US2486497A - Termination for electric discharge lamps - Google Patents

Description

Nov. 1, 1949. e. c SALNEU 2,436,497

TERMINATION FOR ELECTRIC DISCHARGE LAMPS Filed April 23, 1946' 2 Sheets-Sheet 1 INVEN TOR.

SALNEU ATTORNEY Nov. 1, 1949. G. c. SALNEU TERMINATION FOR ELECTRIC DISCHARGE LAMPS Filed A ril 23, '1946 2 Sheet et 2 INVENTOR- GEORGE C. SALNE BYQZMAEQ TOR Y Patented Nov. 1, 1949 TERMINATION FOR ELECTRIC DISCHARGE LAMPS George C. Salneu, Havertown, Pa.

Application April 23, 1946, Serial No. 664,148

2 Claims.

This invention relates to terminations for electric discharge lamps, and, more particularly to methods of forming lamp terminations having guarded contacts,

Heretofore, in elongated electric discharge lamps, of the type provided with electric contacts in the proximity of the ends, these contacts have been of the exposed male type. Since these lamps are frequently installed in high voltage circuits, their installation in the sockets of luminaires presents an electric shockhazard. For example, in certain types of high-voltage luminaires, the usual practice is to have the lamp installed and removed by two men, each of whom inserts one of the lamp terminals in a socket. It is readily understood that the two terminals will not, in general, be inserted simultaneously, so that after one man has completed engagement of lamp and socket contacts at the first end, the unguarded lamp contact at the second end becomes potentially alive. The man handling this second end is thus in a position to receive an electric shock of up to several thousand volts in the event of the lamp flashing over if the electric circuit should accidentally be completed through his person by his contacting simultaneously the unguarded lamp contact and presumably non-current-carrying metallic parts of the luminaire or other grounded structure which may be metallically or capacitively connected to the electric circuit. It is obvious that the same hazard may be encountered where installation or removal is effected by one man.

The primary object of my invention is to provide electric discharge lamp terminations having guarded contacts.

Another object of my invention is to provide A an electric discharge lamp in which the likelihood of electric shock hazard has been eliminated from the operation of installing or removing the lamp.

A further object of my invention is to provide a termination for an electric discharge lamp and a method for constructing the same, in which the lamp contact is recessed within an electric insulating part.

Still another object of my invention is to produce an electric discharge lamp termination and associated luminaire socket having mutually engageable guarded electric contacts.

With these and other objects in view which will appear from the ensuing description and claims, the following sets forth specific embodiments of my invention which are described as 65',

examples. andillustrated in the accompanying drawing, in which Figure 1 is a fragmentary view, partly in section, of the electric discharge lamp and associatedluminaire socket of my invention,

Fig. 2 is a fragmentary perspective View of the electrode and contact assembly of the device of Fig. l.

Fig. 3. is a fragmentary sectional view of a modification of my electric discharge lamp termination and socket.

Fig. 4 is a fragmentary sectional view of another modification of my lamp termination.

Fig. 5 is a perspective view of the electrode,

. sealing disk and contact assembly of the device of Fig. 4- before sealing into the lamp termination.

Fig, 6 is, a fragmentary sectional front elevational view of a further modification of my lamp termination.

Fig. 7 is a fragmentary sectional side elevational view of the device shown in Fig. 6.

Fig. 8 is a fragmentary view, partly in section, of another modification of my invention.

Fig. 9 is a fragmentary sectional view illustrating a mechanically protective ferrule for the terminations of the type of Figs. 1 and 3.

Referring to the drawing, I have shown in Fig. 1, one end of a high-voltage cold-cathode type lamp having a tubular glass body I 0 to which a cylindrical termination I 2 is integrally attached at. right angles. The termination l2 comprises a tubular glass shell l3, enclosing a metallic. disk contact button I6, wires ll welded to an electrode l5 and the contact 16, and a glass sealing insert in the form of a bell l8. The contact button [6 is housed within the sealing, bellv l8, and the depth of the recess formed by thebell is not less than the diameter of the termination 12.

,The bell lBfhas a flared mouth end 19, a cupped. recess 20, and a pinch-seal extension 2| atthe'olosed' end. The. bell I8 is mounted within the shell l3 with the flared lip or and I9 integrally attached to the free end M of the shell 13; The integral assembly of electrode l5, contact button I6 and wires I! is mounted on the bell with the wires l1 extending longitudinally through and pinch-sealed to the extension 2|, with the contact l6 being positioned close to but spaced from the inner end of the recess 20.

To construct the termination illustrated in Fig. l, the wires ll are welded to the electrode l5 and the contact It. The bell I8 is formed from a tubular shape adapted to pass over the contact Hi. With the contact 16 in position 3 within the bell I8, the extension 2| is formed and pinch sealed about the wires I'I, care being taken to space the contact I6 from the walls of the recess 20 or otherwise to prevent setting up internal stresses in the glass which would develop if the contact I was permitted to weld to the adjacent glass walls. This assembly, illustrated in Fig. 2, is then placed within the shell I3 and the flared lip I9 welded by an external ring seal to the end I4 to form the termination -I2. One of these terminations is then welded to each end of body In and the lamp is ready for the usual final processing.

The receptacle or socket 25 of Fig. 1 is of a conventional type having a substantially cylindrical hollow body 26 of glass or other electric insulating material provided with screw threads 21 to engage a threaded metal collar 28 for mounting in a luminaire (not illustrated). However, I have replaced the large-diameter helical contact spring of the receptacles presently available with a helical contact spring 29 of diameter small enough to enter freely the recess 20 of the bell I8 and engage the contact I6. The spring 29 is mounted coaxially within the body 25 and is housed at the base thereof, the spacing between the outer end of the spring 29 and the open end of the body 26 being not less than the internal diameter of the open end of the body 26. The spring 29 is connected to an electric circuit (not illustrated) by the usual screw, nut and washer means, and is of requisite stiffness to maintain its central position and engagement with contact IS.

The operation of this device is as follows:

The termination I2 is placed into the receptacle 25 and completely depressed so that the contact I6 engages the spring 29, thereby energizing the electrode I5. During this operation it is evident that the contact I6 is guarded by the deep recesstion I2, except that the contact button I6 has 7 been replaced by a helical contact spring 33. The receptacle 35 is similar to the receptacle 25 except that the spring 29 has been replaced by a rigid contact 36. This construction has the ad- Vantage that it is not necessary to center and align a relatively long spring in constructing the receptacle.

In the modification illustrated in Fig. 4, I have shown a termination 40 comprising a glass tube 4I which has a necked-down region 42 near the free end 43. In this modification, an insert in the form of a disk 44 of glass is pinch-sealed to the wires I'I, coaxially of the assembly of electrode I5, contact I6 and wires I1, and welded by an internal ring seal to the tube M at a point adjacent the beginning of the necked region. If it is desired to reinforce the single thickness of glass at the free end 43, an annular metal ferrule 45 may be spun tightly over the edge thereof, as illustrated. A simple method for making the disk 44 and sealing it to the wires I1, is to shape the disk 44 from a glass tube and slip it over the wires II, before welding contact It to the ends of the wires, then weld the contact I6 to the wires and finally pinch-seal the disk 44 in the desired position on the wires II. The region 42 may be necked down either before or after welding the 4 assembly illustrated in Fig. 5 into the tube 4I. However, I prefer to preform the tube 4I so that the assembly shown in Fig. 5 can be automatically positioned therein by sliding said assembly into tube 45 from the top until its progress is stopped by the restriction.

In Figs. 6 and 7, I have shown a presently available standard type cold-cathode lamp termination 50 comprising a shell 5I, electrode 52 and external pinch-seal 53, to whose external wire terminals I have attached a contact 54. An extension 55 of molded synthetic resin or other material of suitable electric insulating and mechanical qualities, of the same external diameter as the termination 50, is fitted to the end of said termination to form a substantially smooth continuation thereof. The extension 55 is cupshaped at the end 56 adjacent the termination 50 to complement and fit the rounded end of said termination and is provided with an axial bore 51, rounded at the free end. The bore 51 has a portion 58 of enlarged diameter adjacent the end 55 to receive the pinch-seal 53 and contact 54. Projecting inwardly at diametrically opposite sides of the enlarged portion 58 of the bore, adjacent the termination 50, are two retention points 59. The pinch-seal 53 engages the bore portion 58, with the points 59 adjacent the flat side of the pinch-seal 53, as illustrated in Fig. 6, and the remaining space in the bore portion 58 is filled with suitable cement 60 of good compressive strength. The cement mass 60 between the points 59 and the protruding edges 6| of the fiat side of the pinch-seal 53 provides a locking action which effectively prevents the extension 55 being loosened from the termination 50. The device of Figs. 6 and 7 engages the receptacle 25 in the same manner as the termination I2.

Fig. 8 shows a standard type termination III to which has been welded a tubular extension H having a necked down region I2 similar to that of the region 42 of the termination 40. If desired the free end may be provided with a mechanically protective ferrule (not illustrated) similar to the ferrule 45 of the termination 40.

In the event metallic mechanical protection is desired for the free end of terminations such as I 2 and 32, this may be accomplished in the manner illustrated in Fig. 9 in which the shell I3 and bell I4 are provided externally with a reentrant curvature 80. A metallic ferrule 8| is then spun in place over the outwardly flared end.

In all forms of the invention illustrated and described herein the termination is so recessed and the metallic current carrying elements so disposed therein as to preclude the possibilty of shock due to flash-over, under all normal conditions encountered when installing or removing a lamp.

Although the invention has been described in considerable detail, such description is intended as illustrative rather than limiting, as there will be evident to those skilled in the art other embodiments and obvious modifications in construc tion and arrangement of parts, without departing from the spirit of the invention.

I claim:

1. The method of forming a guarded end for an electric discharge lamp termination having a tubular glass shell enclosing an electrode, fitted with an external contact member recessed in the end of said termination to a depth not less than the diameter of the mouth of the recess, and connected by wires to said electrode, and having a glass seal between the electrode and the contact member, which comprises the steps of welding 5 the wires to the contact member, inserting the contact member within a partially formed tubular glass sealing bell, with said wires extending outwardly from the end of said bell opposite the mouth thereof, disposing the contact member at a depth within the mouth of said bell not less than the diameter thereof and spaced from the glass surfaces of said bell, preparatory to pinch sealing, to avoid the development of excessive stresses in said =bell which would result from too close proximity to said contact member, pinch sealing the bell to said wires, welding said wires to the electrode as an incident to the preliminary steps recited above, and then inserting the assembly of electrode, wires, contact member and bell into said shell so that the mouth of said bell is coterminous with said shell, and then ring-sealing the mouth of said bell to said shell.

2. The method of forming a guarded end for an electric discharge lamp termination having a tubular glass shell enclosing an electrode, fitted with an external contact member recessed in the end of said termination to a depth not less than the diameter of the mouth of the recess, and connected by wires to said electrode, and having a glass seal between the electrode and the contact member, which comprises the steps of forming a glass insert for the end of said lglass shell, welding the wires to said contact member, disposing said contact member so that it is spaced 6 from the surfaces of said insert with the wires passing through an opening therein, sealing said insert about said wires, welding said wires to the electrode as an incident to the preliminary steps recited above, and then inserting the assembly of electrode, wires, contact member and glass insert into said shell and sealing said assembly to said shell, the contact member being so formed and disposed that upon such sealing of said assembly to the shell it assumes a position at a depth within the end of said termination not less than the diameter thereof.

GEORGE C. SALNEU.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,852,020 Metcalf Apr. 5, 1932 2,228,327 Spanner Jan. 14, 1941 2,279,907 Atchley Apr. 14, 1942 2,393,180 Merrill Jan. 15, 1946 2,393,616 De Reamer Jan. 29, 1946 FOREIGN PATENTS Number Country Date 117,427 Australia Mar. 5, 1939 527,940 Great Britain Oct. 18, 1940

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