U.S. patent application number 11/392414 was filed with the patent office on 2007-10-04 for light transmitting building material and method for producing the same.
Invention is credited to Gregory R. Martin.
Application Number | 20070230209 11/392414 |
Document ID | / |
Family ID | 38558649 |
Filed Date | 2007-10-04 |
United States Patent
Application |
20070230209 |
Kind Code |
A1 |
Martin; Gregory R. |
October 4, 2007 |
Light transmitting building material and method for producing the
same
Abstract
A light-transmitting structure for use as a building block or
panel, and a related method of fabrication. The structure includes
a composite of a primary building material and one or more
light-transmitting elements. The primary building material may have
structural and/or insulative characteristics. The
light-transmitting elements extend from one surface of the primary
building material to the other and preferably make up a small part
of the bulk of the structure. One or more light-concentrating
elements are positioned on one or both surfaces of the structure
and are configured to concentrate incoming light rays to the
light-transmitting elements. The light-transmitting elements may be
optical fibers, optical film in a parallel or intersecting
arrangements, or other suitable geometries. The light-concentrating
elements may be spherical, aspherical, or other geometries suitable
for enabling light transmission through the primary building
material via the light-transmitting elements. The structure may be
fabricated in a variety of ways. In one process, the
light-transmitting and light-concentrating elements may be formed
separately and joined together in an aligned manner. In another
process, both elements may be formed at the same time, either using
a preformed mold, extrusion or shaping and selectively curing
portions of a fluid with optical characteristics. The panel may be
used to introduce light and or heating sunshine through the
structure with little impact on its structural and/or insulative
characteristics.
Inventors: |
Martin; Gregory R.; (Acton,
ME) |
Correspondence
Address: |
CHRIS A. CASEIRO
VERRILL DANA, LLP
ONE PORTLAND SQUARE
PORTLAND
ME
04112-0586
US
|
Family ID: |
38558649 |
Appl. No.: |
11/392414 |
Filed: |
March 29, 2006 |
Current U.S.
Class: |
362/576 ;
362/147; 362/580 |
Current CPC
Class: |
E04F 13/16 20130101;
F21S 11/00 20130101; E04C 2/54 20130101; G02B 6/06 20130101; E04C
2/322 20130101; G02B 6/3672 20130101 |
Class at
Publication: |
362/576 ;
362/580; 362/147 |
International
Class: |
E04H 15/10 20060101
E04H015/10 |
Claims
1. A light transmitting building panel comprising: a. a first
surface and a second surface, the first surface including thereon
one or more light-concentrating elements arranged to concentrate
light striking the first surface; b. one or more light-transmitting
elements arranged to receive concentrated light from the one or
more light-concentrating elements, wherein each of the one or more
light-concentrating elements extends from the first surface to the
second surface; and c. a primary building material extending
between the first surface and the second surface, wherein the
primary building material spaces individual ones of the one or more
light-transmitting elements from one another, and wherein the
primary building material does not transmit light as well as the
one or more light-transmitting elements.
2. The light transmitting building panel as claimed in claim 1
wherein the light-concentrating elements are arranged as an array
of lenses.
3. The light transmitting building panel as claimed in claim 1
wherein the light-transmitting elements are optical fibers.
4. The light transmitting building panel as claimed in claim 3
wherein the optical fibers have a cross section that is not
round.
5. The light transmitting building panel as claimed in claim 1
wherein the light transmitting-elements are sheets of optical
material.
6. The light transmitting building panel as claimed in claim 1
wherein the light-transmitting elements form an extended grid of
optical material.
7. The light transmitting building panel as claimed in claim 1
wherein the primary building material is a thermal insulator.
8. The light transmitting building panel as claimed in claim 7
wherein the primary building material is a foam insulation.
9. The light transmitting building panel as claimed in claim 7
wherein the primary building material is an insulative powder
wherein the insulative powder is retained in the panel between the
first surface and the second surface, and wherein the second
surface is formed of a light transmitting material.
10. The light transmitting building panel as claimed in claim 1
wherein the primary building material is a load bearing
material.
11. A method for fabricating a light-transmitting panel having
structural and/or insulative characteristics, the panel including a
material used to form a primary building material with
light-transmitting elements extending therethrough and
light-concentrating elements on at least one surface thereof, the
method comprising the steps of: a. injecting the material used to
form the primary building material into a mold cavity of selectable
dimensions and including an array of pins extending through the
thickness of the cavity and arrayed in a pattern of selectable
configuration of the light-transmitting elements; b. curing the
material with channels in the shape of the pin array to form a
panel; c. removing the array of pins from the channels; d.
inserting a fluid having optical characteristics into the channels;
e. curing the fluid to form the light-transmitting elements; and f.
applying the light-concentrating elements to a surface of the
panel
12. The method as claimed in claim 11 wherein the channels are in
the form of individual ports.
13. A method for fabricating a light-transmitting panel having
structural and/or insulative characteristics, the panel including a
material used to form a primary building material with
light-transmitting elements extending therethrough and
light-concentrating elements on at least one surface thereof, the
surfaces of the panel including an inner wall and an outer wall,
the method comprising the steps of: a. extruding a plurality of the
light-transmitting elements in a grid array, b. cutting the
extruded light-transmitting element array to form a panel, c.
affixed to the inner wall of the one surface of the panel; d.
applying the material used to form the primary building material to
fill the spaces within the light-transmitting element array; and e.
affixing a molded array of the light-concentrating elements to the
outer wall of the surface of the panel.
14. The method as claimed in claim 13 wherein the
light-concentrating elements are formed by polymer injection
molding.
15. The method as claimed in claim 13 wherein the material used to
form the primary building material is a foamable polymer insulative
material.
16. The method as claimed in claim 13 wherein steps c and e are
reversed.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to building structures. More
particularly, the present invention relates to traditionally opaque
building materials including, but not limited to, cement, concrete
blocks, wood, fiber batting and solid, cellular and porous
polymeric structural and cover materials. Still more particularly,
the present invention relates to systems and methods for making
such traditional building materials capable of light
transmission.
[0003] 2. Description of the Prior Art
[0004] Buildings within which people live, work and play must have
certain physical characteristics to ensure structural integrity in
a manner that preserves the condition of the building and the
security and comfort of the people within. That is, buildings are
built to remain in place for some period of time, and to be used as
intended, under the particular environmental conditions to be
expected where the building is located. Unfortunately, these
desired characteristics of a building tend to produce a conflict in
the selection of materials used to build the building.
[0005] The primary conflict in building material selection relates
to the use of materials that can be divided into two general
categories: opaque and light transmitting. Opaque materials are
those that provide structural integrity and protection from the
external environment. Opaque materials most commonly used to
fabricate buildings include cement, concrete blocks, wood, fiber
glass insulation and solid, cellular and porous polymeric
structural and cover materials. Light transmitting materials, on
the other hand, provide the building occupants with day lighting
and optionally the ability to observe the environment beyond the
building without direct exposure thereto. Light transmitting
materials most commonly used in the fabrication of at least
portions of a building, primarily the windows, include glass and
polymeric materials.
[0006] The limitations associated with each type of material are as
fundamental as their advantages. Building occupants cannot see
through the opaque structural materials to the outside environment.
The opaque materials do not let in sunlight. As a result, sunlight
cannot heat the interior of the building and artificial lighting is
required to light the interior of the building. On the other hand,
a window does not have the insulative or structural characteristics
associated with opaque materials. As a result, building heat loss
tends to occur through its windows much more so than through its
opaque walls.
[0007] Some attempts have been made or disclosed to address the
limitations associated with opaque building materials. Published US
patent application Pub. No. 2005/0183372 and PCT application no. WO
03/097954 describe a building block with light-transmitting fibers,
apparently sold under the trade name Litracon.TM. offered by the
Litracon Company of Hungary. The Litracon.TM. product is fabricated
in blocks that may be placed together. The visual image is blurry
through the blocks and light transmission appears to be diffuse
when the sample shown on the company's website is viewed. This is
due to the optical fibers' property of transmitting light entering
from many angles causing mixing and blurring of all but the closest
objects or shadows. Also, the optical fibers provide for some light
transmission but the light transmission is limited to the
percentage of optical fiber included in the material. This creates
a large trade off between light transmission and maintenance of the
physical properties of the building material. U.S. Pat. No.
4,796,404 describes a light-transmitting thermal barrier. The light
is also diffused in this structure. Further, the structure requires
a trade-off between thickness, which determines thermal insulation
characteristics, and light transmission. Finally, the Cabot
Corporation offers an aerogel powder used to fill the core of
lighting panels to enhance thermal insulation. However, the powder
scatters light such that the panel may not be used as a window and,
again, there is a trade off between light transmission and thermal
insulation characteristics. Also, none of the above solutions
provide for the selective transmission of light based on incoming
angle which can allow for heat gain in a building during the winter
months while rejecting building heating light during the summer
months, for example.
[0008] Therefore, what is needed is a building material having
structural and/or insulative characteristics of interest in the
fabrication of commercial and residential buildings while providing
such a material with optimized light-transmitting characteristics.
Also, what is needed is such a building material wherein light
passing therethrough may be focused rather than diffused. Further,
what is needed is such a light-transmitting material that enables
relatively clear viewing from inside the building of features
outside of the building. Still further needed is a building
material that can selectively transmit a majority of sunlight
during the heating season while limiting light transmission during
the non-heating season.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide building
materials having structural and/or insulative characteristics of
interest in the fabrication of commercial and residential
buildings, and further having light-transmitting characteristics.
It is also an object of the present invention to provide such a
building material that transmits a large percentage of the light
striking the panel's outer surface, the percentage being largely
independent of the panel's thickness. In one preferred embodiment
the panel transmits most of the light striking the outer surface
during winter months while rejecting most of the light during the
summer months. It is a further object of the present invention to
optionally provide such a light-transmitting material that enables
relatively clear viewing from inside the building of features
outside of the building. In this embodiment the angles of light
transmitted are tightly controlled such that image transmission is
possible.
[0010] These and other objects are achieved by the present
invention, which is a combination of components including a primary
structural and/or insulative material, one or more
light-transmitting elements, and one or more light-concentrating
elements. The invention is a building block or panel of selectable
thickness formed primarily of the structural and/or insulative
material. The structural material may be, for example, concrete.
The insulative material may be, for example a polymeric foam. This
insulative and/or structural material will henceforth be referred
to as the primary building material. The light-transmitting
element(s) extend completely through the thickness of the panel,
from the panel's first lateral surface to its second lateral
surface. The primary building material occupies all or
substantially all of the space between the faces of the panel not
otherwise occupied by the light-transmitting elements. The
light-transmitting elements are optically transparent materials,
preferably formed of glass or polymeric material. It is intended
that the light-transmitting elements make up a relatively small
portion of the overall cross-section of the panel. The
light-concentrating elements are attached to one or both of the
first and second lateral surfaces of the panel. They are configured
and arranged such that a majority of light (either from a single
angle or multiple angles) striking the lateral surface of the panel
is concentrated into the light-transmitting elements. As a result,
a majority of the light striking the panel made of substantially
opaque building material passes through the light-transmitting
elements from the one lateral surface through to the other. A
substantial amount of light is transmitted into the interior of the
building using a minimal amount of light-transmitting elements,
thereby maximizing the amount of structural and/or insulative
material of the panel.
[0011] In one embodiment of the invention, the light-concentrating
elements concentrate light striking the first side of the panel
oriented to face the exterior of the building from a selectable
specific angle or set of angles such that the light transmitted
from the second or interior-facing surface of the panel forms an
image, as would be the case with a window. In a second embodiment
of the invention, the light-concentrating elements concentrate
light from the exterior through the light-transmitting elements
from as wide a set of entrance angles as possible such that the
panel transmits a maximum percentage of light across the
interior-facing surface to the interior of the building to maximize
lighting and/or heating within the building. In a third embodiment,
the light-transmitting elements are shaped to allow light from the
light-concentrating elements to enter them only from certain angles
of the sun so as to selectively allow sunlight to cross the panel
when desired, such as only during specific hours of the day or
specific days of the year. Additionally, one or more methods of
fabricating the panels of the present invention, including the use
of commercially available materials and existing general
fabrication techniques, are described herein.
[0012] These and other advantages and aspects of the panel and
related method of fabrication of the present invention will become
apparent upon review of the following detailed description, the
accompanying drawings, and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a cross-sectional side view of the
light-transmitting panel of the present invention showing the
interior-facing side of the panel to the left and the
exterior-facing side of the panel with array of light-concentrating
elements to the right.
[0014] FIG. 2 is a front view of the exterior-facing side of the
panel of the present invention showing one embodiment of an array
of light-concentrating elements.
[0015] FIG. 3 is a cross-sectional side view showing an individual
light-concentrating element concentrating light through a
light-transmitting element with the interior-facing side of the
panel of the present invention to the left and the exterior-facing
side of the panel to the right.
[0016] FIG. 4 is a front elevation view of a spherical lens as a
light-concentrating element.
[0017] FIG. 5 is a cross-sectional side view of a set of
cylindrical lenses as the light-concentrating elements.
[0018] FIG. 6 is a front elevation view of a panel of the present
invention showing the light-transmitting elements as an array of
fibers.
[0019] FIG. 7 is a front elevation view of a panel of the present
invention showing the light-transmitting elements as a parallel
array of optical films.
[0020] FIG. 8 is a front elevation view of a panel of the present
invention showing the light-transmitting elements as a grid array
of optical films.
[0021] FIG. 9 is a front elevation view of a close-packed array of
spherical lenses showing the location of curved light guides
arranged for transmitting sunlight through most of the day during
winter months while rejecting most of the sunlight during summer
months.
[0022] FIG. 10 is a cross-sectional side view of the close-packed
array of spherical lenses of FIG. 9, showing a close-up of two
lenses with associated light-transmitting elements.
[0023] FIG. 11 is a sun chart used for calculating the sun's path
for the latitude coordinate indicated to enable selection of the
positioning of the light-transmitting elements of the embodiment of
the invention of FIGS. 9 and 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] A building panel 10 of the present invention is shown in
FIG. 1. The panel 10 includes a first surface 14 that will be
referred to herein as an exterior-facing panel side 14 or simply
exterior side 14. The panel 10 further includes a second surface 12
that will be referred to herein as an interior-facing panel side 12
or simply interior side 12. The panel is preferably fabricated with
a uniform selectable thickness extending from the exterior side 14
to the interior side 12, although it is contemplated that the
thickness may be varied if desired (as when the outside surface is
made to resemble a house's siding). The panel 10 is effectively a
three-dimensional structure having selectable dimensions
establishing the area it covers. The coverage area may be
rectangular, circular or other shape and the panel may be framed or
not for installation. The interior side 12 and the exterior side 14
are referred to as such to provide proper orientation of the
components of the panel 10 when the panel forms part of a building
structure. Specifically, the interior side 12 is that side of the
panel 10 which faces toward the interior of the building, while the
exterior side 14 is that side of the panel 10, which faces the
environment surrounding the building, of which the panel 10 forms a
part.
[0025] With continuing reference to FIG. 1 and reference to FIG. 2,
the panel 10 is fabricated of a combination of components,
including a primary building material 16, one or more
light-transmitting elements 18, and one or more light-concentrating
elements 20. The primary building material 16 provides the
structural integrity and/or any thermal insulation characteristics
of the panel 10. It is to be noted that the primary building
material 16 may be a primarily insulative material, with structural
support provided to the panel 10 by some additional means. For
example, both the interior side 12 and the exterior side 14 of the
panel 10 may be formed of continuous sheets of transparent polymer,
which are held together by the light transmitting-elements 18 to
form a strong panel, even when the primary building material 16 is
a non-structural material such as fiberglass insulation, or an
insulative powder such as aerogel powder or perlite. The
light-transmitting elements 18 extend completely through the
thickness of the panel between the interior side 12 and the
exterior side 14. The light-concentrating elements 20 are
positioned on the exterior side 14 of the panel 10. However, it is
contemplated that the present invention may be formed with the
light-concentrating elements 20 on the interior side 12 instead of
the exterior side 14, or on both the interior side 12 and the
exterior side 14. The location of the light-concentrating elements
20 is dependent upon the particular light and/or heat transmission
characteristics of interest for the panel 10.
[0026] The arrangement of the panel 10 of the present invention
provides improved energy consumption characteristics of the
building of which it forms a part. As previously noted, windows
generally have lower insulative or R-value characteristics than
walls and insulative materials. Windows therefore lose heat at a
faster rate than do the walls when the exterior of the building is
colder than the interior. However, the panel 10 effectively acts as
a window in that it is configured to allow light transmission. It
also has insulative characteristics approaching those of insulated
walls and, in fact, may be a net heat gain as light permitted to
pass therethrough can be used as a heat source at the building's
interior. The panel 10 may be configured to transfer light from a
specified entry angle (or angles) and concentrate it through the
light-concentrating elements 20 to the light-transmitting elements
18 to produce on the interior side 12 of the panel 10 a discernible
image representative of the image in existence at the exterior side
14 of the panel 10. That may be achieved by using lens-like optical
geometries as the light-concentrating elements 20 on the exterior
side 14 of the panel 10. Alternatively, the panel 10 may be
configured to collect light from the outside of the building at
multiple angles in order to maximize light and/or heat transfer,
without regard to image quality. That may be achieved by using
nonimaging optical geometries as the light-concentrating elements
20 on the exterior side 14 of the panel 10. It may also be achieved
by using spherical lens arrays coupled to light guides that are
curved such that as the sun's angle changes in the sky the light
focused to the back side of the lens continues to enter the light
guide as will be described herein with respect to FIGS. 9-11. As an
example, the panel 10 may be used as a skylight or wall panel,
configured to produce either or both of discernible images (without
the inherent heat loss associated with conventional windows and
skylights) and light/heat transfer improvement.
[0027] An effective aspect of the panel 10 of the present invention
is the arrangement of the light-transmitting elements 18 with
respect to the primary building material 16 for both imaging and
light/heat transfer improvement. Specifically, each of the
light-transmitting elements 18, which elements are preferably some
form of light-transmitting fibers, are combined with the primary
building material 16 such that they form a small percentage of the
total volume of the panel 10. In that way, the structural and/or
insulative characteristics of the panel 10 approach that of the
particular material used as the primary building material 16. The
addition of the light-concentrating elements 20 on the surface only
of the panel 10 provides a far greater light-impacting surface than
the ends of the individual fibers that are the light-transmitting
elements 18, but without effect on the structural and insulative
characteristics of the panel 10 as established primarily by the
characteristics of the primary building material 16. That light
hitting the light-concentrating elements 20 is then substantially
captured, the extent of that capturing being dependent upon the
number, type and location of the individual light-transmitting
elements 18 and the light-concentrating elements 20.
[0028] One example of the panel 10 as an insulative panel appearing
to be transparent at least from within the building includes an
array of lenses as the light-concentrating elements 20 positioned
on the exterior side 14 of the panel 10, each lens having a
diameter about 10 times larger than the diameter of the individual
fibers that are the light-transmitting elements 18. In this
arrangement, there would be a one-to-one correspondence of lens to
fiber. In that arrangement, the cross-sectional area of the fiber
is only about 1/100 of the cross-sectional area of the lens. By
close packing the lenses to cover substantially the entire exterior
side 14 of the panel 10, the fibers would only consume about one
percent of the total volume of the panel 10, leaving the remaining
99% of the panel 10 to be formed of the primary building material
16. As a result, the panel 10 is substantially the primary building
material 16, for structural and/or insulative purposes, while at
the same time most all of the light contacting the exterior side
1.4 of the panel 10 from a set of angles is transmitting through to
the interior side 12 of the panel. If used primarily for insulative
purposes, the panel 10 would have an R-value nearly the same as
that of conventional insulative building materials, but without
appearing to be opaque to the individual at the interior side 12 of
the panel 10. The quality of the image observed by that individual
is dependent upon the lens size selected, the observed image formed
of pixels corresponding in size to the size of the lenses
positioned on the exterior side 14 of the panel 10.
[0029] The application of the light-concentrating elements 20 to
the exterior side 14 of the panel 10 resolves the problem
associated with existing attempts to render structural and/or
insulative materials transparent, at least to an extent.
Specifically, the light-concentrating elements 20 enable a much
higher light transmission capability than possible with the
light-transmitting elements 18 alone. As an example, a building
product formed substantially of structural or insulative material
with one percent of light-transmitting fibers extending from one
surface to the other will only transmit to one surface something
less than one percent of the light contacting the other surface,
assuming normal losses such as from surface reflection. If more
light transmission is of interest, more light-transmitting fibers
must be incorporated. However, if there is an interest in
transmitting a substantial portion of the light, then a
corresponding proportion of the building product would have to
include the light-transmitting fibers, with a corresponding
reduction in the amount of structural/insulative material making up
the building product and related reduction in structural/insulative
characteristics.
[0030] FIG. 3 provides a close-up view of the concentrating or
focusing of light into an exemplar one of the light-transmitting
elements 18 by an exemplar one of the light-concentrating elements
20. Initial light rays 22 contacting the light-concentrating
element 20 from a source external to the building of which the
panel 10 forms a part are focused into the light-transmitting
element 18. Dependent upon the particular material selected to form
the light-transmitting element 18, a substantial portion of
concentrating light rays 24 pass therethrough and emerge at the
interior side 12 of the panel 10 as a transmitted light ray
composition 26 producing an image pixel corresponding in size to
the size of the light-concentrating element 20. The size, shape,
material selected and proximity of the light-concentrating element
20 determines the focal point 28 of the focused initial rays 22 and
the percentage of light passing to the light-transmitting element
18.
[0031] Those skilled in the art will recognize the types of
materials and shapes to select for the fabrication of the
light-concentrating elements 20, and their placement with respect
to the location of the light-transmitting elements 18 on the
exterior side 14 of the panel 20. For example, one shape of the
light-concentrating element 20 may be spherical, as shown in FIG.
4, or it may be cylindrical, as shown in FIG. 5. If formed as
spheres, the light-concentrating element 20 may be used to focus
the initial light rays 22 to a point, suitable for
light-transmitting elements 18 that are individual fibers of
circular cross-section. Alternatively the fibers can possess any
cross-sectional shape such as those with an arch-like geometry to
capture the sun's arch like track through the sky as the focused
light forms a point that moves in an arch across the back surface
of the corresponding lens element. If formed cylindrically, the
light-concentrating element 20 may be used to focus the initial
light rays 22 into a line rather than a point, suitable for
light-transmitting elements 20 that are in a form other than
individual fibers. The use of multiple optical elements directing
light into a single light-transmitting element is also envisioned
to aid in the formation of crisp images.
[0032] In the example embodiment of the panel 10 of the present
invention as described above, the light-transmitting elements 18
have been described as light-transmitting fibers arranged within
the primary building material 16. An example representation of the
arrangement of such light-transmitting fibers, identified
individually as fibers 30, is shown in FIG. 6. It can be seen that
the example configuration includes the fibers 30 in an evenly
spaced square pattern within the primary building material 16.
Alternatively, the fibers 30 may be positioned within the primary
building material 16 in a close-packed pattern or a randomized
pattern, dependent upon the particular light-transmitting
characteristic of interest. The number and size of the fibers 30
are also selectable as a function of the particular
light-transmitting characteristic of interest. The fibers 30 may be
used in combination with the light-concentrating elements 20 shaped
as represented in FIG. 4.
[0033] A first alternative embodiment of the configuration of the
light-transmitting elements 18 of the panel 10 of the present
invention is shown in FIG. 7. In that configuration, the
light-transmitting elements, identified as sheets 32, are formed
planar films of light-transmitting material positioned in a uniform
spacing through the thickness of the panel 10 and retained in
position by the primary building material 16. The panel 10 is
formed as a lamination of the primary building material 16
preferably alternating with the sheets 32. The sheets 32 may be
uniformly spaced, as shown, or they may be staggered in alternative
or randomized patterns, dependent upon the light-transmitting
characteristic of interest. Additionally, one or more of the
individual light-transmitting sheets 32 may be formed of uniform
thickness from the exterior side 14 to the interior side 12 of the
panel 10. Alternatively, the sheets 32 may be of varied thickness,
with the sheet thickness substantially uniform through the primary
building material 16, but having either or both ends thereof at the
exterior side 14 and/or the interior side 12 of greater thickness.
This alternative thickness arrangement allows for greater
light-receiving or light-producing capability where the light
enters or exits the sheets 32, but without increasing the overall
volume of the light-transmitting elements within the primary
building material 16. As a result, this particular arrangement aids
in maintaining the structural and/or insulative characteristics of
the panel 10 while enhancing light transmission. The sheets 32 may
be used in combination with the light-concentrating elements 20
shaped as represented in FIG. 5.
[0034] A second alternative embodiment of the configuration of the
light-transmitting elements 18 of the panel 10 of the present
invention is shown in FIG. 8. In that configuration, the
light-transmitting elements, identified as sheets 32, are formed
planar films of light-transmitting material positioned in a grid
pattern through the thickness of the panel 10 and retained in
position by the primary building material 16. The sheets 32 may be
uniformly spaced from one another by the primary building material
16 and crossed, as shown, or they may be staggered in alternative
or randomized patterns, dependent upon the light-transmitting
characteristic of interest. The space of the panel 10 between the
interior side 12 and the exterior side 14 not occupied by the
sheets 32 is occupied by the primary building material 16.
Additionally, one or more of the individual light-transmitting
sheets 32 may be formed of uniform thickness from the exterior side
14 to the interior side 12 of the panel 10. Alternatively, the
sheets 32 may be of varied thickness, with the sheet thickness
substantially uniform through the primary building material 16, but
having either or both ends thereof at the exterior side 14 and/or
the interior side 12 of greater thickness. This alternative
thickness arrangement allows for greater light-receiving or
light-producing capability where the light enters or exits the
sheets 32, but without increasing the overall volume of the
light-transmitting elements within the primary building material
16. As a result, this particular arrangement aids in maintaining
the structural and/or insulative characteristics of the panel 10
while enhancing light transmission. The sheets 32 may be used in
combination with the light-concentrating elements 20 shaped as
represented in FIG. 5.
[0035] A third embodiment of the configuration of the
light-transmitting elements 18 of the panel 10 of the present
invention is shown in FIGS. 9 and 10. In that configuration the
light-transmitting elements 18, extend through the primary building
material 16 from the interior side 12 to the exterior side 14.
However, rather than straight-line individual fibers or flat panels
as shown in FIGS. 6-8, the light-transmitting elements 18 are
arched or curved in cross-section as shown in FIG. 9. The extent of
the curvature of each light-transmitting element 18 is dependent
upon the desire to facilitate or block light transmission through
the panel 10. The curvature may be simple or compound.
[0036] As an example, if there is an interest to aid in warming a
building using the panel 10 during winter months and to minimize
sunlight-generating heat during summer months, the
light-transmitting elements 18 may be arranged as shown in FIG. 9
with respect to the sun's passage through the sky as represented in
FIG. 11. This arrangement would focus and transmit more sunlight
when the sun is low on the horizon (winter months) while focusing
and transmitting less light when the sun is high (summer months).
In general, the light-transmitting elements 18 may be arranged in
the primary building material 16 and in relation to the
light-concentrating elements 20 to maximize or minimize light
transmission through the panel 10 as desired by conforming with the
arch of the sun when and where desired. The light-transmitting
elements 18 may be formed as individual shaped fibers or continuous
sheet with a repeating arch-shaped curve throughout the sheet.
[0037] The embodiment of the present invention shown in FIG. 9 also
shows the array of light-concentrating elements 20 in a
close-packed arrangement. This arrangement may be preferably for
the light-transmitting element 18 orientation shown in any of the
figures. The close packing of the light-concentrating elements 20
minimizes dead spaces, which dead spaces reduce the ability to take
maximum advantage of capturing light transmitted by the sun. The
space between individual lens is packed with primary building
material 16 which is essentially insulative material. That
insulative material does not aid in concentrating light to the
light-transmitting elements 18. Nevertheless, a trade-off may be
made between transmission effectiveness and fabrication goals.
[0038] Any of the three alternative arrangements of the
light-transmitting sheets 32 as shown in FIGS. 7-10 may have
certain advantages over use of the light-transmitting fibers 30 of
FIG. 6. Specifically, it may be easier, and therefore less
expensive, to fabricate the sheets 32 rather than the fibers 30.
Additionally, the sheets 32 enable the individual viewing the
interior side 12 of the panel 10 to observe the transmitted image
from multiple angles within the building. That is, unlike light
emission from a point, light emission from a plane (the sheets 32)
allows for an image to shift when viewed from multiple angled
observances of the plane. Use of the sheets 32 in a grid pattern as
shown in FIG. 8 increases the number of angles from which the panel
10 may be viewed and the observable representation of the image on
the other side of the panel 10 maintained. Of course, the sheets 32
take up a greater portion of the overall volume of the panel 10
than do a corresponding number of fibers 30, such as, for example,
when a like number of like-sized lenses are used as the
light-concentrating elements 20. Further, as noted, the optional
use of light-transmitting with curved arches 19 of the
light-transmitting elements 18 of FIGS. 9 and 10 allows for the
formation of panels that transmit light during selected times of
the day and year to provide building heating during only the winter
months, for example, or lighting at only specific times of the
day.
[0039] The panel 10 of the present invention in the several
embodiments shown and in other related embodiments may be
fabricated in a variety of ways to produce the several arrangements
and configurations of light-transmitting elements 18 as described
herein. The panel 10 may be fabricated using a thermoplastic
material to form the light-transmitting elements 18. The
thermoplastic material may be extruded through a die or set of dies
to create an array of cylinders, strands or fibers. The formed
light-transmitting elements 18 may then be attached as an array of
desired configuration to the inner wall of the component
functioning as the exterior side 14 of the panel 10 to be formed.
The primary building material 16 is then applied to the same inner
wall of the exterior side 14 in a manner that substantially or
completely fills the gaps between individual ones of the
light-transmitting elements 18. The primary building material 16
may be any material suitable for filling the gap and performing as
an insulative or structural material. For example, the filling
material may be a foamable polymer. The light-concentrating
elements 20 may then be applied to the outer wall of the exterior
side 14 of the panel. The light-concentrating elements 20 may be
molded in place on the exterior wall or they may be preformed and
bonded to the exterior wall. For example, the material used to
produce the light-concentrating elements 20 may be a polymer
material capable of being injection molded or thermoform molded in
situ. Generally stated, the panel 10 may include extruded
light-transmitting elements 18 spaced from one another by a filler
material as the primary building material 16, and injection-molded
polymeric light-concentrating elements 20.
[0040] In regard to the panel 10 including one or more fibers 30 as
represented in FIG. 6, there are several fabrication options. In a
first fiber-based panel fabrication option, strands of optical
fiber held on a spool may be pushed or pulled through a fluid,
which fluid may be processed into a solid, such as an insulative
foam solid that is represented as the primary building material 16.
For example, the liquid may be polyurethane curable into a foamed
solid. The fibers are positioned in the uncured fluid where desired
prior to the curing step. Strands of fibers may be repeatedly
positioned within the fluid to build up a grid with an appearance
such as that shown in FIG. 6. The fluid may be cured after the
fiber strands have been positioned where desired. The resultant
foam/fiber strands composition may be cut or otherwise formed into
panels of building material having a light-transmitting
characteristic. The light-concentrating elements 20 may then be
added to a side of the fabricated panel defined as the exterior
side 14 in a concentrator adding process described herein. It is to
be noted that the fiber strands may be extruded and positioned in
the fluid rather than pulled or pushed from a spool. It is also to
be noted that the fluid material may be more structural than
insulative, such as a concrete fluid allowed to cure with the fiber
strands in position where desired.
[0041] In a second fiber-based panel fabrication option, the fluid
may be allowed to cure or otherwise harden but having channels
established therein for subsequent placement of the
light-transmitting elements 1.8. The fiber strands may then be
drawn into the channels so formed. Alternatively, the channels may
be filled with a liquid that will cure into an optical material,
such as an optical epoxy. The cured optical epoxy has
light-transmitting characteristics suitable for the intended
purpose. In this fabrication option, the material used to. form the
primary building material 16 may be poured or injected into a mold
cavity of selectable dimensions and having surfaces treated with a
release material. The mold cavity includes an array of pins
extending through the thickness of the cavity and arrayed in a
pattern of selectable configuration. The poured or injected
material is allowed to cure, foam or otherwise harden and the
resultant solid with channels in the shape of the pin array is
removed. Alternatively, the primary building material 16 can be
extruded with the air channels left open. The optical material is
then inserted into the formed channels. This fabrication method
enables use of relatively sophisticated fiber array geometries.
Additionally, the light-concentrating elements 20 may be formed as
part of the process, based on inserts placed in the mold. For
example, the light-concentrating elements 20 may be formed as
Winston cones. Further, this method of fabrication allows for
fabrication of the light-transmitting elements 18 and the
light-concentrating elements 20 at the same time, rather than
fabrication of the panel and subsequent attachment of the
light-concentrating elements 20 thereto.
[0042] In a third fiber-based panel fabrication option, the fibers
and the structural material would be formed at the same time in a
coextrusion process. That is, the material used to form the primary
building material 16 would be forced in or through a mold or die
along with the material forming the fiber strands oriented in a
desired configuration. The coextruded composition is cut to desired
thickness to produce individual panels in a continuous process.
Optionally, a third material may be extruded to provide an
interface with a low refractive index between the optical material
of the light-transmitting elements 18 and the primary building
material 16. This extrusion method may be well suited for
high-volume automated manufacturing.
[0043] The fabrication of the fiber-based panels may require more
complex operations than the fabrication of the sheet-based panel
represented in FIG. 7. One method for fabricating the sheet-based
panel involves unrolling optical film from a roll into a sheet of
selectable dimensions. The sheet is coated or otherwise treated
with the fluid material, which is then allowed to cure into solid
form with the sheet adjacent thereto. The sheet and material may be
positioned within a retainer, such as a trough or mold, with
dimensions approximating the desired cross-sectional dimensions of
the finished panel. The process of placing sheets and the fluid may
be repeated until a satisfactory buildup of the composition is
completed. Alternatively, the sheets and structural material may be
coextruded in a manner similar to that described above for the
third fiber-based panel fabrication option. In another alternative,
the sheet of optical film and the primary building material 16 may
be preformed sheets of appropriate thicknesses that are alternately
stacked and then bonded to a preformed light concentrating array on
one surface perpendicular to the stack, such as a lenticular array,
and an optical film or sheet on the other side. The primary
building material 16 may be a nonmetallic material such as a
foamable urethane or a concrete. The finished lay up may form a
single panel or may be cut into multiple panels. The
light-concentrating elements 20 may then be applied to a selected
surface of the formed panel.
[0044] The grid pattern of the sheet-based panel represented in
FIG. 8 may be fabricated in a manner as described in the first
fiber-based panel fabrication option, but with fibers of optical
material replaced with the primary building material 16 coated in a
liquid that will cure into the optically transparent grid pattern
when sections of the primary building material 16 are placed
together. Alternatively, the primary building material 16 and the
light-transmitting elements 18 may be coextruded in an intersecting
pattern. Alternatively, the light-transmitting elements 18 may
alone be extruded and then the resultant grid can be filled with
the primary building material 1 6m which may be an insulative
powder.
[0045] The light-transmitting elements 18 as curved light guides
represented in FIGS. 9 and 10 may be fabricated by coextrusion.
They may also be extruded, molded or thermoformed, for example, and
then spaced with sheets of the primary building material 16 or
coated with a liquid that will cure to form the primary building
material 16 with the light-transmitting elements 18 therein. The
light-transmitting elements 18, may also be formed as a grid with
fabrication methods as mentioned above.
[0046] As noted, the light-concentrating elements 20 provide an
advantage of the present invention in maximizing light transmission
while minimizing adverse effects on the structural or insulation
characteristics of the panel 10. For that reason, it is desirable
that they be applied to the exterior side 14 and configured in a
way that focuses incoming light to the light-transmitting elements
18 as effectively as possible. Any geometry that funnels light from
a larger area into a smaller area would be more useful than no
funneling at all. However, favorable geometries include, but are
not limited to, spherical, aspheric, and Winston cone, at least for
the fiber-based panel. That is, geometries that focus the light to
a point or reduced cross sectional area. For the film-based panel
configuration, preferable geometries include, but are not limited
to, ones that produce elongated ray patterns, such that they focus
the light in a line rather than to a point. For the grid-based
panel configuration, preferable geometries include, but are not
limited to, ones that produce elongated ray patterns in two axes,
conforming substantially to the pattern of the grid of
light-transmitting elements. An example would be given by two
lenticular arrays super-imposed upon each other at 90 degree
angles. It should also be noted that the light-concentrating
elements 20 may have a flat geometry and yet still act as light
concentrators of the present in that they may have a gradient in
their refractive indices such as is found in GRIN lenses.
[0047] The light-concentrating elements 20 may be produced in sheet
form and formed directly on the exterior side 14 of the panel 10.
Prior to applying the light-concentrating elements 20 to the
exterior side 14, the light-concentrating elements 20 may be
fabricated using existing lens array manufacturing techniques
including, but not limited to, molding, extruding and embossing.
The array of light-concentrating elements 20 may be formed directly
on the exterior side 14, preferably by first preparing that surface
of the panel 10 to ensure suitable bonding of the array to the
panel 10. That bonding may be achieved by forming the array on the
exterior side 14 or by adhering a preformed array to the exterior
side 14. Alternatively, as described above, the array may be formed
when forming the light-transmitting elements 18. That is, the
light-transmitting elements 18 and the light-concentrating elements
20 are fabricated at the same time such that they are aligned and
have the same fabrication characteristics. That may be done instead
of fabricating each separately and then attaching the array aligned
so that individual ones of the light-concentrating elements 20 are
properly aligned with corresponding ones of the light-transmitting
elements 18.
[0048] In another method of fabrication, the primary building
material 16 is first formed, including with spaced channels where
the light-transmitting elements 18 are to be positioned, as
previously described. This method permits establishment of the
positioning of the light-transmitting elements 18 and the desired
shape of the array of light-concentrating elements 20, such as in
the form of Winston cones. Material used to create the
light-transmitting elements 18 and the light-concentrating elements
20, such as a curable fluid with optical properties when cured, is
then directed into the established channels within the preformed
primary building material 16 phase of the composite panel 10. A
mold including cavities in the desired shape of the array is filled
and then the fluid allowed to cure and solidify in the desired
shape. The mold is then removed.
[0049] In another example of a method of fabricating the
light-concentrating elements 20 to the exterior side 14, a curable
fluid with optical characteristics when cured may be applied in
fluid form to the exterior side 14 of the previously formed primary
building material 16. The fluid may be a UV-curing ink or adhesive
formulated to produce an optical polymer, preferably with a high
refractive index. Light of an appropriate wavelength, dependent
upon the fluid selected, may then be directed from the interior
side 12 through either channels established in the primary building
material 16, or through light-transmitting elements 18 within such
channels, to the curable fluid residing on the exterior side 14.
The light is preferably transmitting at one or more selected and
controlled angles so that the fluid cures on the exterior side 14
in the desired shapes of lenses to establish the array of
light-concentrating elements 20. The light is transmitted for a
controlled period of time so that curing of the fluid stops when
the individual lenses are of the desired size and shape. Any excess
fluid on the surface of the exterior side 14 that is not the
subject of light curing is then removed and the cured material
remaining forms the lens array. Additional light curing may be done
as then needed. The advantage of this method of fabrication is that
the individual light-concentrating elements 20 are automatically
aligned with respective ones of the light-transmitting elements
18.
[0050] The light-transmitting elements 18 and the
light-concentrating elements 20 may be fabricated of any material
that is transmissive of light in the visible and/or infrared range.
The same material may be used for both, or different materials may
be used. The light-concentrating elements 20 may be applied to
either or both of the interior side 12 and the exterior side 14 of
the panel 10. The material selected may be glass or polymeric.
Suitable polymeric materials include, but are not limited to,
thermoplastics such as polymethylmethacrylate, polycarbonate,
polyvinyl chloride, polyvinyl dichloride, polyvinyl difluoride,
polystyrene, polypropylene, and polyester; thermosets such as
optical-grade polyurethanes, epoxies, and acrylics. Materials that
are transmissive in the wavelength range of about 8-14 .mu.m may be
useful for the light-transmitting elements 18 and/or
light-concentrating elements 20 when the light-concentrating
elements 20 are located on the interior side 12 of the panel 10.
For example, that arrangement may be of use when the intent of the
panel 10 is to transmit radiant heat out of a building to cool
it.
[0051] The choice of material as the primary building material 16
of the panel 10 is relatively broad. The choice is dependent upon
the particular structural and/or insulative characteristics desired
for the panel 10. In one application, for which the panel 10 is to
be primarily an insulative component of a building, the primary
building material 16 may be selected from, but not limited to,
foam, glass fiber, polymer microfibers, perlite, and aerogel;
provided the material selected does not remove significant light
from the light-transmitting elements 18, through absorption or
transmission, for example. In another application, for which the
panel 10 is to be primarily a structural component of a building,
the structural material 16 may be selected from, but not limited
to, wood, concrete, and aluminum or other metallic material,
provided the material selected does not remove significant light
from the light-transmitting elements 18. Further, the primary
building material 16 may be, or may be joined thermally to, a
material that functions as a storage mass. That is, the panel 10 or
an array of the panels 10 may be used to transmit light that
produces heat which is conducted to the storage mass material. When
the panel 10 no longer aids in generating heat in the building, the
storage mass material may produce heat for the building. In this
application of the invention, the panel 10 aids in supplying a heat
sink.
[0052] In further consideration of the material selected as the
primary building material 16, it is useful to evaluate the
Refractive Index (RI) of the material. The RI of the material has
an effect on the light-transmitting capability of the panel 10 when
there is no air interface between the materials. Standard
insulation materials do not transmit light without significant loss
and scattering. If the primary building material 16 of the panel 10
is in direct physical contact with the light-transmitting elements
18, and the structural material 16 has a RI equal to or greater
than that of the material of the light-transmitting elements 18,
the majority of light desired to be transmitted through those
elements will be scattered and/or absorbed by the primary building
material 16. However, a material selected as the primary building
material 16 having a RI lower than that of the material of the
light-transmitting elements 18, then the light passing through the
light-transmitting elements 18 will be reflected back and
scattering and/or absorption by that phase of the panel 10 will not
occur. Those skilled in the art will recognize that the greater the
difference in RI between the selected material of the structural
material 16 and the material of the light-transmitting elements 18,
the greater the number of angles of light transmission will result.
When the RI differential is understood, the particular geometry of
the array of light-concentrating elements 20 may be established to
focus light to the light-transmitting elements 18 at angles that
will result in light transmission rather than scattering or
absorption. Those skilled in the art will recognize that any number
of array geometries may be created to work well with the particular
materials selected for the structural material 16 and the
light-transmitting elements 18.
[0053] Optical fibers may be treated or modified to increase the RI
differential between the light-transmitting elements 18 and the
primary building material 16. For example, a glass fiber or an
acrylic fiber may be coated with a fluorine-containing polymer,
such as polyvinyl difluoride (RI=1.42). Alternatively, air with a
RI=1, or polyvinyl acetate with a RI=1.47, may be adjacent to the
fiber, or sheet for the panel construction of FIGS. 7-10. Examples
of air in contact with the light-transmitting elements 18 include
the use of glass or polymer fiber insulation, a packing material
such as perlite or aerogel, or foam delaminated or otherwise
unattached to the surface of the light-transmitting elements 18, to
give an effective RI value that is that of air. In addition,
materials such as polyvinyl acetate or polyvinyl difluoride may be
foamed adjacent to the light-transmitting elements 18 to make
direct contact therewith, or the unfoamed versions may be coated as
a thin coating on the outside of the light-transmitting elements
18, such as during a coextrusion fabrication process. When a
coating or other treatment with relatively low RI value is directly
contacted to the exterior surfaces of the light-transmitting
elements 18, the primary building material 16 may be selected
without regard to its particular RI value. That is, the selected
coating, rather than the selected primary building material 16,
causes the light reflection.
[0054] As expected for the function of the panel 10 of the present
invention, there will be exposure to external elements, including
sunlight itself, which may cause degradation of the materials
chosen to fabricate it. For that reason, the materials may be
treated to minimize ultraviolet degradation and oxidation. There
exist standard commercially available antioxidants, such as
hindered phenols, and UV absorbers, such as modified benzophenones
that are available and can be added to the materials of
construction. Similarly, additives and/or coatings may be employed
in the formation of either or both of the light-concentrating
elements 20 and the primary building material 16 to block UV light
and/or infrared light to allow light transmission while avoiding
transmission of damaging UV wavelengths and heating infrared
wavelengths where lighting but not heating of the building is
desired.
[0055] The panel 10 of the present invention may be used to save
energy within a building by effectively drawing in the heat
associated with sunlight without compromising insulative
characteristics. The insulative properties of the panel 10 may be
improved by increasing its thickness while still enabling light
transmission through the light-transmitting elements 18. The use of
the light-concentrating elements 20 increases the percentage of
light transmitted across the panel 10 with minimal reduction in
physical properties of the primary building material 16. In the
configuration of the panel shown in FIG. 3, light passes mainly in
one direction, from exterior to interior, so that individuals can
see out of the building but others cannot see into the building.
Further, the panel 10 of the present invention may be used any time
there is an interest in bringing light across a thermal barrier.
For example, it may be used as an improvement to a Trombe wall. It
may be used to improve the characteristics of a conventional wall,
such as by providing a better heat source as indicated herein. For
example, the panel 10 may be affixed to a conventional wall
structure, such as a concrete wall. The sun's light would pass
through the panel 10 and heat the concrete. The concrete, in turn,
may then be a thermal source for the building, and would retain
heat without overheating the building. As air is exchanged within
the building, the thermal mass of the concrete wall would heat that
air. This arrangement may supplement or replace existing internal
heating systems, dependent upon the amount of sunlight available.
The use of a panel that selectively transmits light during the
heating season while rejecting light during the warmer months of
the year would be extremely useful for this application. The panel
10 of FIGS. 9-10 would be suitable for this purpose. A panel 10 of
the present invention could also be used for solar hot water
heating with the benefit of bringing the light into the insulated
envelope of the building such that water can be directly heated
without the need for antifreeze solutions and heat exchangers.
Still further, one or more of the panels 10 may be configured with
an external appearance recognized as a conventional building
exterior appearance. To aid this appearance, the light
concentrating sheet can be painted any color on its inner surface
wherever the light-transmitting element 18 is not attached or the
primary building material 16 can be colored any desired color.
[0056] The present invention is an apparatus to improve lighting
and/or energy usage characteristics of a building. The present
invention is also a method of fabricating the structure with such
characteristics. While the present invention has been described
with particular reference to certain embodiments of the panel 10,
including the primary building material 16, the light-transmitting
elements 18 and the light-concentrating elements 20, it is to be
understood that it includes all reasonable equivalents thereof as
defined by the following appended claims.
* * * * *