Electric lamp with insulating base providing improved wire retention

An improved electric lamp including an electrically insulating (e.g., plastic) base which is securedly positioned on the lamp's sealed end portion without the need for adhesives or the like. The base functions to securedly retain the lamp's lead-in wires (a total of four in a dual filament lamp) in a preestablished alignment externally of the lamp's sealed end (from which the wires project) to thereby assure positive electrical connection thereto when the lamp and base are inserted within a corresponding electrical socket. This wire retention is possible by embedding each conductor within designated channels in the base and subsequent deformation of the base's material to substantially cover the embedded wire. In addition, a locking arrangement between the lamp envelope's press sealed end and the base is provided to assist in retaining the sealed end within an opening within the base. The invention is ideally suited for use in a tail light assembly for an automobile.

TECHNICAL FIELD 
The invention relates to electric incandescent lamps and, more 
particularly, to such lamps which include an electrically insulating base 
as part thereof. 
CROSS REFERENCE TO COPENDING APPLICATION 
In Ser. No. 580,929, filed Feb. 16, 1984 and entitled "Electric Lamp With 
Insulating Base" (Inventors: D. Devir et al), there is defined an electric 
lamp having an electrically insulating base wherein lead-in conductors are 
retained therein in fixed alignment to facilitate electrical connection 
when the base is positioned within a respective socket. Ser. No. 580,929 
is assigned to the same assignee as the instant application. The invention 
defined therein is thus owned by the assignee of the present invention and 
was so owned at the time the present invention was made. Ser. No. 580,929 
is now U.S. Pat. No. 4,603,278. 
BACKGROUND 
The features of the present invention are particularly useful as applied to 
the construction of incandescent lamps employed in automobiles, such as 
the dual-filament lamps employed in tail light assemblies. 
One well known example of existing lamps of this type generally employ a 
type S-8 glass bulb cemented in a brass, double contact bayonet base. 
Although used for a number of years, such bases pose a number of 
disadvantages. For example, anyone who has replaced such a lamp in their 
automobile will appreciate the great difficulty experienced in 
position-referencing the base to insure the proper lamp-to-socket 
orientation. The base is usually cylindrical in shape and the only 
orientation reference means are small indexing pins at the sides thereof. 
This referencing problem also holds true for automatic insertion of the 
lamp into the socket during production thereof. Further, the lamp to base 
construction for dual filament lamps of this type requires three soldering 
points for electrical connections (the two lead-in wires serving as the 
common connection are twisted and soldered to the sidewall of the base, 
while the other two wires are respectively soldered to the twin contact 
nodes at the bottom of the base). This leads to corrosion or other contact 
degradation problems caused by soldering fluxes. Finally, the bayonet base 
lamp requires a somewhat complicated and relatively expensive socket 
design. 
One attempted solution to the several aforementioned problems inherent in 
brass base lamps is defined in U.S. Pat. No. 4,028,577 (P. E. Gates et 
al), said patent assigned to the same assignee as the instant invention 
and being a continuation-in-part of U.S. Pat. No. 3,979,627 (S. J. 
Leadvaro et al). In U.S. Pat. No. 4,028,577, there is described an 
electric lamp having a sealed end containing therein (or extending 
therefrom) a reentrant glass stem sealed about its periphery to the glass 
bulb. This end is positiond within a plastic base having a cylindrical 
body portion (for housing the somewhat cylindrical-shaped sealed end) and 
adjacent wedge portion. While this concept has proven advantageous in 
several ways over the aforementioned brass base lamps, it is necessary to 
provide additional features, steps, etc. in order to satisfactorily 
produce and utilize this arrangement. For example, it is necessary to 
position the extending top segment (from the sealed end) a sufficient 
distance from the base's inner, bottom wall in order to provide protection 
thereof. Maintenance of this distance is assured by cementing the bulb 
(along the outer walls) to the base. It is also necessary in this design 
to pass the lamp's projecting lead-in wires through corresponding passages 
(holes) within the base, thus mandating a relatively complex (and 
time-consuming) alignment and insertion procedure. Even further, final 
lead-in wire retention necessitates yet another production step (e.g., 
heat staking) which adds still further to the cost of this lamp. 
In the aforementioned U.S. Pat. No. 4,630,278, there is defined an electric 
lamp and base assembly wherein many of the several problems inherent in 
such prior art designs are overcome. Specifically, the assembly defined 
therein utilizes a base member wherein projecting ends of the assembly's 
lead-in conductors (wires) are oriented in spaced orientation along the 
opposing sides of the base and inserted within corresponding, similarly 
shaped apertures also within the base. In effect, a friction fit between 
the base and each wire is provided. On occasion, it has been determined 
that such a retention may prove insufficient to completely maintain the 
conductors in the desired fixed orientation. That is, on some occasions 
(e.g., wherein high tension forces were applied to both lamp envelope and 
base), the terminal ends of the conductors have become withdrawn from 
their respective base apertures. 
The instant invention overcomes this undesirable feature by providing 
enhanced conductor retention within the base and, in addition thereto, 
means for providing additional restraint on the sealed end of the lamp 
within the base's socket. Such an invention is deemed to constitute a 
significant advancement in the art. 
DISCLOSURE OF THE INVENTION 
It is, therefore, a primary object of this invention to enhance the 
electric lamp art. 
It is a particular object of this invention to provide an electric lamp 
which is relatively simple in design, can be readily and inexpensively 
produced, and which eliminates the need for soldering or the like and the 
typical problems associated therewith. 
It is yet another object of this invention to provide such a lamp wherein 
the lamp's projecting lead-in wires are both positively aligned and 
retained externally of the lamp's sealed end in a more positive manner 
than that described in U.S. Pat. No. 4,603,278 to thereby assure sound 
electrical connection thereto when the lamp is positioned (e.g., inserted) 
within a corresponding socket component and/or removed therefrom for 
possible reinsertion. 
These and other objects, advantages and features are attained, in 
accordance with the principles of this invention, by an improved electric 
lamp including a sealed, light-transmitting envelope having a bulbous 
portion and a press ealed end portion, at least one filament located 
within the interior of the bulbous portion of the envelope, a pair of 
lead-in conductors each connected to the filament and sealed within the 
press sealed end portion of the envelope and exteriorly projecting 
therefrom, and an electrically insulating base member secure to the press 
sealed end portion of the envelope adjacent the bulbous portion. 
Exteriorly protruding portions of the lead-in conductors are positively 
secured within the first portion of the base in predetermined alignment 
against a respective external surface of the insulating base member's 
second portion by embedding each therein and deforming the base material 
to substantially cover the embedded conductor.

BEST MODE FOR CARRYING OUT THE INVENTION 
For a better understanding of the present invention together with other and 
further objects, advantages and capabilities thereof, reference is made to 
the following disclosure and appended claims in connection with the 
above-described drawings. 
With particular attention to the drawings, there is illustrated an improved 
electric incandescent lamp 10 in accordance with the teachings of the 
invention. Lamp 10, as stated above, represents an improvement over the 
lamp in U.S. Pat. No. 4,603,278 and, as described therein, is particularly 
adapted for use as part of a tail light assembly in an automobile. It is 
also understood from the teachings herein, however, that the invention has 
many further uses (e.g., automobile dashboard and aircraft instrument 
lighting, telephone switchboard lighting, etc). and the teachings herein 
are thus not limited to this particular area. Lamp 10, similar to that in 
Ser. No. 580,929, includes a light-transmitting envelope in the form of a 
glass (e.g., lime glass) bulb 13, said bulb containing therein a rare gas 
such as argon established at approximately atmospheric pressure. Bulb 13 
is press (pinch) sealed at one end thereof using a pressing operation 
known in the incandescent lamp industry. Accordingly, further description 
of this operation is not believed necessary. As a result of this pressing 
operation, a flattened, sealed end portion 15 is formed as part of bulb 13 
adjacent the bulbous part of the envelope. End portion 15 is of 
substantially rectangular configuration when viewed in cross section 
therethrough, in comparison to the bulbous shape of bulb 13, which may be 
either substantially cylindrical (tubular) or spherical (round) in shape. 
As will be explained in greater detail below, forming end portion 15 in 
the manner and shape defined constitutes an important aspect of the 
invention. More specifically, end portion 15 as formed by such a pressing 
technique possesses greater strength (resistance to breakage) over ends 
sealed using a tipping operation or the like, or sealed in the manner 
defined in the aforementioned U.S. Pat. Nos. 3,979,627 and 4,028,577. In 
addition, the substantially rectangular (in cross section) shape resulting 
from this technique is particularly suited for placement thereon of an 
insulative base possessing the unique features also taught hereinbelow. 
Located within bulb 13 is a pair of filaments 17 and 19, each of which is 
electrically connected to (and secured by) a corresponding pair of lead-in 
conductors which are hermetically sealed within end portion 15 of bulb 13 
and project exteriorly thereof. The opposing ends of each pair extend 
within the interior of bulb 13 and may be formed (e.g., bent) as indicated 
to assure the desired positioning for both filaments. With particular 
attention to the drawings, filament 17 is connected (and energized) by 
lead-in conductors 21 and 21', while filament 19 is connected by 
conductors 23 and 23'. A total of four conductors thus project exteriorly 
from sealed end portion 15. 
In one embodiment of the invention, filaments 17 and 19 are each of coiled 
configuration and comprised of tungsten. By the term coiled configuration 
is meant that each filament may constitute a singular coil or, 
alternatively, may be a coiled-coil member. Retention of each filament by 
the associated pair of lead-in conductors is attained by crimping the 
interior ends thereof over the opposed ends of the linear filament, said 
procedure known in the art of incandescent lamp making. Each lead-in 
conductor may be comprised of a metallic alloy material (e.g., dumet) or 
similar conductive material known in the art. In one embodiment, each 
conductor possessed an outer (external) diameter (O.D.) of about 0.020 
inch and a total length of about 2.700 inch, of which about 1.400 inch 
projects externally from end portion 15. It is thus understood that a 
substantial (more than half) portion of each conductor projects exteriorly 
of sealed end 15. 
Lamp 10 further includes an electrically insulating (e.g., plastic) base 
member 25 which, as shown, is secured to the press sealed end portion 15 
of the lamp's envelope ajdacent the bulbous portion 13. Base member 25 is 
thus designed for providing a cover for end 15. Base member 25 is of 
unitary construction and includes a relatively larger first portion 24 and 
a smaller (in thickness) protruding second portion 24' adjacent first 
portion 24. Located within second portion 24' are a plurality of apertures 
26 (one shown in FIG. 2) each of which extend through the protruding 
portion 24' and are designed for having a respective exteriorly projecting 
portion of a lead-in conductor pass therethrough. Although individual 
apertures 26 are provided for each conductor, it is also possible to 
utilize a single slot (or channel) for this purpose, wherein all 
conductors are located therein in a side-by-side, non-contacting (to 
assure electrical insulation) relationship. The exteriorly protruding 
portions of the four lead-in conductors are maintained in predetermined 
alignment within an external surface of a respective one of the sidewalls 
of the base's larger first portion and thus capable of being precisely 
aligned with corresponding electrical contacts (i.e., 31, shown in phantom 
in FIG. 1) as might be utilized in a socket 33 (also shown in phantom in 
FIG. 1) into which the invention is designed for being positioned. As 
understood herein, positioning of base member 25 is accomplished by 
inserting the protruding second portion 24' directly within a socket such 
as illustrated in FIG. 1 such that connection is made to the retained and 
aligned exposed portions of the respective lead-in conductors 21, 21', 23 
and 23' in the region of this protruding second portion (and thereby 
against this portion). It is thus possible to provide a socket member of 
relatively simple construction capable of receiving the instant invention. 
Base member 25, as stated, is of unitary construction and defines therein 
an elongated opening 41 also of substantially rectangular configuration 
and designed for having the flattened press sealed end portion 15 
securedly positioned therein. Opening 41 extends into the first portion 24 
of base member 25 an established depth, as indicated in FIG. 2. To assure 
positive positioning therein without causing damage to the sealed end 
portion 15, the first portion 24 of base member 25 further includes 
flexure means 43 therein to enable this part of the base member to expand 
a predetermined amount during said positioning. Flexure means 43 is 
preferably in the form of two elongated slots formed within the narrower 
interconnecting sidewalls of the base member's first portion to thus 
enable the upper parts of the larger sidewalls to expand outwardly during 
positioning of the press sealed end portion 15. Preferably, two slots are 
utilized, although it is possible that only one of these may be provided. 
End portion 15 is thus firmly positioned within base member 25 without the 
need for cement or the like. 
To maintain the externally projecting portions of the four lead-in 
conductors (those portions which project from the protruding second 
portion 24' of base member 25) in the described predetermined alignment 
and thereby assure effective contact therewith at the location indicated, 
base member 25 further includes a plurality of spacedly positioned 
channels 51, each located within the lowermost portion of the larger first 
portion 25 of the base member and designed for having one of the terminal 
ends of a respective conductor inserted therein. As will be described 
below, each of these terminal ends is secured within base 25 in a locking 
relationship to thus prevent subsequent removal thereof during the 
aforementioned positioning of the invention within a corresponding socket 
member. Such retention also serves to assist in maintaining end portion 15 
of lamp 10 firmly within base 25. A total of four channels are provided, 
one for each of the mentioned lead-in conductors. It is understood in the 
broader aspects of its invention, however, that only two such channels may 
be provided in the event that only one filament is utilized (and thus only 
two lead-in conductors similarly employed). Because it is desired to 
position the conductors from each filament on opposite sides of the base 
member's first portion 24, it is understood that if only two channel 
members are employed, these would also be oriented within said opposite 
sides (or sidewalls) of the first portion. 
As better depicted in FIGS. 2 and 3, each channel includes a first tapered 
portion 55 which, as illustrated, facilitates positioning of the 
substantially annular (round) conductors therein. In addition, each 
channel further includes a second tapered portion 56 and an annular 
opening 57 at the bottom thereof (having conductor 23 located therein). 
With particular attention to FIG. 3, each of the illustrated first tapered 
portions 55 abuts a respective one of the second tapered portions 56, 
which in turn are each adjacent to the corresponding annular opening 57. 
As stated, the instant invention defines a means for more positively 
securing the invention's lead-end conductors within the larger, upper 
portion of base member 25. Even more particularly, the invention defines a 
means whereby each of the terminal ends of the conductors is embedded a 
predetermined distance within the base member's first portion and 
substantially covered by a quantity of deformed material of the base. This 
arrangement is illustrated in FIG. 3 wherein a relatively small quantity 
58 of material of the base is shown covering conductor 23. Such an 
arrangement has proven to significantly increase retention of the 
individual conductors and prevent withdrawal (removal) thereof from the 
invention's channels during exertion of forces on both lamp envelope and 
plastic base. In one example, the lamp envelope and base members were each 
subjected to a series of "push-pull" tests wherein said members were 
subjected to opposing tensile forces in an attempt to effect separation 
thereof. In embodiments of the lamp as defined in U.S. Pat. No. 4,603,278, 
forces within the range of about 15 to 22 pounds proved sufficient to 
effect withdrawal of at least one terminal end of the wire conductors from 
the respective openings within the base member. In accordance with the 
teachings of the invention, wherein these ends are firmly embedded and 
covered with deformed base material, forces of approximately 50 pounds 
were required before such withdrawal occurred. This is deemed to 
constitute a significant improvement over the earlier embodiment in U.S. 
Pat. No. 4,603,278. 
In FIGS. 4A-4C, there is shown the preferred technique for embedding the 
conductors of the instant invention within base member 25 and for defining 
the ultimate configuration for channels 51. In FIG. 4A, the respective 
conductor 23 is shown as being positioned above a respective channel 51 
within base member 25. The conductor is engaged by a first tool member 61 
and pushed downwardly (see the directional arrow) toward channel 51. Of 
significance, channel 51 includes the aforedefined first tapered portion 
55 and the annular opening 57. Interconnecting these two portions of 
channel 51, however, is a straight-sided, interim opening 63 having an 
overall width substantially similar to or only slightly smaller than the 
diameter of conductor 23. This conductor is simply inserted within opening 
57 and tool member 61 is subsequently withdrawn. Such placement is 
depicted in FIG. 4B. Once accomplished, a second tool member 65 is then 
lowered (see the directional arrow in FIG. 4B) to engage the end portions 
of tapered walls 55 nearest the aforementioned straight-sided portion 63. 
The forward end 66 of this forming tool member thus causes deformation of 
the plastic material so as to form the double tapered configuration 
depicted in FIG. 4C (and FIG. 3). As shown in FIG. 4C, the aforementioned 
relatively small quantity 58 of deformed material of the base member is 
compressed against conductor 23 to thus assure that the conductor is 
firmly embedded. The second tool member 65 is then withdrawn and the 
product as depicted in FIG. 3 is the result thereof. The preferred first 
and second tool members as shown in FIGS. 4A-4C are of metal (e.g., steel) 
and are thus readily capable of deforming the softer plastic material of 
base member 25 during production of the invention. 
To further assist in retention of the invention's conductors in the manner 
described herein, lamp 10 further includes means 71 (FIG. 2) for 
substantially retaining the press sealed end 15 of the lamp within the 
described opening 41 of the upper, larger portion of base 25. Means 71, as 
shown in FIG. 2, includes at least one protruding segment 73 which 
projects from an internal wall of the opening to extend therein. 
Preferably two such segments are utilized and positioned in an opposing 
relationship (on opposite side walls) as illustrated in FIG. 2. Each of 
these protruding segments is designed for being aligned with and 
subsequently located within a corresponding recessed portion 75 of press 
sealed end 15. One such recessed portion 75 is shown (hidden) in FIG. 1. 
When the press sealed end of lamp 10 is inserted within base member 25, 
each of the protruding segments 73 is inserted within the corresponding 
recesses 75, the result being that the press sealed end is substantially 
"locked" in position. Understandably, this positioning is facilitated by 
the ability of the first portion of base member 25 to expand (flex) 
outwardly during this insertion. It must again be emphasized that this 
retention of base 25 is achieved without the need for cement or the like. 
There has thus been shown and described an electric lamp wherein the 
externally projecting lead-in conductors thereof are positively retained 
in a predetermined alignment to enable positive connection thereto by the 
respective contacts or the like located within a socket member in which 
the lamp is positioned. The combination as defined herein provides a lamp 
wherein the protruding, second portion of the base member, having the 
conductors retained therein, may be directly inserted within a suitable 
socket member to thus assure positive electrical connection of the type 
defined without causing damage to the invention, and in addition thereto, 
without causing removal (withdrawal) of the secure conductors. 
While there have been shown and described what are at present considered 
the preferred embodiments of the invention, it will be obvious to those 
skilled in the art that various changes and modifications may be made 
therein without departing from the scope of the invention as defined by 
the appended claims.