US3160777A

US3160777A - Filament and reflector support for an elongated tube

Info

Publication number: US3160777A
Application number: US232014A
Authority: US
Inventors: Richard H Holcomb
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1962-10-22
Filing date: 1962-10-22
Publication date: 1964-12-08
Anticipated expiration: 1981-12-08
Also published as: GB1055475A

Description

Dec. 8, 1964 R. H. HOLCOMB 3,160,777

FILAMENT AND REFLECTOR SUPPORT FOR AN ELONGATED TUBE Filed Oct. 22, 1962 ITWVTTTOVI Richard H. HoLcomb b9 g/i/fi/i His A t lr neg United States Patent p This invention relates generally to electric incandescent lamps, and more particularly to tubular doubleended lamps comprising an elongated tubular envelope having an incandescible filament extending axially thereof.

There is available on the market an infrared or heat lamp of the type disclosed and claimed in US. Patent 2,864,025, to Foote et al., comprising a slender tubular quartz envelope having an elongated coiled filament extending therethrough and connected at its ends to lead-in conductors sealed through pinch seals at the end of the envelope, the filament being supported in the envelope axis by support members of sheet metal or of Wire engaging the filament and, in turn, engageable with the inner wall of the envelope. In some applications, such lamps are used in conjunction with elongated reflectors where it is desired to concentrate the energy radiated from the lamp in a given direction. It would be desirable to incorporate the reflector as an integral element of the lamp in some applications where an external reflector is not feasible. Accordingly, attempts have been made to place a reflecting surface on the outside of the lamp envelope. Since the envelope becomes heated to a high temperature, approximately 500 C. for example, during operation of the lamp, the reflector material must be exceptionally resistant to oxidation. However, the metals that have good reflecting properties and are suitable for use in an ambient of air, such as gold, platinum or rhodium, adhere poorly to the quartz envelope or are easily abraded. On the other hand, a metallic reflector cannot be incorporated inside the conventional lamp structure because it would short circuit the filament through the support member.

Accordingly, it is an object of the invention to provide a novel structure which permits incorporating the reflector within the lamp. It is a further object to provide a lamp structure wherein the internal reflector and the filament supporting members are effectively maintained out of electrical contact with one another.

To that end, and in accordance with a preferred aspect of the invention, the lamp envelope is provided with a pair of longitudinally extending, circumferentially spaced ridges or ribs which divide the envelope into opposed sides, and the reflector is located at one of said sides between the ribs whereas the filament supports are located at the other side, the ribs thereby serving to maintain the filament supports and the reflector out of electrical contact with each other.

Further features and advantages of the invention will appear from the following detailed description and from the drawing wherein:

FIG. 1 is a side view, partly in section, of a lamp embodying the invention;

FIG. 2 is a transverse section through the lamp;

FIG. 3 is a fragmentary longitudinal section through a portion of the filament and one of the support members;

FIG. 4 is a fragmentary perspective view of one end of a reflector provided with a supporting tab;

FIG. 5 is a front elevation of a support disc;

FIG. 6 is a transverse section through a lamp having a modified form of filament support member; and

FIG. 7 is a fragmentary side view of a portion of the filament and support member of FIG. 6.

Referring to FIG. 1 of the drawing, the lamp illustrated by way of example is of the infrared lamp type 3,160,777, Patented Dec. 8, 1 964 diameter, usually about inch, having each end closed by a. pinch seal 2 through which extends a lead-in conductor 3 having a. thin foliated intermediate portionv 4 1 hermetically sealed in the seal 2. An incandescible helically coiled, tungsten wirefilament 5 extends longitudinally of the envelope 1 and is connected at its end to the inner ends of the respective lead wires 3.

In accordance with the invention, the envelope is provided with a pair of circumferentially spaced, longitudinally extending ridges or rib 6 (FIGS. 1 and 2) on its inner surface. The ribs are here shown diametrically opposed and dividing the interior of the circular tube cross section into opposed halves. In one half of the envelope there is disposed a reflector 7. Although the reflector 7 may in some cases be constituted of a metallic coating vapor deposited on the inner surface of the envelope, it is preferably composed of a sheet metal member supported by and between the ribs 6. In the illustrated example, the reflector 7 consists of a thin arcuate sheet of copper, about .005 inch thick for example. In order to provide adequate support for the reflector, it is in this case provided at each end with an overlying arcuate tab 8 (FIG. 4) of suitable resilient sheet metal such as molybdenum. The tab 8 may be spot welded at its center to the reflector 7 and is originally formed to a larger radius than the reflector 7 so that it springs outagainst the ribs 6 and securely holds the reflector in place. It'will be evident that the reflector 7 may be made in its entirety of a suitable self-supporting resilient metal such as molybdenium and clamped in place between the ribs 6 and the envelope wall. The reflector may also be made of any desired cross sectional shape such as parabolic, elliptical, circular, etc.

Although the tabs 8 hold the reflector 7 in place quite securely, further provision may be made to prevent 1ongitudinal displacement of the reflector by providing suit able stops, for example in the form of inwardly protruding dimples or indentations in the Wall of the envelope 1 as indicated at 20.

As illustrated in FIGS. 2, 3 and 5, the filament 5 is supported in the axis of the envelope 1 by a series of spaced wafers or discs 9 which are preferably a modified form of the conventional disc structure disclosed and claimed in US. Patent 2,813,993 to Fridrich. As shown in FIG. 5, the conventional support comprises a circular disc including the portion 10 shown in broken lines and having a sector shaped radial slot extending inwardly from the periphery of the disc to provide for inserting the disc in place transversely of the filament 5, i.e., a turn of the filament coil 5 extends through said slot 11. At the center of the disc, the slot 11 terminates in a central opening having at its margin a collar portion 13 located within the coil 5 and comprised of a plurality of tongues or tabs engaging and gripping the inner side of an adjacent turn of the coil 5 to assist in holding the disc in place between adjacent coil turns. For purposes of the present invention, a generally sector shaped portion of the disc is formed by removing the portion shown in broken lines by cutting along a radius 14 aligned with the center of the radial slot 11, and along the arc 15 joining the radius 14 and the slot 11. The radius 14 and the remaining full length edge of the slot 11 thus serve to confine the wafer or disc 9 between the ribs 6 (FIG. 2) at the side of the envelope 1 opposite the side occupied by the reflector 7 and out of electrical contact with said reflector. The filament 5 is thereby held at the hub portion of the sector shaped wafer 9 which is in turn supported from the portion of the envelope wall between the ribs 2 or by the ribs themselves, depending upon the orientation of the envelope.

r Y K 1:3

The filament support 16 shown in FIGS. 6 and 7 is formed from a refractory wire such as tungsten. The

Wire is formed with several helical turns 17 at its center and is of a diameter. to snugly-norv forcibly fit betweenthe turns of; the filament coil 5. From the center turn 17 there extend leg portions "IS Whichfit behindtheribs 6 and which preferably terminatein bent. end portions ,19

, which arev engageable with the envelope wallsand assist.vv

in positioning the support. It will be-evidentthat, if desired, the .bent endsl9: may be continuedfto form a'clos'ed loop. The sheetlmetal reflector 7.' isnself.supporting and is locked behind the ribs 6 at the side'ofvthe envelope .op

posite. the side occupied by the. supports. 16... It will be noted that in this case' thereflector 7.[has a curvature differing from that of the inner envelope Wall.

fWhatLclaim as new and desire to secure by Letters Patent of the" United St-ate'sis:

interior of said envelope, an elongated metallic reflector at one side of said envelope between said ribs, and metallic filament support means supporting said filament and confined between said ribs to be engageable with and supported from the other sideof said envelope out of electrical contact with said reflector.

l interior of said envelope, an elongated reflectorofsheet metal supported at one side of said envelope by and betweensaid ribs, and metallic-filament support means supporting saidfilament and confined between said ribs =to be' engageable with and supported from the other side of said envelope out ofelectrical contact withsaidre fiector.

lLAn-electric incandescent lamp comprising. an clon V .gated tubular envelope, a-filamentjextending longitudinally of the-interior of said envelope,anelongat'ed metallic reflector within said envelope at one side thereof, metallic filament support means supporting said filament and engageable with the side of said envelope opposite that occupied by said reflector, and means maintaining said reflector and said filaments support means at. their respective sidesof the envelope, and out ofelectrical contact with each other.

' 2. An electric incandescent lampcomprising an elongated tubular envelope, having a pair of circumferentially spaced internal ribs extending longitudinally of the interior surface" thereof and dividing saidnenvelope into opposedsides, a filament extending longitudinally of the 4. An. electric incandescent lamp comprising an elongatedtubular envelope having a pair of circumferentially spaced internal ribs extending longitudinally of theinteriorJsurfacethereof and dividing said envelope intoop- 1. posed sides, a filament extending longitudinally of theinterior. of said envelope, an elongated metallic vreflector at one side of said envelope between said ribs, and: a

metallic filament supportmember comprising a generally sector shaped Wafer. supporting said filamentadjacent its hub and. having acircumferential extent confining said water betweensaid ribs to be engageable withand supported from theother side ofsaidenvelope out of electrical contact withsaid reflector.

No references cited.

Claims

1. AN ELECTRIC INCANDESCENT LAMP COMPRISING AN ELONGATED TUBULAR ENVELOPE, A FILAMENT EXTENDING LONGITUDINALLY OF THE INTERIOR OF SAID ENVELOPE, AN ELONGATED METALLIC REFLECTOR WITHIN SAID ENVELOPE AT ONE SIDE THEREOF, METALLIC FILAMENT SUPPORT MEANS SUPPORTING SAID FILAMENT AND ENGAGEABLE WITH THE SIDE OF SAID ENVELOPE OPPOSITE THAT OCCUPIED BY SAID REFLECTOR, AND MEANS MAINTAINING SAID REFLECTOR AND SAID FILAMENTS SUPPORT MEANS AT THEIR RESPECTIVE SIDES OF THE ENVELOPE AND OUT OF ELECTRICAL CONTACT WITH EACH OTHER.