US2208423A - Screw thread connection for electric light bulbs and sockets - Google Patents

Description

y 16, 0- A. ILLSCHE 2,208,423

SCREW THREAD CONNECTION FOR ELECTRIC LIGHT BULBS AND SOCKETS Filed Jan. 15, 1940 2 Sheets-Sheet l fi nz'- L 5 III] I I I I a I 9 4 0 2 z July 16, 1940. 2,208,423

SCREW THREAD CONNECTION FOR ELECTRIC LIGHT BULBS AND SOCKETS Filed Jan. 15, 1940 2 Sheets-Sheet 2 Patented July 16, 1940 PATENT OFFICE SCREW THREAD CONNECTION FOR ELEC- TRIC LIGHT BULBS AND SOCKETS Arthur Illsche, Rye, N. Y. Application January 15, 1940, Serial No. 313,917

4 Claims.

This invention relates to terminal screw caps and sockets for electric light bulbs, socket plugs, fuse plugs and the like.

Screw caps for light bulbs or plugs and the sockets for the same, now in common use, are provided with shallow rounded threads of four or five or more turns that are loose fitting until completely engaged and require rotation through an objectionable number of revolutions before such complete engagement is effected. Unless given a final hard turn, to frictionally bind the threaded bulb cap in the socket, poor electrical contact will result from the insecure connection, causing the light to vary more or it less and if subjected to vibration, as frequently happens, the connection will be further loosened until the circuit is completely broken and the light extinguished.

Difficulty is also experienced in preliminarily 29 engaging the threads of the bulb or plug cap and the socket, as the threads are of uniform diameter throughout their length, which makes it necessary to position the bulb or plug in exact axial alignment with the socket, before engagement can be effected and this can only be accomplished, ordinarily, after repeated unsuccessful efforts and frequently has to be done blindly, as the socket, while accessible, is in many instances, concealed from view. As no mechanical aid is provided to bring the members into centered relation, the operation proves difficult, annoying and a severe trial to the patience of the great majority of people who have very little if any mechanical skill or ability.

My invention is designed to avoid the above and other objectionable features of present day light bulbs, plugs and sockets, by first, effecting complete engagement by rotation through less than a single revolution; second, by shaping the threaded portions of the bulb or plug and the socket to enter freely one within the other to substantially their full length, in nested, centered relation, preparatory to engaging the threads and third, by giving the thread a coarse, deep, close fitting form, that will insure permanence in the connection against the action of vibration and maintenance of good electrical contact in the current supply circuit to the lamp.

The accompanying drawings will serve to illustrate a construction suitable for carrying the invention into effect but I do not wish to be understood as intending to limit myself to the formed and if non-conducting, provided with requisite metal contacts, as will be obvious.

In the drawings- Fig. 1 is a view in elevation, partly in section, showing the invention applied to an electric bulb 5 and socket.

Fig. 2 shows the lower portion of the bulb vieweld from the side opposite that shown in Fig.

b Fig. 3 is a view looking at the bottom of the 10 ulb.

Fig. 4 is a top plan view of the socket.

Fig. 5 is a view in elevation showing the invention applied to a fuse plug, and

Fig. 6 is a like view,. showing the application 15 to a socket plug,

Referring to the drawings, I indicates an electric light bulb and 2 a socket .for the same. The bulb and socket will be recognized as well known types now in common use and need not, therefore, be described in detail.

The main departure from the art is in the form of the means employed to separably connect the bulb and socket. To meet practical requirements, the connection must be such as to provide 25 safe and secure support for the bulb, which is ordinarily positioned in pendant relation to the socket and also to insure maintenance of good electrical contact in the circuit connections for the supply of current to the lamp. 30

Counterpart screw threads 3 and 4 are employed for the connection and as formed, not only meet the above requirements, but go further, to great advantage in enabling the cooperating threads to be instantly brought into en- 5 gaging relation without hesitation, uncertainty or the possibility of failure, ready to be secured in interlocked engagement by relative rotation through approximately half a revolution.

The terminal metal cap 5, cemented or otherwise secured to the bulb, serves as one threaded member of the connection and the other, its counterpart 6, is positioned and fixed in the open end of the socket, as illustrated in Fig. 1, where the cooperating threads are shown engaged, clos- 5 ing the circuit through the bulb, in the usual manner.

In general outline, the threaded members 5 and 6, are of frustro-conical form, being tapered and terminating in blunt ends 1 and 8 and thus formed, the male member 5 is freely enterable into the counterpart 6', in nested relation, to almost its full length, before being rotated to bring about engagement of the threads.

This free entrance of one threaded member into the other to substantially fulldepth, resulting from the tapered guide form given the members, enables the lamp bulb to not only be definitely positioned but held in centered relation in the socket, ready to be given the half turn that interlocks the threads.

This mechanical aid in the preliminary positioning of the members, so greatly simplifies the operation of putting in" a bulb, that no skill or mechanical ability is required and any one can do it instantly and blindly from the sense of touch alone. 7

In the preferred form, the thread is of a length sufllclent to make about two turns on the carrying member. One face 9 of the thread is narrow and the other face l0, broad. The narrow face is approximately perpendicular to the axis of the conical carrier and of substantially uniform width throughout the greater portion of its length. The broad face, developed from practically zero dimensions at the small end of the conical carrier, is gradually enlarged to a width several times that of the narrow face.

The narrow face of the thread serves to effectively lock the connection against accidental disengagement and the broad face gives strength and steadiness to the connection and its extended surface area insures a good electrical contact on the ground side of the lamp circuit.

The threaded socket member 6 is open at its smaller end to expose the commonly employed spring contact member H. The threaded bulb cap 5 is closed at its smaller end by the usual insulated metal terminal insert i2, connected with the positive side of the lamp filament, as indicated by the dotted line l3. The lead from the opposite side of the filament is connected to the bulb cap, as indicated by the dotted line ll.

When the threaded members are engaged, as shown in Fig. 1, the terminal I2 engages and depresses the spring contact H, completing the,

lamp circuit through the filament, in the usual manner.

,From the foregoing it will be apparent that the invention may be applied with equal advantage to fuse plugs, as shown in Fi 5. socket plugs, as shown in Fig. 6, and to other circuit closing elements, where difficulty is experienced or delay is met with readily engaging the elements to close the circuit.

Having described my invention, I claim:

1. A connection for supporting an electrical device and closing a circuit through the same,

comprising two members having engaging pora,aos,4as

tions offrustro-conical form, the taper of which is such as to permit entry of one into the other in nested self-centering relation to substantially their full length, screw-threads thereon extending throughout said frustro-conlcal portions and so formed that relative rotation of the members through less than a revolution effects complete interlocking engagement between the threads, the contacting surfaces of which close one side of a circuit through the supported device, one of the members being open at the smaller end and the other member closed by an insulated terminal projecting into said open end of the first mentioned member to close and complete the circuit through the supported device.

2. An electrical plug and socket connection comprising two members having screw threads thereon, one face of the thread being approximately perpendicular to the common axis of the engaged members and the opposite face of the thread inclined to the axis, the formation being such that relative rotation of the members through less than a complete revolution effects complete interlocking engagement between the threads, the contacting surfaces of which close one side of a circuit through the members; the engaging portion of one of the members being at its smaller end and the engaging portion of the other member closed by an insulating terminal projecting into said open end to close and complete the circuit.

3. An electrical plug and socket connection comprising two engageable members having screw threads thereon, one face of each thread being approximately perpendicular to the common axis of the engaged members and of substantially uniform width throughout the greater portion of its length and the opposite face inclined to the axis and gradually increasing throughout its length to a widthgreater than that of the narrow face to provide broad contacting surfaces for passage of current through the members.

4. A screw thread connection, as defined in claim 3, in which the face of the thread disposed at an angle to the common axis of the members is developed within an approximate two-turn length of the thread from substantially zero dimensions to more than double the width of the opposite face thereof to provide broad contacting surfaces as part of the metallic circuit. through which current is supplied through the connection.

- ARTHUR ILLSCHE.

Images