US2888589A - Automatic assembly of radio-tube mounts - Google Patents

Description

y 1959. E. A. LEDERER 2,888,589

AUTOMATIC ASSEMBLY OF RADIO-TUBE MOUNTS Filed Aux. 20, 1953 I 2 Sheets-Sheet 1 WlTNESSESi INVENTOR Ernest A.Lederer.

BY $4 771% XZM ATTORNEY May 26, 1959 E A. LEDERER AUTOMATIC ASSEMBLY OF RADIO-TUBE MOUNTS Filed A112. 20, 1953 2 Sheets-Sheet 2 INVENTOR WITNESSES:

QZMWW Patented May 26, 195

AUTOMATIC ASSEMBLY OF RADIO-TUBE MOUNTS Ernest A. Lederer, Essex Fells, N.J., assiguor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 20, 1953, Serial No. 375,524

10 Claims. (Cl. 313-261) My invention relates to electron tubes and in particular relates to a novel electron tube structure particularly adapted to mass production and to minimizing the amount of hand work required in the making. 1

Electron tubes of the types and ratings largely used in radio receiver and similar weak-current service have in recent years trended to smaller and smaller dimensions and the growing use of very high frequency circuits has accentuated this trend. Such tubes have now become so small in dimension as to make fabrication diflicult and time-consuming, while the rapid extension of the fields of use of tubes throughout industry has created a demand for enormous numbers of them. For these and other reasons, there is a crying need for mechanization of tube manufacture but what may be called the vertical concentric mount of the electrodes, which has been almost universally used for many years, is ill adapted to mechanized manufacture. My Patent 1,830,233 represents steps to get away from the limitations imposed by this conventional type of structure.

One object of my invention is to provide a novel form of structure for electron tubes which is particularly adaptable to manufacture by automatic machinery and to large scale production.

Another object is to provide a novel form of electron tube which minimizes the time required for exhaust by avoiding the use of mica, since the latter emits large amounts of gas during the exhaust process.

Another object is to provide a tube design which avoids the use of strategic materials and employs only substances readily obtainable even during war-time.

Another object is to provide a tube structure in which the electrodes are efliciently shielded from external electric and magnetic fields.

Another object is to provide a tube which permits rapid degassing of the electrode structure and is well adapted to high-frequency heating.

Still another object is to provide a tube structure in which desired elastic and flexible properties of mica are attained by glass fiber instead of mica.

Other objects of my invention will become apparent upon reading the following description taken in connection with the drawings in which:

Figure 1 is a view in perspective, partly broken away, showing one form in which the principles of my invention may be applied to a triode;

Fig. 2 is a view of the shielding container in perspective with the cover portion elevated above the lower portion;

Fig. 3 is a perspective view of the anode in the Fig. 1 structure;

Fig. 4 is a perspective view of the grid used in the Fig. 1 tube; I i Fig, 5 is a view in. section transverse to the axis of Fig. 1 further illustrating the relative positions and forms of the electrodes;

Fig. 6 is a perspective view showing one end of the cathode used in the Fig. 1 tube; and

Figs. 7 and 8 are diagrammatic views of auxiliary 2 means by which the grid-to-cathode spacing may be adjusted after the tube has been exhausted and sealed.

Referring in detail to the drawings the tube electrodes are contained in a shielding chamber which may be of carbonized steel and comprises a box-section 1 and a cover-section 2, shown separated in Fig. 2, and is provided with flanges 3, 4 which may be spotor roller-welded to each other when cover 2 is superposed on box-section 1. The end-walls 5 of the box-section may be of some suit-. able refractory insulation such as steatite, porcelain, or multiform glass which, unlike mica, yield little gas when the electrode chamber is heat-treated during evacuation. The end walls 5 are provided with a central slot 6 dimensioned to receive the cylindrical cathode 7, and also with a pair of slots 8 dimensioned to receive the side-rods 9 of the grid-structure, which is shown in detail in Fig. 4, and a second pair of slots 11 dimensioned to receive the end- tabs 12 and 13 which support the anode which appears in detail in Fig. 3.

The cover-section 2 is provided with end-walls 14 of the same material as end-walls 5, and which have tongues 15, 16, 17 adapted to fit into the slots 6 and in end-walls 5 and lock the cathode grid and anode firmly in place at one end of box-section 1 when cover-section 2 is welded in place on box-section 1. To provide elasticity a band or ribbon of glass-fiber or asbestos fiber is placed between the adjacent faces of end- walls 5 and 14 to act much like a gasket between two flanges. At the other end of boxsection 1 the electrode supports make a loose sliding fit with the end- walls 5 and 14.

Figs. 1 and 2 are, of course, intended for a triode but tetrodes, pentodes or tubes of any higher electrode number will be constructed in the same way except that the necessary number of slots like 8 in the end-walls 5 will be provided to accommodate the greater number of electrodes.

Fig. 5 shows the shielding chamber and the electrode assembly in section with the electrodes in their assembled position.

The cathode 7 comprises a tube 21 of nickel or other suitable metal covered with a coating 22 of thermionicallyemissive oxides. It encloses an electric heater of type well known in the tube art, having its respective ends coming out through insulating bushings 23. One end of the nickel tube fits inside a metallic bushing 24 which supports it from the end wall 5 and is provided with prongs 25, which respectively contact the metal tube 21 only by means of small projections or dimples, so that the conduction of heat from the cathode to the ferrule 24 is reduced to a minimum, while expansion of the cathode on heating is not interfered with and any loose rattling or microphonic vibration prevented.

The grid, as shown in more detail in Fig. 4, comprises two parallel side-bars 9 to which are welded a plurality of U-shaped members of fine nickel or tungsten wire 26 spaced apart in parallel planes to form the grid-proper. As will be seen from the drawings the ends of the U.- shaped wires 26 are bent over, this being done to make it possible to adjust the spacing between the grid wires 26 and the cathode 7 in a way which will be described later in more detail. With this same end in view adjacent ends of the side bars 9 are turned upward at right angles far enough so that they extend above the top of the coversection 2 when the latter is welded in position.

As is shown in Fig. 3 the anode comprises a simple sheet of nickel or other suitable metal bent up into approximately U-shape and having tabs 12 and 13 formed by making cuts a and b near each upper edge and folding back the metal against the sides of the sheet to form a.

stiffened edge and the projecting tabs 12 and 13. This obviously economizes the sheet metal since the blanks from which the anodes are made are obviously simple rectangles which can be stamped out and folded with no waste material.

The autcmatic assembly of the electrode structure will now be described. The box section 1, preformed by simply bending sheet metal up into a channel of proper length, is fed automatically onto a conveyor belt or rotating table, at the first station of which the two end-walls are slipped into position in box section 1 from another hopper. At the next station the plates are picked out of a suitable hopper by an arm carrying an electromagnet or a vacuum-claw and dropped into position in the boxs ection 1 with its tabs 12 and 13 engaging the slots 11 in the end-Wall 5. At the next station the grids are similarly picked up from a hopper by an arm and brought into position within the anode with their side bars 9 engaging the slots 8 in the endwalls 5. At the next station the cathode 7 is picked up from a hopper and dropped into slots 6. After all the electrodes are thus in place a short piece of fiber-glass is laid down on the top of one end plate 5. Such fiber-glass packing holds the electrode parts firmly in place so that rattling and microphonic noise are prevented. At the next station the cover sections 2 which have been made from sheet metal and provided with endwalls 14 in a manner similar to that used for box-section 1 and end-Walls 5, are picked up and dropped into position on the box-section 1. The box-section 1 and coversection 2 are then welded along the flanges 3 and 4 to form a solid and rigid assembly. This electrode assembly may be supported by and fastened to the in-leads of a tube envelope 1A in ways well known in the electron tube art.

The foregoing process of assembly is done entirely by machine without any handling or contact of the parts with the operators fingers. This makes it possible to employ smaller and more exact spacing between parts of the electrodes, reducing the size of the aggregate; insures maximum electron emissivity from the cathode surface, decreases gas emission during exhaust and insures better life by absence of contamination due to handling. The elimination of mica as a structural material decreases the time required for exhaust and insures against decrepitation of the electrode assembly as a result of vibration during the life of the tube. The closed metal box provides excellent shielding and removes the need for coating the enclosing bulb with carbon as is now a common practice in conventional tube manufacture. The smaller size of the electrode aggregate makes it easier to weld into position on the in-leads through the lamp-press.

One of the greatest sources of lossage in prior art manufacture of radio tubes has been in the unavoidable slight variation in the distance between cathode and grid in different specimens being made. Such variances cannot be effectively discovered until the tube is complete and exhausted. In accordance with another important feature of my invention I provide a means by which the spacing between the cathode and the grid can be adjusted to insure desired electrical characteristics after the tube is sealed and completed. One of the preferred ways for doing this makes use of the upturned ends of the side rods 9 of the grid structure. This will make it possible to adjust the tubes which vary more widely from the norm to bring them back to standard characteristics. While I will describe several methods of attaining this result, they all require some means for varying the position of certain portions of the grid structure and such means will be hereafter referred to by the term motor. Such a motor must be capable of control from the outside of the tube envelope. It may employ mechanical forces as gravity or inertia, radiant heat possibly focused by means of a lens or other device, magnetic force, highfrequency heating or other forms of radiant energy. It probably will result in simplification and economy in the structure if the tubes are manufactured with the grid spacing departing in one specified direction from the desired specification, and the motor be capable of mov- Example 1 One expedient for varying the grid spacing is shown in Fig. 4 where the two upturned ends of the sidebars 9 are welded to a cross member which consists of a coiled wire spring 3lembedded in a very low melting glass bead 32. The grid is manufactured with the distance between the upper ends of the U-shaped elements too great. The spring blank is under tension When the glass bead is solidified around it. After the electron tube is exhausted and complete it is inserted in a test-circuit and its electrical characteristic continuously measured while a beam of high frequency radiation is focused upon the coil, thereby heating the glass surrounding it. As the glass bead softens the tension on the spring will start to pull the vertical arms of the side r-ods 9-toward each other thereby shortening the distance between the ends of the U-shaped grid wires 26. The electrical characteristic of the tube will accordingly change, approaching nearer and nearer to specification value as the spring contracts. When the characteristic approaches the desired value the high frequency radiation heating of the coil is stopped; the glass solidifies and further decrease of the grid spacing ceases.

Example 2 Between the vertical ends of the side rods 9 are positioned the ends of a U-shaped bimetal 33 as shown in Fig. 7, and the latter are welded to the ends of a spring 34 which is under stress. After the tube is completed and sealed the bimetal 33 is heated, for example by high frequency radiation, and moves the upper endsof the side' rods 9 towards each other thereby compressing the spring 34 beyond its elastic limit and giving it a set. At the same time the upper ends of the grid members 26 are moved toward each other thereby changing the electrical characteristic of the tube which is under observation at the time. When the characteristic reaches the specification value the heat is removed from bimetal 33 but the set in spring 34 permanently holds the side rods 1 in the position they had reached.

By providing an extra in-lead through the press of the tube the heating referred to in each of the foregoing examples can be carried out directly with conducted current instead of high frequency radiation.

Example 3 Fig. 8 shows a mechanical arrangement for adjusting the spacing between the grid and the cathode. This view is taken normal to the cover-section 2 and the two bent-up ends of the grid side-bars 9 are seen at 35, 36. A camming plate 37, which may for example be of multiform glass, is .pivoted at 38 to the cover-section 2, and is provided with holes 39, 41 through which the side-bar ends 35, 36 project. If the camming-plate 37 turns counterclockwise on pivot 38 the ends 35, 36 are forced toward each other, thus twisting the side-bars 9 of the grid about their axes and increasing the spacing of the grid rungs 26 from the cathode 7. Such a turning of the camming-plate 37 may be produced after the tube is evacuated and sealed by properly tilting the tube and tapping it so that the inertia of camming-plate 37 will cause it to rotate slightly on pivot 38. Other ways of causing rotation of camming-plate 37 will be evident to those skilled in the art. I

To fix the position of the camming-plate 37 after such an adjustment a closed loop of wire 42 is attached to camming-plate 37 and touches a wire 43 which projects over it from flange 4. A high frequency magnetic field of a heating coil outside the tube may be caused to heat loop 42 enough to weld to wire 43 thus preventing further displacement of camming-plate 37.

'5 Y I claim as my invention;

1. An electrode structure for electrical discharge tubes comprising a chamber having a box-section'of sheet metal with end-walls of insulation, each box-section end-wall having a middle'slot and two pairs of slots, each slot of each said pair being spaced on opposite sides of said middle slot, a thermionically-emissive cathode having its end-portions seated in said middle slots, a grid comprising a pair of side-members of metal interconnected by U-shaped rungs of metal transverse to said side-members and having end-portions projecting through one of said pairs of slots, a U-shaped anode of sheet metal material partly enclosing said grids and having end-members seated in another one of said pairs of slots, a cover-section of sheet metal for said box-section having edge-portions engaging the side-Walls of said box-section, said cov- .er-section having end-walls of insulating material locking said cathode, grid and anode in said slots, said side-members each having one end bent laterally projecting beyond the face of said cover-section, a camming-plate pivoted on said cover-section at a point displaced from its center of gravity, and camming-surfaces on said carnming-plate bearing against said bent ends of said side-members to apply torque to said side-members when said cammingplate rotates about its pivot.

2. An electrical discharge tube comprising an envelope enclosing a chamber member including a box-section of conducting material having end-walls of an insulating material, each box-section end-wall having an open-ended middle slot and two pairs of open-ended slots, each slot of each said pair being spaced on opposite sides of said middle slot, a thermionically-emissive cathode having its end-portions positioned in said middle slots, a grid comprising a pair of side-members of conducting material transversely interconnected by conductive U- shaped rungs, said side-members having end-portions positioned in one of said pairs of slots, a U-shaped anode of conducting material partially enclosing said grid, said anode having endmembers positioned in the other pair of slots, said chamber member also including a cover-section of conducting material having end-walls of an insulating material, said cover-section end-walls having a plurality of protruding members being operable to fit into said slots to firmly position said cathode, said grid and said anode within said chamber member.

3. An electrical discharge tube comprising an envelope enclosing a chamber member including a box-section of conducting material having end-Walls of an insulating material, each box-section end-wall having an open-ended middle slot and two pairs of open-ended slots, each slot of each said pair being spaced on opposite sides of said middle slot, a'thermionically-emissive cathode having its endportions positioned in said middle slots, a grid comprising a pair of side-members of conducting material transversely interconnected by conductive U-shaped rungs, said sidemembers having end-portions positioned in one of said pairs of slots, a U-shaped anode of conducting material partially enclosing said grid, said anode having portions cut and bent back to form integral protruding end-members positioned in the other pair of slots, said chamber member also including a cover-section of conducting material having end-walls of an insulating material, said cover-section end-walls having a plurality of protruding members being operable to fit into said slots to firmly position said cathode, said grid and said anode within said chamber member.

4. An electrical discharge tube comprising an envelope enclosing a chamber member including a box-section of conducting material having end-walls of an insulating material, each box-section end-wall having an open-ended middle slot and two pairs of open-ended slots, each slot of each said pair being spaced on opposite sides of said middle slot, a thermionically-emissive cathode having its end-portions positioned in said middle slots, a grid comprising a pair of side-members of conducting material transversely interconnected by conductive U-shaped rungs, said side-members having end-portions positioned in one of said pairs of slots, a U-shaped anode of conducting material partially enclosing said grid, said anode having end-members positioned in the other pair ofslots, said chamber member also including a cover-section of conducting material having end-Wall s of an insulating material, said cover-section end-walls having a plurality of protruding members being operable to fit into said slots, a resilient insulative positioning member placed between one said box-section end-wall and one said coversection end-wall to resiliently position said cathode, said grid and said anode within said chamber member.

5. An electrical discharge tube comprising an envelope enclosing a chamber member including a box-section of conducting material having end-walls of an insulating material, each box-section end-wall having an open-ended middle slot and two pairs of open-ended slots, each slot of each said pair being spaced on opposite sides of said middle slot, a thermionically-emissive cathode having its end-portions positioned in said middle slots, a grid comprising a pair of side-members of conducting material transversely interconnected by conductive U-shaped rungs, said side-members having end-portions positioned in one of said pairs of slots, a U-shaped anode of conducting material partially enclosing said grid, said anode having end-members positioned in the other pair of slots, said chamber member also including a cover-section of conducting material having end-walls of an insulating material, said cover-section end-Walls having a plurality of protruding members being operable to fit into said slots to firmly position said cathode, said grid and said anode within said chamber member, said box-section having a pair of conductive side flanges, said coversection having a pair of corresponding conductive side flanges, said box-section side flanges being joined to said corresponding cover-section side flanges.

6. An electrical discharge tube comprising an envelope enclosing a chamber member including a box-section of conducting material having end-walls of an insulating material having the characteristic of evolving less gas than mica upon heat treatment, each box-section endwall having an open-ended middle slot and two pairs of open-ended slots, each slot of each said pair being spaced on opposite sides of said middle slot, 2. thermionically-emissive cathode having its end-portions positioned in said middle slots, a grid comprising a pair of sidemembers of conducting material transversely interconnected by conductive U-shaped rungs, said side-members having end-portions positioned in one of said pairs of slots, a U-shaped anode of conducting material partially enclosing said grid, said anode having end-members positioned in the other pair of slots, said chamber member also including a cover-section of conducting material having end-walls of an insulating material having the characteristic of evolving less gas than mica upon heat treatment, said cover-section end-Walls having a plurality of protruding members being operable to fit into said slots to firmly position said cathode, said grid and said anode within said chamber member.

7. An electrical discharge tube comprising an envelope enclosing a chamber member including a box-section of conducting material having end-walls of an insulating material, each box-section end-Wall having an openended middle slot and two pairs of open-ended slots, each slot of each said pair being spaced on opposite sides of said middle slot, at thermionically-emissive cathode having its end-portions positioned in said middle slots, a grid comprising a pair of side-members of conducting material transversely interconnected by conductive U-shaped rungs having arm-portions, said side-members having end-portions positioned in one of said pairs of slots, a U-shaped anode of conducting material partially enclosing said grid, said anode having end-members positioned in the other pair of slots, said chamber member also inl I A V '7 eluding a cover-section of conducting material having end-walls of an insulating material, said cover-section end-walls having a plurality of protruding members being operable to fit into said slots to firmly position said cathode, said grid and said anode within said chamber member, and distorting means physically associated with said grid side-members, said distorting means being operable to vary the spacing between said arm-portions of each of said U-shaped rungs.

8. An electrical discharge tube comprising an envelope enclosing a chamber member including a box-section of conducting material having end-Walls of an insulating material, each box-section end-wall having an openended middle slot and two pairs of open-ended slots, each slot of each said pair being spaced on opposite sides of said middle slot, a thermionically-emissive cathode hav ing its end-portions positioned in said middle slots, a grid comprising a pair of side-members of conducting material transversely interconnected by conductive U- shaped rungs having arm-portions, said side-members having end-portions positioned in one of said pairs of slots, a U-shaped anode of conducting material partially enclosing said grid, said anode having end-members positioned in the other pair of slots, said chamber member also including a cover-section of conducting material having end-Walls of an insulating material, said cover-section end-walls having a plurality of protruding members being operable to fit into said slots to firmly position said cathode, said grid and said anode within said chamber member, and distorting means physically associated with said grid side-members, said distorting means being posi tioned entirely Within said envelope, said distorting means being operable to vary the spacing between said arm-portions of each of said U-shaped rungs.

9. An electrical discharge tube comprising an envelope enclosing a chamber member including a box-section of conducting material having end-walls of an insulating material, each box-section end-wall having an open-ended middle slot and two pairs of open-ended slots, each slot of each said pair being spaced on opposite sides of said middle slot, a thermionically-emissive cathode having its end-portions positioned in said middle slots, a grid comprising a pair of side-members of conducting material transversely interconnected by conductive U-shaped rungs having arm-portions, said side-members having end-portions positioned in one of said pairs of slots, a U-shaped anode of conducting material partially enclosing said grid, said anode having end-members positioned in the other pair of slots, said chamber member also including a coversection of conducting material having end-walls of an insulating material, said cover-section end-walls having a plurality of protruding members being operable to fit into said slots to firmly position said cathode, said grid'and said anode within said chamber member, and distorting means physically associated with said grid side-members, said distorting means being positioned entirely within said envelope, a source of radiant energy, said distorting means being responsive to said radiant energy to thereby vary the spacing between said arm-portions of each of said U-shaped rungs.

10. An electrical discharge tube comprising an envelope enclosing a chamber member including a box-section of conducting material having end-walls of an insulating material, each box-section end-wall having an open-ended middle slot and two pairs of open-ended slots, each slot of each said pair being spaced on opposite sides of said middle slot, a thermionically-emissive cathode having its end-portions positioned in said middle slots, a grid comprising a pair of side-members of conducting material transversely interconnected by conductive U-shaped rungs having arm-portions, said side-members having end-portions positioned in one of said pairs of slots, a U-shaped anode of conducting material partially enclosing said grid, said anode having end-members positioned in the other pair of slots, said chamber member also including a coversection of conducting material having end-walls of an insulating material, said cover-section end-walls having a plurality of protruding members being operable to fit into said slots to firmly position said cathode, said grid and said anode within said chamber member, and distorting means physically associated with said grid side-members, said distorting means being positioned entirely within said envelope, a source of radiant energy positioned outside said envelope, said distorting means being responsive to said radiant energy to thereby vary the spacing between said arm-portions of each of said U-shaped rungs.

References Cited in the file of this patent UNITED STATES PATENTS 1,565,570 Housekeeper Dec. 15, 1925 2,059,072 White Oct. 27, 1936 2,091,047 Kaufieldt Aug. 24, 1937 2,429,301 Wimpy Oct. 21, 1947 2,467,420 Binneweg Apr. 19, 1949 2,608,744 Starre et a1 Sept. 2, 1952 2,644,998 Klinkert et al July 14, 1953 2,649,553 Cisne Aug. 18, 1953 FOREIGN PATENTS 567,079 France Dec. 1, 1923 237,680 Great Britain Aug. 6, 1925 506,386 Great Britain May 18, 1939

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