Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates generally to a heatable backlight
panel, and more particularly, to a plastic composite
backlight panel for convertible vehicles.
The use of heatable window assemblies for removing ice
snow from the windows of aircraft and similar vehicles are
well-known in the art.
U.S. Patent No. 3,020,376 discloses a laminated plastic
panel for aircraft that is electrically conductive so as to
be kept free of ice and fog formations. In addition to the
polyvinyl butyral sheet, the panel includes a sealer layer,
an adhesive layer, an electrically conductive layer, a second
adhesive layer, and a protective layer. The electrically
conductive layer is deposited onto the panel by thermal
evaporation methods.
U.S. Patent No. 3,041,436 involves a transparent,
electrically conductive window for aircraft for anti-fogging
and de-icing applications. The window consists of an outer
face sheet, an interlayer, and an inner ply. The inner side
of the face sheet is coated with an electrically conductive
coating.
U.S. Patent No. 3,180,781 relates to a composite
laminated structure consisting of two sheets of rigid plastic
sandwiched around an interposed layer. The composite
structure is primarily used for aircraft to prevent fogging
and icing. An unbroken, electrically conductive film is
applied to one of the laminated sheets, and may consist of a
series of layers placed
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; over each other. The interposed layer oonsists o~ a sealin~
layer, an adhe~i~e layer, a oonduoting film layer, snd a ~econd
adhesive layer.
U.S. Patent 3,636,311 dlsoloses a heatinA devio~ for
S defrosting or deicing sutomobile windows. The layer of
- oonduoti~e material iA printed or sprayed onto the sur~aoe of
v the polrester resin sheet. A self-adhesive border surrounds the
sheet which is used to subsequently attaohe the sheet to a
window or A windsoreen.
Removin~ ioe and snow from the flexlble plastic
backli~ht panels manually with sorapers and the like, is a
problem beosuse of the likelihood that the plastic will be
soratohed or otherwise damaged. De~rosting the baoklight panel
with blasts of hot air requires considerable time for the air to
heat up in cold weather, and generall~y results in uneven heat
distribution aoross the baoklight panel.
Much of this prior art teohnolo8y althou~h applicable
to automobilos, was developed primarily for the aircraft
industry. Hence, the laminates are made of rigid plastic panels
to withstand the extreme temperature and pressure differentials
- normally encountered at extre~e fli~ht altitudes.
Althou8h rigid Klass panels whioh may be heated through
a plurality of electrical members ~ounted within the panel~ have
been used in automobiles for many years, this technology has not
~5 bee refined for application to the thinner, flexible, plastic
panels that are used in convertible tops. What i8 needed is an
: inexpensive, rug~ed, ~lexible, composite plastic backlight panel
that provides an even heat distribution across the entire
surfa¢e of the panel. The flexibilitr of the panel is critical
because when the baokli~ht panel i8 iD the raised position, the
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panel will assume a curved configuration so as to enable the
designer to provide sleek lines and an aerodynamically
efficient design, but must lie flat in the retracted position
for efficient storage.
In one aspect the invention provides a heatable
backlight panel for a convertible top of a vehicle, which
comprises: (a) a first laminate, the first laminate made of
a first nonconductive material, having an anode and a cathode
disposed on a first surface thereof: ~b) a plurality of
electrical members being applied onto the first surface of
the first laminate by a silk screening process, the
electrical members forming a plurality of electrical paths
between the anode and the cathode, the anode and cathode
being electrically engageable with a power source; and (c) a
second laminate disposed over the first surface of the first
laminate, the second laminate being made from the first
nonconductive material, the first laminate being fused to the
second laminate to form a composite structure.
In a further aspect the invention provides a method of
forming a convertible top having a heatable backlight panel,
the method comprising: (a) providing a first laminate of
flexible plastic material, the first laminate being made from
a first nonconductive material, an elongated anode and an
elongated cathode being disposed on a first surface of the
first laminate; (b) silk screening conductive inks to the
first surface of the first laminate, the conductive inks
providing a plurality of electrical connections between the
anode and the cathode; (c) covering the first side of the
first laminate with a second laminate, the second laminate
being made of the first nonconductive material; (d)
positioning the first laminate and the second laminate
between two plates; (e) applying sufficient temperature and
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pressure for a sufficient period of time to fuse the first
laminate to the second laminate to form a composite
substantially homogeneous 8tructure: and ~f) dielectrically
bonding a material about the perimeter of the substantially
homogeneous structure.
In a still further aspect the invention provides a
heatable backlight panel for a convertible top of a vehicle,
which comprises: (a) a nonconductive portion being formed by
fusing a first laminate being made from a first nonconductive
material to a second laminate, the second laminate being made
from the first nonconductive material; and (b) a conductive
interlayer having a plurality of electrical members disposed
between an anode and a cathode, the electrical members
lS forming a plurality of electrical paths between the anode and
the cathode, the interlayer being applied onto the first
surface of the first laminate by a silk screening process,
the anode and the cathode being electrically engageable with
a power source.
The invention also provides a backlight panel having a
first laminate formed of a nonconductive material fused to a
second laminate formed of a nonconductive material, an anode
and a cathode being disposed between said first and second
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laminates, and a plurality of electrical paths electrically
connecting said anode and cathode, said paths being disposed
between said anode and cathode and being silk screened onto
said first laminate.
For a more complete understanding of the composite
backlight panel of the present invention, reference is made
to the following presently preferred embodiment of the
invention which is illustrated by way of example. It is
expressly understood, however, that the drawings are for
purposes of illustration and description only, and are not
intended as a definition of the
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limits the invention. Also, throughout the description and
drawings, identical reference numbers refer to the same
component throughout the several views.
Figure 1 is a perspective view of the heatable composite
backlight panel in relation to a convertible automobile: and
Figure 2 is an assembly view of the heatable composite
backlight panel, showing the laminates, the wires, and the
conductive members.
A three layer capacitor-type construction forms the
heatable backlight panel 10, using a power supply 45, which
can be either ac or dc. The two outside layers consist of an
inner and outer flexible plastic laminate 22 and 24
respectively, sandwiched about an interlayer 28 containing
multiple electrical elements electrically interengaged. Two
opposed wires 40 and 42 are each electrically engaged to a
plurality of equally-spaced and parallel conductive members
50.
Conductive members 50 are used to heat the laminates 22
and 24 which are each made of Ultralite TM, is a flexible
polyvinyl chloride that is commercially available from
Herbert Lushan Plastics Manufacturing Corp. of Newton, Mass.
One wire 40 is electrically engaged to the anode of
power supply 45, and the other wire 42 is electrically
engaged to the cathode. Preferably, the car battery acts as
power supply 45. The other end of each wire 44 and 46 is
sandwiched between laminates 22 and 24 on the extreme,
opposed sides thereof. The wire lengths are preferably about
550 mm. The combination of power supply 45, two wires 40 and
42, and
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oonduotive members 50 form a olosed loop eleotrlo olrouit. When
the oircuit is qner~ized; the eleotrioal ener~y flowinK throu~h
conduotive memb~r~ 50 is oonverted into thermal energy that is
transmitted into the outer laminate 24. The ao power
requirements are in the ran~e o~ from 100 to 180 volts, at 0.5
to 1.0 amps, and at a frequenoY of B0 to 500 herte.
The do power rQquirements are 6.0 to 8.0 amps at 13.0
~olt~ The available power is 96 watts ~l80.o vr~, x 0.53
amps). This pow~r dissipation will yleld a surfaoe temperature
of 90F - 1200F at an amblent temperature of 60F. Based
upon the si~e oonstraints of the backll~ht, the resistance of
the conduotlve members may be ohan~ed by varying the amount of
material, and the material oompositlon.
The conduotlve members 60 extend essentially across the
entire length of the interlayer 28. The memhers 50 amy be wires
or conductive tape, but are preferably conductive inks because
of flexibility requirements for panel 10. Althou8h a sliver
conductive ink i8 preferred, a ~raphite oonduotive lnk may also
be used. The conductive lnks are oommerolally available from
ao MK8, Inc. of Indianapolis, Indiana. The oonduotive lnks ~re
applied by usinB a sllk-screen process onto laminate 22.
Subsequently, la~nate 24 is disposed 80 that it sandwichea the
interlayer 28 forming the backlight panel 10, whlch is heat
treated by applying suitable temperature and pressure as both
; 25 the laminates 22 and 24 become transparent.
The flexible heated backli~ht panel 10 is proces~ed by
first cutting a 0.020 inch thick laminate 22 from a polyvin~l
chloride sheet. The heated grid pattern is soreen printed onto
one side of the laminate 22. The ink used i8 conductive and is
resistance to the current flow, which i8 ~pecified according to
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the vehiole appllontion. The ink i~ oomposed of vehiole flakes
suspended in a thermoplastio oomposition.
A thin strip of oopper m8terial ~not shown) i8 applied
to the interlayer 28 to provide a uniform heat flow across the
backlight panel 10. A 0.030 inch thick ooppur strlp whloh 18
0.376 inohes lon~ i~ then bondod to the bu~s bars at oith~r slde
of the grid psttern to sssure even heatin8 throughout the
assembly. The strip 18 applled to the ink before the heat
treatment. Conduotive members 60 are orlmped to ensure proper
eleotrical oonneotions, and to provlde strsin relle~ durln~ the
hest treatment. The printed slde of the laminate 22 is then
oovered with another polyvinYl ohloride laminate 24 having
similar dimensions.
These two laminates 22 and 24 are then placed between
two hiKhly pollshed steel plates and pressed together at a
temperature of at least 1800F and a pressure of at least 200
p~i. Initially, the laminate 22 and 24 are opaque. During
compression, whioh takes about two minute~, the laminates 22 and
24 are fused together and beoome olear. The electrioal leads
are preferablY conneoted to the bscklight panel 10 assembly
staplinK the appropriate terminal to the laminated asRembly
through the oopper buss bars deposed at both sides thereof.
The panel assembly 10 is then dieleotrioally bonded to 25 the convertible top oover or the backli~ht oarrier. Thi~
bonding material is a synthetio whioh is oapable of remaining
flexible after the dielectric bonding. The bonding oaterial has
butyl rubber inner ply, such as a diamond ~rain vinyl or a
~tarfast cloth. Prior to seouring the backliRht panel 10 to the
fabrio convertible roof, a blaok piece of the bondin8 material,
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which is about 5/8" thick is bond heat sealed around the
panel 10. A dielectric bond is formed around the heat
treated laminates 22 and 24.
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