(19)
(11) EP 2 369 225 A2

(12) EUROPEAN PATENT APPLICATION

(43) Date of publication:
28.09.2011 Bulletin 2011/39

(21) Application number: 11159802.5

(22) Date of filing: 25.03.2011
(51) International Patent Classification (IPC): 
F21S 8/00(2006.01)
F21V 15/015(2006.01)
F21V 31/00(2006.01)
F21Y 101/02(2006.01)
 F21V 15/06(2006.01)
F21W 131/10(2006.01)
F21S 8/08(2006.01)
(84) Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Extension States:
BA ME

(30) Priority: 25.03.2010 GB 1004999

(71) Applicant: ABL IP Holding LLC
Conyers GA 30012 (US)

(72) Inventors:
  • Fernandez Bastos, Victor
    Rugby, Warwickshire CV23 0WU (GB)
  • Javes, Frederick
    Milton Keynes, Buckinghamshire MK19 6NA (GB)

(74) Representative: Phillips & Leigh 
5 Pemberton Row
London EC4A 3BA
London EC4A 3BA (GB)

   


(54) Management of light fixture surface temperature


(57) Embodiments of the present invention are directed to management of light fixture housing temperature. In one embodiment, the light fixture includes a housing with a top end (22) having an aperture (24), a light source (12), a membrane (18), and a cap (16). The membrane (18) is positioned on the top end (22) of the housing between the light source (12) and the cap (16) to impede the convection flow of heat from the light source (12) to the cap (16) by creating a barrier between the heat source and the cap (16). The membrane (18) has an outer perimeter shape that substantially conforms to the outer perimeter of the top end (22) of the housing and substantially covers the aperture (24) in the top end (22).




Description

FIELD OF THE INVENTION



[0001] This invention relates to management of light fixture surface temperature.

BACKGROUND OF THE INVENTION



[0002] A bollard light fixture is a type of outdoor lighting encased in a vertical post at ground level. Bollard light fixtures are commonly used for ground illumination. Generally, bollard light fixtures include a bollard housing, wherein a light source is located within the bollard housing. A cap is then affixed to the top of the bollard housing. A gasket is typically located at the junction of the cap and the bollard housing. Bollard light fixtures may have a variety of sizes, shapes, and capabilities.

[0003] In a typical bollard design, the light source emits heat that travels via convection to the inner surface of the cap. The heat then transfers via conduction to the outer surface of the cap, such that the touchable surface temperature of the cap exceeds maximum allowable safety standards.

[0004] Accordingly, there is a need for a thermal management device to control the amount of heat transferred to the touchable outer surface of the bollard housing cap, so that the touchable upper surface temperature is below the maximum allowable temperature for such fixtures.

SUMMARY



[0005] The present invention is as set out in the appended claims. Embodiments of the present invention are directed to management of light fixture housing temperature. In one embodiment, a light fixture includes a housing with a top end having an aperture, a light source, a membrane, and a cap. The membrane has an outer perimeter that substantially conforms to the outer perimeter of the top end of the housing and substantially covers the aperture in the top end. The membrane may be a silicone-containing material and/or a translucent material. In some embodiments, additional insulating material is placed in an area formed between the cap and the membrane.

[0006] The membrane may be installed in existing light fixtures, where the existing light fixture comprises a housing with a top end having an aperture, a light source, a gasket, and a cap. The method of installation includes the steps of removing the cap, removing the gasket, providing a membrane that substantially conforms to the outer perimeter of the top end of the housing and substantially covers the aperture in the top end, placing the membrane over the top end of the housing, placing the cap over the membrane, and securing the cap to the top end of the housing. In some embodiments, the method further comprises removing material from the membrane so that the membrane comprises an outer perimeter that is configured to substantially conform to the outer perimeter of the top end of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS



[0007] Figure 1 is an exploded perspective view of a bollard light fixture according to one embodiment of the present invention.

[0008] Figure 2 is an assembled perspective view of the bollard light fixture of Figure 1.

[0009] Figure 3 is a cross-sectional view taken along line 3-3 in Figure 2..

[0010] Figure 4 is a cross-sectional view of a bollard light fixture with a traditional gasket.

[0011] Figure 5 is a cross-sectional view taken along line 5-5 in Figure 3.

[0012] Figure 6 is a perspective view of a bollard light fixture according to an alternative embodiment of the present invention.

[0013] Figure 7 is an exploded perspective view of a bollard light fixture according to another alternative embodiment of the present invention.

DETAILED DESCRIPTION



[0014] Embodiments of the invention provide components that manage the touchable surface temperature of a light fixture. While the components are discussed for use with bollard light fixtures, they are by no means so limited. Rather, embodiments of the temperature-management components may be used in light fixtures of any type.

[0015] Figures 1-3 and 5 illustrate an embodiment of the bollard light fixture 10 having a light source 12, a bollard housing 14, a cap 16, and a membrane 18. The light source 12 is located within the bollard housing 14. The light source 12 may be located anywhere within the bollard housing 14. The light source 12 may be any suitable light emitting source including, but not limited to, fluorescent, metal halide, high pressure sodium lamps, light emitting diodes ("LEDs"), or organic light emitting diodes ("OLEDs").

[0016] In one embodiment, the bollard housing 14 surrounds the light source 12. The bollard housing 14 has a generally elongated shape along its vertical axis. The cross-sectional shape of the bollard housing 14 may be any appropriate shape that provides sufficient interior space for the location of the light source 12. Examples of such cross-sectional shapes include but not limited to circular, rectilinear, oval, triangular, clover-leaf, or other similar shape. The bollard housing 14 may be formed of any material suitable for use in close proximity to a light source including, but not limited to, aluminum, iron, steel, composite material, acrylic, polycarbonate, polystyrene, or copolymers thereof, or other similar material. In some embodiments, the bollard housing 14 itself is light-transmissive. The bollard housing 14 has two ends - a base end 20 and a top end 22. The base end 20 is configured to be mounted to a surface such as the ground. The top end 22 has an aperture 24 to allow access to the light source 12.

[0017] In some embodiments, the bollard housing 14 includes at least one refractive lens 26. The at least one refractive lens 26 may be formed from glass, plastic, or other similar material that provides suitable optical properties, as well as allowing visible light to escape the bollard housing 14. In some embodiments, as shown in Figure 6, multiple refractive lens 26 are located on the surface of the bollard housing 14.

[0018] The cap 16 is located adjacent the top end 22 of the bollard housing 14. The cap 16 encloses an area 28 surrounding the top end 22 to prevent introduction of contaminants into the bollard housing 14. The cap 16 is connected to the top end 22 via any appropriate mechanical fasteners 29 including, but not limited to, clips, screws, bolts, or other similar devices. The cross-sectional shape of the cap 16 may have any shape that complements the shape of the housing 14, including, but not limited to, circular, rectilinear, oval, triangular, clover-leaf, or other similar shape. Moreover, the surface contour of the cap 16 may have a domed, flat, or other contoured shape. The cap 16 may be formed of any material suitable for use in close proximity to a light source including, but not limited to, aluminum, iron, steel, composite material, acrylic, polycarbonate, polystyrene, or copolymers thereof, or other similar material.

[0019] The membrane 18 is located between the light source 12 and the cap 16. While the membrane 18 may be positioned in a variety of locations within the housing 14, in one embodiment the membrane is positioned on the top end 22 of the housing 14 to cover aperture 24. The outer perimeter of the membrane 18 is shaped to substantially conform to the outer perimeter of the top end 22. When the membrane 18 is shaped to substantially conform to the outer perimeter of the top end 22 it may be sandwiched between the bollard housing 14 and the cap 16 such that the membrane 18 is visible from the outside of the bollard light fixture 10 during normal use. Accordingly, the membrane 18 may have any shape including, but not limited to, circular, rectilinear, oval, triangular, clover-leaf, or other similar shape. As shown in Figure 5, the presence of the membrane 18 in place of a gasket 34 impedes the convection flow of heat from the light source 12 to the cap 16 by creating a barrier between the heat source and the cap 16. The membrane 18 may be formed of silicon or any other suitable material that reduces the amount of heat transmitted to an area 28 encapsulated between the membrane 18 and the cap 16.

[0020] The membrane 18 may also impart optical properties to the bollard light fixture 10. In some embodiments, the membrane 18 may be formed of a translucent material that creates a luminous highlight at the junction of the top end 22 and the cap 16. In other embodiments, the color of the luminous highlight at the junction of the top end 22 and the cap 16 may be altered by forming the membrane 18 of a color-tinted translucent material or by incorporating a colored light source to impart a colored appearance to the luminous highlight.

[0021] The membrane 18 may have any appropriate thickness that allows the membrane 18 to sufficiently impede heat transfer to the area 28. In some embodiments, the thickness of the membrane 18 is at least approximately 0.0508 cm (0.02 inches), but may range from 0.0508 cm (0.02 inches) to 2.54 cm (1.0 inches) depending on the type of material used to form the membrane 18. The area 28 is filled with any suitable insulating material including, but not limited to, air, fiberglass, foam insulation, or other similar components that has the effect of further reducing the amount of heat transfer from the light source 12 to the cap 16. The membrane 18 and/or the insulating material of area 28 maintain the surface temperature of the cap 16 below 60 °C, and preferably below 45 °C. The membrane material, membrane thickness, or type of insulating material in area 28 may be adjusted as need to achieve a desired maximum surface temperature of the cap 16.

[0022] Optionally, the refractive lens 26 may also include louvres 30, as shown in Figure 7. In one embodiment, the louvres 30 are located within the bollard housing 14 adjacent the at least one refractive lens 26. As shown in figure 7, the louvres 30 may be placed behind the refractive lens so that in use, the louvres 30 are located between the light source 12 and the refractive lens 26. Furthermore, the louvres may be formed as a separate component to the lens 26 such that the separate component comprises one or more louvres 30, the component being removably attachable to the light fixture 10. The louvres may be removably attachable to the housing 14 or the refractive lens. In other embodiments, the louvres 30 are placed adjacent the external surface of the at least one refractive lens 26. In either embodiment, the angle of louvres 30 may be adjusted to control the distribution of light exiting the at least one refractive lens 26. The louvres 30 may have any shape including, but not limited to, rectilinear, cylindrical, hemicylindrical, or any other shape that complements the shape of the refractive lens 26 to allow adjustment of the angle of the louvres 30.

[0023] In some embodiments, a reflector 32 may surround the light source 12 (see Figure 3). The reflector 32 may have any shape that directs light emitted from the light source 12 toward the at least one refractive lens 26, including, but not limited to, rectilinear, frustoconical, cylindrical, and dome-shaped. The reflector 32 may be formed from aluminum or other similar material. The inner surface of the reflector 32 preferably has extremely high surface reflectivity, preferably, but not necessarily, between 96%-99.5%, inclusive and more preferably 98.5-99.5%. To achieve the desired reflectivity, in one embodiment the inner surface of the reflector 32 is coated with a highly reflective material, including, but not limited to, paints sold under the tradenames GL-22, GL-80 and GL-30, all available from DuPont ®. Other embodiments may utilize textured or colored paints or impart a baffled shape to the reflector surface to obtain a desired reflection.

[0024] The membrane 18 may be installed in an existing bollard light fixture 10. In the existing light fixture 10, as shown in Figure 4, the gasket 34 may be positioned at the junction between the cap 16 and the bollard housing 14. As an initial step in the installation process, the cap 16 must be removed from the top of the bollard light fixture 10. In some embodiments, the existing gasket 34 is then removed from the top end 22 of the bollard housing 14. The outer perimeter of the membrane 18 is compared to the outer perimeter of the now-removed gasket 34. If necessary, excess material may be trimmed from the new membrane 18 to achieve an outer perimeter shape that substantially conforms to the outer perimeter of the top end 22. Alternatively, any excess material may be trimmed from the new membrane 18 after installation. In some embodiments, additional insulating material may be added to the area 28 between the cap and the membrane 18. The new membrane 18 is then placed over the top end 22 and the cap 16 is re-connected to the top end 22.

[0025] The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of the present invention. Further modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of the invention.

Features of the invention



[0026] Features of the invention may include:
  1. 1. A light fixture comprising:
    1. a. a housing comprising a top end having an outer perimeter, wherein the top end comprises an aperture;
    2. b. a light source, wherein the light source is located within the housing;
    3. c. a cap positioned adjacent the top end; and
    4. d. a membrane positioned between the cap and the light source and having an outer perimeter, wherein the outer perimeter of the membrane substantially conforms to the outer perimeter of the top end of the housing and substantially covers the aperture in the top end.
  2. 2. The light fixture of feature 1, wherein the membrane comprises silicon.
  3. 3. The light fixture of feature 1, wherein the membrane comprises a translucent material.
  4. 4. The light fixture of feature 3, wherein the translucent material is color-tinted.
  5. 5. The light fixture according to any preceding feature, wherein the membrane comprises a thickness of at least 0.02 inches.
  6. 6. The light fixture according to any preceding feature, wherein the cap has a surface temperature of less than 60 degrees Celsius when the light source is activated.
  7. 7. The light fixture according to any preceding feature, wherein the cap is configured to enclose an area between the cap and the membrane.
  8. 8. The light fixture of feature 7, wherein the area between the cap and the membrane is filled with air, fiberglass, or foam insulation.
  9. 9. The light fixture according to any preceding feature, wherein the light source comprises a fluorescent lamp, a metal halide lamp, a high pressure sodium lamp, or a light emitting diode.
  10. 10. The light fixture according to any preceding feature, wherein the light fixture comprises at least one refractive lens coupled to the housing.
  11. 11. The light fixture of feature 10, wherein the refractive lens comprises a set of louvres.
  12. 12. A method of installing a membrane in a light fixture, the light fixture comprising: (i) a housing comprising a top end having an aperture and an outer perimeter; (ii) a cap positioned adjacent the top end; and (iii) a gasket positioned between the cap and the housing, wherein the method comprises:
    1. a. removing the cap from the top end of the housing;
    2. b. removing the gasket from the top end of the housing;
    3. c. positioning a membrane over the top end of the housing to substantially cover the aperture in the top end of the housing;
    4. d. positioning the cap over the membrane to enclose an area between the cap and the membrane; and
    5. e. securing the cap to the top end of the housing.
  13. 13. The method of feature 12, further comprising removing material from the membrane so that the membrane comprises an outer perimeter that substantially conform to the outer perimeter of the top end of the housing.
  14. 14. The method according to any of features 12 to 13, wherein the membrane comprises silicon.
  15. 15. The method according to any of features 12 to 13, wherein the membrane comprises a translucent material.
  16. 16. The method of feature 15, wherein the translucent material is color-tinted.
  17. 17. The method according to any of features 12 to 16, wherein the membrane comprises a thickness of at least 0.02 inches.
  18. 18. The method according to any of features 12 to 17, further comprising adding an insulating material to the area between the cap and the membrane.
  19. 19. The light fixture of feature 18, wherein the insulating material comprises air, fiberglass, or foam insulation.
  20. 20. The method according to any of features 12 to 19, wherein the cap has a surface temperature of less than 60 degrees Celsius when the light source is activated.



Claims

1. A light fixture (10) comprising:

a. a housing (14) that in use comprises a top end (22) having an outer perimeter, wherein the top end comprises an aperture (24);

b. a light source (12), wherein the light source is located within the housing;

c. a cap (16) positioned adjacent the top end; and

d. a membrane (18) positioned between the cap and the light source and having an outer perimeter, wherein the outer perimeter of the membrane substantially conforms to the outer perimeter of the top end of the housing and substantially covers the aperture in the top end.


 
2. The light fixture (10) as claimed in claim 1, wherein the cap (16) is configured to enclose an area (28) between the cap and the membrane (18).
 
3. The light fixture (10) of claim 2, wherein the area (28) between the cap (16) and the membrane (18) is filled with fiberglass, or foam insulation.
 
4. The light fixture (10) as claimed in any preceding claim, wherein the light source (12) comprises a fluorescent lamp, a metal halide lamp, a high pressure sodium lamp, or a light emitting diode.
 
5. The light fixture (10) as claimed in any preceding claim, wherein the light fixture comprises at least one refractive lens (26) coupled to the housing (14).
 
6. The light fixture (10) of claim 5, wherein the refractive lens (26) comprises a set of louvres (30).
 
7. A method of making a light fixture (10) as claimed in any of claims 1-6 from an existing light fixture (10), the existing light fixture comprising:

(i) a housing (14) that in use comprises a top end (22) having an aperture (24) and an outer perimeter;

(ii) a cap (16) positioned adjacent the top end;
wherein the method comprises:

a. removing the cap from the top end of the housing;

b. positioning a membrane over the top end of the housing to substantially cover the aperture in the top end of the housing;

c. positioning the cap over the membrane to enclose an area (28) between the cap

and the membrane; and

d. securing the cap to the top end of the housing.


 
8. The method of claim 8, wherein the existing light fixture (10) further comprises a gasket (34) positioned between the cap (16) and the housing (14); wherein the method further comprises the step of:

removing the gasket from the top end (22) of the housing.


 
9. The method of claims 7 or 8, further comprising removing material from the membrane (18) so that the membrane comprises an outer perimeter that substantially conform to the outer perimeter of the top end (22) of the housing (14).
 
10. The method as claimed in any of claims 7 to 9, or the light fixture as claim in any of claims 1-6 wherein the membrane (18) comprises a thickness of at least 0.0508 cm.
 
11. The method as claimed in any of claims 7 to 10, further comprising adding an insulating material to the area (28) between the cap (16) and the membrane (18).
 
12. The method of claim 12, wherein the insulating material comprises fiberglass, or foam insulation.
 
13. The method as claimed in any of claims 7 to 13, or the light fixture (10) as claimed in any of claims 1 to 7, wherein the membrane (18) comprises any of:

I) silicon; and/or,

II) a translucent material.


 
14. The method or light fixture (10) of claim 13, wherein the translucent material is color-tinted.
 
15. The method as claimed in any of claims 7 to 14, or a light fixture (10) as claimed in any of claims 1-6 and 13-14 wherein the cap (16) has a surface temperature of less than 60 degrees Celsius when the light source (12) is activated.
 




Drawing