US2642561A - Lighting fixture - Google Patents

Description

June 16; 1953 A. JUDSON 2,642,561

I LIGHTING FIXTURE .Filed Feb. 14, 1949 INVENTOR. A/berf L, (Judson ATTURNEYS 'on the 1ine4-4 of Figures;

Patented June 16, 1953 LIGHTING FIXTURE Albert L. Judson, Portland, reg., assignor, by mesne assignments, to On-A-Lite Corporation, Peoria, 111., a corporation of Oregon Application February 14, 1949, Serial No. 76,211 5 Claims. (01. 33999) mounted at random on an extension cord or the like without the use of tools.

The invention relates particularly to a type of fixture having a pair of contact prongs in the bottom of a conductor cord slot to pierce through. the insulation of a twin conductor cord and establish electrical connection with the wires in the cord. The fixture has a body member and acap and in most of the modifications disclosed the cap has screw threaded engagement with the body member and contains a relatively rotatable piston element adapted to enter into the slot in the body member and force the conductor cord onto the contact prongs whenthe cap is screwed on the body member. The cap also carries a mounting clip for attaching the lighting fixture to a Christmas tree branch or other support.

The general object of the presentinvention is to improve the construction of the cap for a fixture of the type referred to. A particular. object is to provide improved means for securing the piston element and the mounting clip in the cap member, which means is inexpensive and easy to assemble, and which does not requirethe flexing or distortion of the piston element in orderto ,insert it in the cap. Another object is to provide 7 a novel form. of retainer for insertion over'the piston element to hold the piston element in the cap, while at the same time allowing for, the free a rotation of the piston in the cap. Another object is to make provision for limited rotation of the mounting clip so that it may be turned intoalignment with a tree branch or other support without Other objects and advantages and details of construction are described in the following speci-.

fixture shown in Figure 1;

Figure 3 is a bottom plan View of the cap member to show the provision for limited rotation of the mounting clip; I v v Figure Us a fragmentary sectional view taken Figure 5 is a sectional view showing a cap memher having a difi'erent form of retaining ring;

Figure 6 is a plan view of theretaining' ring .turning eith-er the body or the cap of the fixture.

ving one form of the invention embodied ina lighting fixture of the type described;

Figure 2' is a perspective view of the. capiof the Figure? is a sectional view of a capmember showing another form of retaining ring; and

Figure 8 is a plan view of the retaining ring shown in Figure '7.

Figure 1 shows the general features of the type of lighting fixture to which the present invention pertains. The numeral [0 designates a body member of a synthetic plastic or other insulating material. containing the usual metallic socket shell l l which is screw threaded tofit a standard base on a light bulb [2, such as a decorative light used on Christmas trees and the like. The socket also has a central lamp contact i3, and these two contact elements are connected with a pair of metallic pins or prongs I4 and I5 projecting into the bottom of a transverse conductor cord slot 16 in the body [0. The slot I6 is of a width'just equal to the width of common flat twin conductor cord, so that such cord may be disposed fiat in the bottom of the slot without twisting. The prongs l4 and I5 are of sufiic-ient length to pierce through one side of the usual rubber or plastic insulation on such cord,-andthey are spaced in the bottom of the slot to contact the stranded conductors in the cord when the cord is pressed over the prongs in the manner shown.

' In connecting such a fixture, the conductor cord I is merely laid fiat in the slot I B'across the points of the two prongs l4 and I5, and then a cap so that as the cap is screwed down on the body the piston element is forced to advance be- "tween the parallel walls of the slot, pushing the conductor cord ahead of it and onto the prongs, JIhei piston element has a fiat, circular base 23 to seat in the bottom of the cap, and the present invention is concerned with means to secure the piston'elementin the cap for free relative rota 'tion. I

a In addition to forcing the conductor cord onto the prongs i4 and IS, the piston element 2! per.-

forms the further function of holding a mounting clip 25 in operative position in the cap for attaching the fixture to a convenientsupport. The .clip 25 comprises two separate strips of spring metal, each having an inner end 26 bent at substantially right angles to its external part in order to lie fiat against the inside surface of the cap, Interposed between the oppositely directed endsv 26 and base 23 of the piston elegrooveto retain the piston 21.

ment is a thin disc 21 forming a bearing element to facilitate free rotation of the piston element and to hold the end portions 26 flat against the inside of the cap. Further details of the mounting clip will be hereinafter described.

A principal feature of the present invention resides in the use of a. retaining ring above thebase 23 of the piston element to engage and wedge against the inner cylindrical wall of the cap mem ber to hold the piston in the cap while permitting free relative rotation. Difierent forms of retaining ring for this purpose are shown in Figures 1, 6, and 8. The retainer shown inFigures .1, 2, and 4 comprises an annular ring'30- of fiat springy material, such as brass. The ring 30 is dished to have a downwardly directed inner edge 3| dis; posed against the top surface of the base 23 and an upwardly directed outer edge 32 to be wedged into binding engagement with the inner wall of theoap. The outer edge 32 is preferably provided with sharp teeth orserrations 33 to bite into the material of the cap. The ring 30 may be secured in place, either by engagement 'of the outer edge 32 behind a turn of the thread 22 in the cap, or in a lower position by the biting of the teeth 33 directly into a smooth, cylindrical wall surface 34. below the end. of the thread 22, as shown in Figure 4. Thus, the thread 22 may terminate a short distance above. the end of, the cap to leave smooth, cylindrical walls in the space beyond the end of the body which is occupied by the base 23, clip ends 26 and disc 21.

In any event, regardless of the depth to which the thread 22 is formed, the retaining ring 39' is equally effective for this purpose and the parts are readily assembled by merely pressing the ring down into the cap with a suitable tool. If the outside diameter of the ring 30 is slightly larger than the inside diameter of the cylindrical wall or thread which it is to engage, the ring will be slightly contracted when it is pressed downward to its desired position so that when it is released to expand, its dished shape will cause its outer edge 32 to wedge firmly against the surrounding Wall without causing its inner edge 3| to bind against the piston base 23 and interfere with rotation of the latter. The shoulder on the in,- terior cylindrical wall of the cap, shown in Figure 4, serves as a stop to prevent jamming of the retaining ring tightly against the base of the piston element. While thus retained by the ring 30, the piston element 2! is capable of unlimited free rotation in the cap, and the mounting clip 25 is capable of limited rotation, as will be presently described.

In Figures 5 and 6, the retainin ring 40 is essentially a flat annulus of spring metal. .In-

stead of the Whole ring being dished like the ring m'b'er of advantages.

assembled in the cap by a simple direct moveplifies-assembly. The use of a retainer ring also 7 38 to expand to a diameter slightly exceeding the 1 inside diameter of the cap wall, this ring has three projections 4| extending therefrom to engage the cap wall at only these three points. Thus, if the interior of the cap is threaded down to the top surface of the base 23, the projections 4| may:

bend, to varying degrees to bindingly engage the groove of the spiral thread to make the ring The piston element rotates freely under ing the form of a round wire snap ring. The gap 46 between the ends of the wire is sufficient. to

permit contraction of the ring past the threads in the cap, but the relaxed diameter of the ring causes it to expand to seat firmly in the thread ring at 46 also permits the ring to deform the amount required by the pitch of the thread, so that the entire ring will lie in the thread groove as shown. The rounded surface of the wire permits the ring to be pressed through the threaded portion of the cap so that it does not have to be screwed-into position.

'Tlieuse of a resilient retaining ring, or snap ring, to secure the piston in the cap has a num- It permits the piston to be ment without involving rotation of either of the parts. The retainingring may be inserted along with thespi'ston so that the use of this extra part reduces the number of manipulations and simmakes a variety of materials available for use in the piston element which are not naturally sufliciently flexible or otherwise deformable to permit the base. of; the piston to. be; contracted to pass the, threads: in the cap, and then expanded into anundercut. groove as in a, prior construction. Also, in addition to facilitating, assembly, the use of a retainer ring obviates the necessity for forming an undercut groove to hold the base of the pistonjin the head :of the cap. With the present form of construction, the circular base 23 of the piston has a diameter less than the internal. clearance diameter of the threaded opening, and the internal wall portion ofthe cap surrounding the piston. base. may, therefore, be equal to or less than. the clearance diameter through the threads. Thissimplifies. the. manufacture. of the cap itself.

Another feature of the present construction is the. provision for rotating the mounting clip 25. relative to the, fixture without loosening the cap, so that. in placing a string of the lights on p a Christmas tree or the. like each clip may be turned in the'direction of the branch on which the fixture isto be mounted regardless of the direction of the cord. It will be apparent that amnety degree rotation of the clip 25 is suflicient to enable it: to be placed on .a tree branch at any angle without objectionablebending of the cord. This amount of rotation is provided by making an opening 50 in the endv of the cap of double sector shape to subtendapproximately vertical The opening thereby angles of ninety degrees. has a projecting wall portion 5| toengage one side-of the clip and a similar wall portion 52 to engage the other side of the clip, to center the 'clip'in any position it may assume.

These wall portions 51 and 52 engage not only opposite sides of the projecting spring arms but also the under 'sides of the bent end portions 26 to provide bearing surfaces under the full length of each 'end ZG. With this form of construction, the clip is securely held so that it may be madein two pieces to facilitate assembly without losing the effectiveness of the spring action necessary to hold the fixture in an upright position on a support.

Having now described myinvention and in what manner the same'may be used, what I claim as new and desire to protect by-Letters Patent is:

1. In an electrical fixture having a cap memfber with apiston element to force a conductor cord onto a pair of prongs to make electrical connection with conductors in said cord, an apertured end wall in said cap member, and a mounting clip extending through said aperture and 'having 'a portion inside offljsaid cap clamped be.-

tween the inside surface of said end wall and said piston element to hold the fixture upright when the clip is engaged with a support'in an upstanding position, said wall having portions defining said aperture in the general shape of a lemniscate wherein certain of said wall portions extend inwardly toward each other from opposite sides of said aperture to engage opposite sides of said clip and allow limited rotation of the clip in the aperture.

2. In an electrical fixture having a cap with a piston element to force a conductor cord onto prongs to make electrical connection with conductors in the cord, an apertured end wall in said cap, and a mounting clip for the fixture having a pair of fiat resilient strips extending through said aperture and held within the cap by said piston element, said aperture being in the general shape of a lemniscate having opposed arcuate portions to permit limited rotation of said clip and having opposed projecting wall portions between said arcuate portions to engage opposite sides of the clip in different rotative positions of the clip.

3. In an electrical fixture of the type having contact prongs to pierce a conductor cord to make an electrical connection, a generally cylindrical cap for the fixture having a bottom end wall, a piston element in the cap having a fiat generally circular base portion rotatably seated on said end wall to force the conductor cord against the prongs when the cap is applied to the fixture, a cylindrical wall portion of smaller interior diameter than the remainder of the cap extending from said end wall a distance greater than the thickness of said base portion of the piston element to form a shoulder in the cap, and a circumferentially inelastic and radially resilient retaining ring in the cap having a peripheral edge portion in radial binding engagement with the interior of said cap immediately above said shoulder and having another portion in axial engagement with said shoulder, said ring having a smaller inside diameter than said base portion of the piston element to retain said piston element in the cap, said shoulder preventing binding of the retaining ring against the piston element.

4. In an electrical fixture of the type having contact prongs to pierce a conductor cord to make an electrical connection, a generally cylindrical cap for the fixture having a bottom end wall, a piston element in the cap having a fiat generally circular base portion rotatably seated on said end wall to force the conductor cord against the prongs when the cap is applied to the fixture, a cylindrical wall portion of smaller interior diameter than the remainder of the cap extending from said end wall a distance greater than the thickness of said base portion of the piston element to form a shoulder in the cap, and an annular, circumferentially inelastic radially resilient retaining ring of larger outside diameter than the inside diameter of the cap immediately above said shoulder, said retaining ring being initially flat when unstressed and being sprung to dished shape in the cap with a peripheral edge portion of the ring in radial binding engagement with the interior of said cap immediately above said shoulder and the underside of the dished surface engaging said shoulder, said ring having an inside diameter smaller than said base portion of the piston element to retain said piston element in the cap, said shoulder preventing binding of the retaining ring against the piston element.

'5. In an electrical fixture of the type having contact prongs to pierce a conductor cord to make an electrical connection, a generally cylindrical cap for the fixture having a bottom end wall, a piston element in the cap having a fiat generally circular base portion rotatably seated on said end wall to force the conductor cord v against the prongs when the cap is applied to the fixture, a cylindrical wall portion of smaller interior diameter than the remainder of the cap extending from said end wall a distance greater than the thickness of said base portion of the piston element to form a shoulderin the cap, a circumferentially rigid and radially resilient retaining ring in the cap having a peripheral edge portion in radial binding engagement with the interior of said cap immediately above said shoulder and having another portion in axial engagement with said shoulder, said ring having an inside diameter smaller than said base portion of the piston element retaining said piston element in the cap without binding the piston element, said end wall of the cap having a central aperture in the general shape of a lemniscate, and a spring mounting clip having a flat portion projecting through said aperture and having a portion clamped between the inside surface of said end wall of the cap and said base portion of the piston element to hold the fixture upright on the clip when the clip is engaged with a support in an upstanding position.

ALBERT L. JUDSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 886,262 Smith Apr. 28, 1908 1,172,704 Harter Feb. 22, 1916 1,315,317 Letiecq Sept. 9, 1919 1,542,706 Lang June 16, 1925 1,578,311 Grosset Mar. 30, 1926 1,954,756 Kidston Apr. 10, 1934 2,188,596 Hebert Jan. 30, 1940 2,465,700 Tuttle Mar. 29, 1949 2,491,463 Brooks Dec. 13, 1949 2,559,706 Brooks July 10, 1951 FDREIGN PATENTS Number Country Date 455,196 England Oct. 15, 1936

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