Note: Descriptions are shown in the official language in which they were submitted.
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BIRD COLLISION-AVERTING WINDOW PANES
FIELD OF THE INVENTION
[00011 This invention relates to glass. In particular, the invention
relates to bird
collision-averting window panes that reduce the incidence of birds flying into
a window.
BACKGROUND OF THE INVENTION
[0002] Birds flying into window panes, particularly into windows in high
rise
structures which often make up the greater part of the surface of the walls in
a high rise
structure, is a significant ecological problem. Particularly in the case of
migratory birds,
during peak migration periods the number of bird fatalities from striking
window panes is
staggering. Some sources estimate that in the United States alone over one
billion birds
die each year from flying into windows.
[00031 The bulk of window collisions occur for two primary reasons. In
daylight when
the outdoor ambient light is bright, birds crash into windows when they see
the reflection
of a landscape off of the window, or when they see plants or other natural
vegetation
through the window. The second reason occurs at night when windows are
illuminated
from inside a structure, which for reasons that are not entirely clear seems
to attract
nocturnal migrant species and divert them from their intended flight path.
[00041 There are many sources of information and suggestions on how to
prevent birds
from hitting windows. Some solutions involve substantially eliminating the
illumination
of a window by such actions as turning out interior lights or closing blinds
or other
window coverings at night. Turning out lights is not practical where there are
persons in
the premises at night, and further relies on individuals to remember to take
such steps, as
does closing window coverings. Outdoor coverings such as bird exclusion
netting are not
practical for use on high rise buildings due to wind and installation issues.
Other
solutions involve imprinting or forming the window with a material having an
opaque or
translucent pattern, which a bird processes as an obstruction, but applying a
permanent
pattern to the glass itself reduces visibility through the window to humans
and occludes
outdoor light coming into the structure, even at times when bird collisions
are unlikely.
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[0005] It would accordingly be advantageous to provide a means of
encouraging birds
to avoid flying toward window panes that does not require human intervention
in order to
be effective and does not substantially obscure the view through the window or
occlude
light shining into the premises.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] In drawings which illustrate by way of example only a preferred
embodiment of
the invention,
[0007] Figure 1 is a perspective view of a first embodiment of a laminated
window
pane according to the invention.
[0008] Figure 2 is a partially exploded view of the construction of the
window pane of
Figure 1.
[0009] Figure 3 is a perspective view of a further embodiment of a
laminated window
pane according to the invention.
[0010] Figure 4 is a partial cross-sectional elevation of the window pane
of Figure 3.
[0011] Figure 5 is a perspective view of a further embodiment of a window
pane
according to the invention.
[0012] Figure 6 is a side elevation of the window pane of Figure 5.
[0013] Figure 7 is an enlarged partial cross-sectional elevation of the
window pane of
Figure 5.
DETAILED DESCRIPTION OF THE INVENTION
[0014] According to the invention, in order to avert bird collisions a
window pane 10 is
coated, filmed or laminated with at least one layer containing an optical
brightener.
[0015] Optical brighteners, also known as "fluorescent whitening agents,"
are used to
"whiten" or "brighten" the appearance of such materials as clothing fibers,
plastics,
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paints, inks and other materials where a white colour is considered to be
aesthetically
relevant or important. An optical brightener is a fluorescing compound which
fluoresces
by absorbing light in the ultraviolet (UV) portion of the electromagnetic
radiation (EMR)
spectrum, for example typically within the range generally between 300 and 400
nanometers, and emitting light in visible EMR wavelengths, generally within
the visible
blue portion of the spectrum between 400 and 500 nanometers.
100161 As used herein the term "optical brightener" means a compound that,
either
alone or in solution, fluoresces by absorbing ultraviolet light and emitting
EMR of a
lower wavelength, typically in the visible light portion of the EMR spectrum.
An optical
brightener, such as (by way of non-limiting example only) 2,2'-(1,2-
ethenediy1)bis(4,1-
phenylene)bisbenzoxazole, may be mixed into a resin in the liquid phase, or
into certain
types of plastics in the liquid phase, to produce an optical brightening layer
that can be
applied to a pane of glass to avert bird collisions, for example in the
manners described
below.
Optical brightening laminate layer
[0017] Figures 1 and 2 illustrates a first embodiment of a window pane 10
comprising
an optical brightening laminate layer 16 disposed between two glass panes 12,
14. The
laminate layer may be formed from a plastic film such as (without limitation)
polyvinyl
butyral (PVB) or ethylene-vinyl acetate (EVA) that has been doped during
manufacture
with a suitable amount of an optical brightener. In this embodiment the doped
laminate
may be applied to the glass in conventional fashion, for example by
interposing the
optical brightening laminate layer 16 between the glass panes 12, 14 and
applying heat
and pressure to adhere the laminate layer 16 to the glass panes 12, 14 and
form an
integrated double-glazed window pane 10.
[0018] In a further laminated embodiment, illustrated in Figures 3 and 4, a
double-
glazed window pane 20 is produced with an optical brightening laminate layer
22
between the two panes of glass 12, 14 formed from a liquid laminate, such as
(without
limitation) polyester (PE) or polyurethane (PUR) doped with an optical
brightener. This
can be constructed, for example, by applying a 1/16 inch silicon-based double-
sided
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adhesion tape 24 around the periphery of one glass pane 14, as shown in Figure
3, and
adhering the second glass pane 12 to the tape 24. The void between the two
panes 12, 14
is filled with the doped resin 22, which intrudes into the air gap between the
panes 12, 14
by capillary action. Once the resin 22 has cured, the collision-averting
window pane 10 is
ready to be installed.
[0019] In this embodiment the base resin is doped with an optical whitener
by mixing
the optical whitener (which may for example be in powder form) into the resin
in a
desired proportion, for example 2g per 1000cc resin. This may vary depending
upon the
type of optical brightener, the type of resin and the desired degree of
fluorescence.
[0020] Many species of birds are sensitive to wavelengths in the
ultraviolet portion of
the EMR spectrum, which is believed to be involved in mate selection,
territorial displays
and foraging for food. It is not clear whether it is the absorption of UV
wavelengths or
the emission of visible wavelengths by the doped resin layer 20 that makes the
window
pane 10 look unusual to a bird, however it has been found that the
construction of a
window pane with the doped resin layer 20 has the effect of averting a
substantial number
of bird collisions. In tests, the laminated embodiment of Figures 3 and 4
scored 82 to 86
aversions per 100 potential collisions.
Optical brightening films and coatings
[0021] Further embodiments of a bird collision averting window pane 30 are
illustrated
in Figures 5 to 7. In these embodiments a single glass pane 32 is coated with
a doped
optical brightening film layer 34 or with a sputtered or possibly pyrolytic
optical
brightening coating.
[0022] The doped film layer 34 may for example (without limitation)
comprise
conventional window film such as polyester (PE), polyethylene terephthalate
(PET) or
any other film capable of being doped with a suitable amount of fluorescent
brightener
and adhered to a glass pane 32. This embodiment is particularly suitable for
retrofitting
the doped film layer 34 to an existing window pane, for example by
conventional
window application adhesives and methods.
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[0023] The film layer 34 containing the optical brightener need not be
homogenous. It
is also possible to apply a shape or pattern utilizing for example the film
illustrated in
Figures 5 to 7. Optical brighteners have such a minimal effect on transparency
of the
window pane in the visible wavelengths that it would ordinarily be
unnecessarily
complicated and costly to apply an optical brightening layer 34 in the shape
of a pattern.
However, it may in certain circumstances be advantageous to utilize a pattern
or shape,
for example the silhouette of a predator bird species that may appear to a
bird as a hazard
rather than merely an obstruction.
[0024] Combinations of the embodiments described above are also possible.
This
allows for the creation of multiple optical brightening layers and as such
would provide
the opportunity to use different optical brighteners in a single window pane.
[0025] It may also be possible to 'hard-coat' a glass pane with an optical
brightener to
achieve the desired collision-aversion effect. For example, a coating material
doped with
an optical brightener may be applied to the surface of glass in a molten
state, typically
during manufacture of the pane, known as -pyrolytic" coating.
[0026] Alternatively, a doped solution may be applied to a glass pane 32 in
the solid
state by conventional sputtering techniques, for example by chemical vapour
deposition
or plasma vapour deposition in an arc coating reactor. In this embodiment it
may be
possible to apply the optical brightening layer 34 at the same time as a low-
e' layer,
commonly used in windows for high rise buildings, in which a metal oxide layer
may be
applied to the glass by various methods including magnetron sputtering.
t00271 Experimentation with processed glass panes, for example sandblasted
glass,
anti-reflective glass etc. may yield improved collision-aversion results.
