GB2277580A

GB2277580A - Three-way lamp base using a push-on contact and method of making same

Info

Publication number: GB2277580A
Application number: GB9406811A
Authority: GB
Inventors: Jr Harvey Walter Krage; Glenn Howard Kuenzler; John Richard Agoston
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1993-04-08
Filing date: 1994-04-06
Publication date: 1994-11-02
Also published as: GB9406811D0; CA2119804A1

Abstract

A method of forming a base for a three-way lamp includes molding a shell (14) and an eyelet (28) at opposite ends of an insulating material (22). A radial shoulder is formed in the insulating material between the eyelet and shell and adapted to receive an annular contact (38) after the insulating material has cured. Adjacent the shoulder, a recess (58) is formed in the insulating material that communicates with a lead wire opening (56). This permits a lead wire (66) to be fed through the opening, deformed outwardly into the recess, and the annular contact advanced over the eyelet into engagement with the radial shoulder. The lead wire and annular contact are then subsequently secured together. <IMAGE>

Description

THREE-WAY P BA8E U8ING A PUSH-ON CONTACT AND METHOD OF FORKING SANE Background of the Invention This invention pertains to the art of lamp bases and more particularly to a base for a three-way lamp.

The invention is particularly applicable to an incandescent lamp and a method of forming a three-way lamp base using a push-on contact. However, it will be appreciated that the invention has broader applications and may be advantageously employed in other environments and applications.

Three-way lamps are well known in the industry, the general characteristics of which are described in detail in commonly assigned U.S. Patent Nos. 3,131,986; 4,556,822; and, 4,605,877. These types of lamps include a first or minor filament and a second or major filament to provide three distinct light levels by selectively supplying current to the filaments individually and simultaneously.

The conventional three-way lamp base has three electrical contact surfaces. The first contact is defined by an externally threaded, generally cylindrical metal shell that extends axially from a base of a glass envelope or bulb. The threaded portion of the shell cooperates with a similarly threaded region in an associated lamp socket to secure the lamp therein.

A second metal contact is of annular configuration and is typically radially and axially spaced from the shell by an insulating material such as glass or a thermosetting plastic. The annular contact, or ring contact, is positioned for engagement with an axially extending intermediate electrode or tang defined in the socket.

Lastly, an eyelet defines a third metal contact and is also axially and radially spaced from the first and second contacts by the insulating material. It, too, is positioned for mechanical and electrical engagement with a central electrode or tang extending from the socket.

Conventionally, the three contacts are held in place in a die or mold and the insulating material introduced into the mold. The insulating material is pressed and sets up hard and thereby secures the three contacts in a fixed, desired relation. Typically, projecting tangs extend from both the eyelet and intermediate contact to facilitate securing these contacts in the insulating material. The tangs are not always properly buried or molded in the insulating material and, on occasion, the lamp base is rejected on that basis. The protruding tang may inhibit proper threading of a lead wire to the annular contact.

According to the prior art method of assembly, the lead wire is fed through an opening in the annular contact and soldered thereto. Although the solder provides a secure interconnection, it is deemed undesirable for a number of other reasons. For example, it is expected that forthcoming regulations will limit the amount of lead-based solder that can be used because of environmental concerns. Moreover, solder is not the most desirable material for use as a surface contact with the tang of an associated lamp socket since it flows under high stress and its application is difficult to control. For example, an excessive amount of solder can inhibit proper threading of the lamp base into an associated socket.

Accordingly, an alternative method for forming a three-way lamp base is desired.

8ummarv of the Invention The present invention contemplates a new and improved base for a three-way lamp and a method of forming same that overcomes all of the above-referenced problems and others and provides a simple, dimensionally accurate structure that provides good electrical contact between the lead wire and annular contact, as well as good electrical contact between the annular contact and associated lamp socket tang.

According to a more limited aspect of the invention, a method of forming the three-way lamp base includes molding an eyelet in a first end of an insulating material and a shell in a second end of the insulating material. An annular contact is subsequently advanced onto the insulating material after the molding operation, and a lead wire connected thereto.

According to another aspect of the invention, the insulating material has a lead wire opening formed therein during the molding step.

According to yet another aspect of the invention, a depressed area is formed in the insulating material about the lead wire opening, the lead wire deformed into the depressed area, cut to size, and secured to the annular contact.

A principal advantage of the invention is the ability to dimensionally control the location of the annular contact.

Another advantage of the invention is found in the good electrical connection between the socket tang and annular contact.

Still other advantages and benefits of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed description.

Brief DescriDtion of the Gravings The invention may take physical form in certain parts and arrangements of parts, preferred embodiments and a method of forming same to be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof, and wherein: FIGURE 1 is a longitudinal cross-sectional view of a lamp base formed in accordance with the teachings of the subject invention; FIGURE 2 is a plan view of a preferred form of annular contact; FIGURE 3 is a plan view of another preferred embodiment of the annular contact; FIGURE 4 is a plan view of a third preferred embodiment of the annular contact; FIGURE 5 is a plan view of a fourth preferred embodiment of the annular contact; FIGURE 6 is an elevational view of another preferred embodiment; and, FIGURE 7 is a flow chart representing the various steps in forming a lamp base in accordance with the subject invention.

Detailed Description of the Preferred Embodiments and Method Referring now to the drawings wherein the showings are for purposes of illustrating the preferred embodiments and method of assembly, and not for purposes of limiting same, the FIGURES show a three-way lamp base A.

More particularly, and with reference to FIGURE 1, the lamp base includes a first contact or metal shell 10 that has a generally cylindrical configuration, centered about a longitudinal axis 12. An external portion of the shell is preferably threaded at 14 to facilitate mating receipt in a threaded portion of an associated lamp socket. Details of the lamp socket are not illustrated nor described since they are readily known to one of ordinary skill in the art.

A first end 20 of the shell is molded to a first end 22 of an insulating material 24. Preferably, the insulating material is a glass, or a thermosetting plastic if desired, that electrically insulates and mechanically secures the first end of the shell. Of course it will be recognized that still other materials than glass can be used as a suitable alternative for the insulating material. A second end 26 of the insulating material secures a metal eyelet 28. As best seen in FIGURE 1, the eyelet is centrally aligned along the longitudinal axis 12 and includes one or more tangs 30 that aid in securing the eyelet to the insulating material. Moreover, the eyelet is axially and radially spaced from the shell first end 20 by the insulating material.

During the molding operation, the shell and eyelet are held in place and the insulating material fills the void or die cavity therebetween. The die cavity will assume any desired configuration between the eyelet and shell but typically has a slight frusto-conical or tapered configuration to the sidewalls 32a, 32b.

Further, the insulating material has a stepped configuration to axially and radially space the shell from the eyelet, in addition to providing a radial shoulder adapted to receive the annular contact as will be described in greater detail below.

More particularly, the first end 22 of the insulating material is of substantially the same diameter as the first end of shell 10. In fact, the shell and insulating material form a radial shoulder 34 at the shell first end. Extending axially outward from the shoulder, the insulating material has a first reduced diameter portion 36 that extends toward the second end 26 of the insulating material and terminates at a second radial shoulder 38. This radial shoulder is disposed generally perpendicular to the longitudinal axis 12 and has a substantially planar conformation for receipt of an annular contact 40. Thus, and as shown in a first preferred embodiment of the annular contact in FIGURE 2, the annular contact has an outer periphery 42 substantially identical to the minimum diameter of the reduced diameter portion 36 adjacent the shoulder 38.The annular contact includes an inner periphery 44 that has a diametrical dimension slightly less than a second reduced diameter portion 46 of the insulating material. The second reduced diameter portion also extends axially a predetermined distance toward the eyelet so as to radially and axially separate the annular contact from the eyelet. Additionally, its axial outer end 26 has a chamfered edge 50 that facilitates alignment of the annular contact over the second reduced diameter portion 46 as will be described below.

According to the preferred method of assembly, the shell 10 is placed at one end of a die and the eyelet 28, with its securing tang 30 extending toward the shell, positioned at the other end of the die. The insulating material is introduced into the die and is pressed and allowed to setup and harden or cure, so that the shell and eyelet are then axially and radially spaced from one another by the insulating material.

The die is configured to form the first and second reduced diameter portions 36, 46, respectively as described above.

Moreover, a lead wire opening 56 is formed in the insulating material and terminates adjacent radial shoulder 38, more particularly a recessed area or cutout 58 thereof. As best shown in FIGURES 2 - 4, the recessed area 58 has opposed side walls 60, 62 that diverge angularly outward or lie parallel as they extend radially from the lead wire opening toward the periphery of the radial shoulder 38. Moreover, the recessed area 58 has an axial dimension measured from the shoulder 38 that receives a lead wire 66 therein.

Thus, the shaped base when readied to the lamp, has the lead wire 66 fed through the opening 56 in a direction generally parallel with the longitudinal axis 12. The lead wire 66 is then wiped or deformed radially outward into the recessed area 58 where a terminal end 68 of the lead wire extends radially outward from the first reduced diameter portion 36. The annular contact 40 is then advanced axially over the second reduced diameter portion 46. The chamfered edge 50 facilitates alignment of the annular contact relative to the lamp base and assists in initial mechanical deformation of the inner periphery 44 of the contact.

As shown in FIGURES 2 - 4, either the inner periphery of the contact or the outer periphery of the second reduced diameter portion 46 is modified to provide good torque resistance and frictional contact.

In FIGURE 2, circumferential relief areas 70, 72 provide sufficient deformation of the inner periphery of the annular contact as it is axially advanced over the second reduced diameter portion 46. Additionally, if desired, the second reduced diameter portion may include parallel flat surfaces for receiving the relief areas 70, 72 to increase the ability to resist rotation when the annular contact is turned against the socket tang.

Similarly, a series of radial cuts 74 in the inner periphery of the contact shown in FIGURE 3 provide a circumferentially continuous relief region. Moreover, the reduced diameter portion 46 of the insulating material may include relief areas 76 to stake the inner diameter of the annular contact and resist rotation when the annular contact engages the socket tang.

Alternatively, and as shown in FIGURE 4, the reduced diameter portion 46 may have a serrated peripheral configuration 80 about which the inner diameter 44 of the annular contact provides a tight mechanical fit.

In FIGURES 5 and 6, axially extending tab or tabs may be provided on the outer periphery of the annular contact. In FIGURE 5, the tabs are circumferentially spaced apart and would cooperate with corresponding grooves formed in sidewall 32a of the insulation material. Again, this arrangement would resist rotation of the annular contact when it engages the socket tang. In the embodiment of FIGURE 6, the tab or skirt 79 is circumferentially continuous and forms a cap-like structure whose outer skirt 79 extends axially over the sidewall 32a. Preferably, the skirt does not extend over the lead wire recess 58.

As will be appreciated from a review of FIGURES 2 - 6, a number of different configurations can be used to provide mechanical retention of the annular contact on the insulating material. Once the annular contact is advanced into seated relation on the radial shoulder 38, the lead wire 66, particularly the terminal end 68, is cut or trimmed to length so that it does not extend radially outward from the outer periphery 42 of the contact. The lead wire and annular contact are then secured together, preferably by an arc welding operation that provides a sound electrical and mechanical interconnection.

This arrangement eliminates conventional tangs used in three-way lamp annular contact arrangements where the annular contact is molded along with the eyelet and shell in the insulating material. If solder is used to interconnect the lead wire and annular contact, the connection is protected by the annular contact. Alternatively, solder need not be used and the lead wire is welded to the annular contact. For example, welding can be any number of different types, such as resistant welding, arc welding, discharge welding, sonic welding, etc. Moreover, with some welding processes, it is desired to leave an extended length of wire rather than cutting the lead wire as described above. The welding will melt the wire and the molten end rolls up due to surface tension to a point where the wire no longer extends outside the annular contact but has has fused into the annular contact material.Still other means of securing the lead wire to the annular contact are contemplated and deemed to fall within the scope and intent of the subject invention.

This arrangement will place solder away from being exposed for electrical contact with an associated socket tang. Also, lead solders are not desired for environmental concerns. Instead, and according to the subject invention, a more desirable material that comprises the annular contact is assured better electrical contact with the socket tang. The dimensional control problems associated with a soldered lead wire connections are also eliminated.

As the lamp base is threaded into an associated socket, torque resistance is required from frictional engagement between the annular contact and the socket tang. To assure sufficient torque resistance, the outer edges of the reduced diameter portion 46 can be roughened or shaped to enhance the torque resistance.

Alternatively, the annular contact can be formed of a slightly thicker material than prior art arrangements to address these concerns. Alternatively, various combinations of securing arrangements as shown or suggested by FIGURES 2 - 6 can be used to maximize the mechanical connection between the contact and insulating glass.

FIGURE 7 summarizes the various steps of forming a lamp base using a push-on annular contact. As will be understood, the details of the method as described above are applicable to any one of the annular contact embodiments of FIGURES 2 - 6. Moreover, the particular configurations of the insulating material, contacts, etc. do not impact on these steps as generally outlined in FIGURE 7.

The invention has been described with reference to the preferred embodiments and method. Obviously, modifications and alterations will occur to others upon a reading and understanding of this specification. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

CLAIMS:

1. A method of forming a three-way lamp base having an eyelet, shell, and annular contact electrically insulated from one another by an insulating material, said method comprising the steps of: providing an eyelet and a shell; molding said eyelet in a first end of said insulating material and said shell in a second end of said insulating material; providing an annular contact; advancing said annular contact on said insulating material after said molding step; and connecting a lead wire to said annular contact.

2. A method of forming a three-way lamp base as defined in claim 1 comprising the further step of forming a lead wire opening in the insulating material during said molding step.

3. A method of forming a three-way lamp base as defined in claim 1 comprising the further step of forming a radial shoulder on said insulating material generally perpendicular to a longitudinal axis of said shell to receive said annular contact.

4. A method of forming a three-way lamp base as defined in claim 1 wherein said advancing step includes the further step of deforming an inner.periphery of said annular contact to mechanically connect said annular contact to said insulating material.

5. A method of forming a three-way lamp base as defined in claim 1 wherein said connecting step includes the further steps of forming a lead wire opening in said insulating material during said molding step and forming a recessed area in said insulating material to receive said lead wire prior to said advancing step.

6. A method of forming a three-way lamp base as defined in claim 5 comprising the further step of deforming said lead wire into said recessed area for receiving said annular contact thereover prior to said connecting step.

7. A method of forming a three-way lamp base as defined in claim 6 comprising the further step of cutting said lead wire after said deforming step to prevent extension of said lead wire from said insulating material.

8. A method of forming a three-way lamp base as defined in claim 1 wherein said connecting step includes welding said lead wire to said annular contact.

9. A method of forming a three-way lamp base having an eyelet, a cylindrical shell having a longitudinal axis, and an annular contact that is axially and radially spaced from both said eyelet and shell by an insulating material, the method comprising the steps of: molding said eyelet and said shell on opposite ends of said insulating material with a radially extending shoulder interposed between said eyelet and said shell, and said insulating material having a first diameter portion from said eyelet to said shoulder for receiving said annular contact thereover; advancing said annular contact over said eyelet and said first diameter portion into engagement with said shoulder after said insulating material has hardened; providing a lead wire that extends through said insulating material and exits said insulating material at said shoulder; and securing said lead wire to said annular contact.

10. A method of forming a three-way lamp base as defined in claim 9 wherein said molding step includes the step of forming an opening for said lead wire through said insulating material.

11. A method of forming a three-way lamp base as defined in claim 10 wherein said lead wire opening forming step includes the further step of forming a recess in said shoulder for receiving said lead wire beneath said annular contact.

12. A method of forming a three-way lamp base as defined in claim 11 comprising the further step of deforming said lead wire into said recess.

13. A method of forming a three-way lamp base as defined in claim 12 comprising the further step of cutting said lead wire so that it does not extend outwardly from the first diameter portion.

14. A method of forming a three-way lamp base as defined in claim 13 wherein said securing step includes welding said annular contact to said lead wire.

15. A method of forming a three-way lamp base as defined in claim 9 wherein said securing step includes welding said annular contact to said lead wire.

16. A method of forming a three-way lamp base as defined in claim 9 wherein said advancing step includes the step of mechanically deforming an inner peripheral portion of said annular contact around said first diameter portion.

17. A base for a three-way lamp that includes first, second and third lead wires associated with first and second filaments, said base comprising: a shell having a first end adapted for connection with said first lead wire and a second end spaced along a longitudinal axis from said first end; an insulating material molded to said shell second end and having a stepped configuration defining first and second radial shoulders as it extends axially outwardly from said shell, said first radial shoulder including a recess receiving said second lead wire; an annular contact received on said first radial shoulder and overlying said second lead wire, said annular contact and second lead wire being mechanically and electrically secured together; and an eyelet disposed on said second radial shoulder and secured to said insulating material.

18. A base for a three-way lamp as defined in claim 17 wherein said insulating material and said annular contact have cooperating surfaces that mechanically hold said annular contact against said first radial shoulder.

19. A base for a three-way lamp as defined in claim 17 wherein an inner periphery of said annular contact has plural relief areas that deform over said insulating material and hold said annular contact against said first radial shoulder.

20. A method substantially as hereinbefore described with reference to the drawings.

21. A base substantially as hereinbefore described with reference to the drawings.

22. A lamp comprising a base according to any one of claims 17 to 19 and 21.

23. A lamp made by the method of anyone of claims 1 to 16 and 20.