US 2205502 A
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Description (OCR text may contain errors)
Filed Feb. -l'l'. 1939 NIMH HHIIH f .P. Y mm E TR N N l R E O I wp. Wn I 5 I 6 m A o I M 2 M r/U/ 0 1 ,l E Il |111/ m ,1 i0/ Y B Patented June 25, 1940 ELEc'rRoN DISCHARGE TUBE Theodoor Philibert Tromp, Eindhoven, Netherlands, assignor, by mesne assignments, to Radio Corporation of America, New York, N. Y., a corporation ol.' Delaware Application February 17, 1939, Serial No. 256,917 In Germany June 8, 1938 2 Claims.
This invention relates to electric discharge tubes with envelopes which may be closed at one end with a plate-shaped or disc-shaped member consisting of glass or similar material, which serves as a carrier for the contact pins without a separate base or cap being used. In addition, the invention relates to a tube socket to be used in conjunction with such a tube.
According to one form of construction of the invention, the tube wall may consist of two pressed glass parts, namely the bulb proper and the header or obturation member, each of which has a flange, by means of which these parts are sealed together. Contact pins connected to the electrodes are sealed into the header and a central pin or centering lug of irregular shape may be provided, whose shape corresponds to an aperture in the tube socket to ensure that the tube can only be inserted into the socket in one position.
To reduce undesirable couplings between the di'erent electrodes and other conductors, particularly between a control grid and an anode and their supply conductors, screen electrodes are usually placed between the anode and grid. The control grid and anode supply conductors are usually led out at diiierent ends of the tube.
Although this construction is good as far as screening is concerned, it has constructional drawbacks, particularly in tubes with pressed glass wall parts. It is desirable to seal all conductors into the glass header member which is united to the bulb by means of a ange. Less expensive machines may be used in the manufacture of glass tubes with the leads all sealed in the header.
In the event of all lead-in conductors being sealed at one end, the different electrodes may be mutually screened by providing screens on the inside of the tube which extend vto the tube wall, and metallizing the tube on the outside in the known manner.
According to this invention, a discharge tube comprises a preferably plate-shaped or a discshaped glass header which closes the bulb and serves as a carrier for all of the contact pieces and comprises a central re-entrant part extending inwardly at least over the part of the supply conductors sealed into the header. According to a very simple form of construction of the present invention the re-entrant part provided in the header member has an irregular shape and receives a metal lug or cam xed on the tube socket.
Alternatively the lug may be secured in the re-entrant part of the header with cement, and
the socket provided with a hole shaped to receive the lug in only one angular position, to insure insertion of the contact pins in their proper contactors of the socket.
According to this invention, the exhaust tube is arranged in the re-entrant part in the header so that the exhaust does not project either at the top or at the bottom of the tube and accordingly cannot be damaged. A corresponding aperture must be provided of course in the locating'lug.
The invention will be more clearly understood with reference to the gures of the attached drawing, in which Figures 1, 3 and 5 are cross sectional views of the header members of a discharge tube according to the different forms of construction of this invention, Figures 2 and 4 show a socket which may be used in conjunction with a tube in Figure 1 or 3, and Figure 6 is a plan view of the header member of Figure 5.
In Figure 1 is shown a disc-shaped header member I with a flared rim cylindrical skirt along the rim of the header in registry and joined to the ared rim of bulb la. A plurality of lead-in conductors 2 arranged in a circle are sealed in the header. The outer ends of the lead-in conductors are of sufficient side to serve as contact pins for the tube, the inner ends of the conductors being connected to their respective electrodes. Centrally in the header is a recess or reentrant portion 3, preferably cylindrical in cross section with a longitudinal keyway 4 molded into one side of the re-entrant portion.
In Figure 2 is shown a tube socket constructed to receive the tube of Figure 1. The socket comprises insulating disc or Wafer 8 carrying socket contactors 5 and a cylindrical centering lug 6 staked centrally in the socket disc. The centering lug is preferably of sheet metal with a key pressed or formed along one side. The pins of the tube can be inserted in the holes in the socket in only one rotational position of the tube where the key of the socket is in registry with the keyway l in the header.
In Figure 3 exhaust tube I0 is shown joined to the bottom of the re-entrant portion 3. In this case the tubular centering lug 6, Figure 4, is open ended at its top to receive the exhaust tube upon insertion of the tube in the socket.
In Figure 5 the tubular centering lug 1 is carried by the tube and is xed with cement or other adhesive in the re-entrant portion 3 of the header with the outer end of the lug extending beyond the ends of the contact pins.
'Ihe centering lug extends inwardly beyond the inner surface of the header and effectively intercepts electrostatic lines of force between the lead-in conductors and prevents high frequency coupling. Preferably the lead-in conductors to the control grid and to the anode are placed on opposite sides of the metal centering lug. Inter-lead capacity is effectively minimized and obviates the necessity of sealing the input and output electrode leads in opposite ends of the tube.
The lug 'I may be pressed from light sheet metal into a deep cup-shaped thimble with a circumferential bead or embossing between its ends and a longitudinal key along its side below the bead. The upper end of the tubular lug encircles the exhaust tube and extends inwardly above the plane of the header disc. Within the envelope may be placed a vertical metal partition 9 placed preferably between the anode and control grid leads and connected to and supported by a lead that may be grounded. The partition is notched and placed over the re-entrant member 3 to overlie the upper end of the lug 1.
1. An electron discharge tube comprising a tubular envelope, a relatively thick glass disclike header sealed gas tight to and closing one end of said tube, contact pins arranged in a circle and carried directly on said header, a tubular glass re-entrant portion integral with and centrally in said header extending into the envelope beyond the inner surface of theheader, and means for shielding said pins comprising a tubular metal member extending from near the ends of said conductors into said tubular glass portion beyond the inner surface of said header,
the sides of the inwardly extending portion of the tubular metal member being adhesively attached to the surface of the inner wall of said tubular glass portion.
2. A header for a bulb of an electric discharge tube comprising a disc-shaped header member oi insulating material for closing one end of the bulb, l a plurality of lead-in conductors sealed in a circle in the header, the outer ends of said conductors serving as contact pins of the tube, said header having an integral re-entrant portion within the circle of conductors, the reentrant portion extending -inwardly beyond 'the plane of the header, and a metal cylinder coaxial with said circle telescoped at one end. into said re-entrant portion, and secured to the inner surface of said re-entrant portion, said one end of the cylinder extending through the plane of the header.
THEODOOR PHILIBERT TROMP.