Bulb cooling

Abstract

A system and method of cooling a bulb of a type that requires cooling in one part, but not in others. A deflector assembly is coupled through a reflector, to the bulb, to cool only one part.

Description

BACKGROUND

The present application relates for special techniques for cooling a special kind of bulb.

Special metal halide bulbs have special cooling requirements. The bulbs, such as Philips metal halide projection lamps, often have a central portion which emits light, and two “pinch” portions around the central portion.

A diagram of an exemplary one of these bulbs is shown in FIG. 1. The bulb has a central light emitting portion 100, and the two surrounding “pinch” portions 102, 104.

In some bulbs, it is desirable to keep the pinch portions 102, 104 cooler than the center portion. This is easy to do in a laboratory condition, but more difficult to do in practice.

SUMMARY

While it may be possible easy to cool only an edge and not the center in a laboratory, the inventor recognized that doing this in practicality can be more difficult. For example, in a laboratory, the bulbs are often cooled using pipes of air. Those pipes could get in the way of the light output from the bulb, and/or the bulb's reflector. Therefore, it has been difficult to cool these kinds of bulbs.

The present application teaches a way of cooling a bulb of this type, by cooling only a pinch portion, and not the center portion. This is done by using a special combination of structure that cools at least one of the edges, but does not cool the center.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects will be described in detail with reference to the drawings in which:

FIG. 1 shows a pinch-type bulb;

FIG. 2 shows the bulb relative to a portion of the reflector;

FIG. 3 shows the rear of the reflector and the fan assembly;

FIG. 4 show the bulb/reflector from the bottom, showing the special interface piece;

FIG. 5 shows air flow over the pinch, from the side;

FIG. 6 shows air flow over the pinch from the orthogonal direction as FIG. 5;

FIG. 7 shows the bulb with the reflector removed;

FIG. 8 shows the air interface assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A bulb of the preferred type is shown in FIG. 1. This bulb has a central portion 100 which emits light, and edge portions 102, 104, at least one of which need to be cooled. The central portion 100, which emits the light, is preferably not cooled. The bulb used herein is called an MSR SA, or short arc discharge bulb. Other bulbs have similar cooling requirements.

The edge portions 102, 104 should preferably be kept between 400 and 450° C. The bulb is mounted as shown in FIG. 2. When mounted in this way, the far edge portion 104 is often sufficiently cooled by ambient to be kept within the desired range. However, the near edge portion 102 gets very hot, due to the proximity to the ceramic base 110 and also because of its electrical connection. Also, as described above, cooling should not, or should only minimally, touch the center portion 100.

FIG. 2 shows the bulb 99 placed relative to a portion of the reflector 200. The base portion 110 of the bulb is shown connected. The reflector 200 includes an outer edge 210 and an inner edge 220. A metal air deflecting portion 230 fits within the inner edge 220, and directs air from a fan to the close pinch portion 102 of the bulb which is close to the reflector.

FIG. 3 shows the rear view of the system. An air chamber 300 is attached to a fan assembly shown generically as 310. The fan assembly 310 forces into the air assembly 300, and through the air coupling mechanisms 230, to eventually end up at the bulb. Further detail is shown in the other Figures.

FIG. 4 shows more detail of the shape of the air deflection assembly. FIG. 5 shows schematically how the air is coupled. The air couples through the assembly as 500. It hits the far end wall 502 of the air coupling assembly 230. This air is then deflected back towards the near pinch 102, and travels thereover, cooling the near pinch 102 as it passes. The air is traveling away from the main portion of the bulb. In this system, the air preferably travels from the central portion towards the pinch.

FIG. 6 shows a cross-section along the line 5—5 in FIG. 5. The air travels outwardly, as shown, and hence again travels away from the pinch portion.

FIGS. 5 and 6 show the air chimney defined by the metal pieces 230. These pieces are aligned relative to the bulb. The alignment is shown in more detail in FIG. 7 which shows the air producing assembly 230, held in place relative to the bulb. The alignment can be via connection to the reflector in a way that holds the chimney relative to the desired cooled area of the bulb. It can be, alternatively, held by a clip that is placed around the bulb. The air producing assembly includes inner surfaces 232 which are adapted to press against the face 110, to hold the air deflection assembly in place relative to the bulb or the bulb's expected position.

FIG. 8 shows a diagram of only the air producing assembly and the attachment to the air chimney. The fan assembly 310 comprises two separate fans mounted one on top of the other as shown. Fans 312 and 314 produce air at the same rate as one fan would have produced but at a higher air pressure.

Although only a few embodiments have been disclosed in detail, other embodiments are possible. All such modifications are intended to be encompassed within the following claims.

Claims

1. A method, comprising: using a bulb with a reflector to project light along a specified direction; andcooling one portion of said bulb that does not emit light, said one portion being a portion of the bulb that is closest to said reflector, without cooling an other portion of said bulb that does emit light, while projecting said light, wherein said bulb includes two electrode portions, and a lighted portion between said two electrode portions, one of said electrode portions being cooled as said one portion, and said lighted portion not being cooled.

2. A method, comprising: using a bulb with a reflector to project light along a specified direction; andcooling one portion of said bulb the t does not emit light, said one portion being a portion of the bulb that is closest to said reflector, without cooling an other portion of said bulb that does emit light, while projecting said light, wherein said cooling comprises forcing air along an axis toward a portion of the bulb that emits light, and deflecting the air front said axis towards said one portion of said bulb that does not emit light.

3. A method, comprising: using a bulb with a reflector to project light along a specified direction;cooling one portion of said bulb that does not emit light, said one portion being a portion closest to said reflector, without cooling an other portion of said bulb that does emit light, while projecting said light; and channeling air into a chamber that extends along an axis, and first directing said air an a direction generally along said axis, and deflecting said air in a direction generally at an angle with said axis, to a part to said one portion of said bulb without directing said air to said other portion of said bulb.

4. A lighting fixture, comprising: an optical reflector, having a first reflecting part, and a second non reflecting part;a bulb socket, formed in said second non reflecting part; anda cooling air chimney portion, extending from a first point outside said optical reflector, to a second point inside said optical reflector, and forming a channel for cooling air inside said optical reflector that is directed along a confined path, inside said chimney portion directing air only to a portion of the bulb socket closer to said reflector, without directing said air to another portion of the bulb more distant from the reflector.

5. A fixture as in claim 4, wherein said chimney portion is formed of bent sheet metal.