US2733417A - Metal sleeve base for double ended tubular lamp - Google Patents

Description

Jan. 31, 1956 D. D. HINMAN ET AL 2,733,417

METAL SLEEVE BASE FOR DOUBLE ENDED TUBULAR LAMP Filed Oct. so, 1952 2 Sheets-Sheet 1 inventors: Donald D Hinman, John F Schmerheim by MC Their Attorney Jan. 31, 1956 D. D, HINMAN ET AL METAL SLEEVE BASE FOR DOUBLE ENDED TUBULAR LAMP 2 Sheets-Sheet 2 Filed Oct. 50, 1952 Inventors: D onald D Hinman,

John F Schmerheim, by/ r (z Their" Attorney MIETAL SLEEVE BASE FOR DOUBLE ENDED TUBULAR LAMP Donald D. Hinman, Chagrin Falls, and John F. Schmerheim, South Euclid, Ohio, assignors to General Electric Company, a corporation of New York Application October 30, 1952, Serial No. 317,674

2 Claims. (Cl. 339-50) The present invention relates to electric lamp basesv 7 electrically insulating organic plastic material and are in the form of a longitudinally split sleeve provided with recesses at its ends for receiving the ends of the lamp. A plurality of metal contact pins are afiixed to one longitudinal section of the sleeve and project transversely outward from the base. The sections of the base are held together on the lamp by a single bolt engaging both sections.

Movement of the base between the lamp ends in a longitudinal direction is limited by shoulders provided in the end recesses of the base and which butt against the lamp ends. The base is held anti-turningly on the lamp ends by projections extending into internal notches in the base. The ends of the glass lamp envolope are provided with metal discs for facilitating shaping of the envelope during manufacture of the lamp and the aforesaid projections are provided on these discs.

In bending the tubular glass envelope of the lamp in the mass production of such lamps it has proven difiicult to accurately space and position the ends of the envelope with respect to each other and to bring the said envelope ends to within the tolerances of the base. In order to avoid a loose physical connection between the base and the envelope the base tolerances are necessarily rather close. Frequently enough to add appreciably to the cost of manufacture of the lamps the base has to be ground down to fit between the envelope ends when ends are too closely spaced, or an annular zone on the glass envelope has to be heated to soften the glass thereat sufliciently to permit readjustment of the lamp ends when the gap therebetween is too large or when the ends are offset from each other. These are hand operations and therefore expensive.

The principal object of the present invention is to provide an inexpensive base of simple structure quickly attachable to the justaposed ends of such lamps and which allows larger tolerances in the spacing between the ends of the lamps and in the relative positions of the lamp ends in the manufacture of the lamps to reduce substantially the overall cost of the based lamp. Still further objects and advantages of the invention will be apparent from the following detailed description of a species thereof and from the appended claims.

A feature of the base embodying the invention is a metal sleeve having the same degree of curvature as the juxtaposed end portions of the lamp and made up of two interlocking longitudinal sections enclosing the space between the lamp ends and overlapping and embracing the end portions of the lamp with a firm but yielding grip to. hold the base substantially anti-turningly thereon.

nited States Patent 2,133,411 Patented Jan. 31, 1956' The ends of the new base overlapping and engaging the end portions of the lamps are of substantial width to eliminate the necessity for close tolerances in the spacing and positioning of the lamp ends. Another feature of the base is an electrical contact pin bearing body of electrically insulating material which is readily secured to one section of the said longitudinally split metal base by means integral with the said base section. A further feature of the new base is the provision of interlocking means on the, longitudinal edges of the base sections Whereby the sections are hinged together to facilitate assembly of the base on the end of the lamp envelope.

In the drawings accompanying and forming part of this specification an embodiment of the invention is shown in which:

Fig. 1 is a perspective view as seen from above of a circular lamp having a tubular envelope with spaced ends on which the new base is mounted.

Fig. 2 is a front view on a greatly enlarged scale of the base shown in Fig. 1 and showing one of its interlocking means.

Fig.3 is a back view of the lamp base shown in Fig. 2 with the sections thereof spaced apart slightly to show the other interlocking means.

Fig. 4 is a sectional view along line 4-4 of Fig. 2 taken in the direction of the arrows.

Fig. 5 is a sectional view along the line 55 of Fig. 2 taken in the direction of the arrows.

Fig. 6 is a sectional view along the line 66 of Fig. 3 taken in the direction of the arrows and showing one of the sleeve sections before the contact pin bearing body of electrical insulating material is attached thereto.

Fig. 7 is a perspective view of the contact pin bearing body of electrically insulating material as seen from above with part thereof broken away to show the internal structure.

Referring to Fig. 1 of the drawings, the lamp shown is a commercial fluorescent discharge lamp having a sealed, tubular, light transmitting glass envelope 1 filled with a starting gas, such as argon, at a pressure of several millimeters and provided at its ends with filamentary tungsten electrodes coated with an electron emissive material, such as alkaline earth oxide. The envelope 1 also contains a small quantity of mercury, the vapor of which is at a pressure of about 10 microns during operation of the lamp so that the mercury vapor is highly emissive of 2537 A. radiation. The inner surface of the envelope is coated with fluorescent powder which is responsive to the 2537 A. radiation and which emits visible light. Lamps of this type are disclosed in'Patent No. 2,259,040, issued to George E. Inman and assigned to the assignee of this application.

The tubular glass envelope 1 is bent into a circular shape with its spaced ends juxtaposed. The apparatus disclosed and claimed in Patent No. 2,494,872, issued January 17, 1950, to A. Greiner et a1. and assigned to the assignee of the present application, is useful for so shaping the lamp envelope.

As shown in Figs. 1 to 4 of the drawings the base 2 of the lamp is in the form of a sheet metal tubular sleeve 3, 4 slightly smaller in diameter at its center portion than at its open ends which engage the envelope 1. The base 2 is curved to conform to the curvature of the lamp envelope 1 and encloses the space between the ends 5 and 6 of the lamp envelope 1. Projecting from the side of the base are four contact pins 7, 8, 9 and 10, to which are aifixed in the usual manner the usual four insulated inleads (not shown) extending from the ends of the envelope 1 and constituting terminals for the filamentary axis of the tubular envelope 1 of the lamp, are staked to an electrically insulating body 12 attached to the section 3 of the base and extend generally inwardly of the circular lamp for attachment to socket means of a power supply in the usual manner.

7 The base 2 is made up of two longitudinal sheet metal sections 3 and 4 each extending, at least in part, slightly more than 180 of the cross-section of the base. The corresponding longitudinal edges 13 and 14, 15 and 16 of the sections 3 and 4, respectivley, overlap and interlock in part as described later herein and lie generally in the plane including the circular axis of the tubular envelope The interlocking parts of the metal base sections 3 and 4 are so arranged according to the invention that a firm physical connection is made between the end portions of the metal base 2 and the end portions 5 and 6 of the glass envelope 1 when the interlocking parts of the base sections are engaged. The connection is not a rigid one, however, but, on the contrary, is sufficiently yielding so that the difierent rates of expansion of the metal base 2 and the glass envelope 1 under changes in temperature encounteredin shipment and service result neither in a loose connection nor one so tight that the envelope is cracked or the base deformed.

Thus, the interlocking parts of the base sections include the three tabs 17, 18 and 19 extending from the outer longitudinal edge 16 of the section 4 which engage the three slots 20, 21 and 22 near the corresponding longitudinal edge 14 of the section 3. The section 3 has a single wide tab 23 in the center portion of the inner longitudinal edge 13 of the section 3 which overlaps the corresponding edge of section 4 (Figs. 2 and 3) and is interlocked with the center portion of the section 4 to lock the base 2 on the envelope 1 as described below. The three tabs 17, 18 and 19 of section 4 are provided with the inwardly projecting indents 24, 25 and 26, 27, respectively, which engage the lower edge of the slots 26, 21 and 22, respectively, of section'3. The wide tab 23 on the section 3 is provided with the three inwardly projecting indents 23, 29 and 30.

In mounting the base 2 on the envelope 1 the three tabs 17, 18 and 19 are first inserted in the slots 21), 21 and 22, respectively, from the outside of sleeve section 3 until the indents 24 to 27 pass and then engage the lower edges of the slots as shown at 21 and 25 in Fig. 4. The two sections 3 and 4 are then in effect hinged together with the edge 14 of section 3 inside section 4, as shown in Figs. 2 and 4, and may be clamped about the lamp ends 5 and 6. In so doing tab 23 is first positioned inside the center portion of section 4 and pressure is then exerted inwardly on the center portions of the sections 3 and 4 to spring these portions slightly inward. With the pressure still applied a nail punch is driven through the wall of section 4 opposite each of the indents 28, 29 and 30 to pierce the said wall and spread the sides of the openings 45, 46 and 47 (Fig. 2) made thereby in the said wall into interlocking engagement with the sides of indents 23, 23 and 3G in tab 23 which last sides are also spread by the driven nail punch, as shown at 28 and 47 in Fig. 4. Thus sections 3 and 4 are interlocked with the center portions of the sections 3 and 4 flexed inward slightly. This completes the mounting of the base on the envelope. 7

The provision of the tab 23 at only the center portion of the base section 3 rather than three tabs positioned as are the tabs 17, 18 and 19 of section 4 is important because the ends of the base then embrace the ends of the lamp envelope with a firm but yielding grip rather than with an inflexible clamping action which may result in damage to the lamp envelope, the base, or both under extreme changes in temperature as discussed above.

The firm grip of the base 2 on the envelope ends, together'with the curvature of the assembled base 2 holds the base on the lamp envelope anti-turningly. Even when the grip of the base is comparatively weak, rotation of the base on the envelope through an angular distance of more than a few degrees is prevented, which is commercially acceptable. The projections on the envelope used heretofore to hold the base anti-turningly on the envelope therefore are nolonger necessary.

The section 4 has extensions 31 at its ends which project beyond the edge 15 of the section 4 and into overlapping engagement with the inner surface of end portions of section 3 as shown in Fig. 2. Also, the edge 16 of the section 4 overlaps the edge 14 of the section 3 and engages the outer surface of said section 3, as best shown in Fig. 2. The space between the envelope ends 5 and 6 is thus totally enclosed by the base 2 for purposes of safety.

The center portion of the base section 3 has an opening 32 which is directed generally inward of the based lamps as shown in Figs. 1, 2 and 4 and through which extend the pins 7, 8, 9 and 10 affixed to the electrically insulating body 12.

The insulating body 12 covers the said opening 32 completely and is clamped to the base section 3 by two tongues 33 and 34 (Figs. 5 and 6) integral with the said section 3. Slots 35 and 36 are provided in the body 12 for receiving the tongues 33 and 34 and the body 12 is undercut as shown at 37 (Fig. 7) to facilitate bending of the ends of the inserted tongues into the position shown in Fig. 5.

The sides of the opening 32 are constituted by a rolled over edge 38 (Figs. 4 to 6) of section 3 and extend in an are between the tongues 33 and 34. The edge 38 fits into and engages the sides 39 of a flat depressed portion in the convex surface 40 of the body 12. The said surface 419 conforms in shape to and engages the concave inner surface of the center portion of section 3 so that a large contact area is provided between the body 12 and the base section 3 when these elements are fastened together by the tongues 33 and 34. Also, as shown in Fig. 4, the end of tab 23 is bent over an edge portion 41 of the body 12.

The body 12 thus is firmly held in fixed position on the base section 3 against forces tending to move it in any direction relative to said sections 3 when the con tacts 7 to 10 are thrust into or pulled out of frictional engagement with electrical socket means for the lamp.

The convex surface 40 of the body 12 has three notches 42, 43 and 44 (Figs. 4 and 7) therein to provide space for the inwardly driven indents 28, 29 and 30.

In assembling the base 2 on the lamp envelope 1, the insulating body 12 with the pins 7 to 10 affixed thereon is first attached to the base section 3 as described above. The end of tab 23 is then bent over the edge portion 41 of the body 12, as shown in Fig. 4. The base section 3 is then positioned on the ends 5 and 6 of the envelope 1 and the insulated inleads extending from the envelope ends 5 and 6 are threaded through the hollow pins 7 to 10 and soldered or crimped thereto in the usual manner.

The base section 4 is then attached to the base section 3 by inserting the tabs 17, 18 and 19 into the slots 26, 21 and 22 to hinge the base sections 3 and 4 together as described above.'

The hinged base sections 3 and 4 are then manually forced together by pressing inward on their center portions with the tab 23 of section 3 behind the center portion of the section 4. With the base sections thus forced together around the envelope ends 5 and 6 with sufiicient pressure to slightly spring their center portions inwardly, a nail punch is driven through and pierces the wall of section 4 and each of the indents 28, 29 and 31B of the tab 23 on section 3 leaving the perforations 45, 46, and 47 (Figs. 2 and 4) in the sleeve and locking the sleeve sections 3 and 4 together as explained above.

This completes the assembling of the base 2 on the envelope 1. The perforations 45, 46 and 47 in the sleeve wall are backed by the insulating walls of notches 42, 43 and 44 (Figs. 4 and 7) in the body 12 for purposes of safety.

As best shown in Figs. 2 and 4 the insulating body 12 is dimensioned so as to extend into the gap between the lamp ends and to limit relative longitudinal movement between the base and the envelope to less than that which would allow one end of the base to slip off one of the lamp ends. The outer edges 48 and 49 of the base (Fig. 2) are turned inward at an angle of about 45 so as to fit snugly around the lamp envelope 1 without leaving an unsightly gap. Each of the sections 3 and 4 may be stamped out of thin sheet metal stock, such as sheet aluminum.

In using the base 2 for lamps having tubular envelopes with an outer diameter smaller than the diameter of the center portion of the base, the diameter of the end portions of the base may be made the same as or smaller than that of the center portion, if necessary, to fit the end portions of such envelopes. The diameter of the center portion is determined by the size of the existing sockets for the comercial plastic bases and is conveniently made of a size suitable for fitting the base to the socket.

While the three tabs 17, 18 and 19 on the section 4 and the three slots 20, 21 and 22 on the section 3 are preferred for maximum strength and for appearance, ob-

viously the end tabs 17 and 19 and the end slots 20 and 22 may be omitted Without substantially weakening the base.

What we claim as new and desire to secure by Letters Patent of the United Sttaes is:

l. A base for attachment to an electric lamp having a double ended tubular vitreous envelope shaped with its ends juxtaposed and directed toward one another and having electric terminals extending from its ends, said base comprising a flexible sheet metal sleeve open at its ends for receiving and embracing the envelope ends and having an opening in its side defined by a rolled over edge and a pair of oppositely disposed tongues integral with said edge and extending generally inwardly of said sleeve, said base comprising also an electrically insulating body mounted in said sleeve and having a convex surface fitting the concave inner surface of said sleeve and provided with a flat depressed portion completely covering said opening with the side surfaces thereof engaging the said rolled over edge, and spaced electrical contacts afiixed to the said depressed portion of said body for connection with the envelope terminals, said tongues engaging said insulating body to clamp said body to said sleeve with said contacts at said opening and spaced from the sides of the opening.

2. A base for an electric lamp having a double ended tubular vitreous envelope of substantially circular configuration with the ends juxtaposed and directed toward one another and having electric terminals extending from its ends, said base comprising a flexible sheet metal sleeve curved to conform to the curvature of the envelope and having open ends to receive the said envelope ends, said sleeve being made up of two longitudinal sections having corresponding overlapping edges, one pair of said edges being interlocking at their end portions and at their center portions, the other pair of said edges being interlocking at their center portions only to hold the center portions of the interlocked sections in an inwardly flexed position and exert a firm but yielding grip on the envelope ends embraced by the end portions of said sleeve, one of said sleeve sections having an opening in its center portion facing generally inwardly of the arc of curvature of the base and said base comprising also a body of electrically insulating material and spaced electrical contacts mounted on said body for connection with said envelope terminals, said body being mounted within said sleeve and afiixed to the sidewardly opening section, said body completely covering said opening with its contacts at said opening and spaced from'the sides thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,191,641 Willette July 18, 1916 1,228,028 Klein May 29, 1917 2,367,984 Webster Jan. 23, 1945 FOREIGN PATENTS 429,802 Italy Feb. 3, 1948 649,443 Great Britain Jan. 24, 1951

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