US2125317A - Electron discharge device - Google Patents

Description

Filed Feb. 4, 1956 FIG. 3

lNVENTOR V. LRONC/ A T TORNEY Patented Aug. 2, 1938 UNITED STATES PATENT [OFFICE Telephone Laboratories,

Incorporated, New

' York, N. Y., a corporation of New York Application February 4, 1936, Serial No. 62,254

Y 2 Claims.

This invention relates to electron discharge devices and more particularly to'such devices suitable for the generation and amplification of ultrahigh frequency impulses.

In ultra-high frequency .systems employing electron discharge devices, the high frequency electrostatic fields set up by the potentials applied to the electrodes of the discharge devices cause interference in the system by undesired interaction between the input and output circuits of the discharge devices. This interference reduces the sensitivity of the system and impairs the stability of the amplifier, oscillator or other generating or translating apparatus in the system.

One object of this invention is to eliminate interference by electrostatic fields between the input and output circuits of electron discharge devices.

Another object of the invention is to completely shield the terminal conductors in the input circuit of the discharge device from the output circuit terminal conductor.

In one illustrative embodiment of this invention, an electron discharge device comprises a unitary main electrode assembly including a metallic closure member or disc which serves as a shield. The disc is hermetically sealed to a dished or bell-shaped vitreous envelope in which a cylindrical anode is mounted. The disc is provided with integrally formed eyelets which are sealed by glass beads carrying conductors supporting the individual electrodes, such as the cathode and oneor more grids, of the main assembly. The electrodes also may be assembled as a unit on the disc and are held in uniform spaced relation by insulating spacers at both ends of one of the grids, for example, the shield or suppressor electrode, and the internal electrodes are completely shielded from stray fields within the device.

One feature of this invention relates to the fabrication of the device whereby all the electrodes but the anode may be assembled as a unit on the shielding disc and the enclosing vessel carrying the anode subsequently may be sealed to the disc to form a compact and eilicient structure.

Another feature relates to the combination of the device with an external shield structure whereby the internal disc shield may be placed in physical contact with the external shield to insure complete and positive shielding between the input and output circuits.

The invention and the features thereof will be understood more clearly and fully from the following detailed description with reference to the accompanying drawing:

Fig. 1 is an elevational view in cross-section of an electron discharge device illustrative of one embodiment of this invention and showing the relationship of the electrodes in the device;

Fig. 2 is an elevational view in perspective of an electron discharge device illustrative of another embodiment of this invention, a portion of the enclosing vessel being broken away to show the internal structure more clearly;

Fig. 3is a partly exploded view in perspective of the electron discharge device shown in Fig. 2, portions of the enclosing vessel, anode and, the unitary electrode assembly being broken away to show details of construction more clearly;

Fig. 4 is a plan view, to a reduced scale, showing the association of the leading-in conductors with the electrodes of the unitary electrode assembly in the discharge device shown in Figs. 2 and 3; and

Fig. 5 is a detail view in cross-section of the cathode embodied in the discharge device shown in Figs. 2and 3.

Referring now to the drawing, the electron discharge device shown in Fig. 1 comprises an enclosing vessel including a vitreous dished or bellshaped envelope or portion l0 and a metallic disc H, for example of copper, closing the open end of the envelope ID. The envelope l0 and a vitreous backing ring l2 may be fused to the disc II by heating the disc by high frequency induction as described more fully in my copendlng application, Serial 'No. 62,253, filed February 4, 1936. A metallic rod or wire conductor I3 is sealed into the envelope Ill at the top thereof, as indicated at H, and supports a cylindrical anode The metallic disc I l is provided with a plurality of integral eyelets or sockets l6, into each of which a vitreous bead I1 is sealed. The vitreous beads II have sealed therein metallic wires or rods l8, l9 and 20 which serve as leading-in conductors for electrodes of the device. The wires or rods l8 are connected electrically to end extensions 2l of a heater element for the cathode 22, the cathode being coaxial with the anode l5 and supported from the disc II and electrically connected thereto by a rod or wire 23. The rod or wire I9 is secured to and supports a rigid metallic rod or wire 24 which carries a helical wire control electrode or grid 25 encompassing the cathode 22 and coaxial therewith. Similarly, the rod or wire 20 supports a helical wire shield or screen grid 21 encompassing and coaxial with is encompassed in turn by a helical wire shield or suppressor grid 23, only a portion of which is shown, supported by and electrically connected to the disc I I by rigid metallic uprights or rods 29.

In the fabrication of the device shown in Fig. 1, all of the electrodes except the anode are fabricated in a unitary assembly with the disc II. The beads Il may be sealed in the sockets I3, for example, by high frequency heating of the disc as described in my copending application aforementioned. The electrodes of this assembly, namely, the cathode 22 and grids 25, 21 and 23, are positioned in proper relation within the anode I5 and the disc II is seated upon the edge of the envelope III. Subsequently, the envelope I0 and backing ring I2 are fused to the disc I I as stated hereinbefore to form a hermetic seal therewith.

As shown clearly in Fig. 1, the disc II is of greater diameter than the envelope I0 and may be seated upon an external metallic shield 30. The disc II and shield 30, it will be clear, effectively screen the leading-in conductors I3, I9 and 23 from the leading-in conductor I4 for the anode so that the input circuit is substantially completely shielded from the output circuit of the device and undesired interaction between these circuits is prevented. If desired, an annular insulating disc, not shown, may be positioned between the disc II and shield 33 so that these members may be at diflerent potentials although still performing their shielding function.

Inasmuch as all the electrodes but the anode may be fabricated as a unitary assembly exteriorly of the envelope III and may be fixed in proper relation to the anode I3 by a single operation, the fabrication of discharge devices is materially simplifled and expedited. Furthermore, it will be apparent that in a device constructed in accordance with this invention, the length of the leading-in conductors for the cathode and the several grids may be made very short so that the inductances of these conductors will be very small and the device may be used efliciently at ultra-high frequencies.

In the construction illustrated in Figs. 2 and 3, which are enlarged approximately five times for clarity, the several electrodes of the unitary assembly are maintained in their proper space relation by insulating spacer members and additional shields are provided for segregating the input and output electrodes. As shown in these figures, the rods or wires 23 carrying the suppressor grid 23 are suitably secured, as by welding, at one end to the disc I I and support a metallic collar or ring shield 3I having an annular flange 32 which extends to immediately adjacent the inner wall of the envelope III. Seated upon the flange 32 is an insulating spacer 33, for example, of mica, which may be provided with peripheral recesses 34 to render the edge of the disc more resilient and thereby compensate for variations in the inner di meter of the envelope I II. Another insulating spacer disc 35, which also may be of mica, is affixed, as by a friction fit, to the rods or wires 23 adjacent the free ends thereof.

The screen grid 21 is carried by two metallic uprights or rods 36 which extend through the insulating spacers 33 and 35, one of the rods 36 being held against longitudinal movement by a metallic stub 31 secured thereto and resting upon the insulating spacer 33. Similarly, the control grid is carried by a pair of metallic uprights or rods 33 which are fitted at opposite ends into apertures in the insulating spacers 33 and 35.

2,125,511? the control grid 23. The shield or screen grid 21 The cathode embodied in the device illustrated in Figs. 2 and 3, as shown more clearly in Fig. 5, comprises an outer metallic sleeve 33 having a coating oi. thermionic material thereon, which is carried by and electrically connected to a central metallic standard 43. The standard 43 is encompassed by a heater wire lI which is embedded in or coated with insulating material 42, one end 43 ofthe heater wire being secured to the standard. The cathode is supported between the insulating spacers 33 and 35, the standard III extending through central apertures in these spacers and the insulator extension 42 abutting against the lower spacer 35.

The portions of the rods or wires 36 and 33 and the standard 43 extending above the insulating spacer are substantially enclosed by a metallic cap 44 which is seated upon the insulating spacer 35 and is provided with integral tabs 45 secured, as by welding, to the rods or wires 29 of the suppressor grid. The cap 44 forms a shield between the elements enclosed thereby and the anode and its support I3, thereby effectively screening these elements electrostatically from the anode.

As shown more clearly in Fig. 4, the end 36 of the heater wire 42 is electrically connected to one of the rods or wires I3 by a short wire or stub 41, and the standard which serves as a leading-in conductor for both the cathode 39 and the heater wire ll, is connected electrically to the other rod or wire I3 by a short wire or stub 43. Similarly, one of the rods or wires 33 carrying the control grid is connected to the rod or wire I9 by a short wire or stub 49, and one of the rods or wires 36 carrying the shield grid is connected to the rod or wire 20 by a short wire or stub 53.

In the fabrication of the device shown in Figs. 2 and 3, the cathode 39 and grids 25, 21 and 23, together with the insulating spacers 33 and 35, collar 3I and disc II may be assembled as a unitary structure. The electrodes may then be inserted into the envelope III in proper coaxial relation with the anode I 5 and the envelope sealed hermetically by fusing the envelope and the backing ring I2 to the disc I I.

This construction provides a high degree of shielding between the anode and the other electrodes so that the input and output elements and circuits are effectively segregated. The cap 43, as previously mentioned, effectively shields the upper ends of the cathode and grid supports from the anode. Similarly, the collar 3|, 32 effectively shields the lower ends of the cathode and grid 'ductors for the cathode and the control and screen grids from the anode and the leading-in conductor therefor. Hence, undesired interaction between the input and output circuits of the de vice is prevented and stable and eiiicient operation of the device is obtained.

Although specific embodiments of this invention have been shown and described, it will be understood, of course, that modifications may be made therein without departing from the scope and spirit of this invention as defined in the appended claims.

What is claimed is:

1. An electron discharge device comprising an enclosing vessel including a dished vitreous portion and a metallic closure disc sealed to the edge of said vitreous portion, a cylindrical anode within said vessel and supported by a leading-in 15 conductor sealed in said vitreous portion, and a unitary electrode assembly supported from said disc including a cathode and a grid within said anode, a support carrying said grid and secured to said disc, and an insulating member spacing said cathode and said support, said insulating member having portions engaging said vitreous portion to position said assembly with respect to said anode.

2. An electron discharge device comprising an enclosing vessel including a dished vitreous portion and a metallic closure disc sealed to the edge of said vitreous portion, a cylindrical anode within said vessel and supported by a leading-in conductor sealed in said vitreous portion, and a unitary electrode assembly including a cathode, a plurality of grids? metallic supports for one oi said grids secured to said disc, and an insulating disc carried by said supports and spacing said cathode and said grids with respect to each other, said insulating disc having a flexible peripheral portion engaging said vitreous portion to posi- 10 tion said assembly with respect to said anode.

. VICTOR L. RONCI.

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