GB2231717A

GB2231717A - Improved reflector lamp unit construction

Info

Publication number: GB2231717A
Application number: GB9006417A
Authority: GB
Inventors: Robert Melville Argo; Gerard Anthony Melfi; Bruce Emerson Shanks; Daniel Raymond Campbell
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1989-03-24
Filing date: 1990-03-22
Publication date: 1990-11-21
Also published as: GB9006417D0; JPH0315149A; FR2644933A1; DE4008817A1

Description

IMPROVED REFLECTOR LAMP UNIT CONSTRUCTION r, 1 J - -7 1 -7 LD9964 This

invention relates generally to a reflector lamp unit employino an inner tungsten-halogen lamp component to project illumination efficiently and more particularly to an improved structural configuration for the tunosten-halogen lamp component in such reflector lamp unit.

Reflector lamp units of various types are well known to include lamp units employing particular type reflector members which cooperate optically with the light source of the lamp unit to project illumination forwardly in an efficient manner. The latter type lamp units are particularly adapted to provide precisely focused illumination for such end product applications as photographic projectors, airport runways and display lighting. One such type of precisely focused reflector lamp unit is disclosed in U.S. Patent No. 4, 021,659, wherein a multifaceted reflector member has an inner tungsten- halogen lamp positioned substantially at its focal point to spread the optical image formed by the reflector lamp into a larger and smoother pattern. The tungsten filament of the light source is further aligned substantially LD9964 along the central lamp unit axis in order to reduce the amount of imaging by the lamp filament and support post in the projected light beam pattern. In a variation for this type reflector lamp unit construction, the tungsten lamp filament is again positioned at the reflector focal point but extends longitudinally in a direction substantially transverse to the central lamp unit axis. Both lamp unit embodiments can employ a refledtor member having the same multifaceted reflecting surface described in the cited patent, however, wherein an elliptical reflecting surface is provided which includes a multifaceted pattern having a plurality of radial bands and a plurality of concentric circular bands which mutually intercept one another.

Various type tungsten-halogen lamps can also be employed as the light source in the aforementioned precisely focused reflector lamp unit construction. For example, the lamp construction can employ a vitreous lamp envelope formed with fused quartz but which generally further reauires that the inlead wires supporting the lamp filament be hermetically sealed within the lamp envelope with thin refractory metal foil elements as illustrated in the above cited prior art patent. Alternately, various glass-halogen lamp constructions can be employed wherein the vitreous lamp envelope is formed with a refractory glass, such as an aluminosilicate glass composition, and which differs structurally from a quartzhalogen lamp primarily with respect to the means employed to hermetically seal the filament lead-in wires to the lamp envelope. In this regard, a closer match in thermal expansion between the selected glass material and molybdenum metal, generally employed to form said filament inlead wires, enables elimination of the foil elements conventionally employed for a hermetic seal in the quartz- LD9964 halogen lamp construction. A further economic benefit in the lamp cost is generally realized with such glasshalogen type lamp construction. Less costly metal wire of larger diameter can be joined to the filament lead- in wires in a pinch seal region of the lamp glass envelope and further provide structural support of the lamp member. Both quartz-halogen and glass-halogen lamps are provided with exhaust means located at either end of the lamp envelope and with a fill of rare gas, such as argon, xenon and krypton, together with a vaporizable alkyl halide substance also being contained within the lamp envelope. The lamp fill is generally employed at substantially suDeratmospheric pressure in order to improve lamp eff-icacy all. higher operating temperatures.

By reason of the foregoing considerations, a grow- ing variety of the glass-halogen lamp constructions now re place use of a quartz-halogen lamp in the reflector lamp units.

An early rounded end glass-halogen lamp suitable for this pur pose is disclosed in U.S. Patent No. 3,798,491, which employs an aluminosilicate glass comprising in percent by weight Sio 2 between 59-70, Al 2 0 3 between 10-20 and BaO between 7.4 to 28 and having a coefficient of linear thermal expansion between 36 and 40 x 10- 7 per 0 C with a tungsten filament being connected to a single pair of lead-in wires which are directly sealed into the envelope. One end of the lamp envelope is rounded while the other end is pinch sealed together to include the tipped-off residue of an exhaust tube with the tipped-off residue further including a spiral of tungsten wire to keep the exhaust tube open during the lead wire sealing operation. Another U.S. Patent No. 4,409,516 discloses a glass-halogen lamp employing a first pair of lead-in wires connected at one end to the lamp filament LD9964 while being connected at the opposite end to larger diameter lead-in wires at the pinch sealed region of the lamp envelope. This particular lamp construction further includes an exhaust tube tipped-off residue together with a particular high temperature aluminosilicate glass being selected for the lamp envelope which eliminates need for a refractory metal spiral being contained within said exhaust tube in order to keep said exhaust tube open while the lead-in wires are being hermetically sealed in the lamp envelope. The selected glass composition comprises in approximate weight percent 56-63 SiO 29 13-17 Al 2 0 31 19-24 BaO, 1-4.5 CaO and 0-3 R 2 0 wherein R is an alkali metal ion alono with minor amount of incidental impurities, residual fluxes and refining agents such that the aggregate BaO and CaO --cntent lies within the approximate rance 21-26 weight percent. Still another U.S. Patent No. 4,737,685 discloses a glass- halogen lamp construction employing an axially-aligned tungsten filament assembly which is hermetically sealed within the lamp envelope formed with a different aluminosilicate glass composition. A minor amount up to approximately 3 weight percent ZrO 2 is included in the glass material as a refining agent to reduce the glass seed count and the glass further exhibits a higher strain point for less stress when such high temperature lamps are operated.

Decreasing the physical size for the above type glasshalogen lamps in the present reflector lamp units is now desired to more accurately project the forward illumination. Likewise, higher operating temper- atures for these lamps is desired to increase the illumination being provided and with both objectives enhancing mechanical lamp failure particularly at the sealed end of the lamp envelope for the inlead components especially during lamp operation. Still larger diameter L09964 1 inlead wires also prove desirable in the glass-halogen lamp component for certain end product applications in order to enable interconnection of the reflector lamp unit to conventional socket arrangements. It becomes desirable, therefore, to alter such glass-halogen lamp constructions in a manner accommodating all these objectives.

The present invention seeks to achieve one or more of the following objectives namely: to provide a reflector lamp unit employing a glass-halogen lamp which has an improved structural configuration; to provide modified structural support means for a glass halogen lamp when employed in a reflector lamp unit; to provide a glass halogen lamp mounted in a reflector member that enables modified electrical connection to the reflector lamp unit.

These and other objectives will become apparent upon considering the following description.

A novel structural configuration is provided for a glass-halogen lamp employed in a reflector lamp unit which ameliorates the difficulties above pointed out in connection with conventional reflector lamp units. More particularly, the presently improved glass-halogen lamp construction employs a modified filament assembly with the first inlead wires being connected at one end to the lamp filament and protruding from the pinch seal region at one end of the sealed lamp envelope for joining outside the lamp envelope to second inlead wires having a larger diameter than the first inlead wires.

LD9964 Such modified filament assembly is more easily inserted into the increasingly smaller internal diameters of glass tubing now being employed for forming the lamp glass envelope. By keeping the larger diameter second inleads in the present filament assembly remote from the internal diameter of the lamp envelope cavity there is also substantially less physical interference with a glass exhaust tube commonly located at the same end of the lamp envelope tubing. A more reliable heat sealing of the lamp glass tube end about the first inlead wires is thereby achieved without having to further modify the othe.-wise conventional lamp manufacturing procedure in doino so. Upon further completing the modified lamp manufactur-Lno process in an already known manner, such as disclosed in U.S. Patent No. 3,798,491, wherein the opposite end of the lamp envelope tubing is next heat sealed, the lamp cavity then exhausted and the fill constituents then inserted into said cavity, such finished glass-halogen lamp can now be physically combined in the cooperating reflector member in a particular manner.

In general, one form of composite reflector lamp unit employing such improved structural configuration comprises a concave reflector member terminating at its base or apex in an elongated hollow cavity pro- truding from the rear side of the reflector member, a tungsten-halogen lamp being mounted in the elongated hollow cavity, the tungsten-halogen lamp having a hermetically sealed lamp envelope which contains a fill including a vaporizable halogen substance along with a tungsten incandescent filament being suspended between a pair of first refractory metal inlead wires sealed at one end of the lamp envelope in a pinch seal region and protruding from the sealed end of the lamp envelope, the protruding end of the first refractory metal inlead wires n 1 1 LD9964 being further Joined outside the lamp envelope to second inlead wires having a larger diameter and with the tungsten-halogen lamp being secured in the elongated hollow cavity of the reflector member with an adhesive cement so that junction between the first and second inlead wires is positioned within said cavity while the opposite ends of the second inlead wires protrude rearwardly from said cavity. As previously indicated, the lamp filament is desirably positioned substantially at the focal point of the reflector member with the lamp filament either being axially aligned substantially along the central lamp unit axis or aligned in a direction substantially transverse to said central lamp unit axis. In one aspect of the present invention, a suitable reflector member for the presently improved reflector lamp unit employs a reflectina surface having a plurality of reflective facets such as disclosed in the previously cited 4,021,659 patent.

Also in general another form of representative reflector lamp unit embodying the invention comprises a concave molded glass reflector with an elliptical reflecting surface which includes a plurality of reflective facets and terminating at its apex in an elongated hollow cavity protruding from the rear side of the reflector member, a tungsten-halogen lamp which includes a coiled tunasten incandescent filament assembly being mounted in the elongated hollow cavity so that the tungsten filament coil is positioned substantially at the focal point of the reflector member, the tungsten- halogen lamp further including a lamp envelope formed with an aluminosilicate glass composition to have a rounded end and a sealed end which contains a fill at superatmospheric pressure of at least one rare gas and a vaporizable halogen substance, the tungsten coil filament assembly suspending opposite ends of the tungsten filament coil within the lamp envelope between a pair of LD9964 first refractory metal inlead wires both protruding from the sealed end of the lamp envelope but pinch sealed thereat and with the protruding ends of the first refractory metal inlead wires being further joined directly to second inlead wires having a larger diameter, the sealed end of the lamp envelope still further including sealedoff exhaust tube means positioned between the joined inlead wires, and the tungsten-halogen lamp being secured in the elongated hollow cavity of the reflector member with an adhesive cement so that the junction between the first and second inlead wires is positioned within said cavity while the opposite ends of the second inlead wires Protruoe rearwardly from said cavity. In said represen tative embodiment, the external periphery of the elonoa4Led hollow cavity can further have a cylindrical shape.

In the accompanying drawings:

FTG. 1 is a perspective view depicting one form of rep,-esentative reflector lamp according to the present invention.

FIG. 2 is a side view of the present invention for the class-halogen lamp employed in the FIG. 1 embodiment.

Referring to the drawings, there is depicted in FIG. 1 an improved reflector lamp 10 having a molded glass reflector member 12 which includes a concave reflecting surface 14 and terminates at its apex in an elongated hollow cavity 16 protruding from the rear side of said member.

Reflecting surface 14 has a multifaceted configuration 14a, formed with a plurality of radial bands 14b which intersect a plurality of concentric circular bands 14c. The elon- 1 LD9964 gated hollow cavity 16 is formed with a rectangular shaped external projection 18 having a central opening 20 aligned along the central lamp unit axis A-A. A glass-halogen lamp 22 is inserted into the central opening 20 for coaxial alignment along the central lamp unit axis as well as physically positioning its source of illumination substantially at the focal point in the cooperating reflector member. The glass-halogen lamp 22 comprises a hermetically sealed lamp glass envelope 24 with a dome end 26 opposite a sealed end 28 enclosing a tungsten coil filament assembly 30, a closed exhaust tube residue 31 and a gaseous fill (not shown) which includes at least one rare gas and a vaporizable alkyl halide substance. Tungsten coil filament assembly 30 has a tungsten filament coil 32 physically sus- pended at each end between a pair of first refractory metal inlead wires 34 and 34a which are hermetically sealed within the lamp glass envelope 24 by conventional pinch seal means but further extend from the sealed end of the lamp envelope to be joined externally to a second pair of larger diameter metal inlead wires 36 and 36a. Physical support of the entire glass- halogen lamp 22 in the reflector opening 20 is provided with a conventional adhesive cement 38 and which further requires that the junction between the pairs of interconnected inlead wires be located within the reflector opening 20 as shown in the present drawing. As can be further seen, the free ends of the larger diameter inlead wires 36 and 36a protrude from the reflector opening 20 in order to provide electrical terminal means for the depicted reflector lamp embodiment.

The above described physical configuration in the present reflector lamp unit effectively separates the glass to-metal seal function from the physical connection being made between different diameter lead-in wires. More particularly, physical support of a glass-halogen lamp in LD9964 the conventional reflector lamp units most commonly features inlead wires connected to the lamp filament which are interconnected to larger diameter inlead wires within the lamp glass envelope at the sealed end. Such construction readily transmits mechanical shocks and vibration during the lamp manufacturing process to the lamp glass envelope risking mechanical failure, such as cracking or spalling. Residual stresses are also commonly produced in the pinch seal region of conventional glass- halogen lamps which are attributable to a junction between dissimilar diameter lead-in wires thereat. As distinct, therefrom, only relatively flexible inlead wires are physically connected to the lamp glass envelope in the presently improved lamp unit construction thereby promoting greater shock resistance and manufacturing reliability but also necessitating further physical support of the lamp in the reflector. Since it follows that total lamp support is provided according to the present invention with otherwise conventional bonding of the modified lamp to the reflector member, however, the customary lamp manufacturing procedure need not be further unduly altered.

FIG. 2 depicts the representative glass-halogen lamp employed in the FIG. 1 reflector lamp unit with greater details being provided with respect to typical lamp manu- facture. More particularly, the glass-halogen lamp 22 includes a lamp glass envelope 24 formed by heat sealing both ends of a length of aluminosilicate glass tubing 25 to provide a central hermetically sealed cavity 25a. The tungsten coil filament assembly 30 is constructed for in- sertion into one end of the glass tubing length and with such pre- assembly having the filament coil 32 suspended between first inlead wire 34 and 34a which are further interconnected to second inlead wire pair 36 and 36a. A domed end 26 is formed by heating one end of the glass tubing LD9964 25. The opposite end seal is formed by inserting the tungsten coil filament assembly 30 into the opposite end 28 of said tubing together with a glass exhaust tube 31. Subsequent heating of the latter tubing end causes the molten glass to collapse around the filament assembly 30 and exhaust tube 31 to form a hermetic seal including both inlead wires 34 and 34a. This end seal configuration is formed with customary pinch seal means (not shown). The pinch sealed end 28 of the lamp glass envelope 24 leaves both ends of the inlead wires 34 and 34a protruding from the glass so that interconnection of said inlead wires to the remaining larger diameter inlead wires 36 and 36a takes place outside the lamp envelope. The depicted exhaust tube 31 enables the lamp envelope to be evacuated and a suitable fill inserted therein after the above described pinch sealing operation has been conducted and with the protruding exhaust tube end also being closed by heat sealing at such time to form a residue as depicted in the present drawing. As can also be noted in the present drawing, a relatively close physical proximity exists at the sealed lamp end 28 between the inlead wires and exhaust tube components. By maintaining the larger diameter inlead wire pair 36 and 36a outside the lamp glass envelope it follows that more lateral spacing is gained to center lead wire and exhaust tube components in the present lamp configuration than would otherwise be provided. It also follows that the smaller diameter inlead wires being employed can be more easily deformed hence produce less residual mechanical stress in the final lamp product. It likewise follows that a more reliable hermetic seal of the composite inlead wire arrangement can be expected in the present lamp configuration due to having the glass-to-metal joint area limited to smaller diameter lead wire components. Still further, the less extensive heating found to be needed to LD9964 hermetically seal the present inlead wire configuration can eliminate in many lamp designs any requirements for a refractory metal spiral to be provided within the exhaust tube component in order to keep the exhaust tube open when fabricating the presently modified lamp construction. The present invention also contemplates a still further modified lamp configuration wherein the exhaust tube means 31 is located at the opposite closed end 26 of the illustrated lamp envelope 24, It will be apparent from the foregoing description that a generally improved reflector lamp unit has been provided exhibiting desirable performance advantages. It is contemplated that modifications can be made in the glasshalogen lamp and reflector constructions herein illus- trated, however, without departing from the scope of the present invention. For example, the reflector member can be constructed with a protruding cavity shaped for mounting in various other already known socket configurations to include havina the rearward end of said cavity modified to mate with a particular socket fixture. Likewise, the concave reflecting surface of said reflector member can be provided with different contours, including parabolic, as well as having the reflecting surface provided with a specular reflective coating, stippled surface, or some other already known multifaceted reflective configuration. Similarly, the present glass-halogen lamp construction can include various tungsten filaments, sized and shaped for the particular wattage and voltage requirements of the intended lamp application.

LD9964

Claims

CLAIMS:

1. A reflector lamp unit having a concave reflector member terminating at its base in an elongated hollow cavity protruding from the rear side of the reflector member, a tungsten-halogen lamp being mounted in the elongated hollow cavity, the tungsten-halogen lamp having a hermetically sealed lamp envelope of vitreous material which contains a fill including a vaporizable halogen substance along with a tungsten incandescent filament being suspended between a pair of first refractory metal inlead wires sealed at one end of the lamp envelope in a pinch seal region and protruding from the sealed end of the lamp envelope, the protruding end of the first refractory metal inlead wires being further joined outside the lamp envelope to second inlead wires having a larger diameter, the tungsten-halogen lamp being secured in the elongated hollow cavity of the reflector member with an adhesive cement so that the junction between the first and second inlead wires is positioned within said cavity while the opposite ends of the second inlead wires protrude rearwardly from said cavity.

2. The reflector lamp unit of claim 1 wherein the lamp filament is positioned substantially at the focal point of the reflector member.

3. The reflector lamp unit of claim 1 wherein the lamp filament is axially aligned substantially along the central lamp unit axis.

4. The reflector lamp unit of claim 1 wherein the lamp filament is aligned in a direction substantially transverse to the central lamp unit axis.

LD9964

5. The reflector lamp unit of claim 1 wherein the reflector member includes a plurality of reflective facets.

6. The reflector lamp unit of claim 1 wherein the tungsten-halogen lamp further includes exhaust means located in the pinch seal region.

7. The reflector lamp unit of claim 1 wherein the tungsten-halogen lamp further includes exhaust means located at the opposite ends of the lamp envelope from the pinch seal region.

8. The reflector lamp unit of claim 1 wherein the lamp envelope is formed with an aluminosilicate glass composition.

9. The reflector lamp unit of claim 1 wherein the tungsten filament has a coiled configuration.

10. A reflector lamp unit having a concave mold ed glass reflector with an elliptical reflecting surface which includes a plurality of reflective facets and terminatina at its base in an elongated hollow cavity protruding from the rear side of the reflector member, a tungsten-halogen lamp which includes a coiled tungsten incandescent filament assembly being mounted in the elongated hollow cavity so that the tungsten filament coil is positioned substantially at the focal point of the reflector member, the tungsten-halogen lamp further including a lamp envelope formed with an aluminosilicate glass composition to have a rounded end and a sealed end which contains a fill at superatmospheric pressure of at least one rare gas and a vaporizable halogen compound, the tungsten filament assembly suspending LD9964.

opposite ends of the tungsten filament coil within the lamp envelope between a pair of first refractory metal inlead wires both protruding from the sealed end of the lamp envelope but pinch sealed thereat and with the protruding ends of the first refractory metal inlead wires being further joined directly to second inlead wires having a larger diameter, the sealed end of the lamp envelope still further including sealed-off exhaust tube means positioned between the joined inlead wires, and the tungsten-halogen lamp being secured in the elongated hollow cavity of the reflector member with an adhesive cement so that the junction between the first and second inlead wires is positioned within said cavity while the opposite ends of the second inlead wires protrude rearwardly from said cavity.

11. The reflector lamp unit of claim 10 wherein the lamp filament is axially aligned substantially along the central lamp unit axis.

12. The reflector lamp unit of claim 10 wherein the lamp filament is aligned in a direction substantially transverse to the central lamp unit axis.

13. The reflector lamp unit of claim 10 wherein the plurality of reflective facets provided in the reflector member are formed with a plurality of radial bands and a plurality of concentric circular bands which mutually intersect one another.

14. The reflector lamp unit of claim 10 wherein the external periphery of the elongated hollow cavity has a rectangular shape.

15. Areflector lamp unit substantially as hereinbefore described with reference to the accompanying drawings.

ried 1990 atThePatent Office, Stat,. House. 66,71 High Holborn, London WC1R4TP. Further copies maYbe obtainedfrom The Patent Office.

Published 1990 atThe II&Tier, --------------- I------- -- ---