US2936391A

US2936391A - Frame grid

Info

Publication number: US2936391A
Application number: US674659A
Authority: US
Inventors: Gerald T Curry; Stanley J Gartner
Original assignee: Sylvania Electric Products Inc
Current assignee: GTE Sylvania Inc
Priority date: 1957-07-29
Filing date: 1957-07-29
Publication date: 1960-05-10
Anticipated expiration: 1977-05-10

Description

y 1960 s. T. CURRY ET AL 2,936,391

FRAME GRID Filed July 29, 1957 2 Sheets-Sheet 1 FIG. l.

/35 K//// j// A $5 1 FIGB.

INVENT Rs GERALD T. CUR Y STANLEY J. GARTNEIQ TTORNEY y 1960 G. T. CURRY ETAL Y 2,936,391

FRAME GRID Filed July 29, 1957 2 Sheets-Sheet 2 INVENTOR$ GERALD T. CURRY STANLEY J. GARTNEQ United States Patent FRAME can) Gerald T. Curry and Stanley J. Gartner, Emporium, Pa., assignors, by mesne assignments, to Sylvania Electric Products Inc, Wilmington, Del., a corporation of Delaware Application July 29, 1957, Serial No. 674,659

11 Claims. (Cl. 313-348) This invention relates generally to electron discharge devices and more specifically to electron discharge device electrodes and methods of manufacture.

The lateral wires used in grid electrodes for electron discharge devices are, generally stretched across heavy support wires or side rods which are notched at spaced intervals to receive the grid wires and then peened in such a manner as to attach each lateral grid wire to each side rod. Though the vast majority of electron discharge devices utilize grid electrodes fabricated by this method, there are serious tolerance and other difficulties which arise when attempts are made to use this method to fabricate grids having a relatively high number of lateral grid wires per unit length of grid, i.e., a relatively high number of turns per inch. In addition, the heat dissipation characteristics of grids with side rod supports is so poor asjto. often require the use of radiator elements to avoid excessive emission from cathode material which tends to deposit on the grid structure during normal. tube life.

Another type of grid structure which is currently used is known as a frame grid. This type of structure is characterized by the use of an apertured fiat metal frame rather than side rods to support the lateral grid wires. The frame grid has not been used in many tube types, primarily because the lateral grid wires have been joined to the sides of the frame by either a welding process, a brazing process or some form of soldering process. All of these processes, not only are diincult to use in conjunction with high speed machinery, but they also require the use of specific and relatively expensive materials which are unnecessary as far as electrical characteristics of the completed electrode are concerned.

It would be desirable to provide grid structures and methods of manufacture which are suitable for mass pro duction from relatively low cost materials wherein the grids have sufficient strength to hold more lateral wires per unit length of grid, or turns per inch, than current techniques will allow.

Thus it is an object of this invention to eliminate the need for costly grid structure material which fails to contribute toward improved electrical characteristics.

It is a further object of this invention to improve grid heat dissipation and minimize grid emission.

It is a still further object of this invention to facilitate rapid production of grid structures having a maximum number of lateral grid wires in selectable spaced relationship.

Briefly, one aspect of the invention comprises an electrode having an apertured sheet metal frame formed to provide a pair of grid wire supporting ridges in spaced relationship, and a plurality of parallel grid wires laterally disposed across the frame aperture and tightly held in closed ridge notches of a depth less than the height of said ridges.

For a better understanding of the present invention,

together with other and further objects, advantages and capabilities thereof, reference is made to the following 2,936,391 Patented May 10, 1960 disclosure and appended claims in connection with the accompanying drawings in which:

Fig. 1 shows, in representative form, fabrication of a grid; and I Fig. 2 shows the cross section of one side of a grid frame; and

Fig. 3 shows an exploded view ,of a plural grid structure.

Referring to Fig. 1 there is shown a grid frame blank 11 having tabs 13 and coined ridges or sections 15 which are notched and peened to support the lateral grid wires 17 stretched across an aperture 19, defined by internal edges 21 and '23. Grid blank 11 may be formed from sheet metal strip selected from a range of materials having suitable strength, thermal and electrical charac teristics and having a thickness sufficiently greater than the desired thickness of the complete grid frame to sup-- ply the metal necessary for forming coined ridges 15. The selected sheet metal strip is preferably first fed through a coining or forming process to move or flow a portion of the metal sheet into ridges 15 of a desired cross sectional shape. Ridges 15 may be shaped to facilitate access of cutting, peening and cut-off tools.

, As can be seen in Fig. 2 coined ridges 15 extend from the grid frame blank 11 for a given height. The minimum height of the coined ridges 15 is generally related to the minimum necessary depth of the lateral grid wire holding notches and the diameter of the lateral grid wire while the maximum height of the coined ridges 15 is generally related to the desired electrode spacing in the finished discharge device.

The minimum height of the ridge is also related to the depth of penetration. of the work hardened material which arises from the notching and peening process. It has been found preferable to avoid penetration of this work hardened area into the portion of the frame adjacent

internal aperture edges

21 and 23 in order to minimize distorition of the frame in subsequent grid and tube process heating steps.

After the ridges 15 are formed, aperture 19 and tabs 13 are blanked out by a cutting tool or a press. Then, if desired, the blanks may be heated to soften the material in preparation for notching. As can be seen in Fig. 1, a notching wheel or tool 25 is then used to notch ridges 15 along their length at each point where it is desired to attach a lateral grid wire. Though the notching tool is shown as cutting a single notch, it is to be noted that any number of notches may be made at once if desired. Grid wires are fed through a tool, such as the hollow finger member 27,,into the receiving notches which are then peened over by peening tool 29. A cut-off tool 31 cuts off excess grid wire material extending outside of the ridges.

In order to complete formation of the electrode structure, strengthening side frame portions 35 are bent, as shown in Fig. 2, at an angle selected to strengthen the structure and yet avoid interference between electrodes in the final assembly. After bending it has been found preferable, in some embodiments, to fire the completed grids in order to clean them.

The completed grid is then ready for assembly into an electron discharge device as shown in the exploded view of Fig. 3. In Fig. 3 there is shown a pair of mica or insulating spacers 41 each having a plurality of apertures for receiving the various electrode tabs and mounting portions. Cathode 43 surrounds a conventional heater wire 45 and may include a cathode bead 47 as shown. First grids 49 are positioned immediately adjacent the sides of cathode 43 and second grids 51 are positioned external of the first grids; 49. Beam confining plate 53 is positioned external the second grids and the electrode as-.

sembly of the basic discharge device is completed by the addition ofthetwo halves of anode 55. The apertures in the various grids and beam confining plate are in fixed alignment.

It is to be noted that the strengthening side frame por- I tions' 35 of grid 51 are slightly longer than the'strengthening side frame portions 35 of grids 49 and that the upper and lower edges of these side frame portions extend along the surfaces of the insulating spacers. As has been mentioned heretofore, the angle of bend of the strengthening side frame portions is governed at leastin part by the desired electrode spacings.

The resulting structurehas many advantages over electrodes using conventional side rods. The metal frame allows increased dissipation of heat. It is possible to greatly increase the number of lateral grid wires per unit length of grid. Electron discharge devices using a frame grid structure as described above have been made with higher perveance and higher zero bias plate current than normally found in similar discharge devices using side rod supported lateral grid wires. These factors are exceedingly important in many tube types, especially those of the beam power amplifier type used for television horizontal deflection drive purposes.

In one embodiment built and tested nickel clad steel sheet metal was used to form the grid frame and nickel material was used for the lateral grid wire. In another embodiment the grid wire was gold plated to improve electrical characteristics. With 'a lateral grid wire of approximately two thousandths ofan inch in diameter it was found possible to use a notching depth of three to three and one half thousandths of an inch, The height of the ridge in this particular electrode structure was six. to eight thousandths of an inch and it was found that there was little if any distortion in the final grid structure arising from processing of the discharge device.

Having thus described our invention, we claim:

. 1. An electrode for an electron discharge device comprising a sheet metal frame formed to provide a pair of grid wire supporting ridges in spaced relationship and an intermediate substantially rectangular aperture having a width less than said spaced relationship, and a plurality of parallel grid wires laterally disposed across the frame aperture and tightly held in closed ridge notches of a depth less than the height of said ridges.

' 2. An electrode for an electron discharge device comprising a sheet metal frame formed to provide a pair of grid wire supporting ridges of given height in spaced relationship and an intermediate aperture 7 substantially centered between said ridges, and a plurality of parallel grid wires laterally disposed across the frame aperture and tightly held in closed ridge notches of a depth less than the height of said ridges.

3. An electrode for an electron discharge device comprising a sheet metal frame formed to provide a pair of grid wire supporting ridges of given height in spaced relationship with an intermediate aperture having a width less than said spaced relationship, and a plurality of parallel grid wires lateraly disposed across the frame aperture and tightly held in closed ridge notches of a depth sufficiently shallow to avoid substantial penetration into the portion of the frame adjacent the aperture, of the work hardened area arising from opening and closing th ridge notches.

4. An electrode for an electron discharge device comprising a sheet metal frame formed to provide an aperture of given width intermediate a pair of grid wire supporting ridges :of given height in spaced relationship greater than said width, and a plurality of grid wires laterally disposed across the frame aperture and tightly held in closed ridge notches of a depth less than the height of said ridges and sufficiently shallow to keep the work hardened area, resulting from opening and closing the ridge notches, subst-antially in the portion of the frame away from the aperture.

5. An electrode for an electron discharge device comprising a sheet metal frame formed to provide side and end frame portions around an aperture of given width and formed to provide a ridge of given height in each side frame portion spaced from the aperture and outside edges and a plurality of parallel gridwires laterally disposed between ridges across the frame aperture in a plane intermediate the planes of the frame aperture and the tops of the frame ridges, whereby the work hardened area resulting from opening and closing the ridge notches does not substantially penetrate the frame portion adjacent the aperture. p

6. An electrode for an electron discharge device comprising a sheet metal frame formed to provide side and end frame portions around a substantially rectangular aperture of given width, at least one side frame portion being bent along a line intermediate the aperture edge and the outside edge, a ridge of given height in each side frame portion spaced from the aperture and outside edge and a plurality of parallel grid wires laterally disposed between ridges across the frame aperture and lying at least partly in a plane intermediate the plane of the sides of the frame aperture and the plane of the top of the frame ridges.

7. An electrode for an electron discharge device comprising a sheet metal frame formed to provide side and end frame portions around a substantially rectangular aperture of given width, said side frame portions being bent along a line substantially parallel to and intermediate the aperture edge and outside edge to form a strengthening frame edge portion lying outside of the plane of the frame aperture, a ridge of given height in each side frame portion spaced from the aperture and outside edges and a plurality of parallel grid wires laterally disposed across the frame aperture in a plane intermediate the planes of the frame aperture sides and the tops of the frame ridges. i

8. An electrode for an electron discharge device comprising a tab mounted sheet metal; frame formed to pro: vide side and end frame portions around a substantially rectangular aperture of given width, at leastone of said side frame portions being bent along a line substantially parallel to and intermediate the aperture edge and outside edge to form a strengthening frame edge portion lying outside of the plane of the frame aperture, a ridge of given height in each side frame portion spaced from the aperture and outside edges and a plurality of parallel grid wires laterally disposed across the frame aperture in a plane intermediate the planes of the frame aperture sides and the tops of the frame ridges.

9. A method of manufacturing grids for electron discharge devices comprising the steps of forming ridges in spaced relationship on a strip of sheet metal, cutting an aperture between the ridges to form a frame blank, notching the ridges and inserting the grid wires into the notches,

peening each notch after insertion of the grid wire into the notch so as to rigidly hold the grid wire. 7 i

10. A method of manufacturing grids for electron discharge devices comprising the steps of forming parallel ridges in spaced relationship on a strip of sheet metal, cutting an aperture between the ridges having a width less than said spaced relationship to form a frame blank, notching the ridges and inserting the grid wires into the notches, peening each notch immediately after insertion of the grid wire into the notch so as to rigidly hold the gird wire and shaping the side portions of the frame.

11. A method of manufacturing grids for electron discharge devices comprising the steps of forming ridges in spaced relationship on a strip of sheet metal, cutting an aperture between the ridges having a width less than said spaced relationship to form a frame blank, notching the ridges and inserting the grid wires into the notches,

V peening each notch immediately after insertion ofthe References Cited in the file of this patent UNITED STATES PATENTS 2,166,744 Seelen et a1. July 18, 1939 6 Beggs July 4, 1944 Diggle Apr. 11, 1950 Gehrke June 1, 1954 Cook et a1 Nov. 27, 1956 Te Gude Apr. 1, 1958 Miller Nov. 25, 1958