US3843879A - Cooling system for xenon arc lamps - Google Patents

Abstract

A cooling system for lamps, such as Xenon arc lamps used in motion picture projectors, where the lamp is elongate with a terminal and seal at each end, with one terminal and seal mounted within the mirror and thereby subjected to excessive heating. A concentric sleeve construction for the seal within the mirror and an air supply duct providing cooling air flow diectly about the seal and protecting the seal from reflected radiation.

Description

United States Patent 1 1 [111 3,843,879 Eddy 1451 Oct. 22, 1974 [54] COOLING SYSTEM FOR XENON ARC 3,559,816 2/1971 Hirata 240/47 x L S 3,626,176 12/1971 Tsugami... 353/61 X 3,700,881 10/1972 Slomskim. 240/4135 R n o Richard dy, C sta Mesa. Calif. 3,703,635 11/1972 Burkarth 240/4135 R 73 Assi nee: Christie Electric Cor Los 1 g Angeles Ca p Primary Examiner-Rwhard M. Sheer Attorney, Agent, or Firm-Harris, Kern, Wallen & [22] F1led: Feb. 12, 1973 Tinsley [21] Appl. No.: 332,020

[57] ABSTRACT [52] U S Cl 240/47 352/202 353/61 A cooling system for lamps, such as Xenon arc lamps [51] Fzlv 29/00 used in motion picture projectors, where the lamp is [58] Fieid 353/52 elongate with a terminal and seal at each end, with 353/57 one terminal and seal mounted within the mirror and thereby subjected to excessive heating. A concentric [56] References Cited sleeve construction for the seal within the mirror and an air supply duct providing cooling air flow diectly UNITED STATES PATENTS about the seal and protecting the sea] from reflected 3,188,459 6/1965 Bridwell 240/47 radiation 3,305,680 2/1967 Berkl 240/47 3.465.140 9/1969 061661111111 240/47 x 3 Cla ms, 4 Drawmg Figures 1, COOLING SYSTEM FQR XENON ABC LAMPS being used in place of the earlier carbon arc lights toprovide a light source for motion picture projectors. The Xenon lamps provide a superior light output, but considerable problems have been encountered in the installations due to premature failure of the lamps.

A typical Xenon arc lamp comprises a generally tubular glass housing with an electrode projecting from eachend and defining the arc space between the electrodes at the center of the housing. A glass-to-metal seal is provided at each end of the lamp between the housing and respective electrode, with the end of the electrode projecting from the seal to serve as a terminal for electrical connection.

It has been determined that the majority of the premature failures of the Xenon lamps results from excessive heating of the area around the seal. Attempts have been made to reduce the heating by directing a jet of air onto the seal area of the lamp, but this approach has not been satisfactory, particularly with regard to the seal positioned within the elliptical mirror. Although a part of the heat generated by the lamp is conducted through the electrode and the glass envelope to the I seal, I have found that a very substantial amount of heat is reflected by radiation from the mirror to the seal area. By providing a bright reflecting shield around the seal area, in addition to a cooling air stream properly conducted within the shield, it is possible to greatly lower the seal temperature.

Accordingly it is the object of the invention to provide a new and improved cooling system particularly adapted for use with the end of a Xenon arc lamp positioned within the mirror of a motion picture projector lamp housing or the like. A further object is to provide such a cooling system incorporating a unique sleeve construction about the seal with an air supply for directing air in a predetermined path around this seal. An additional object is to provide such a cooling system including a highly reflecting sleeve about the seal protecting the seal from radiation from the reflecting mirror. Other objects, advantages, features and results will more fully appear in the course of the following description.

In the drawing:

FIG. 1 is an isometric view of a light source for a motion picture projector or the like, incorporating a presently preferred embodiment of the invention;

FIG. 2 is an enlarged sectional view of the lamp installation of the source of FIG. 1; I

FIG. 3 is an enlarged sectional view taken along the line 3-3 of FIG.'2; and

FIG. 4 is a sectional view taken along the line 44 of FIG. 3.

In FIG. 1, the cooling system of the invention is incorporated in an otherwise conventional light source. An elliptical mirror is supported on a mirror frame 11 within a cabinet 12. A Xenon arc lamp 13 is positioned within the mirror 10, as shown in detail in FIG. 2, with the lamp output being directed by the mirror 10 through a lens 15. A power supply for the lamp, appropriate controls, and a blower to supply cooling air may be incorporated in the cabinet 12, with a duct 16 serving as an exhaust duct. The levers 17' are conventional dowser handles for shutting off the light output, and plate 18 is a cover for the conventional lens cleaning access opening.

The lamp 13 may be a conventional Xenon arc lamp and is shown in greater detail in FIG. 2, including a housing 21 and electrodes 22, 23. The electrode 22 is joined to the housing 21 at a glass-to-metal seal 24, with the electrode projecting from the housing to provide an electrical terminal at 25. Similarly the electrode 23 is joined to the housing 21 in a glass-to-metal seal 26, with the electrode projecting to provide another terminal 27.

The lamp may be supported by the terminal pin 25 carried in a bracket 34 and secured by a nut 35. The bracket 34 is fastened to a plate 33 carried by a support bracket 37. An electrical connection may be made to terminal 25 by the conducting bracket 34 and the nut 35. A power supply may be connected to the bracket 34 at a terminal 36.

A sleeve 38 may be carried on the plate 33 about the lamp, and be held in place by springs 39 positioned between pins carried on the plate 33.

A tube 31 is carried between the sleeve 38 and the mirror 10 and another tube 32 is carried on the tube 31 and the plate 33. Cooling air is supplied to the left end of the sleeve 38 from a blower (not shown) for flow through the tube 31 about the seal 24 and also for flow through openings 40 in the sleeve 38 into the annular passage between the tubes 31, 32. Thetubes 31 and 32 are of sufiicient diameter to eliminate direct radiation to the seal 24.

The cooling system of the invention is installed about the seal 26 and is shown in greater detail in FIG. 4. A duct is supported at its lower end in a block 51 typically mounted in a bracket 52. Air is supplied to the duct 50 from a blower (not shown) through a line 53 and the block 51.

A sleeve 54 is carried at the upper end of the duct 50, with an opening 55 in the side of the sleeve providing for air flow from the duct to the sleeve. Another sleeve 56 is carried within the sleeve 54 by means of an end plate 57 and an intermediate plate 58. The duct, the sleeves and the plates may be fastened together to form a unitary structure, typically by welding. Openings 60 are provided in the sleeve 56, with the openings 60 disposed around the sleeve.

The lamp 13 is positioned with the seal 26 within the sleeve 56 and with the terminal 27 projecting through the end plate 57 for connection to an electrical fitting 62.

In the preferred embodiment illustrated in the drawing, the inner sleeve 56 projects over the glass-to-metal seal of the lamp, while the outer sleeve 54 projects beyond the inner sleeve toward the arc zone of the lamp. In operation, the electrical supply is connected to terminal 36 and fitting 62 to produce an are between the electrodes in the lamp. The major portion of the radiation from the arc is directed to the right by the mirror 10, but a portion of the radiation is directed toward the seal area of the lamp. The sleeves function to protect the seal from this radiant heating, and the performance of the sleeves is enhanced by providing a bright reflecting finish on the outer surface of the outer sleeve 54. Air under pressure is directed through the duct 50 into the zone between the outer and inner sleeves 54, 56 and the plates 57, 58. This zone serves as a manifold for feeding air through the opening 60 so that the cooling 3 air directly contacts all sides of the glassto-metal seal, with the air exhausting along the annular passage beinto the outer sleeve and exits generally radially through slot 64 in the outer sleeve 54. The air flow paths are indicated by the arrows on FIG. 4.

With the unique cooling system of the invention, the lamp seal is maintained at a temperature sufficiently low as to not adversely affect the glass-to-metal seal so that the operating life of a lamp is not reduced by seal failure.

I claim:

1. In a lamp cooling system, the combination of:

a cabinet;

a generally ellipsoidal mirror having an axis and mounted within said cabinet;

an elongate lamp having a lamp housing with first and second seals, said lamp having first and second inline terminals entering the lamp housing at the first and second seals, respectively, with the lamp positioned within said mirror along said axis with said first seal and terminal in front of said mirror;

a sleeve positioned about said lamp at said first seal substantially concentric with said axis and defining an annular air flow passage between said seal and tween the lamp and the inner sleeve. The air then flows sleeve, with said sleeve substantially closed at one end;

a radially positioned supply duct coupled to said sleeve between said first seal and one end;

means for supplying air under pressure to said supply duct for flow into said sleeve and through said annular passage about said first seal;

a second sleeve positioned about said one sleeve and extending along said lamp beyond said first seal and terminating short of the source of light within said lamp housing; and

baffie means'engaging said sleeves defining a manifold therebetween;

said supply duct being connected to said second sleeve at said manifold, and said one sleeve having passage means for air flow from said manifold into said one sleeve. I 2. A system as defined in claim 1 wherein said passage means comprises a plurality of openings spaced around said one sleeve.

3. A system as defined in claim 1 wherein said second sleeve includes an exhaust opening in the side thereof for air flow from said annular passage in a generally radial direction away from said lamp.

Claims (3)

1. In a lamp cooling system, the combination of: a cabinet; a generally ellipsoidal mirror having an axis and mounted within said cabinet; an elongate lamp having a lamp housing with first and second seals, said lamp having first and second in-line terminals entering the lamp housing at the first and second seals, respectively, with the lamp positioned within said mirror along said axis with said first seal and terminal in front of said mirror; a sleeve positioned about said lamp at said first seal substantially concentric with said axis and defining an annular air flow passage between said seal and sleeve, with said sleeve substantially closed at one end; a radially positioned supply duct coupled to said sleeve between said first seal and one end; means for supplying air under pressure to said supply duct for flow into said sleeve and through said annular passage about said first seal; a second sleeve positioned about said one sleeve and extending along said lamp beyond said first seal and terminating short of the source of light within said lamp housing; and baffle means engaging said sleeves defining a manifold therebetween; said supply duct being connected to said second sleeve at said manifold, and said one sleeve having passage means for air flow from said manifold into said one sleeve.

2. A system as defined in claim 1 wherein said passage means comprises a plurality of openings spaced around said one sleeve.

3. A system as defined in claim 1 wherein said second sleeve includes an exhaust opening in the side thereof for air flow from said annular passage in a generally radial direction away from said lamp.

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