US2889670A - Method of manufacturing an electron tube - Google Patents

Description

June 9, 1959 H. J. KocH 2,889,670

METHOD OF MANUFACTURING AN ELECTRON TUBE Filed April 21. 1954 2 Sheets-Sheet 1 IN VEN TOR.

HENRY J. KOCH ATTOE/VEK June 9, 1959 J KOCH 2,889,670

METHOD OF MANUFACTURING AN ELECTRON TUBE Filed April 21, 1954 2 Sheets-Sheet 2 INVENTOR. f/E/VEY J KOCH United States PatentO METHOD OF MANUFACTURING AN ELECTRON TUBE Henry J. Koch, Belleville, NJ, assignor to National Union Radio Corporation, Hatboro, Pa, a corporation of Delaware, now by change of name to National Union Electric Corporation Application April 21, 1954, Serial No. 424,665

3 Claims. (Cl. 53-9) This invention relates to electron tubes and more especially it relates to tubes of the so-called miniature kind.

A principal object is to produce a novel form of tippedoff exhaust tubulation for electron tubes and the like.

Another object is to provide a novel construction of glass header with a tipped-off exhaust tubulation which is recessed within the external surface of the header.

A feature of the invention relates to an electron tube or similar device having a glass header or base through which contact prongs or lead-ins project internally, and having a recess in its external face within which is seated a bent tipped-off exhaust tubulation.

A further feature relates to the novel organization, arrangement and relative location of parts which cooperate to provide an improved electron tube of the type having a tipped-off exhaust tubulation in the base thereof.

- Other features and advantages will be apparent after a consideration of the following detailed descriptions and the appended claims.

In the drawing which shows, by way of example, one preferred embodiment,

Fig. l is a top-plan view of an electron tube header or base according to the invention, prior to assembly in the finished tube.

Fig. 2 is a sectional view of Fig. 1, taken along the line 22 thereof.

Fig. 3 is a sectional view of the header of Fig. 1 having an exhaust tubulation attached thereto.

Fig. 4 is a schematic plan view of a conventional tube assembly and exhaust machine for manufacturing the mbe according to the invention.

Fig. 5 is a detailed view explaining one step in the operation of the machine of Fig. 4 according to the invention.

Fig. 6 is a view similar to Fig. 5, showing a succeeding step in the operation of the machine.

Fig. 7 is a detailed view, partly in section, of a finished tube according to the invention.

In present day electron tubes of the so-called miniature type, the tube consists of a flat button-like glass header through which are directly sealed the contact prongs or lead-in members and this header has sealed thereto the conventional glass bulb or envelope. In such tubes, no separate supporting base is necessary since the contact prongs emerge directly from the glass header. In order to exhaust the air or other gases within the tube, prior to scaling off, it is necessary to provide the tube With a conventional exhaust tubulation. In certain types of tubes, this exhaust tubulation is attached to the upper end of the bulb and when the bulb has been exhausted, the tubulation is tipped off in the conventional way to leave a vertically extending tip at the top of the tube, which presents a source of trouble in that it is likely to be broken off at any time and thus destroy the usefulness of the tube. It has not been found practicable heretofore to manufacture such tubes with the exhaust tubulation at the base of the tube because it is impossible to tip off this tubulation so that the extreme tip thereof does not 2,889,670 Patented June 9, 1959 extend beyond the external face of the base. If the exhaust tubulation does extend below the base, the pluggingin of the tube into the conventional tube socket would cause the tip of the exhaust tubulation to be subject to breakage.

In accordance with the present invention, I have devised a method of making a tube of the so-called miniature type, wherein the exhaust tubulation is attached to the glass header or base and is processed so that in the final tube the exhaust tubulation does not extend below the external surface of the glass base or header.

For the purpose of explaining the invention, there is shown in Figs. 1 and 2, a glass header or base 10, through which are sealed in circular array the usual rigid plug-in prongs or lead-ins 11. In the standard miniature tube the header has nine such lead-ins sealed directly therethrough so that the externally projecting portions 12 form the plug-in connector members for making contact with the usual nine-pin tube socket (not shown). Heretofore, it has been customary to make the bottom or external surface 13 of the glass header completely flat. However, in accordance with one feature of the invention, the header 10 is provided with a central recess 14 to which the conventional elongated glass tubulation 15 (Fig. 3) can be united by conventional machinery so as to provide a continuous exhaust path through the tubulation into the contents of the bulb 16 which is to be sealed to the peripheral margin of header 10 in the conventional way.

Merely for purposes of explanation, there is shown in Fig. 4, in schematic plan view, any well-known form of tube making machine which is well known in the art, for example a Sealex machine. Such machine comprises a rotatable platform 17 carrying a plurality of heads indicated schematically by the numerals 18-24. The platform 17 in the well-known manner, is adapted to be indexed or rotated intermittently in the direction of the arrow and also the heads 18-24 are arranged to be individually rotated in front of the usual gas jets or sealing fires located at respective stages. Merely for illustrative purposes, one of the rotatable heads 18 is shown adjacent the loading position wherein the operator inserts into the conventional stem holder the unit consisting of the header 1t? and the exhaust tubulation 15 shown in Fig. 3. Each of the heads is also provided with the conventional bulb holder indicated schematically in Figs. 5 and 6 by the numeral 25.

When the operator has loaded a tubulated stem and bulb into the head 18, the platform 17 is indexed counterclockwise to the next position where the bulb 16 has its lower end sealed to the peripheral margin of the glass header it) in the conventional way. The platform 17 is then indexed to the exhaust position where the tubulation 15 is connected to any well-known form of vacuum pump so as to exhaust the air and other gases from Within the sealed bulb. After the bulb has thus been evacuated, the platform 17 is indexed to bring the evacuated bulb into the tipping-off position wherein the exhaust tubulation 15 is melted and pinched as closely adjacent to the bottom face of the header 10 as possible. It has not been found practicable heretofore to effect this tipping-off without having some of the exhaust tubulation 15 project below the surface of the header 10 as illustrated in Fig. 5.

In accordance with the present invention, the platform 17 is indexed to a tip-recessing position wherein the tippedoff bulb with the downwardly projecting tipped-01f tubulation 15 is brought into registry with a special gas flame 26 which softens the tubulation 15. When the tubulation has thus been softened, the gas flame 26 is removed and a tool 27 is forced upwardly into contact with the softened tubulation as shown in Fig. 6, causing that tubulation to be bent out of the vertical position until it is Since the center of the stem or header 10 has been i heated to effect the bending of the tubulation 1S, undesirable strains may exist in that central region which may render it necessary to anneal the glass header. For this purpose, the platform 17 may be indexed to the annealing position at which the tipped-off and exhausted tube can be subjected to a suitable annealing temperature, for example 430 C. in the case of soft glass, and then allowed to cool down uniformly to about 100 C. During this annealing stage, if it is found that gases are evolved within the tube, a suitable getter of known construction within the tube can be flashed in the well-known manner so as to pick up these released gases. The platform 17 can then be indexed to the final or unloading position from which the completed tipped-01f exhausted tube can be re moved. The finished tube then has the appearance shown in Fig. 7, wherein the upper end of the bulb 16 is completely smooth and free from the usual tipped-01f exhaust tubulation.

While the invention has been described in connection with the sealing and tipping-01f of an electron tube, it will be understood, of course, that it is equally well applicable to the sealing and tipping-01f of other similar devices such as electric lamps, vacuum switches, gas tubes or any device having an evacuated tipped-01f bulb with contact prongs integrally sealed through the base or header ing an exhaust tubulation to a preformed recessed portion in the external face of said flattened button-like glass header, softening and tipping said tubulation adjacent said header with the tip extending outwardly beyond said header, and pressing back said tip while in a softened state until it is completely housed within said recess and is completely external to said header.

2. The method of making an electron tube and the like, which comprises, sealing a relatively thin-walled glass bulb to a relatively thick header of the button-like kind having an external preformed recess with a central exhaust tubulation extending therefrom, evacuating the bulb through said header, tipping off the tabulation adjacent said header, reheating the tipped-off tubulation to render it plastic, and bending the plastic tipped-01f tubulation back into said recess within the bottom of said header, the tubulation being completely external to said bulb and being substantially free from any portion extending externally beyond said header.

3. The method of tipping off an electron tube of the kind having a relatively thin-walled bulb portion and a relatively thick button-like header having a preformed external recess carrying an external exhaust tubulation, which comprises, melting the tubulation adjacent the header to form a softened tip which extends outwardly from said recess, and subjecting the softened tip to a mechanical flattening force to flatten it and to press the flattened portion into said recess and without changing the shape of said bulb portion.

References Cited in the file of this patent UNlTED STATES PA'YENT S 793,211 McDonnell June 27, 1905 1,056,971 Coleman Mar. 25, 1913 1,398,033 Maurer Nov. 22, 1921 1,982,317 Nouromtseff Nov. 27, 1934 2,169,112 Scott et al Aug. 8, 1939 2,200,911 Bowie May 14, 1940 2,229,436 Beggs Jan. 21, 1941 2,262,760 Gardner et al Nov. 18, 1941 2,400,635 Eitel May 21, 1946 2,401,638 Herzog et al June 4, 1946 2,464,765 Palmer Mar. 15, 1949

Images