U.S. patent number RE38,217 [Application Number 09/372,020] was granted by the patent office on 2003-08-19 for tubular skylight with improved dome.
This patent grant is currently assigned to ODL, Incorporated. Invention is credited to Gwen H. Barber, David A. DeBlock, Ronald L. Sitzema, Jr..
United States Patent |
RE38,217 |
DeBlock , et al. |
August 19, 2003 |
**Please see images for:
( Certificate of Correction ) ** |
Tubular skylight with improved dome
Abstract
A tubular skylight having an improved dome improving the
efficiency of the skylight. The dome includes an integral prism in
a portion of its outer surface to reflect light downwardly through
the skylight. The dome is hemispherical, and the prism includes a
plurality of grooves extending along great circles that pass
through the apex of the dome. The prism covers only an angular
segment of the hemispherical dome; and the grooves stop short of
the apex of the dome.
Inventors: |
DeBlock; David A. (Holland,
MI), Sitzema, Jr.; Ronald L. (Ellsworth, MI), Barber;
Gwen H. (Roseville, CA) |
Assignee: |
ODL, Incorporated (Zeeland,
MI)
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Family
ID: |
24789349 |
Appl.
No.: |
09/372,020 |
Filed: |
August 10, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
694558 |
Aug 9, 1996 |
05655339 |
Aug 12, 1997 |
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Current U.S.
Class: |
52/200;
359/591 |
Current CPC
Class: |
E04D
13/03 (20130101); E04D 13/033 (20130101); F21S
11/00 (20130101); G02B 5/045 (20130101); E04D
2013/0345 (20130101) |
Current International
Class: |
E04D
13/03 (20060101); F21S 11/00 (20060101); E04D
013/03 (); G02B 017/00 () |
Field of
Search: |
;52/80.1,82,107,3,200
;359/591-598 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Canfield; Robert
Attorney, Agent or Firm: Warner Norcross & Judd
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. An improved tubular skylight including a dome to be mounted on a
roof, a light diffuser to be mounted on a ceiling, and a reflective
tube extending between the dome and the light diffuser, wherein the
improvement comprises said dome comprising: a generally
hemispherical body having an apex, an interior surface, and
exterior surface, said interior surface being generally smooth,
said exterior surface including a generally smooth portion being an
angular section of said dome, said prismatic portion including a
plurality of vertical grooves extending along great circles of said
hemispherical body passing through said apex.
2. An improved tubular skylight as defined in claim 1 wherein said
smooth portion of said exterior surface includes a circular area of
non-zero radius centered on said apex.
3. A skylight dome assembly comprising: a flashing to be mounted on
a roof; and a skylight dome to be mounted on said flashing, said
dome having an interior surface and an exterior surface, said
exterior surface including a prismatic portion.
4. A skylight dome assembly as defined in claim 3 wherein: said
dome includes a base and an apex above said base; and said
prismatic portion including a plurality of grooves located between
said base and said apex.
5. A skylight dome assembly as defined in claim 4 wherein: said
dome is generally hemispherical and said base is generally
circular; said grooves extend along great circles of said dome
passing through said apex.
6. A skylight dome assembly as defined in claim 5 wherein said
prismatic portion comprises an angular segment of said dome.
7. A skylight dome assembly as defined in claim 6 wherein said
grooves stop short of said apex.
8. A skylight dome assembly as defined in claim 4 wherein said
prismatic portion comprises an angular segment of said dome.
9. A skylight dome assembly as defined in claim 3 wherein said
prismatic portion is entirely outside of a circle surrounding said
apex.
10. A skylight dome comprising a body having a base and a dome
portion extending above said base, said dome portion including an
apex, an interior surface, and an exterior surface, said exterior
surface defining a prismatic portion, said prismatic portion
defining a plurality of grooves between said base and said apex
along said dome portion.
11. A skylight dome as defined in claim 10 wherein: said base is
generally circular and said dome portion is generally
hemispherical.
12. A skylight dome as defined in claim 11 wherein said grooves
extend along great circles of said dome portion passing through
said apex.
13. A skylight dome as defined in claim 12 wherein said prismatic
portion is an angular sector of said dome portion.
14. A skylight dome as defined in claim 13 wherein said grooves
stop short of said apex.
15. A skylight dome as defined in claim 10 wherein said prismatic
portion is an angular sector of said dome portion.
16. A skylight dome as defined in claim 15 wherein said grooves
stop short of said apex.
17. A skylight dome as defined in claim 10 wherein said grooves
stop short of said apex..Iadd.
18. An improved tubular skylight including a dome to be mounted on
a roof, a light diffuser to be mounted on a ceiling, and a
reflective tube extending between the dome and the light diffuser,
wherein the improvement comprises said dome comprising: a generally
hemispherical body having an apex, said body including a prismatic
portion, said prismatic portion being an angular section of said
dome, said prismatic portion including a plurality of vertical
grooves extending along great circles of said hemispherical body
passing through said apex..Iaddend..Iadd.
19. An improved tubular skylight as defined in claim 18 wherein
said body includes a circular area of non-zero radius centered on
said apex, said prismatic portion and said circular area being
mutually exclusive..Iaddend..Iadd.
20. A skylight dome assembly comprising: a flashing to be mounted
on a roof; and a skylight dome to be mounted on said flashing, said
dome including a prismatic portion and a nonprismatic portion, said
prismatic portion positioned to reflect sunlight passing through
said non-prismatic portion downwardly through said
flashing..Iaddend..Iadd.
21. A skylight dome assembly as defined in claim 20 wherein: said
dome includes a base and an apex above said base; and said
prismatic portion includes a plurality of grooves located between
said base and said apex..Iaddend..Iadd.
22. A skylight dome assembly as defined in claim 21 wherein: said
dome is generally hemispherical and said base is generally
circular; and said grooves extend along great circles of said dome
passing through said apex..Iaddend..Iadd.
23. A skylight dome assembly as defined in claim 22 wherein said
prismatic portion comprises an angular segment of said
dome..Iaddend..Iadd.
24. A skylight dome assembly as defined in claim 23 wherein said
grooves stop short of said apex..Iaddend..Iadd.
25. A skylight dome assembly as defined in claim 21 wherein said
prismatic portion comprises an angular segment of said
dome..Iaddend..Iadd.
26. A skylight dome assembly as defined in claim 20 wherein said
dome includes an apex and said prismatic portion is entirely
outside of a circle surrounding said apex..Iaddend..Iadd.
27. A skylight dome comprising a body having a base and a dome
portion extending above said base, said dome portion including a
prismatic portion defining a plurality of grooves, said dome
portion further including a non-prismatic portion, said prismatic
portion positioned to reflect sunlight passing through said
non-prismatic portion downwardly through said
base..Iaddend..Iadd.
28. A skylight dome as defined in claim 27 wherein: said base is
generally circular and said dome portion is generally
hemispherical..Iaddend..Iadd.
29. A skylight dome as defined in claim 28 wherein said grooves
extend along great circles of said dome portion..Iaddend..Iadd.
30. A skylight dome as defined in claim 29 wherein said prismatic
portion is an angular sector of said dome
portion..Iaddend..Iadd.
31. A skylight dome as defined in claim 30 wherein said dome
portion includes an apex and said grooves stop short of said
apex..Iaddend..Iadd.
32. A skylight dome as defined in claim 27 wherein said prismatic
portion is an angular sector of said dome
portion..Iaddend..Iadd.
33. A skylight dome as defined in claim 32 wherein said dome
portion includes an apex and said grooves stop short of said
apex..Iaddend..Iadd.
34. A skylight dome as defined in claim 27 wherein said dome
portion includes an apex and said grooves stop short of said
apex..Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention relates to skylights, and more particularly
to tubular skylights, which include a reflective tube extending
downwardly from the dome.
Tubular skylights have acquired increasing popularity as a means of
introducing natural light into a building interior. These skylights
include a dome mounted on the building roof, a light diffuser
mounted in the building ceiling, and a reflective tube
interconnecting the dome and the diffuser. Natural light entering
the skylight through the dome reflects downwardly through the tube
to the diffuser. The tube in a sense acts as a gigantic optical
fiber. Typically, the domes are fabricated of acrylic; and the tube
is fabricated of reflective aluminum. A tubular skylight of this
type is sold by ODL, Incorporated, the assignee of the present
invention, under the trademark EZ LIGHT.
The efficiency of such skylights (i.e. the amount of natural light
reaching the building interior) is primarily a function of the
amount of light passing through the dome into the tube and of the
reflective efficiency of the tube. It is desirable to channel or
steer as much light as possible downwardly through the tube to
illuminate the building interior. One such approach includes
positioning a reflector inside the dome above the roof to reflect
light downwardly into the tube. A tubular skylight of this type is
illustrated in U.S. Pat. No. 5,099,622, issued Mar. 31, 1992, to
Sutton, and entitled "Skylight." However, this approach is
relatively complex structurally, relatively expensive, and
aesthetically deficient. Further, the reflector may actually
decrease the performance of the skylight when no direct sunlight is
present, because the reflector blocks a portion of the ambient
light.
SUMMARY OF THE INVENTION
The aforementioned problems are overcome in the present invention
wherein the dome of a tubular skylight includes an exterior surface
having a prismatic portion to reflect light downwardly into the
tube. Preferably, the prismatic portion is located on the northern
portion of the dome. Consequently, sunlight entering the southern
portion, and to a lesser extent the eastern and western portions,
of the dome at relatively low angles is reflected by the prismatic
surface downwardly into the tube.
In the disclosed embodiment, the dome is hemispherical including a
base and an apex. The prismatic surface includes a plurality of
vertical grooves each extending between the base and the apex along
great circles passing through the apex. The grooves begin at the
base and terminate short of the apex. Further preferably, the
grooves are located in an angular segment of the hemispherical
dome.
The prismatic surface increases the amount of light directed or
steered downwardly through the tube. The enhancement is most
notable when the sun is relatively low in the sky as in the
morning, the late afternoon and evening, and during the winter
months. The dome also increases both the portion of the day and the
number of seasons during which the skylight provides effective
interior lighting.
These and other objects, advantages, and features of the invention
will be more fully understood and appreciated by reference to the
detailed description of the preferred embodiment and the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing a tubular skylight having the
dome of the present invention mounted within a building;
FIG. 2 is a perspective exploded view of the tubular skylight;
FIG. 3 is a top plan view of the dome;
FIG. 4 is a sectional view of the dome taken along line IV--IV in
FIG. 3;
FIG. 5 is a fragmentary sectional view of the prismatic portion of
the dome showing the grooves in the exterior surface;
FIG. 6 is a schematic illustration of noon-day sun rays at the
vernal and autumnal equinoxes; and
FIG. 7 is a schematic illustration of morning sun rays at the
vernal and autumnal equinoxes.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A tubular skylight constructed in accordance with a preferred
embodiment of the invention is illustrated in FIGS. 1 and 2 and
generally designated 10. As perhaps most clearly illustrated in
FIG. 2, the skylight includes a dome assembly 12, a diffuser
assembly 14, and a tube assembly 16 interconnecting the dome and
diffuser assemblies. The skylight 10 is installed in a building B
having roof R and ceiling C. More particularly, the dome assembly
12 is mounted within the roof R; and the diffuser assembly 14 is
mounted within the ceiling C. The tubular assembly 16 extends
between the dome assembly 12 and the diffuser assembly 14 to
channel light from the dome to the diffuser. With the exception of
the dome, the skylight 10 is generally well known to those skilled
in the art.
The dome assembly 12 includes a dome 20 and a roof flashing 22. The
dome 20, which is new, will be described in greater detail below.
The flashing 22 mounts within a building roof R to provide a
structural support for the dome 20. The roof flashing 20 includes a
curb 24 and an integral flashing flange 26 extending therefrom. The
roof flashing 22 is available in a variety of constructions to
accommodate shingle roofs, tile roofs, and other selected
applications.
The diffuser assembly 14 includes a diffuser 30, a ceiling trim
ring 32, and a tube/ring seal 34. The diffuser 30 is a prismatic
light diffuser. The ceiling trim ring 32 supports the diffuser 30
within the ceiling C. The tube/ring seal 34 fits about the tube
assembly 16 as will be described and provides a mechanical
interlock between the tube assembly and the diffuser assembly
14.
The tube assembly includes upper and lower adjustable tubes 40 and
42, respectively, and an interconnecting adjustable tube 44. The
upper adjustable tube 40 fits within the roof flashing 22, and the
lower adjustable tube 42 connects to the diffuser assembly 14 by
way of the tube/ring seal 34 as will be described. The adjustable
tube 44 telescopically interfits with both of the adjustable tubes
to accommodate a variety of heights of the roof R above the ceiling
C. Additional adjustable tubes 44 can be used as necessary to
accommodate unusual heights between the roof and the ceiling.
Again, as thus far described, the tubular skylight components are
conventional and generally well known to those in the relevant art.
The novelty of the present invention resides in the dome 20 to be
described hereinafter.
The dome 20 is illustrated most clearly in FIGS. 3 and 4. The dome
includes a circular base 60 and a generally hemispherical portion
62 extending upwardly therefrom and reaching an apex 63. The base
60 includes steps 64 and 65 that fit over and receive the stepped
curb 24 of the roof flashing 22 (see FIG. 2). The second step 65
rests on the top of the curb and is defined by four pairs of
fingers 66 located at 90.degree. intervals around the circumference
of the base 60. Holes 67 are provided to receive fasteners to
secure the dome to the curb.
The generally hemispherical dome portion 60 includes an interior
surface 70 and an exterior surface 72. The exterior surface
includes a prismatic surface or portion 68 and a nonprismatic
surface or portion 69. The prismatic portion is illustrated perhaps
most clearly in FIG. 3 and includes the patterned surface covering
somewhat less than the left half of the dome in a pattern as
described below. The interior surface 70 has a radius 72, and the
exterior surface 74 has a radius 76 in the nonprismatic portion and
a radium 78 in the prismatic portion. The radius 76 is slightly
greater than the radius 78. The nonprismatic portion 69 is
generally uniform in thickness between the inner surface 70 and the
exterior surface 74. The dome portion 60 has an increased thickness
in the prismatic portion 68. Because the prismatic surface is
uneven (i.e. grooved) the distance between the interior surface and
the exterior surface varies. The minimum thickness in the prismatic
portion 68 is approximately equal to the thickness in the
nonprismatic portion 69, and the maximum thickness in the prismatic
portion is approximately twice the thickness in the nonprismatic
portion.
The shape and configuration of the prismatic portion 68 is perhaps
best illustrated in FIG. 3. The prismatic portion 68 includes a
plurality of grooves 71 that molded, cut, or otherwise formed in
the exterior surface 74. Each of the grooves 71 extends along a
great circle passing through the apex 63. Each of the grooves 71
extends from the base 64 to a location short of the apex 63. In the
preferred embodiment, 37 first grooves 71 are formed at 4.degree.
intervals, and 38 second grooves 71 are formed at 4.degree.
intervals offset 2.degree. from the first set of grooves so that
each first groove is bracketed by a pair of second grooves. As
currently contemplated, the grooves 71 are formed by molding;
however, other forming techniques, such as cutting, can be
used.
The exterior angle between the walls of a groove 71 when using the
preferred material is preferably in the range of 86.degree. to
94.degree., with the most preferred angle being 92.degree.. The
groove angles may change with other materials depending on their
indices of refraction. The angle is selected so that direct light
from the dome interior is reflected by the internal reflection of
the prism--not refracted--as it strikes the interior side of the
groove walls. The structure and effect of the described technique
is disclosed in U.S. Pat. No. 4,839,781, issued Jun. 13, 1989 to
Barnes et al, and entitled "Reflector/Refractor."
The prismatic portion 68 comprises an angular segment of the
hemispherical dome. In the preferred embodiment, this segment is
approximately 148.degree. of the 360.degree. circumference. The
grooves 71 stopping short of the apex leaves a pie-shaped portion
82 surrounding the apex of the dome that is part of the
nonprismatic portion 69 of the exterior surface.
The entire dome 20 is fabricated of a single piece of acrylic. The
currently preferred material is that sold under the designation
V825UVA-5A by Rohm & Haas. For a dome 10 inches in diameter,
the dome portion 60 is 0.114 inch thick in the nonprismatic portion
and up to 0.204 inch thick in the prismatic portion. Other
materials suitable for skylight domes may be used and includes
polycarbonates and nylons. Other materials may be used if they
provide the light transmittance and strength characteristics
required in skylight domes.
The particular pattern of the prism will depend on the performance
desired and the anticipated location of the skylight. The
illustrated dome has been designed for use at 40.degree. latitude
as representative of a "normal" U.S. location. The pattern follows
the highest path of the sun, which of course occurs during the
summer.
The light reflectance provided by the prismatic portion 68 is
perhaps best illustrated in FIG. 5. Each of the grooves 71 provides
two apparent reflective surfaces to light rays striking the
surfaces from inside the dome because of the high index of
refraction. Consequently, light impinging on the grooves 71 from
the interior of the dome are reflected back into the interior of
the dome.
Turning specifically to FIG. 5, a light ray L from the interior of
the dome passes through the interior surface 70, then reflects off
the surfaces of two grooves 71 to be returned to the dome interior.
Consequently, light at low angles which would pass directly through
the dome is instead reflected back into the dome interior.
The prismatic portion 68 does not significantly block ambient light
from passing through the dome. Therefore, the dome does not
significantly reduce the amount of ambient light; and the dome does
not decrease the amount of direct light passing into the skylight.
The only losses (approximately 8% in the preferred material) are
due to the material from which the dome is fabricated.
Assembly and Operation
The tubular skylight 10 is installed within a building in
conventional fashion. Vertically aligned holes are cut in the roof
R and the ceiling C. The roof flashing 22 is installed in the roof.
The upper adjustable tube 40 is fitted within the curb 24 of the
roof flashing 22 and slid downwardly until the upper edges of both
are aligned. The dome 20 is fitted over the curb 24 (with the upper
adjustable tube 40 fitted therein) and secured in position using
screws (not shown).
The ceiling trim ring 32 is secured to the underside of the ceiling
C. The tube/ring seal 34 is placed over the lower adjustable tube
42, and the assembly is pushed into the ceiling trim ring from
above the ceiling C. The extension tube 44 is then slid as
necessary to a connecting position between the upper and lower
adjustable tubes 40 and 42. All seams are taped with duct tape.
Finally, the diffuser 30 is installed within the trim ring 32 using
a partial-turn coupling.
FIGS. 6 and 7 illustrate the functional performance of the new dome
20. Turning first to FIG. 6, the dome 20 and tube assembly 16 are
schematically illustrated. Direct light rays 90 are shown entering
the skylight at a 50.degree. angle from the horizontal, which is
the angle of the sun at 40.degree. latitude and 98.degree.
longitude on the vernal and autumnal equinoxes. When the sun is at
this angle, virtually all of the direct rays 90 pass through the
nonprismatic portion of the dome 20 to enter the skylight 10 in
conventional fashion. The reflected rays 90' are illustrated in
dotted lines and illustrate how the light is reflected downwardly
through the skylight assembly.
FIG. 7 illustrates the performance of the skylight dome when the
sun is relatively low in the sky. Specifically, the direct sunlight
rays 90 arrive at the skylight dome basically on the horizontal.
The direct rays 90 pass directly through the nonprismatic portion
69. Without the prismatic portion 68 of the present invention, the
direct rays 90 would continue to pass through the skylight dome so
that none of those rays would pass downwardly into the tube.
Instead, the prismatic portion 68 reflects the direct rays 90
downwardly through the dome at a variety of angles. The reflected
rays 90' are illustrated as dashed lines and pass downwardly at a
variety of reflected angles.
The object of the present invention is to direct light downwardly
through the tube at virtually any angle on the premise that all of
the downwardly direct light enhances, even in some small fashion,
the light exiting the bottom of the tube. Additionally, as can be
seen, some of the rays pass directly through the tube without
further reflection off the tube wall to the bottom of the tube
assembly 16.
The present invention greatly enhances the performance of the
tubular skylight by directing or steering a larger percentage of
the available light downwardly through the tube. The prismatic
portion 68 enhances the performance of the skylight tube
particularly when the sun is relatively low in the sky as occurs in
the morning, the late afternoon, and the winter.
The above description is that of a preferred embodiment of the
invention. Various alterations and changes can be made without
departing from the spirit and broader aspects of the invention as
defined in the appended claims, which are to be interpreted in
accordance with the principles of patent law including the doctrine
of equivalents.
* * * * *