US3910668A

US3910668A - Socket for light bulb without threaded base

Info

Publication number: US3910668A
Application number: US443955A
Authority: US
Inventors: Albert Wasmeier
Original assignee: Rafi Raimund Finsterholzl Elektrotechnische Spezialfabrik
Current assignee: Rafi Raimund Finsterholzl Elektrotechnische Spezialfabrik
Priority date: 1973-03-01
Filing date: 1974-02-20
Publication date: 1975-10-07
Anticipated expiration: 1992-10-07
Also published as: FR2220103B3; DE2310151A1; DE2310151C3; FR2220103A1; DE2310151B2

Abstract

A socket for a light bulb with oppositely outwardly projecting wire ends comprises an insulating housing having a bore for insertion of the bulb, the bore being formed with two opposite, axially extending guide grooves open toward its insertion end. Transverse slots in the housing, intersecting the guide grooves, accommodate bent-over extremities of two terminal tabs secured to the outer housing surface, these extremities having arcuate contact edges centered on the bore axis which resiliently engage the glass envelope of the inserted bulb through its projecting wire ends received in the grooves, these wire ends having been bent back alongside the envelope in the first phase of insertion by engagement with a pair of oppositely sloping lands at the socket mouth.

Description

Wasmeier Oct. 7, 1975 SOCKET FOR LIGHT BULB WITHOUT THREADED BASE [75] Inventor: Albert Wasmeier, Vorbef'g, Germany [73] Assignee: RAFI Raimund Finsterholil Elektrotechnische Spezialfabrik, Ravensburg, Germany [22] Filed: Feb. 20, 1974 [21] ,Appl. No.1 443,955

[30] Foreign Application Priority Data Mar. 1, 1973 Germany ..a. 2310151 [52] U.S. C1 339/65; 339/95 D; 339/211 L [51] Int. C1. HOIR 13/20 [58] Field of Search 339/45 T, 65, 176 L, 254 R, 339/254 A, 74 L, 95 D, 91 L, 177 L, 221 L [56] References Cited UNITED STATES PATENTS 3,259,868 7/1966 Irwin 339/45 T X 3,702,455 11/1972 Raynor et al 339/176 L X Primary Examiner-Roy Lake Assistant ExaminerE. F. Desmond Attorney, Agent, or Firm-Ernest G. Montague; Karl F. Ross; Herbert Dubno [5 7 ABSTRACT A socket for a light bulb with oppositely outwardly projecting wire ends comprises an insulating housing having a bore for insertion of the bulb, the bore being formed with two opposite, axially extending guide grooves open toward its insertion end. Transverse slots in the housing, intersecting the guide grooves, accommodate bent-over extremities of two terminal tabs secured to the outer housing surface, these extremities having arcuate contact edges centered on the bore axis which resiliently engage the glass envelope of the inserted bulb through its projecting wire ends received in the grooves, these wire ends having been bent back alongside the envelope in the first phase of insertion by engagement with a pair of oppositely sloping lands at the socket mouth.

US. Patent Oct. 7,1975 3,910,668

SOCKET FOR LIGHT BULB WITHOUT:

THREADED BASE The present invention relates to a socket of insulating material for small electric light bulbs without threaded base whose filament-supporting wires have bare ends projecting from opposite sides of a preferably cylindrical glass envelope and are brought into electric contact with respective terminal tabs in the socket.

In order to assure a dependable contact of the exposed wire ends of such a bulb with the terminal tabs and a sufficiently firm seat of the bulb in the socket, the ends of the line wires have heretofore been soldered or sealed in the socket, the glass envelope of the bulb being provided, for instance, with a press base.

However, the disadvantage of this was that a tool was necessary for the insertion, and possibly also the removal, of the bulb, whereby furthermore the socket could be damaged, so that it also had to be replaced.

Accordingly it is an object of the present invention to provide a socket for small electric bulbs of the abovementioned type wherein a replacement of the bulb can be effected without the use of a tool, and therefore in a shorter time and with less expenditure than heretofore, my invention also aims at insuringa slip-proof contact and seating of the bulb in the socket.

I realize this object, in accordance with my present invention, by the provision of a socket housing of insulating material formed with a bore open at an insertion end for receiving an elongate, preferably cylindrical glass envelope of an electric light bulb with laterally projecting wire ends, this bore being provided with two diametrically opposite lateral grooves substantially parallel to the bore axis and open toward the insertion end or mouth of the socket. The housing is further provided with two aligned slots, transverse to the bore axis, extending from opposite outer surfaces of the housingto the bore and intersecting its grooves. A pair of resilient contact tabs, secured to the housing at these outer surfaces, terminate in bent-over extremities freely traversing the slots and extending toward the axis across the grooves in the absence of an inserted bulb; upon insertion of such a bulb, its wire ends are bent back axially against the glass envelope and lodge in the lateral grooves where they are conductively engaged by the bent-over extremities.

Advantageously, the tabs are wider than the grooves .and their edges contacting the wire ends in these vide the socket mouth with oppositely sloping lands axially spaced from the transverse slots, these lands forming outwardly flared extensions of the groove bottoms. The above and other features of my invention will now be described in detail with reference to the accompanying drawing in which:

FIG. 1 is a side view of an electric light bulb to be fitted into a socket according to my invention;

. FIGS. 24 are longitudinal sections through a socket in accordance with the present invention with the bulb of- FIG. 1 shown in different stages of insertion; and

FIG. 5 is a cross-sectional view taken on the line VV of FIG. 4.

In FIG. 1 I have shown a light bulb 1 whose cylindrical glass envelope is pinched at its lower end to form a foot 2. In a rounded transition region 3, the uninsulated end of a pair of filament-supporting wires 4 extend out of the bulb at diametrically opposite locations.

The socket shown in FIGS. 2-4 has a housing 5, made of insulating material, with outer lateral recesses 16 accomodating a pair of contact tabs 6 whichare made of elastic material, for instance spring bronze, and are fastened to the housing 5, for instance, by rivets 7. The lower ends of the contact tabs extend out of the housing 5 so that connecting tongues 8 are formed. The other end of each tab 6 is provided with a bent-over extremity 9 guided inwardly in a housing slot 10 which extends transversely to the direction of insertion E, i.e. to

i the housing axis.

A central bore 12 for the insertion of the bulb l by its foot 2 is provided in the housing 5. This bore is provided with two diametrally opposite guide grooves 13 for the wires 4 which cross the slots 10 and whose bottoms 13 are provided at the insertion end with outwardly flared extensions in the form of bevels 14 inclined, for instance, at an angle of 45 to the axial direction E. The two bent-over extremities 9 of tabs 10 intersect the guide grooves 13 and extend into the bore 12 in the absence of bulb 1, as shown in FIG. 2.

For the insertion of the bulb 1 into the socket housing 5, the line wires 4 are, first of all, bent outwardly to such an extent that they assume approximately the position shown in FIG. 2. Upon further insertion. a bending of the wires 4 takes place at the bevels 14, as shown in FIG. 3, the wires then coming into contact with stamped arcuate edges 15 of extremities 9 which in the repressed position of FIG. 5 are centered on the axis of bore 12 and whose radius therefore approximately equals that of the bore. As the contact tabs 6 are pressed outward (FIG. 4), their spring tension is increased and the contact between the tabs and the wires 4 is intensified. At the same time, as the bulb 1 slides past the extremities 9 which are resiliently biased toward the socket axis, the curved edges 15 perform a scraping action on the surface of the wires 4, so that any insulating coating present thereon, caused for instance by oxidation or grease, will be definitely removed. The wires 4 are thus immobilized in the grooves The light bulbl which has thus been inserted into the socket (FIGS. 4 and 5) is now held in the housing 5 by the spring tension of the contact tabs bearing upon its envelope by their arcuate edges 15.

Instead of relying only on the natural elasticity of the contact tabs in order to produce the contact pressure, I may use biasing means such as screws for pressing the contact tabs against the bulb.

While I have disclosed one embodiment of the present invention, it is to be understood that this embodiment is given by way of example only, and not in a limiting sense.

I claim:

1. A socket for an electric light bulb having an elongate glass envelope and a pair of wire ends projecting from opposite sides of said envelope, comprising:

I a pair of resilient contact tabs secured to said housing at said outer surfaces and terminating in bent-over extremities yieldably traversing said slots and extending toward said axis across said grooves in the absence of said envelope for conductive engagement with said wire ends upon insertion of said envelope into said bore with said wire ends bent back axially against said envelope and received in said grooves.

2. A socket as defined in claim 1 wherein said housing is provided at said insertion end with oppositely sloping lands axially spaced from said slots, said lands forming outwardly flared extensions of the bottoms of said grooves.

3. A socket as defined in claim 2 wherein said lands include with said axis an angle of substantially 45.

4. A socket as defined in claim 1 wherein said outer surfaces are provided with axially extending recesses receiving said tabs.

5. A socket as defined in claim 1 wherein said bore is cylindrical and said extremities are wider than said grooves and have arcuately concave contact edges with a radius of curvature approximately equaling the radius of said bore.

Claims

1. A socket for an electric light bUlb having an elongate glass envelope and a pair of wire ends projecting from opposite sides of said envelope, comprising: a housing of insulating material formed with a bore open at an insertion end thereof for receiving said envelope, said bore being provided with a pair of diametrically opposite lateral grooves substantially parallel to the bore axis and open toward said insertion end, said housing being further provided with two aligned slots transverse to said axis extending from opposite outer surfaces of said housing to said bore and intersecting said grooves; and a pair of resilient contact tabs secured to said housing at said outer surfaces and terminating in bent-over extremities yieldably traversing said slots and extending toward said axis across said grooves in the absence of said envelope for conductive engagement with said wire ends upon insertion of said envelope into said bore with said wire ends bent back axially against said envelope and received in said grooves.

3. A socket as defined in claim 2 wherein said lands include with said axis an angle of substantially 45*.