a flange 32 secured to ring I of the lower envelope section by screws 33. When the envelope sections are brazed together the bracket flange 32 is caught between rings 6 and I as clearly shown in the drawing.

The electrode mounting arrangement and sectional envelope structure above described has several important advantages. For one thing, the cathode and grid structures are both mounted on. lower section 3 in such a manner that these electrodes are readily aligned and fastened in place, it being understood that these electrodes are mounted on section 3 before the envelope sections are brazed together. Since the cathode and grid lie above plane 4 they are in the open and easy to get at. I prefer to first mount the oathode structure on the stem members and then slip the grid over the cathode and anchor it by screws 33. Accurate alignment may thus be attained even with very close grid-to-cathode spacings. This is important in high frequency tubes where close spacings are essential.

After the grid and cathode assembly is completed the upper section 2 carrying anode 9 is moved axially into position until the outer edges of rings 5 and l are registered. Since the electrodes are coaxial with these rings the anode is automatically aligned with the other electrodes when the rings are fitted together. Uniting'the rings by fused bond 8 completes the assembly and the envelope is then ready for evacuation. Bond 8 may be made by brazing or weldinggeither of which may be simply accomplished by inducting heating from a high frequency coil placed around the nested rings. The cup-shape of the rings is important because such shape enables registering the edges, and places the edges sufficiently far away from the. seals to prevent cracking at the time of brazing, yet retaining a compact structure with a minimum envelope diameter.

Another important feature of my tube construction is that short direct connections are provided for the electrodes, it being observed thatring member 6-1 provides the grid terminal. 'Grid bracket 35 is preferably of a metal, such as copper, having good thermal conductivity, so that a good path is provided for heat flow outwardly from the grid to the terminal member. The fact that the relatively heavy bracket flange 32 extends outwardly and is caught between rings 6 and 1 is an advantage from the standpoint of both electrical and heat conduction. These structural features all contribute to improved tubeoperation, particularly at the higher frequencies.

The external type of anode illustrated is preferred because it is adapted for external cooling, as by forced air directedagainst fins I3,

thereby providing for ample heat dissipation from the anode to achieve higher power outputs. It is understood, however, that other types of anodes may be employed, either of the internal or external anode variety. Likewise, while I have shown a unipotential type of cathode, it

' transverse plane, said sections having cup-shaped Number cmetallic rings fitted together at the junction with downturned' flanges having lower edges lying in-register, and having vitreous portions sealed to said rings, a fused metallic bond uniting said rings at said edges only an electrode carried by the vitreous portion of the upper section, an electrode carried by the vitreous portion of the lower section, and an electrode carried by one of said rings.

RICHARD H. CHAMBERLIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Espe June 21, 1938 Espe Nov. 7, 1939 Bowie Nov. 7, 1939 Bondley Jan. 16, 1945 Glauber Apr. 2, 1946

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