Jan- 23, 1940. R. scHARr-NAGEL 2,188,061
ELECTRI C DIS CHARGE VESSEL Filed May 13, 1958 2 Sheets-Sheet l Jan.'23, 1940. R. scHARr-NAGEL ELECTRIC DISCHARGE VESSEL Filed May 13, 1958 2 Sheets-Sheet 2 /flre/I/ar:
vPatented Jan. 23, 1940 UNITED STATES PATENT OFFICE or to C. Lorenz Aktiengesellschaft, Berlin- Tempelhof, Lorenzweg, Germany, a company Application May 13, 1938, Serial No. 207,756 In Germany May 14, 1937 7 claims. `(ci. 25o-27.5)
The invention relates to electric discharge vessels of the kind in which a disc-shaped member. of ceramic or similar material is united with the bulb of the vessel by a glass seal arranged as a coating on such ceramic member, this member and seal forming av cover for the bulb. Preferably, such cover is used also to support the electrode system. It has been customary to apply the glass intended to form this seal to both the ceramic member and bulb at the same time. Also it has been proposed to apply this glass to an insulating member, preferably of ceramic material, and simultaneously to apply it to an annular metal member arranged to encircle such insulating member, and then to unite this metal member with the bulb.
In accordance with the invention a cover of the said kind comprises a ceramic member and a glass body moulded on this member, the two thus being firmly secured together. This cover is fastened to the bulb by means of the glass body. In this way the formation of strains in the glass seal and hence cracks therein are more effectually avoided than has been possible heretofore.
The invention is also concerned with means for producing the *novel covers in mass, as will be understood. irom the following description,
$0 reference being had to the accompanying drawings in which:
Fig. l is a somewhat diagrammatic sectional view of an electron tube of the type referred to by the invention, Fig. 2 is a fragmentary sectional View showing an example of a device for manufacturing one embodiment of the novel cover, Fig. 3 is a fragmentary sectional view illustrating an example of a device for manufacturing a second embodiment thereof, Fig. 4
is a fragmentary sectional View representing a second example of devices for manufacturing covers of the type shown in Fig. 2, Fig. 5 is an alternative form of a detail of the arrangement represented in Fig. 4.
5 'I'he electron tube shown in Fig. l by way of example comprises a bulb A, an electrode system B, leads 6 joined to this system, and a cover composed of a ceramic disc-shaped member I and of a glass seal 5. Bulb A may be of a'metal or of asuitable glass, and has a ange b to which seal 5 is fastened. Flange b is tapering toward its edge, being intended to be here of foil thickness, or nearly so. If the bulb A is of glass,
ange b and seal 5 may be united with each other by the heat of a gas `iet, for instance, while in the case of a metal bulb, preferably high frequency energy is employed for heating the bulb, thus securing flange b and seal 5 together. The latter operation may be effected by the same high frequency coil that in a well known man- 5 ner serves for outgassing the bulb A.
For manufacturing the cover l, 5 the device represented in Fig. 2 may be used. This device comprises a patrix or die 3 and a matrix compo'sed of the ceramic member I itself and of a 10 plate-shaped part 2 of iron in which member I is seated. Member I carries the leads 6. 'I'he 'die 3 has bores c for the leads to pass through and is fitted with heating coils 4. Matrix I, 2 is heated from below, as indicated by the ar- 15 rows d, in order to melt glass arranged thereon. This glass may be in a preheated condition or may be poured on the matrix, thus being applied thereto in liquid condition. By means of die 3 the melted glass on matrix I, 2 lis moulded 20 to form a pressed glass body 5 of disc shape. Part 2 is of a material to whichthe glass body 5 does ,not stick. The ceramic member I, however, is by die 3 caused to form a firmly interlocked structure with the glass body 5. There- 25 fore, after removal of the die this sturcture I, 5
Vmay be removed from matrix part 2 in order to be united with the bulb A of an electron tube in the manner described with reference to Fig. l.
Member i may have bores e or recesses into 30 which the material of body 5 may enter. Suchl bores or'recesses may be dispensed with if the porousness of the ceramic material is sufficient.
in the arrangement shown in Fig. 3 the. matrix i, is carried on a heating body 8 of iron pro- 35 vided with heating coils l. Part 2', not able to stick to glass, is displaceable in a guide II so that it may be moved into the position shown in dotted lines. Die 3 is disposed in a guide 9.' With part 2 in the position represented in full 40 lines, this being the position of rest, there is a hollow space above member I. This space is somewhat larger in diameter than die 3 and is to receive the glass from which the glass body 5 is to be produced. The softened glass is in a 45 rst moulding operation pressed by die 3' against the ceramic member or matrix part I and thus caused to form therewith a firmly interlocked structure in the same manner as described with reference to Fig. 2. Then matrix part 2 is raised 50 into the dotted-line position while-die 3 is still in its lower position. As a result, glass body 5 is formed with a tubular extension I2 by which it shall be fastened to the bulb of an electrpn tube. u
temperature of the glass is reached, i. e., the
lower limit of the destraining or release range` decisive for all temperature variations. At this moment coil I1 is deenergized and a fine gas jet I5 of a burner I5 is caused to act within bore |18 upon the centre portion of member I-. In this way a glowing spot is produced in the middle of member I so tha-t glass disc 5 and member I will be secured together in the middle at iirst. Bores e in member I enable the heat produced by jet I6 to act directly on the disc 5. The circumferential portion of disc'5 is protected from a harmful iniiuence of the heat by the chill 2" being of a comparatively large volume. Air ducts g in the chill cause the gas jet I6 to be suiciently fine. Bore I8 is tted with a lining I4 of heatproof insulating material such as asbestos or clay. The chill is mounted on a table I8 that can be raised or lowered by a suitable gearing 20 in order to adjust the distance by which member I is spaced from the jet I6. Die 3" has pins I3 for producing bores in the glass body 5 in accordance with corresponding bores in member I, while providing body 5 with a glass Wart around each such bore. In these bores the leads for the electrode system are iixed after the assembly or cover I, 5 has been removed from the chill.
If mass production is concerned, die 3" is replaced by the die 3A shown in Fig. 5. Die 3A has the leads 6 arranged instead of the pins I3, Fig. 4. These leads are provided with glass collars 2|. After die 3A has been lowered to press the `leads 6 into the softened disc 5, member I having corresponding bores to such end, the heat of jet I6 at once acts to unite the leads 6 with disc 5 and member I. Preferably, the glass from which disc 5 is made is harder than that of the collars 2 I. The hot assembly I', 5, 5 is then subjected to a compressed air cooling acting from bel'ow, whereupon the cover I, 5, Lmay be at once removed from the chill. l
In lieu of a gas burner I5 an electric heating device may be employed whose heat radiation is concentrated toward the centre portion of member I by means of a diaphragm.`
The glass disc 5 instead of being supported by both member I and chill 2" may be held by member I alone, thus being out of contact with the chill. In the case represented, where disc 5 is lying on the chill tooit is advisable to outgas` the metal from which the chill is to be made. since otherwise air bubbles may form in the disc 5.
Chill 2" is preferably of the same or approximately the same coelicient of expansion as glass body 5.
The ceramic member I may be previously coated with glass.
What is claimed is:
1. A cover for electric discharge vessels which comprises a ceramic member and a glass body moulded on this member to form an interlocked structure therewith.
2. A cover according to claim 1, wherein the ceramic member is of suillcient porousness for the adhesion of the glass body.
3. An electric discharge vessel having a cover that comprises a ceramic member and a glass body moulded on this member, and further having electrodes held in place by said ceramic member.
4. A cover according to claim 1, wherein the ing a bulb whose wall has a part of foil thickness.
with which the said glass body is united.
'7. A cover according to claim 1, wherein the glass is interlocked with the ceramic member by means of bores located therein.