US3268760A - Plural electrode unit electron tube - Google Patents

Description

Aug- 23, 966 v R. A. BONNETTE ETAL 3,

I PLURAL ELECTRODE UNIT ELECTRON TUBE Fi led May 5, 1964 2 Sheets-Sheet l INVENTORS HIEHFIRD H. Bowman-e i'fi-mmns E DEEEHN 3, 1966 R. A. BONNETTE ETAL 3,268,760

PLURAL ELECTRODE UNIT ELECTRON TUBE Filed May 5, 1964 2 Sheets-Sheet 2 INVENTORS RIEHHBD F1. BEINNET'IE 3;: TI-mMas E. DEEEBN p 3,268,769 Patented August 23, 1965 3,268,760 PLURAL ELECTRQDE UNIT ELECTRQN TUBE Richard A. Bonnette, New Providence, N.J., and Thomas Edward Deegan, Brewster, N.Y., assignors to Radio Corporation of America, a corporation of Delaware Filed May 5, 1964, Ser. No. 364,932 8 Claims. (Cl. 313-296) This invention relates to plural electrode unit electron tubes, and particularly to plural electrode unit electron tubes wherein the electrode units have matched electrical characteristics.

By electrode unit is meant a plurality of cooperating electrodes providing the electrical characteristics of a triode or pentode electron tube, or the like. Several electrode units may be provided within a single electron tube envelope. By matched electrical characteristics is meant that there is a preselected relationship between the electrical characteristics of the different electrode units. Generally, the desired relationship is that the electrical characteristics of the electrode units be substantially identical.

This invention further relates to plural electrode urn't tubes wherein one or more electrodes are common to, or shared by, all the electrode units.

Heretofore, two modes of construction have been generally used in the manufacture of plural electrode unit electron tubes having common electrodes.

According to one mode of construction, a single electrode, usually the cathode electrode, is mounted between and extends through two or more axially spaced pairs of spacer plates. Mounted between each of the pairs of spacer plates, and in surrounding relation with a portion of the cathode, are a plurality of concentric electrodes. Each cathode portion and the concentric electrodes disposed there around constitute an electrode unit.

A disadvantage of this mode of constnuction is that electron tubes made in this fashion are complicated and difiicult to assemble, and are expensive.

According to another mode of construction, only one pair of spacer plates is used, and the electrodes of each electrode unit are grouped in separate sectors with respect to the common electrode. Thus, for example, in one type of electron tube including a pair of matched triodes, a single rectangular cathode is mounted between a pair of spacer plates, and a grid electrode and an anode are mounted between the spacer plates on opposite sides of the rectangular cathode. Each cathode side and the grid and anode opposite that side constitute a triode unit.

A disadvantage of this mode of constnuction, however, is that it has been found extremely difficult to provide the different electrode units with electrode spacings which are sufficiently similar so as to provide matched electrical characteristics. One reason for this difficulty is that any inaccuracy in the location of the common electrode generally causes the common electrode to be closer to one of the electrode units and correspondingly further from another of the electrode units. Thus, the amount of mismatch between the electrode spacings of these two units is twice the amount of the inaccuracy of location of the common electrode.

An object of this invention is to provide a plural electrode unit electron tube having one or more electrodes common to the electrode units, said electrode units being electrically matched, and said tube being relatively simple and inexpensive to fabricate.

A further object of this invention is to provide a plural electrode unit electron tube having one or more electrodes common to the units, wherein all the electrodes of the units are mounted between a common pair of spacer plates, and wherein the matching of the electrical characteristics of the electrical units is relatively unaffected, as compared with prior art tube constructions, by inaccuracies in the location of the various electrodes of the several electrode units.

For achieving the objects of this invention in accordance with one embodiment of the invention, a duel electrode unit electron tube may be provided comprising an elongated cathode mounted between a pair of spacer plates. Disposed around each of two longitudinal portions, such as each longitudinal half of the cathode, are two or more electrodes. Each cathode longitudinal portion and the electrodes disposed there around form an electrode unit. Except for the cathode, and any other electrodes common to both electrode units, support means for the electrodes of each electrode unit extend past the other electrode unit. The support means of all the electrodes of both electrical units are mounted between a single pair of spacer plates.

A more detailed description of an embodiment of this invention, and a discussion of advantages of the invention follow in connection with a description of the drawings, wherein:

FIGS. 1 and 2 are schematic end views showing the relative spacings of the electrodes of a prior art triode electron tube;

FIG. 3 is a view similar to FIGS. 1 and 2 but showing a prior art double triode;

FIG. 4 is a view in perspective with the envelope broken away of an electron tube embodying the invention and showing the electron tube mount;

FIG. 5 is an exploded view, in perspective, of the plural electrode unit electron tube mount of FIG. 4, and

FIG. 6 is a series of figures which, when taken together, show the cathode and grid arrangement of another plural electrode unit electron tube which may be made according to this invention, each pair of FIGURES 6a-6l1, 60-641, 6e-6f, and 6g-6h, showing, in side elevation and plan view, respectively, the arrangement of the lateral wire helix of each of the electron tube gride electrodes.

FIGS. 1 and 2 show, in schematic form, the relative dispositions of the electrodes of a conventional triode comprising a rectangular cathode 1d, a .grid 12 including a pair of side rods 14 and a lateral wire helix 16 wound around and secured to the side rods, and a box-like anode 18. In the tube shown in FIG. 1, the electrodes are perfectly coaxial, and the spacing between the various electrodes on each side of the tube are the same. In the tube shown in FIG. 2, however, the cathode 10 is displaced (shown greatly exaggerated) from the center line of the tube, as occurs, for example, due to inaccuracies in the spacer plates used to position the electrodes, and the electrode spacings on one side of the tube are different from the spacings on the other side of the tube.

Although different electrode spacings provide diflierent electrical characteristics, as known, the electrical characteristics of the tubes shown in FIGS. 1 and 2 will be relatively matched. This is because the tube electrodes are in surrounding relation with respect to one another and the effect on the tube electrical characteristics of the decreased grid to cathode spacing on one side of the tube shown in FIG. 2 is largely compensated for by the effect of the increased grid to cathode spacing on the other side of the tube.

FIG. 3 shows, schematically, the relative dispositions of the electrodes of a prior art double triode, the cathode electrode 20 being shown (greatly exaggerated) misaligned with respect to the grids 22 and 24 and the anodes 26 and 28 of each electrode unit A and B, respectively. Because the grid and anode of each electrode unit are disposed on one side only of the cathode 20, the compensating effect provided by electrodes which surround a common cathode (as described in connection with the tubes shown in FIGS. 1 and 2) is not present in the tube shown in FIG. 3. Hence the difference in the cathode to grid spacing of each electrode unit caused by the mis-alignment of the cathode 20 causes susbtantial mismatching between the electrical characteristics of the two units.

FIG. shows a mount assembly of a double triode unit made according to this invention. The mount assembly comprises a stem assembly 32 having a plurality of leads 33 therethrough to which are welded the ends of electrodes of a cage assembly 34. Each longitudinal half of cage assembly 34 is a separate triode unit C and D. Cage assembly 34 comprises a pair of spacer plates 36 and 38 between which all of the electrodes of each triode unit C and D (see FIG. 4) are mounted, extending ends of the electrodes extending through spaced apertures in the spacer plates 36 and 38.

Mounted between the spacer plates 36 and 38 and com mon to both triode units C and D is an elongated rectangular cathode 40. The cathode is coated over substantially its entire length between the spacer plates 36 and 38 with a known electron emitting material, such as a combination of strontium and barium carbonates. The electrodes of each electrode unit C and D have electron affecting portions concentric with only one-half the length of the cathode between the spacer plates.

Triode unit C comprises a control grid 42 including a pair of side rods 44 and a lateral wire helix 46 wound around and secured to a portion of the side rods. The ends of the side rods 44 extend through apertures 48 in the spacer plates 36 and 38. Side rods 44 are disposed opposite the narrow sides of rectangular cathode 40 and in this position, as known, have substantially no effect on the electrons emitted from the cathode. The electron affecting or controlling portion of control grid electrode 42 is the lateral wire helix 46 wound around the side rods and disposed around the cathode. As shown in FIG. 5, the lateral wire helix 46 of grid 42 is disposed around only the upper half of the cathode. Thus, only electrons emitted from the upper half of cathode 40 are controlled by grid electrode 42.

Disposed around grid 42 (FIG. 4) is an anode 50. As shown in FIG. 5, anode 50 is substantially U-shaped in cross section, and has a pair of wings or legs 52 extending laterally from the ends of sides 54 of the anode. The lower portions of sides 54 are cut-away leaving a further pair of legs 56. Extending tabs or ears 58 are provided at the ends of the legs 52 and 56 and sides 54 for receipt within apertures 59 in the spacer plates 36 and 38. The portions 60 of sides 54 of the anode 50 are the electron receiving portions of the anode. Sides 54 of the anode 50 are joined by connecting straps 66.

When mounted in the cage assembly 34, as shown in FIG. 4, the electrode receiving portions 60 of the anode 50 are disposed opposite the lateral wire helix 46 of grid 42, and the support legs 52 and 56 extend between the spacer plates 36 and 38. Ears 58 are received through the apertures 59 in the spacer plates to provide the proper positioning of the anode 50 with respect to the other tube electrodes. The connecting strap 66 (not visible in FIG. 4) of the anode 50 are positioned opposite and outside the side rods 44 of grid 42. Anode connecting straps 66 are thus shielded from the cathode 40 by the side rods and have substantially no affect upon electrons emitted from cathode 40.

Triode unit D is similar to triode unit C except that the lateral wire helix 46 (FIG. 5) of control grid 42' and the electron receiving portions 60' of anode 50 of this unit are disposed around the lower half of the cathode 40. Side rods 44 of grid 42, as shown, are disposed in a plane through the axis of cathode 40 and the side rods 44 of grid 42 of unit C, and side rods 44 are mounted in staggered relation with respect to the side rods 44 of grid 42. Anode 50' of triode unit D is identical to anode 50 of triode unit C.

Avoidance of electrical coupling between the triode units C and D is achieved by disposing the support members of the electrodes of the two units, with the exception of the common cathode 40, in positions where they have little or no afiect upon the electrons emitted from the cathode. The side rods 44 and 44' of control grids 42 and 42', respectively, are disposed opposite the narrow sides of the rectangular cathode 40. Since control grids are usually negatively biased, the side rods cut-off all electron emission from the narrow sides of the cathode; hence, the side rods 44, 44' have little or no effect upon the electrical characteristics of the triode units.

The side straps 66, 66' of the anodes 50, 50' are disposed beyond the side rods 44, 44, and are shielded from the cathode 40. Legs 52, 52' of each anode 50, 50 extend outwardly from sides 54, 54' of the anodes, and as shown in FIG. 4, the legs 52, 52 of each anode 50, 50' are disposed outside the electron receiving portions 60, 60 of the other anode 50', 50.

For providing identical electrical characteristics of triode units C and D, the dimensions of the grid electrodes 42 and 42' and anode 50 and 50' of each triode unit C and D are made the same. Thus, when assembled into cage assembly 34 the portions of the lateral wire helix 46 of grid 42 which extend parallel to the wide sides of rectangular cathode 40 lie in the same surfaces as the corresponding portions of the lateral wire helix 46 of grid 42. Also, the pitch of the turns of the lateral wire helices 46, 46' and the diameter of the wires in the lateral wire helices of the grids 42, 42 are the same. Also, the electron receiving portions 60, 60' of the anodes 50, 50' lie within the same surfaces when the anodes are assembled into the cage assembly.

The anodes 50, 50' are identical and may be used interchangeably. Also, because of the staggered relation of the side rods 44, 44 of the grids, the grids are also identical and may be used interchangeably. The interchangeability of the anodes and grids simplifies manufacture and storage of the electron tube parts.

As mentioned the electrodes of each unit C and D are mounted between the same pair of spacer plates 36 and 38. This provides a tube structure considerably less complicated and expensive than the prior art tubes described above which provide separate spacer plate pairs for each electrode unit.

A further advantage of the tube construction shown in FIGS. 4 and 5 is that inaccurate positioning of the various electrodes 40, 42, 42', and 50, 50' with respect to one another has relatively little affect upon the matching of the electrical characteristics of the triode units C and D. This is because the electrodes of each triode unit C and D are in surrounding relation with respect to one another, and the compensating effect of this relation, as described in connection with the tubes shown in FIGS. 1 and 2, is present in the tube shown in FIGS. 4 and 5. Also, any misalignment of the common cathode electrode 40 with respect to the axis of the tube tends to cause similar changes in the grid to cathode spacing of each unit C and D, and the electrical characteristics of the two units tend to remain matched.

In FIG. 6 is shown a dual pentode, such pentodes having utility, for example, in color demodulator circuits of color television receivers, as known. For clarity, each pair of FIGS. 6a-b, 6c-d, 6e-f, 6g-h, show the arrangement of the lateral wire helix of one grid electrode.

The pentode comprises a common cathode 70 mounted between a pair of spacer plates 72, only one of which is shown in FIG. 6. Surrounding cathode 70 is a first control grid 74 having a lateral wire helix 76 (FIGS. 6ab). The helix 76 surrounds substantially the entire length of the cathode 70 between spacer plates 72. Disposed around grid 74 is a screen grid 78 having a lateral wire helix 80 (FIG. 6c-d). The lateral wire helix 80 of grid 78 is coextensive with the lateral wire helix 76 of first control grid 74.

Disposed around portions of grids 74 and 78, as shown in FIGS. 6e through 6h, are a pair of second control grids 84, 84'. Second control grid 84 has a lateral wire helix 86 disposed around the upper half of the lateral wire helix 80 of screen grid 78, and second control grid 84' has a lateral wire helix 86 disposed around the lower half of the lateral wire helix 80 of screen grid 78. The portions of lateral wire helices 86, 85 opposite each of the wide sides of rectangular cathode 7!) lie in the same surface.

Although not shown, two anodes, which may be identical to the anodes 5t 50 shown in FIGS. 4 and 5 are provided. The anodes are mounted between the spacer plates 72 so that the electron receiving portions (such as portions 60, 60' of anodes 50, 50) of the anodes are disposed adjacent a different one of lateral wire helices 86, 86' respectively, of the two second control grids 84, 84.

The dual pentode illustrated in FIG. 6 thus comprises a cathode 70 common to both electrode units, a first control grid 74 common to both electrode units, a screen grid 78 common to both electrode units, and separate second control grids 84, 84' and anodes for each electrode unit. The various electrodes are in surrounding relation, and the control grids 84, 84', and the anodes (not shown in FIG. 6); but which may be identical to the anodes 50, 50' shown in FIGS. 4 and 5 for each unit are identical and interchangeable. This tube also, therefore, possesses advantages of economy of manufacture as well as electrical similarity of the two sections.

What is claimed is:

1. An electron discharge device comprising a pair of spacer plates and a plurality of electrodes, said electrodes including a cathode mounted between said spacer plates, a pair of grid electrodes each having an electron controlling portion, the electron controlling portion of one of said grids being disposed around one portion only of said cathode, the electron controlling portion of the other of said grids being disposed around another portion only of said cathode, each of said grid electrodes having support means extending past the electron controlling portion of the other of said grid electrodes and mounted between said spacer plates, and a pair of anodes mounted between said spacer plates, each of said anodes having an electron receiving portion adjacent to a different one only of the electron controlling portions of said pair of grids.

2. An electron discharge device comprising a pair of spacer plates and a plurality of electrodes, said electrodes including an elongated cathode mounted between said spacer plates, a pair of grid electrodes each having electron controlling portions, the electron controlling portions of one of said grids being disposed around one longitudinal portion only of said cathode, the electron controlling portions of the other of said grids being disposed around another longitudinal portion only of said cathode, each of said grid electrodes having support means extending past the electron controlling portions of the other of said grid electrodes and mounted between said spacer plates, and a pair of anodes, each of said anodes having electron receiving portions adjacent to a di'fierent one only of the electron controlling portions of said pair of grids, and each of said anodes having support means extending past the electron receiving portions of the other of said anodes and mounted between said spacer plates.

3. An electron discharge device comprising a pair of spacer plates and a plurality of electrodes, said electrodes including an elongated cathode mounted between said spacer plates, a pair of grid electrodes each having electron controlling portions, the electron controlling portions of one of said grids being disposed around one half only of the length of said cathode between said spacer plates, the electron controlling portions of the other of said grids being disposed around the other half only of the length of said cathode between said spacer plates, the electron controlling portions of each of said grids lying in common surfaces, each of said grid electrodes having support means extending past the electron controlling portions of the other of said grid electrodes and mounted between said spacer plates, and a pair of anodes, each of said anodes having electron receiving portions disposed around a different one of the electron controlling portions of said pair of grids, the electron receiving portions of said anodes lying in common surfaces, and each of said anodes having support means extending past the electron receiving portions of the other of said anodes and mounted between said spa-oer plates.

4. An electron discharge tube comprising a plurality of coaxial electrodes and a pair of spacer plates, said electrodes including a cathode mounted between said spacer plates, a first grid having a lateral wire helix disposed around one longitudinal portion only of said cathode between said spacer plates, a second grid having a lateral wire helix disposed around another longitudinal portion only of said cathode between said spacer plates, each of said grids having side rods extending past the lateral wire helix of the other of said grids and mounted between said spacer plates, and first and second anodes, each of said anodes having an electron receiving portion adjacent to a different one only of the lateral wire helices of said first and second grids, and each of said anodes having support means extending past the electron receiving portion of the other of said anodes and mounted between said spacer plates.

5. An electron discharge tube comprising a plurality of coaxial electrodes and a pair of spacer plates, said electrodes including a cathode mountedbetween said spacer plates, a first grid having a lateral wire helix disposed around one half only of the length of said cathode between said spacer plates, a second grid having a lateral wire helix disposed around the other half only of the length of said cathode between said spacer plates, portions of the lateral wire helices of said first and second grids lying in common surfaces, each of said grids having side rods extending past the lateral wire helix of the other of said grids and mounted between said spacer plates, and first and second anodes, each of said anodes having electron receiving portions disposed around a different one of the lateral wire helices of said first and second grids, the electron receiving portions of said anodes lying in common surfaces, and each of said anodes having support means extending past the electron receiving portion of the other of said anodes and mounted between said spacer plates.

6. An electron discharge tube comprising a plurality of coaxial electrodes and a pair of spacer plates, said electrodes including a cathode mounted between said spacer plates, a first grid having a lateral wire helix disposed around one half only of the length of said cathode between said spacer plates, a second grid having a lateral wire helix disposed around the other half only of the length of said cathode between said spacer plates, portions of the lateral wire helices of said first and second grids lying in common surfaces, each of said grids having side rods extending past the lateral wire helix of the other of said grids and mounted between said spacer plates, the side rods of said grids being in staggered relation and lying in a common plane, and first and second anodes, each of said anodes having electron receiving portions disposed around a difierent one of the lateral wire helices of said first and second grids, said electron receiving portions lying in common surfaces, and each of said anodes having support means extending past and outside the electron receiving portions of the other of said anodes and mounted between said spacer plates.

7. An electron discharge device comprising a plurality of coaxial electrodes and a pair of spacer plates, said electrodes including a cathode mounted between said spacer plates, first, second, third, and fourth grid electrodes, each of said grid electrodes comprising a pair of side rods mounted between said spacer plates and a lateral wire helix wound around at least portions of said side rods, the lateral wire helix of said first grid being displates, each of said anodes having electron receiving 10 portions adjacent to a difierent one of said lateral wire helices of said third and fourth grids.

8. An electron discharge device comprising a plurality of coaxial electrodes and a pair of spacer plates, said electrodes including a cathode mounted between said spacer plates, first, second, third, and fourth grid electrodes, each of said grid electrodes comprising a pair of side rods mounted between said spacer plates and a lateral Wire helix wound around at least portions of said side rods, the side rods of said third and fourth grid electrodes being staggered, the lateral wire helix of said first grid being disposed around substantially the entire length of said cathode between said spacer plates, the lateral wire helix of said second grid being disposed around substantially the entire length of the lateral wire helix of said first grid, the lateral wire helix of said third grid being disposed around one half only of the length of the lateral wire helix of said second grid, the lateral wire helix of said fourth grid being disposed around the other half only of the length of the lateral wire helix of said second grid, portions of the lateral wire helices of said third and fourth grids lying in common surfaces, the side rods of each of said third and fourth grids extending past the lateral wire helix of the other of said third and fourth grids, and first and second anodes, each of said anodes having electron receiving portions disposed around a different one of said lateral Wire helices of said third and fourth grids, the electron receiving portions of said anodes lying in common surfaces, and each of said anodes having support means extending past and outside the electron receiving portions of the other of said anodes and mounted between said spacer plates.

References Cited by the Examiner UNITED STATES PATENTS 2,156,079 4/ 1939 Beggs 313-298 2,187,591 1/1940 Manthorne 313-265 X 2,311,672 2/1943 Leyan 3133 2,798,903 7/ 1957 Spencer 313-245 2,936,391 5/1960 Curry et a1. 3l3350 JOHN W. HUCKERT, Primary Examiner.

A. I. JAMES, Assistant Examiner.

Claims (1)

1. AN ELECTRON DISCHARGE DEVICE COMPRISING A PAIR OF SPACER PLATES AND A PLURALITY OF ELECTRODES, SAID ELECTRODES INCLUDING A CATHODE MOUNTED BETWEEN SAID SPACER PLATES, A PAIR OF GRID ELECTRODES EACH HAVING AN ELECTRON CONTROLLING PORTION, THE ELECTRON CONTROLLING PORTION OF ONE OF SAID GRIDS BEING DISPOSED AROUND ONE PORTION ONLY OF SAID CATHODE, THE ELECTRON CONTROLLING PORTION OF THE OTHER OF SAID GRIDS BEING DISPOSED AROUND ANOTHER PORTION ONLY OF SAID CATHODE, EACH OF SAID GRID ELECTRODES HAVING SUPPORT MEANS EXTENDING PAST THE ELECTRON CONTROLLING PORTION OF THE OTHER OF SAID GRID ELECTRODES AND MOUNTED BETWEEN SAID SPACER PLATES, AND A PAIR OF ANODES MOUNTED BETWEEN SAID SPACER PLATES, EACH OF SAID ANODES HAVING AN ELECTRON RECEIVING PORTION ADJACENT TO A DIFFERENT ONE ONLY OF THE ELECTRON CONTROLLING PORTIONS OF SAID PAIR OF GRIDS.

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