CA1136689A - Filament shields for par lamps - Google Patents
Filament shields for par lampsInfo
- Publication number
- CA1136689A CA1136689A CA000329694A CA329694A CA1136689A CA 1136689 A CA1136689 A CA 1136689A CA 000329694 A CA000329694 A CA 000329694A CA 329694 A CA329694 A CA 329694A CA 1136689 A CA1136689 A CA 1136689A
- Authority
- CA
- Canada
- Prior art keywords
- filament
- lamp
- shield
- lens
- par
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A filament shield for pressed glass reflector lamps consists of an iron base having an aluminum coating thereon heated to produce an FeAl3 outer layer having a dark, matte finish.
A filament shield for pressed glass reflector lamps consists of an iron base having an aluminum coating thereon heated to produce an FeAl3 outer layer having a dark, matte finish.
Description
~i36689 This invention relates to filament shields for PAR
(parabolic aluminized reflector) lamps and, in particular, to a new material for such shields.
Filament shields are well known in the prior art as a means for controlling light: the light is, in theory, simply blocked from directly radiating through the lens.
("Lens" is used in the generic sense well known in the art; namely, a glass cover for the reflector, which glass-cover may be clear or fluted.) The remainder of the light from the filament is re-directed and controlled by the reflector. The result is a well-controlled beam of light which, if desired, may be refracted by flutes in the lens to produce the desired beam pattern. In practice, there is some "spill light" due to the fact that the focus of a paraboloid is a point, whereas a filament is not a point source of light.
The beam pattern is on-ly one of a plurality of con-siderations in making a lamp. Another is the life of the lamp, or more specifically, avoiding shortening the design life of the filament by extrinsic conditions. For example, low carbon steel has been used in the past for filament shields because of its low material cost, ease of fabrication moderately low surface reflectivity. However, as known in the art, the interior of a lamp is analogous to a high temperature chemical factory due to the filament, which runs in excess of 2200C when the lamp is lighted. Whatever the behavior at lower temperatures, it is difficult to predict the behavior of materials within a lamp. Carbon steel shields for example are gassy, i.e. absorbed gases are driven out when the lamp is lighted and can recombine in various ways. The contaminants thus produced, in turn, attack the filament and shorten the life of the lamp.
Depending on the design life of the lamp, this poses a 1~36~89 serious problem, eg. for lamps with a rated life in excess of 200 hours.
To minimize the contamination problem, a vapor de-posited aluminum coating has been provided to enclose the shield. This increases costs and produces a highly re-flective surface, increasing spill light.
In view of the foregoing, it is therefore an object of the present invention to provide a PAR lamp having an improved filament shield.
Another object of the present invention is to provide a PAR lamp having less spill light.
The foregoing objects are achieved in the present invention wherein a filament shield is provided comprising aluminum clad steel in which the shield is heat treated to produce a dark, matte finish on the aluminum, thereby sealing the iron surface but without the reflectivity of vapor deposited aluminum.
A more complete understanding of the present invention can be obtained by considering the following detailed description in conjunction with the accompanying drawings, in which:
FIGURE 1 illustrates a PAR lamp in accordance with the prior art.
FIGURE 2 illustrates a PAR lamp in accordance with the present invention.
FIGURE 3 comprises intensity distribution curves comparing the present invention with the prior art.
FIGURE 1 illustrates a PAR lamp in accordance with the prior art having an aluminum coated, steel filament shield 10 therein. In accordance with the present invention, as illustrated in FIGURE 2, the PAR lamp has a shield 11 formed of aluminum-clad iron which has been heat treated to produce a dark, matte finish. Aluminum clad iron is commercially available, eg. under the trade mark "Aliron"
from Texas Instruments, Inc., Attleboro, Massachusetts.
In this material the aluminum coating not only seals the surface of the steel as in vapor deposited aluminum coatings, but further, upon heat treating, provides the added benefit of improved light control.
For example, as illustrated in FIGURE 3 curve 31 illustrates the intensity distribution in the vertical plane of a 50 watt PAR 36 lamp in accordance with the present invention. Curve 32 illustrates the intensity distribution in the vertical plane of an otherwise identical lamp except that it has a vapor deposited aluminum coating on the filament shield. Similarly, curves 33 and 34 represent the intensity distribution in the horizontal plane of these same lamps, respectively.
As can be seen from these curves the light control is improved in accordance with the present invention in addition to the prevention of contaminants from entering the lamp from the shield. The improved light control is immediately apparent upon viewing the beam patterns of the lamp directly on the screen. Lamps in accordance with the present invention have a noticably more definite cutoff off-axis as compared to lamps of prior art.
While not to be constrused as limiting, the following dimensions have been found to produce satisfactory filament shields in accordance with the present invention.
A steel core having a thickness of from 5 to 30 mils and a coating on each side thereof of from .1 to 1.0 mils produces satisfactory shield. The heat treatment, which causes the dark, matte surface, may be performed in either 1~36689 LD-7664 air or hydrogen. For example, satisfactory surface characteristics are obtained by heating the shield to a temperature of 700C in air for approximately 10 minutes.
A hydrogen or ammonia atmosphere and a temperature of up to 800C for approximately the same time also produces satisfactory surface characteristics.
The heat treatment appears to cause a chemical change in the material so that the shield, after treatment, may best be described as having an iron core with FeA13 on the outer surface.
There is thus provided by the present invention an improved shield for PAR lamps which, in combination with a PAR lamp, provides superior light control without caus-ing deterioration of the life of the lamp. Having thus described the invention it will be obvious to those of skill in the art that various modifications can be made within the spirit and scope of the present invention.
For example, various thickness and treatment times may be utilized other than those specifically enumerated above.
Further, while shown in FIGURE 2 as a solid shield, shield 11 may be provided with any desired aperture to enhance maximum beam candle power or other characteristic.
(parabolic aluminized reflector) lamps and, in particular, to a new material for such shields.
Filament shields are well known in the prior art as a means for controlling light: the light is, in theory, simply blocked from directly radiating through the lens.
("Lens" is used in the generic sense well known in the art; namely, a glass cover for the reflector, which glass-cover may be clear or fluted.) The remainder of the light from the filament is re-directed and controlled by the reflector. The result is a well-controlled beam of light which, if desired, may be refracted by flutes in the lens to produce the desired beam pattern. In practice, there is some "spill light" due to the fact that the focus of a paraboloid is a point, whereas a filament is not a point source of light.
The beam pattern is on-ly one of a plurality of con-siderations in making a lamp. Another is the life of the lamp, or more specifically, avoiding shortening the design life of the filament by extrinsic conditions. For example, low carbon steel has been used in the past for filament shields because of its low material cost, ease of fabrication moderately low surface reflectivity. However, as known in the art, the interior of a lamp is analogous to a high temperature chemical factory due to the filament, which runs in excess of 2200C when the lamp is lighted. Whatever the behavior at lower temperatures, it is difficult to predict the behavior of materials within a lamp. Carbon steel shields for example are gassy, i.e. absorbed gases are driven out when the lamp is lighted and can recombine in various ways. The contaminants thus produced, in turn, attack the filament and shorten the life of the lamp.
Depending on the design life of the lamp, this poses a 1~36~89 serious problem, eg. for lamps with a rated life in excess of 200 hours.
To minimize the contamination problem, a vapor de-posited aluminum coating has been provided to enclose the shield. This increases costs and produces a highly re-flective surface, increasing spill light.
In view of the foregoing, it is therefore an object of the present invention to provide a PAR lamp having an improved filament shield.
Another object of the present invention is to provide a PAR lamp having less spill light.
The foregoing objects are achieved in the present invention wherein a filament shield is provided comprising aluminum clad steel in which the shield is heat treated to produce a dark, matte finish on the aluminum, thereby sealing the iron surface but without the reflectivity of vapor deposited aluminum.
A more complete understanding of the present invention can be obtained by considering the following detailed description in conjunction with the accompanying drawings, in which:
FIGURE 1 illustrates a PAR lamp in accordance with the prior art.
FIGURE 2 illustrates a PAR lamp in accordance with the present invention.
FIGURE 3 comprises intensity distribution curves comparing the present invention with the prior art.
FIGURE 1 illustrates a PAR lamp in accordance with the prior art having an aluminum coated, steel filament shield 10 therein. In accordance with the present invention, as illustrated in FIGURE 2, the PAR lamp has a shield 11 formed of aluminum-clad iron which has been heat treated to produce a dark, matte finish. Aluminum clad iron is commercially available, eg. under the trade mark "Aliron"
from Texas Instruments, Inc., Attleboro, Massachusetts.
In this material the aluminum coating not only seals the surface of the steel as in vapor deposited aluminum coatings, but further, upon heat treating, provides the added benefit of improved light control.
For example, as illustrated in FIGURE 3 curve 31 illustrates the intensity distribution in the vertical plane of a 50 watt PAR 36 lamp in accordance with the present invention. Curve 32 illustrates the intensity distribution in the vertical plane of an otherwise identical lamp except that it has a vapor deposited aluminum coating on the filament shield. Similarly, curves 33 and 34 represent the intensity distribution in the horizontal plane of these same lamps, respectively.
As can be seen from these curves the light control is improved in accordance with the present invention in addition to the prevention of contaminants from entering the lamp from the shield. The improved light control is immediately apparent upon viewing the beam patterns of the lamp directly on the screen. Lamps in accordance with the present invention have a noticably more definite cutoff off-axis as compared to lamps of prior art.
While not to be constrused as limiting, the following dimensions have been found to produce satisfactory filament shields in accordance with the present invention.
A steel core having a thickness of from 5 to 30 mils and a coating on each side thereof of from .1 to 1.0 mils produces satisfactory shield. The heat treatment, which causes the dark, matte surface, may be performed in either 1~36689 LD-7664 air or hydrogen. For example, satisfactory surface characteristics are obtained by heating the shield to a temperature of 700C in air for approximately 10 minutes.
A hydrogen or ammonia atmosphere and a temperature of up to 800C for approximately the same time also produces satisfactory surface characteristics.
The heat treatment appears to cause a chemical change in the material so that the shield, after treatment, may best be described as having an iron core with FeA13 on the outer surface.
There is thus provided by the present invention an improved shield for PAR lamps which, in combination with a PAR lamp, provides superior light control without caus-ing deterioration of the life of the lamp. Having thus described the invention it will be obvious to those of skill in the art that various modifications can be made within the spirit and scope of the present invention.
For example, various thickness and treatment times may be utilized other than those specifically enumerated above.
Further, while shown in FIGURE 2 as a solid shield, shield 11 may be provided with any desired aperture to enhance maximum beam candle power or other characteristic.
Claims (3)
1. In a lamp having a reflector, a lens and at least one filament, the improvement comprising:
a filament shield interposed between said fila-ment and said lens, said filament shield comprising an iron core having the surface thereof sealed by an FeAl3 coating characterized by a dark matte finish.
a filament shield interposed between said fila-ment and said lens, said filament shield comprising an iron core having the surface thereof sealed by an FeAl3 coating characterized by a dark matte finish.
2. The lamp of claim 1, wherein said filament shield comprises an iron core from 5 to 30 mils thick covered by an FeA13 coating from 0.1 to 1.0 mil thick.
3. The lamp of claim 1 or 2, wherein said fila-ment shield is predeterminedly positioned to block substantially all direct light going to said lens.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000329694A CA1136689A (en) | 1979-06-13 | 1979-06-13 | Filament shields for par lamps |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000329694A CA1136689A (en) | 1979-06-13 | 1979-06-13 | Filament shields for par lamps |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1136689A true CA1136689A (en) | 1982-11-30 |
Family
ID=4114447
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000329694A Expired CA1136689A (en) | 1979-06-13 | 1979-06-13 | Filament shields for par lamps |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1136689A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4494286A (en) * | 1982-10-25 | 1985-01-22 | Tecumseh Products Company | Connecting rod arrangement |
-
1979
- 1979-06-13 CA CA000329694A patent/CA1136689A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4494286A (en) * | 1982-10-25 | 1985-01-22 | Tecumseh Products Company | Connecting rod arrangement |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |