Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3700881 A
Publication typeGrant
Publication dateOct 24, 1972
Filing dateApr 29, 1971
Priority dateApr 29, 1971
Also published asDE2219927A1, DE2219927B2
Publication numberUS 3700881 A, US 3700881A, US-A-3700881, US3700881 A, US3700881A
InventorsSlomski Stanley L
Original AssigneeGen Electric
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Lamp and reflector assembly
US 3700881 A
Abstract
A high-intensity arc lamp having anode and cathode stems extending in opposite directions from the bulb, is positioned in a reflector. The anode stem extends within a tapered hollow collar at the rear of the reflector, and the lamp is attached to the reflector by means of cement at the remote ends of the anode stem and hollow collar, whereby the hollow collar provides a heat-confining space around the anode stem for controlling the temperature and reducing the likelihood of thermal-stress cracking of the anode stem. A specially shaped connector within the reflector provides electrical connection to the cathode lead.
Images(1)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent Slomski Oct. 24, 1972 [54] LAMP AND REFLECTOR ASSEMBLY [72] lnventor: Stanley L. Slomski, Lyndhurst, Ohio [73] Assignee: General Electric Company [22] Filed: April 29, 1971 211 App]. No.: 138,474

[52] US. Cl ..240/41.35 R, 240/11.4, 240/47 [51] Int. Cl ..F2lv 7/00 [58] Field ofSearch.....240/l1.4 R, 11.2 R, 47, 41 A,

[56] References Cited UNITED STATES PATENTS 3,379,868 4/1968 Taillon ..240/41.35 R

FOREIGN PATENTS OR APPLICATIONS 644,341 9/1962 Italy .[240/1 1.2 R 6,801 ,1 l7 8/ 1968 Netherlands ..240/1 1.2 R

Primary Examiner-Samuel S. Matthews Assistant Examiner-Richard L. Moses Attorney-Norman C. Fulmer, Henry P. Truesdell, Frank L. Neuhauser, Oscar B. Waddell and Joseph B. Forman [57] ABSTRACT A high-intensity arc lamp having anode and cathode stems extending in opposite directions from the bulb, is positioned in a reflector. The anode stem extends within a tapered hollow collar at the rear of the reflector, and the lamp is attached to the reflector by means of cement at the remote ends of the anode stem and hollow collar, whereby the hollow collar provides a heat-confining space around the anode stem for controlling the temperature and reducing the likelihood of thermal-stress cracking of the anode stem. A specially shaped connector within the reflector provides electrical connection to the cathode lead.

10 Claims, 2 Drawing Figures PATENTEDOcI 24 I972 Invenfiror: S tanLeg 1.. SLomski His A ti'crneg LAMP AND REFLECTOR ASSEMBLY CROSS-REFERENCE TO RELATED APPLICATION Patent application, Ser. No. 876,708, filed Nov. 14, 1969, of Charles J. Miller, entitled Lamp and Housing Assembly now U.S. Pat. No. 3,636,341, issued Jan. 18, 1972 and assigned to the same assignee as the present invention (in Patent Office Group 285 BACKGROUND OF THE INVENTION The invention is in the field of high-intensity lamp and reflector assemblies, such as are particularly useful for photographic projection purposes, e.g., movie projectors and slide projectors. Such an assembly of a lamp and reflector is disclosed in U.S. Pat. No. 3,379,868 of John K. Taillon, issued Apr. 23, 1968 and assigned to the same assignee as the present invention. The high-intensity arc lamp, which operates at a high temperature, comprises a quartz envelope having a bulb-like arc chamber and, for d-c operation, an anode stem and a cathode stem extending in opposite directions therefrom. The anode and cathode stems are elongated, and hermetic lead-in seals are made near the outer ends thereof, preferably by sealing the stems to thin metal foil sections welded intermediate the lamp electrodes and the inleads. In the aforesaid Taillon patent, the arc lamp is mounted perpendicular to the axis of the optical surface of revolution of the reflector, the end regions of the lamp being cemented in openings provided in the reflector.

Arc lamps of the aforesaid type have a tendency to develop cracks in their envelopes at the vicinity of the stem seals, due to thermal stress caused by high operating temperature and high thermal gradient along the stems. Such cracks are likely to permit air to enter, and fill gas to leave, the envelope thus destroying usefulness of the lamp. In directcurrent operation the anode electrode operates at higher temperature than the cathode electrode, and hence the anode stem seal is particularly prone to cracking due to thermal stress. One technique for reducing the seal temperature is to increase the length of the stems of the lamp. For a d-c lamp, in which the anode operates hotter than the cathode, the anode stem may be made longer than the cathode stem, as shown in the aforesaid Taillon patent, to provide a more gradual thermal gradient. However, it is costly to lengthen the stems, and it is unfeasible to extend them unduly, particularly in vapor lamps, and particularly the anode stem. The aforesaid Miller patent application is directed to the use of a heat-confining shield placed around one or both stems to confine heat ahd reduce the temperature gradient along the stem-seal region, to reduce the likelihood of the seal cracking.

SUMMARY OF THE INVENTION Objects of the invention are to provide an improved lamp and reflector assembly, and to provide such an assembly that has improved optical efficiency and reduced likelihood of seal cracking.

The invention comprises, briefly and in a preferred embodiment, a lamp of the type having a bulb portion and at least one lead-in stem extending therefrom, said lamp being positioned in a concave reflector having a hollow collar extending axially of the reflector at the rear thereof, a lead-in stem of said lamp extending within said hollow collar, and means attaching said lamp to said reflector at the end region of said stem within said hollow collar, whereby the hollow collar provides a heat-confining space around the stem. The hollow collar may be tapered for further controlling the temperature gradient. In an embodiment of the invention, the lamp is provided with a second lead-in stem extending forwardly of the bulb portion, and a lead-in connector extends into the concave reflector from said hollow collar and is shaped to extend frontwardly within the reflector in adjacency to the inner surface thereof and thence substantially laterally and into attachment with the inlead of said second lead-in stem. Further in accordance with the invention, the lamp may be an arc lamp for d-c operation having anode and cathode electrodes respectively terminating in inleads at the ends of anode and cathode stems extending in opposite directions from the bulb portion, it being the anode stem that extends into said hollow collar and is attached thereto.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front view of a lamp and reflector assembly in accordance with a preferred embodiment of the invention, and

FIG. 2 is a cross-sectional view of FIG. 1, taken on the line 2-2 thereof, the cross-section of the reflector being taken through an axis thereof, and the lamp and connector leads being shown in side view.

DESCRIPTION OF THE PREFERRED EMBODIMENT The lamp shown in the drawing is a compact high-intensity arc tube lamp 11, comprising a quartz envelope having a bulb portion 12 and stem portions 13 and 14 extending therefrom on opposite sides thereof, on a common axis. Elongated tungsten anode and cathode electrodes 16 and 17 are positioned on the axis of the lamp with the inner ends thereof spaced apart within the bulb portion 12, and respectively extend into the anode stem 13 and the cathode stem 14. The outer ends of the anode and cathode electrodes 16 and 17 are respectively welded to molybdenum foils 18 and 19, these foils in turn being welded to inleads 21 and 22. In the process of manufacture, the foils 18 and 19 are wetted by the quartz of the stems l3 and 14, to provide hennetic seals. The lamp contains an ionizable filling which includes an inert gas such as argon and a halogen or metal halide such as indium iodide. Further details of the lamp l1 and its manufacture are disclosed in U.S. Pat. No. 3,305,289 of Elmer G. Fridrich, issued Feb. 21, 1967 and assigned to the same assignee as the present invention. The lamp shown is intended for direct-current operation, which causes the anode electrode 16 to operate at a considerably higher temperature than the cathode electrode 17, and therefore the anode electrode 16 is made thicker and longer than the cathode electrode 17. A concave reflector 26 preferably is made of glass and has an ellipsoidal inner surface covered with a reflective coating 27. The inner surface of the reflector may be provided with radial gores to relatively increase the light intensity at the outer periphery of the projected light beam. The inner or rear part of the reflector 26 terminates in a hollow collar 28 extending rearwardly of the concave reflector surface 27, coaxially with the optical axis 29 of the reflector surface 27. The inner diameter of the hollow collar 28 tapers toward a relatively smaller diameter at the rear thereof.

The are tube lamp 11 is mounted along the optical axis 29, with the anode stem 13 extending into the hollow collar 28, and with the arc region of the lamp coinciding with the near focus point fl of the reflector surface 27. Preferably, the anode stem 13 and the hollow collar 28 are dimensioned so that end of the anode stem 13 lies in a plane common with the rear end .of the hollow collar 28, as shown. The end portion of the anode stem 13 is attached to the end region of the hollow collar 28 he means of a refractory cement 31. In manufacture, the arc tube 11 may be adjusted so that the brightest part of the arc thereof is exactly at the near focus fl of the reflector, and held in this position until the cement 31 hardens. More cement 31 is added later, as will be described, for attaching a ceramic end cap to the assembly. The end of the anode stem 13 may be provided with an outwardly extending flange 32, if desired, to facilitate secure anchoring of the end region of the anode stem 13 in the cement 31.

A cathode connector conductor 36 is shaped to have an end portion 37 thereof extend outwardly of the hollow collar 28, through a slot or opening 38 in the wall of the hollow collar 28. The connector 36 is shaped, as shown, so as to extend frontwardly out of the hollow collar 28 and to extend frontwardly within the reflector 26 in adjacency to the inner reflecting surface 27 thereof, and thence substantially laterally inwardly at 39 and into welded attachment with the cathode inlead 22 of the arc tube 11. The connector 36 may be secured to the hollow collar 28 at the slot 38 thereof, by means of a glob of the cement 31.

Flexible insulated anode and cathode connector leads 41 and 42 are provided, an end of the flexible anode lead wire 41 being welded to the anode inlead 21, and an end of the flexible conductor of wire 42 being welded to the outwardly extending end of the cathode connector 36. In manufacture, after the flexible conductors -41 and 42 have been connected as described, additional cement 31 is applied at the rear of the anode stem 13 and hollow collar 28, for securing a cup-shaped ceramic end cap 43 over and around the hollow collar 28, as shown. This additional cement also fills into a portion of the collar slot 38, thus locking the mass of cement 31 to the collar 28 and preventing rotation with respect thereto. A slot or other suitable opening 44 is provided in the wall of the cover 43, through which the anode and cathode flexible insulated connectors 41 and 42 extend externally of the assembly. The outer ends of the flexible conductors 41 and 42 may be provided with a plug or other means for connecting the wires to a source of electrical power for operating the lamp 1 1.

Preferably the cathode inlead 22 and the exposed portion of the cathode connector 36 are coated with a ceramic glaze or other suitable electrical insulation, for reducing electrical shock hazard.

in accordance with a feature of the invention, the inside diameter of the hollow collar 28 is larger than the outer diameter of the anode stem 13, thereby defining a heat-confining space around the anode stem 13 and along a substantial portion of the length thereof, thus causing a more uniform and more gradual temperature gradient along the anode stem 13, and particularly at the region of the hermetic sealto the foil 18, thereby reducing the likelihood of cracking of the anode stem, particularly at the hermetic seal region thereof. The inner diameter of the hollow collar may be tapered, as shown, to further control the temperature gradient. Also, in accordance with a feature of the invention, the cathode connector 36 is shaped as shown, i.e., in adjacency with the inner reflective surface 27 insofar as feasible, and this arrangement is found to minimize shadow and light obstruction effects by the cathode connector 36.

The construction of the invention, as described above, increases the efficiency and light output of the assembly, over the crosswise-mounted arc tube arrangement of the aforesaid Taillon patent. Due to the axial mounting of the arc tube with respect to the reflector, a full circle of radiation from the arc tube illuminates a full circle of the reflective surface of the reflector, this cooperative effect improving the collection efficiency of the system. These factors contribute more towards increasing the overall light output, than the slight reduction of light output caused by the cathode stem 14 being in front of the arc bulb 12.

While a preferred embodiment of the invention has been shown and described, various other embodiments and modifications thereof will become apparent to persons skilled in the art, and will fall within the scope of invention as defined in the following claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A lamp and reflector assembly comprising a lamp having an envelope including a bulb portion and an elongated lead-in stem extending from the bulb portion, and a concave reflector provided with a hollow collar coaxial with the optical axis of said reflector at the rear thereof, and attachment means positioning said lamp with respect to said reflector such that said lead-in stem extends into said hollow collar, said hollow collar having an inner diameter greater than the outer diameter of said lead-in stem thereby defining a heatconfining space around and along at least a portion of said lead-in stem and adapted to control the temperature along said lead-in stem when said lamp is operating, said inner diameter of said hollow collar being tapered along the axis thereof.

2. An assembly as claimedin claim 1, in which said inner diameter of the hollow collar tapers toward a relatively smaller diameter at the rear thereof.

3. A lamp and reflector assembly comprising a lamp having an envelope including a bulb portion and a first elongated lead-in stem extending from the bulb portion, and a concave reflector provided with a hollow collar coaxial with the optical axis of said reflector at the rear thereof, and attachment means positioning said lamp with respect to said reflector such that said lead-in stem extends into said hollow collar, said hollow collar having an inner diameter greater than the outer diameter of said lead-in stem thereby defining a heatlead-in stem extending from the bulb portion in the opposite direction from the first lead-in stem, and a leadin connector positioned to extend from said hollow collar into said concave reflector, said lead-in connector being shaped to extend forwardly within the reflector in adjacency to the inner surface thereof and thence substantially laterally and into contact with the inlead of said second lead-in stem.

4. An assembly as claimed in claim 3, in which said lamp is a direct-current arc lamp having anode and cathode electrodes, said first lead-in stem providing electrical connection to said anode electrode and said second lead-in stem providing electrical connection to said cathode electrode.

5. An assembly as claimed in claim 3, in which said hollow collar is provided with an opening through the wall thereof, and in which an end region of said lead-in connector is shaped to extend laterally outwardly through said opening.

6. An assembly as claimed in claim 5, in which said opening in the collar wall is at the outer end of the collar, said attachment means comprising cement configured to hold the outer end region of said first lead-in stem with respect to the outer end of said hollow collar, said cement extending into said opening in the wall of the collar to prevent relative rotation with respect thereto. 4

7. An assembly as claimed in claim 5, including a pair of flexible conductors electrically connected respectively to said outwardly extending end region of said lead-in connector and to the inlead of said first lead-in stem.

8. An assembly as claimed in claim 6, including a cap member attached to the rear of said reflector over said hollow collar, said cap member being provided with an opening in the wall thereof, said pair of flexible conductors extending outwardly through said opening of the cap member.

9. An assembly as claimed in claim 3, in which said inner diameter of said hollow collar is tapered along the axis thereof. v

10. An assembly as claimed in claim 9, in which said inner diameter of the hollow collar tapers toward a relatively smaller diameter at the rear thereof.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3379868 *Dec 10, 1965Apr 23, 1968Gen ElectricElectric discharge projection lamp
IT644341A * Title not available
NL6801117A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3798441 *Oct 16, 1972Mar 19, 1974Illumination Ind IncIlluminator for exposing color television tubes during the manufacturing process thereof and the like
US3843879 *Feb 12, 1973Oct 22, 1974Christie Electric CorpCooling system for xenon arc lamps
US4053809 *Jun 18, 1976Oct 11, 1977General Electric CompanyShort-arc discharge lamp with starting device
US4290097 *Aug 15, 1979Sep 15, 1981Robert Bosch GmbhHigh-pressure discharge lamp and reflector combination
US4423348 *Aug 28, 1981Dec 27, 1983Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen MbhCombined high pressure discharge lamp and reflector assembly
US4920459 *Dec 21, 1988Apr 24, 1990Gte Products CorporationArc discharge headlamp system
US5059146 *Feb 22, 1990Oct 22, 1991Welch Allyn, Inc.Method of adjusting a light source for color temperature and chromaticity
US5205642 *Oct 29, 1991Apr 27, 1993Ushio DenkiMirror and lamp assembly
US7158207 *Feb 27, 2004Jan 2, 2007Robert R MiniaciFilm projector with high efficiency illumination
US7758213 *Jul 20, 2010Ushiodenki Kabushiki KaishaLight source unit
US7762687 *Jul 27, 2010Hon Hai Precision Industry Co., Ltd.Light source device
US7859176Nov 23, 2004Dec 28, 2010Koninklijke Philips Electronics N.V.High-pressure discharge lamp assembly
US20040239879 *Feb 27, 2004Dec 2, 2004Miniaci Robert R.Film projector with high efficiency illumination
US20060126333 *Nov 18, 2005Jun 15, 2006Ushiodenki Kabushiki KaishaLight source unit
US20070114940 *Nov 23, 2004May 24, 2007Koninklijke Philips Electronics, N.V.High-pressure discharge lamp assembly
US20090097253 *Apr 25, 2008Apr 16, 2009Hon Hai Precision Industry Co., Ltd.Light source device
DE2840031A1 *Sep 14, 1978Apr 3, 1980Patent Treuhand Ges Fuer Elektrische Gluehlampen MbhAnordnung mit hochdruckentladungslampe und reflektor als baueinheit
DE4116244A1 *May 17, 1991Nov 21, 1991Koito Mfg Co LtdEinstellbarer scheinwerfer mit einer entladungslampeneinrichtung und einer beleuchtungsschaltung hierfuer
EP0157357A2 *Mar 27, 1985Oct 9, 1985Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbHHigh-pressure discharge lamp having a cap at one side
EP0374846A2 *Dec 19, 1989Jun 27, 1990Gte Products CorporationArc discharge headlamp system
EP1312856A1 *Aug 17, 2001May 21, 2003Iwasaki Electric Co., LtdShort-arch discharge lamp with reflection mirror
WO2005055272A2 *Nov 23, 2004Jun 16, 2005Koninklijke Philips Electronics N.V.High-pressure discharge lamp assembly
WO2005055272A3 *Nov 23, 2004Feb 26, 2009Koninkl Philips Electronics NvHigh-pressure discharge lamp assembly
WO2008072159A2 *Dec 10, 2007Jun 19, 2008Koninklijke Philips Electronics N.V.Lamp with protected power supply wires reaching outside the lamp
WO2008072159A3 *Dec 10, 2007Aug 14, 2008Koninkl Philips Electronics NvLamp with protected power supply wires reaching outside the lamp
Classifications
U.S. Classification362/265
International ClassificationH01J61/98, F21V19/00, H01J61/00
Cooperative ClassificationF21V19/0005, H01J61/98
European ClassificationF21V19/00A, H01J61/98