GB2146850A - Incandescent lamps - Google Patents

Abstract

An adapter for an incandescent electric lamp having an envelope (11) with a portion through which a pair of lead-in studs (18) are brought out, has a body (52) of electrically insulating material having at one ends pair of arcuate slots which receive the studs and which each contain a contact means (78,79). The studs contain recesses and the end of the body carries a washer (82) which has two keyhole shaped slots arranged to engage in the recesses to retain the lamp to the adaptor. The contacts are connected to means (61,64) which are receivable in a lamp socket. <IMAGE>

Description

SPECIFICATION Incandescent lamps The present invention relates to an incandescent electric lamp and more particularly to a type of lamp in which it is desired to mount the filament in a given location.

Conentional incandescent electric lamps are manufactured with a glass envelope having a reentrant stem portion of glass which extends into the interior ofthe envelope. The lead-ins for mounting the lamp filament are brought into the lamp through the stem and the filament is mounted thereon. Such a stem is adequate for high-speed assembly of lamps on automatic machinery. However, in conventional incandescent lamps,thefilament need not be placed at any special location with respect to the interior ofthe envelope.

In various types of lamps, for example a lamp with a full or partial infrared (IR) energy reflective coating, two problems are encountered. First of all, the filament must be placed at a desired location within the interiorofthe envelope with respect to it.

Normally, this will be atthe optical centre of the envelope so that IR energy can be reflected from the envelope back to the filament. It is also possible to mountthe filament off-centre in various applications.

Neither type of precise location would be readily accomplished with a glass stem whose dimensions are quite variable at the temperatures encountered during some ofthe lamp processing stems. In addition, since large quantities of heatare present due to IR reflection at various portions ofthe envelope, the possibility arises that a glass stem mightfully or partially melt.

According to the present invention there is provided an incandescent electric lamp combination comprising: an envelope of a glass material having a base portion, a pairofrigidfilamentwire mount means of electrically conductive material hermetically sealed to the base portion ofthe envelope, each mount means having a first portion extending into the envelope, an incandescent filament electrically connected between the first portions ofthe mount means, each mount means having a second portion extending exterior of the envelope to which electrical contact is to be made tosupplycurrenttothefilament, and an adaptor, the second portion of at least one ofthe mount means also being formed with a means for positively locking the lamp to the adaptor, the adaptor including a body of electrical insulating material, means on the body for receiving the bottom portion oftheenvelope and mating means on the body for receiving the locking means of the second portion of the at least one filament mount means positively to lockthe lamp to the adaptor, meansfor making electrical contact with the second portion of each of the mount means, and means electrically connected to the means for making electrical contactfor mounting the adaptorto a lamp socket.

Accordingly, the present invention relates to an incandescent lamp in which the conventional glass reentrant stem is eliminated. The lamp includes an envelope which is sealed off at a portion (which may be made structurally strongerthan the remainderof the envelope) and a pair of lead-in mounting studs are provided therethrough. Lead-in wires are connected to the lead-in mounting studs and the filament is connected to these wires. An adaptor socket is provided which connects to the lead-in studs so that the lamp may be mounted in a conventional base which supplies it with electrical current.

The invention also provides a baseless incandescent electric lamp adapted for detachable mounting to an adaptor comprising: an envelope of glass material, a pair of rigid studs of electrially conductive material hermetically sealed directlyto a portion of the envelope, each stud being integrally formed with a first portion extending into the envelope, an incandescent filament electrically connected between the first portions ofthe studs, each stud having a second portion extending exterior of the envelope to which electrical contact is to be made with means in the adaptorto supply current to the filament, andthe second portion of at least one ofthe studs having a means for positively locking the lamp to the adaptor in a detachable manner.

Further there is provided an adaptorfor holding and making electrical contact with such a baseless incandescent lamp, the adaptor comprising: a body of electrical insulating material, means on one end ofthe body for receiving and holding each ofthe filament mount means including a pair of slots into which the filament mount means extend, at least one ofthe slots being arcuate, first means in each of the slots for making electrical contact with a respective one ofthe electrically conductive filament mount means, means electrically connectedto each of the first means for connecting the adaptor and therefore the lamp heldtherebyto a lamp socket, and means at the one end of the body for locking the lamp to the adaptor including a portion formed over the one arcuate slot having a keyhole shaped engage and lock a part of the filament mount means inserted into the arcuate slot as it is rotated from the wider to the narrower part of the keyhole slot as the lamp is rotated into the adaptor.

The invention is illustrated byway ofexamplewith reference to the accompanying drawings in which: Figure 1 is an elevational view, partly in section, of the lamp and the adaptor socket; Figure 2 i5 a cross-sectional top viewtaken along lines 2-2 of Figure 1; Figure 3 is a cross-sectional top viewtaken along lines 3-3 of Figure 1; and Figure 4 is a fragmentary view, in cross-section, of a portion ofthe adaptor.

Referring to the drawings, an incandescent lamp 10 includes an envelope 11 of a conventional glass material, for example, lime glass or borosilicate glass.

Envelope 11 is is 11 generally spherical shapeexceptfor the bottom portion 13thereofwhich isgenerallyflat.

The bottom portion 13 is reinforced with respect to the remainder ofthe envelope 11 by being made considerablythicker, for example, in the order of 3-8 times thicker.

Envelope 11 can be blown and/or moulded. The flat portion 13 is formed with a tube 15 through which the envelope 11 can be exhausted and filled with a suitable fill gas for operating the lamp orthrough which the lamp can be evacuated for vacuum operation. Any suitable gas or vacuum operation can be used with the lamp.

All ora portion ofthe interiorandiorexteriorof envelope 11 can be coated with an IR reflective material which can also be lighttransmissive. This is shown diagrammatically bythe letter Con the interior ofthe envelope.

Sealed into the base portion 13 ofthe envelope are a pair of lead-in studs 18 which are of a suitable, electrically conductive material,forexample, brass, copper, etc. If desired, the portions of the studs 18 which extend into the envelope can be coated with a material which is reflective to IR energy, one such material being silver. Each stud 18 is of generally circularcross-section (although other shapes can be used) and has an enlarged diameter intermediate body portion 19 which is sealed to the thick base 13.

Each stud also has a portion of narrow diameter 20 which extends through base 13 into the interior of envelope 11. Exterior to the envelope, each ofthe studs 18 has a reduced diameter portion 22. The exterior portion 24 of each stud terminates in an enlarged diameter head through which electrical contact is made.

Connected to the top end of each ofthe studs 18 is a respective lead-in wire 32 and 34. The wire is of any suitable material, for example, nickel ortungsten. The longerwire 32 has an inwardly bent over section 33 and the shorterwire 34 has an inwardly bent over section 35. The bottom end of each of the two wires 32 and 34 is connected to a respective stud 18 by any suitable means, for example, welding, brazing, etc.

Afilament40 has its ends connected to the respective portions 33 and 35 ofthe two lead-in wires 32 and 34. The connection is made by any suitable technique,for example, welding, crimping, staking, etc. Filament40 can be of the single coiled, doublecoiled ortriple-coiled type. The latter is preferred for higher emissivity.

In the manufacture of the lamp 10, the base portion 13 is made separate from the remainder ofthe spherical envelope 11. The base 13 can be moulded and the studs 18 are placed in holes formed in the base. The base has a slight upwardlyflared portion 13a which thins outto the thickness of the remainder of envelope 11. The studs can be moulded as part of the bores or held therein by glass solder as shown at 42. The studs are precisely located in the base 13, since the base is relatively thick and has good dimensional stability. Also, the studs 18 are thick and rigid and have good dimensional stability.

Thewires32and34arethen mounted to the studs togetherwiththefilament40.Atthis particular point in time, the filament can be placed ata desired location, relative to the base 13 by, for example, bending one or both ofthe leads 32 and 34.

Afterthe filament assembly is completed to base 13, the base 13 is assembled to the envelope 11. This is done by, for example, making a glass weld in the area shown as 43 around the entire circumference of the base 13 which is originally formed with a sleight upward flare. At this point in time, it is still possible to align thefilamentwith respect to the wall ofthe envelope by, for example, placing an instrument through the tube 15. This would be difficult to do in a glass bulb which has only a re-entrant stem. The filament 40 can be adjusted to be located atthe optical centre of envelope 11 or at any other desired locatfon, for example, off ofthe optical centre by a desired amount.

After the filament is aligned in the desired manner, the envelope is exhausted and/orfilled with a fill gas, if this is desired, through the tube 15. The tube is then sealed and tipped off. The lamp is now completed.

Figures 1 to4showa preferred form of adaptor50 for use with the lamp af Figure 1. The adaptor includes a body portion 52 of an insulating material, such as plastics, which is generally cylindrical and has a central bore 54. The upper end of body 52 has a narrow shoulderarea 56 and an upwardlyflared skirt 58 is placed in the area 56. It is held, for example, by an adhesive. The upwardly flared skirt 58 protects the bottom ofthe envelope base 13 and to provide a more aesthetic design.

Attached to the outside ofthe main portion ofthe body 50, by an adhesive orby a mechanical lock, is a shell 60 of aluminium, brass or other suitably electrically conductive material having screwthreads 61 thereon. Awasher 62 of electrically insulating material such as plastics, fibre orothersimilar material, is placed atthe bottom ofthe body and the end of a stud 64 of electrically conductive material such as copper or brass, is received in and held by the central bore 54.

This can be by a force fit, adhesive, etc. The shell 60 and stud 64 form electrical contacts, the same as in a conventional electric lamp, so that electrical contact can be madeto contact in a conventional socket (not shown). As also seen in Figure 1,the end ofthe envelope stem 15 is received in and protected by the bore 54.

Thetop of the adaptor body 50 is formed with two arcuate key slots 72,74 in each of which a respective electrical contact member78 is located. Attached to the top ofthe body is a washer 82 of an electrically insulating material. Thewasher is attached by an adhesive or heatsealing. It also has a pair of slots 73, 75 corresponding to and overlying slots 72,74. Each slot 73,75 has a respective wide mouthed entry portion 73a, 75a and a respective narrow neck locking portion 73b, 75b. The contacts 78,79 are each of a springtype of material,forexample, phosphor-broru:e etc. Each ofthe electrical contacts 78,79 is held within a respective slot 72,74 by, for example, a rivet 80 which is embedded in the body 50 (see Figure4). Each contact has a flat section (only contact 78being shown in Figure4) 78a attached to the stud 80, an anglect central part78bterminating in a ridge78cana! a platform 78d. Connected to the bottom end ofthe rivet 80 ofthe contact 78 is a wire 84which runs through the central bore 54 and is electrically connected to the base button 64. Connected to the rivet 80 of contact 79 is a metal tab 81 which is bent over and electrically connected to the shell 61 for example, by soldering or welding.

To connect a lamp 10 to the adaptor 50, it is only necessary to place the enlarged diameter extending heads 24 ofthe studs 18 into the entry mouths 73a, 75a of the slots 73,75 of washer 82 until the reduced diameter areas 22 of the studs, which are slightly longerthan the thickness of washer82, are in a position to receive the washer. The lamp is then rotated to bring the stud heads 24 underthe locking areas 73b, 75b ofthe washer 82. The heads of the studs are largerthan the openings 73b, 75b. The lamp 10 is thus held securely against washer 82 by the stud heads 24 as the electrical spring contacts78,79 apply an upward pressure againstthestuds. The bottom of each stud head is firmly seated on the respective platform 78d, 79dat the end ofthe respective contact member 78, 79. The studs will then lock against the ribs ofthe contact members 78.

Claims (5)

1. An adaptorfor holding and making electrical contact with a baseless incandescent lamp of the type having a pair of rigid filamentwire mount means of electrically conductive material which extend exterior ofthe envelope, the adaptor comprising: a body of electrical insulating material, means on one end ofthe bodyfor receiving and holding each ofthe filament mount means including a pair of slots into which thefilament mount means extend, at least one ofthe slots being arcuate, first means in each of the slots for making electrical contact with a respective one of the electrically conductive filament mount means, means electrically connected to each of the first means for connecting the adaptor and therefore the lamp held thereby to a lampsocket, and means at the one end ofthe body for locking the lamp to the adaptor including a portion formed over the one arcuate slot having a keyhole shape to engage and locks part ofthefilament mount means inserted into the arcuate slot as it is rotated from the wider to the narrower partofthe keyhole slot as the lamp is rotated into the adaptor.

2. An adaptor according to claim 1 wherein both the slots are keyhole shaped to lock both the mount means.

3. An adaptoraccordingto claim 1 or2whereinthe locking means comprises a cover member which is separately attachable to the one end of the body.

4. An adaptor according to claim 3 wherein the locking means comprises a cover memberwhich is separately attachable to the one end of the body and has the keyhole shaped slots formed therein.

5. An adaptoraccordingto claim 1 substantially as described with referenceto and illustrated in the accompanying drawings.