Note: Descriptions are shown in the official language in which they were submitted.
CA 02910816 2015-10-29
Modular Headlamp Assembly with a Heating Element for Removing Water Based
Contamination
Brief Description of the Drawings
FIG. 1 is a front view of a modular headlamp assembly according to the present
application.
FIG. 2 is a front perspective view of the modular headlamp assembly of Figure
1
with a lens removed.
FIG. 3 is a perspective view of a low beam module of the the modular headlamp
assembly.
FIG. 4 is a bottom view of the low beam module of the modular headlamp
assembly.
FIG. 5 is a perspective view of a high beam module of the modular headlamp
assembly.
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CA 02910816 2015-10-29
FIG. 6 is a bottom view of a high beam module of the modular headlamp
assembly.
FIG. 7 is a top view of a high beam module of the modular headlamp assembly.
FIG. 8 is a bottom view of a high beam module of the modular headlamp
assembly.
FIG. 9 is a front view of the lens of the modular headlamp assembly.
FIG. 10 is a back view of the lens of the modular headlamp assembly.
FIG. 11 is a detail view of a lens heating element circuit board of the
modular
headlamp assembly.
FIG. 12 is a back perspective view of the heating element circuit board and
lens of
the modular headlamp assembly.
FIG. 13A is a top view of the heating element circuit board.
FIG. 13B is a back view of the heating element circuit board.
FIG. 14A is a perspective view of a seal for the modular headlamp assembly.
FIG. 14B is a cross-sectional view of the seal of FIG. 14A.
FIG. 15 is a back perspective view of the modular headlamp assembly.
FIG. 16 is a perspective view of a drive circuit housing of the modular
headlamp
assembly.
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Brief Summary
A modular headlamp assembly includes a low beam headlamp module, a high
beam headlamp module, and front turn/parking lamp module. The low beam
headlamp
module and the high beam headlamp module are supported by a reflector carrier.
Each of
the high and low beam headlamp modules includes a heat sink and mounting
assembly
with a heat sink portion bisecting a reflector member. The headlamp includes a
lens with
a wire heating element embedded therein and a wire heating element circuit
board affixed
to the lens. A thermistor is affixed to the lens for sensing when the lens
reaches a
predetermined condition and a micro-controller is provided for activating or
deactivating
the wire heating element based on the predetermined condition sensed by the
thermistor.
Detailed Description
As illustrated in Figure 1, a modular headlamp assembly is generally indicated
at
10. Modular headlamp assembly 10 includes a low beam headlamp module 15 and a
high beam headlamp module 20. A front turn/parking lamp module 22 having a
reflector
23 and a bulb 24 is also included. Low beam headlamp module 15 and high beam
headlamp module 20 and a side reflex reflector 26 are supported by a reflector
carrier 30,
which is adjustably fastened to a housing 35. The modular headlamp assembly
according
to the present application also includes a lens 300 provided over housing 35
for light to
pass through from low beam headlamp module 15, high beam headlamp module 20,
and
front turn/parking lamp module 22. Lens 300 includes heating elements 305 and
a circuit
board 320 for removing water based contamination in the form of snow and ice
build-up,
which will be described in detail below.
Figure 2 is a front view of headlamp assembly 10 with lens 300 removed.
Reflector carrier 30 is shown supporting low beam headlamp module 15 and high
beam
headlamp module 20 and a side reflex reflector 26. Front turn/parking lamp
module 22
and reflector carrier 30 are positioned within housing 35. An aperture 302 is
formed
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within a bottom corner of housing 35 for providing a path for heating element
wires, as
will be discussed below.
Figure 3 is a perspective view of low beam headlamp module 15 of modular
headlamp assembly 10 including a heat sink and mounting assembly 36, which has
a low
beam heat sink portion 37 and a low beam mounting portion 38. Heat sink and
mounting
assembly 36 is formed from a thermally conductive material such as die cast
aluminum,
copper or magnesium. In addition, the heat sink and mounting assembly 36 is
treated
with a black thermally emissive coating to facilitate heat transfer through
radiation. The
coating may be an E-coat, an anodized coating, or a powder coat. In the
embodiment
shown, low beam heat sink portion 37 is oriented and bisects low beam headlamp
module
vertically in order to aid in thermal transfer. However, in other embodiments
low beam
heat sink portion 37 may be oriented horizontally such that it bisects low
beam headlamp
module 15 horizontally.
In general, low beam headlamp module 15 includes at least one low beam LED
light source 40, which may be a 1x2 or a 1x4 Altilon LED Assembly manufactured
by
Philips Lumileds. Low beam LED light source 40 is mounted to low beam heat
sink
portion 37, having first and second sides 46 and 47, that extends through a
low beam
reflector member 50 such that low beam heat sink portion 37 bisects reflector
member 50
into first and second segments 52 and 53. In the embodiment shown low beam LED
light
source 40 is oriented such that the axis of the light emitting die on the
light source is
arranged substantially parallel with the axis of emitted light. Alternatively,
the axis of the
light emitting die on low beam LED light source 40 may be oriented
substantially
perpendicular to the axis of the emitted light. At least one of first and
second sides 46
and 47 of low beam heat sink portion 37 includes a light source receiving
portion 55 for
containing low beam LED light source 40 and a light shield 57 positioned
adjacent to low
beam LED light source 40 for blocking a portion of the light in a low beam
pattern. In
particular, in the embodiment illustrated, light shield 57 blocks light from
low beam LED
light source 40 in the range of 10U-90U. With the illustrated light shield 57,
the light
intensity in the light pattern from 10 degrees UP to 90 degrees UP and 90
degrees LEFT
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to 90 degrees RIGHT will not exceed 125 candela. The shape and location of
light shield
57 may vary according to the shape and design of modular headlamp assembly 10.
There
are several factors which dictate the location and shape of the part, such as
orientation of
the LED die, reflector shape, and position within reflector. A thermally
conductive
compound is disposed between low beam heat sink portion 37 and low beam LED
light
source 40. Low beam mounting portion 38 includes alignment features 65 formed
on
stepped portions 66 that extend from mounting structure for facilitating the
alignment of
low beam reflector member 50 with low beam mounting portion 38. In particular,
low
beam reflector member 50 includes tabs 67 with apertures 68 formed therein for
mating
with alignment features 65 of low beam mounting portion 38.
Figure 4 illustrates bottom view of low beam module 15. Low beam mounting
portion 38 includes a base portion 70 which may be adapted to receive a driver
circuit
assembly (not shown). A plurality of mounting extensions 71 protrude from side
edges
76 and 77 of base portion 70 adjacent to edges 78 and 79. In addition,
channels 82 and
83 are formed within base portion 70 along edges 76 and 77 to accommodate
electrical
leads 84 and 85 from low beam LED light source 40.
Figures 5-8 illustrate a perspective, bottom, top, and back views of high beam
headlamp module 20. High beam headlamp module 20 includes a high beam heat
sink
and mounting assembly 100 having a high beam heat sink portion 102 and a high
beam
mounting portion 103. Heat sink and mounting assembly 100 is formed from a
thermally
conductive material such as die cast aluminum, copper or magnesium. In
addition, the
heat sink and mounting assembly 100 is treated with a black thermally emissive
coating
to facilitate heat transfer through radiation. The coating may be an E-coat,
an anodized
coating, or a powder coat. A high beam reflector member 104 mounted to high
beam
heat sink and mounting assembly 100 such that high beam heat sink portion 102
extends
outward towards a bottom end of reflector member 104.
Reflector member 104 includes an upper reflective portion 105 and a lower
portion 106, which are separated by high beam heat sink portion 102. Upper
reflective
CA 02910816 2015-10-29
portion 105 has a complex reflector optic design. The complex reflector
optical design
includes multiple intersecting segments. The segments intersect at points that
may be
profound and visible or blended to form a uniform single surface. Reflector
member 104,
in the embodiment shown, is a single component surrounding high beam heat sink
portion 102. Alternatively, reflector member 104 may be composed of multiple
separate
and distinct reflector components individually mounted on either side of high
beam heat
sink portion 102. Reflector member 104 is formed of a thermoplastic or
thermoset
vacuum metalized material. For example, reflector member 104 may be formed of
ULTEM, polycarbonate, or a bulk molding compound.
High beam heat sink portion 102 includes first and second sides 110 and 115. A
high beam LED light source 120 is mounted to first side 110 of high beam heat
sink
portion 102 in a light source receiving portion 122 formed therein. Light
source
receiving portion 122 may take the form of an indented area sized to receive
High beam
LED light source 120. Alignment posts, 123, may be formed in light source
receiving
portion 122 for aligning with apertures 124 in High beam LED light source 120
to insure
that High beam LED light source 120 is accurately located on heat sink portion
102. In
addition, light source receiving portion 122 may include holes (not shown)
formed
therein for accepting fasteners, used for securing the LED light source to
heat sink
portion 102. A thermally conductive compound may be disposed between high beam
heat sink portion 102 and High beam LED light source 120.
In the embodiment shown lower portion 106 is formed integrally with upper
reflective portion 105 such that it extends below high beam heat sink portion
102, as
shown in figure 7. In addition high beam reflector member 104 includes a tab
127
extending from a back end 130 of upper reflective portion 105. Tab 127
includes an
aperture 133 formed therein for mating with an alignment feature 135 formed on
high
beam mounting portion 103 (see Figure 7). Further, tabs 136 extend from a back
end 137
of lower portion 106. Each of tabs 136 includes an aperture 138 formed therein
for
mating with alignment features 139 formed on high beam mounting portion 103,
as
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shown in Figures 5 and 6. High beam mounting portion 103 includes fins 140 for
heat
dissipation which terminate at a base portion 141. A plurality of mounting
extensions,
one of which is indicated at 145, protrude from high beam mounting portion 103
for
mounting high beam headlamp module 20 to reflector carrier 30. Additional
details of
the modular headlamp assembly are disclosed in U.S. Patent Application No.
13/246,481,
which is incorporated herein by reference.
In accordance with embodiments of the invention, with reference to FIG. 9,
lens 300 includes an exterior surface 311 and an optical area 314, which
covers high
and low beam modules 15 and 20. Heating element 305 is positioned behind
optical
area 314 and is connected to a heating element circuit board 320. Lens 300 is
typically
an optical grade exterior lens which is exposed to the outside environment.
FIG. 10
illustrates a back view of lens 300, with interior surface 312, wherein
resistive wire
heating element 305 is embedded into interior surface 312 of lens material
using
ultrasonic technology. The embedding via ultrasonic technology may be
performed
through robotics to easily accommodate variations in lens surface, variables
in wire
patterns, and for improved accuracy and speed. Wire heating element 305 may
also be
attached to non-embeddablc materials using ultrasonic technology with the use
of
coated wire wherein the coating material is melted ultrasonically, thereby
becoming an
adhesive between wire heating element 305 and the non-embeddable material.
Resistive wire heating element 305 may include a copper core with a silver
coating to
prevent corrosion of wire heating element 305. Typically resistive wire
heating
element 305 is embedded in lens 300 at a depth approximately 2/3 of the full
wire
diameter (2/3d). In one embodiment, the diameter of resistive wire heating
element 305 is
approximately 3.5/1000 inches so the embedding depth is between .0023 to .0035
inches.
The wire is embedded by tapping it into the lens at a frequency which locally
excites the
lens molecules causing the lens to melt locally to the wire.
In particular, wire 305 is embedded using a sonic energy source to excite the
plastic hydro-carbon polymer of lens 300 into a thermal state condition,
softening the
hydro-carbon polymer surface, which allows wire 305 to be embedded into a
portion of
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the lens surface that is in contact with the wire at the time of the embedment
process. The
wire embedment process utilizes thermal transfer, coupled with a force control
device
that provides constant pressure and velocity to the wire such that a wire is
consistently
applied on the optical surface. The embedded wire can be applied to any
complex and
contoured surface using the force control device and the sonic energy in an
isolated
pattern to heat the wire embedded. Force control is used to prevent pushing
the wire down
farther than desired (so that the embedding head does not directly impact the
lens). The
embedded wire is then terminated to a printed circuit board by soldering,
thermal
compression bonding, etc. The wire may be embedded in the area of the lens
which
contributes to the photometric pattern of the low beam and high beam light
sources, but
could include the entire inner surface of the exterior lens, low beam only,
etc.
An encapsulating material may be used to cover wire heating element 305 on
interior surface 312 of lens 300 to prevent localized superheating (i.e.
fusing) of wire
heating element 305 due to exposure to air. If wire heating element 305 is
exposed
directly to the air the heat generated in wire heating element 305 cannot
transfer fast
enough to the air through convection. Thus, the temperature of wire heating
element 305
exceeds the melt temperature of wire heating element 305. The encapsulating
material
prevents overheating by accepting heat transfer through conduction on the
order of 1000
times faster than convection to the air. Thus, the temperature of wire heating
element
305 is not raised enough to melt the wire, the lens, or the encapsulating
material(s). In
particular, the inside surface of the embedded lens is coated with a
Hexamethyldisiloxane
compound to totally surround the copper wire that is embedded into the lens.
The coating
is optically clear to reduce photometric degradation. Other encapsulating
materials that
are Department of Transportation compliant, as specified for optical grade
materials /
coatings, must have adequate adhesion to the lens material, must have
temperature
limitations not less than that of the lens material or the heater wire maximum
temperature under prescribed conditions, and must not violate other design
features /
parameters. The encapsulating material also helps to prevent wire heating
element 305
from coming free from lens 300 due to random vibration or impact.
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A coating or encapsulating material may also be applied on an outer surface
311
of lens 300 to protect lens 300 against deterioration from weather (UV rays,
heat, cold,
rain, snow, and ice). It also resists damage from sand and dirt. It is
specifically required
on polycarbonate headlamp lenses to meet FMVSS 108 abrasion test requirements
and
chemical resistance (ASTM Fuel Reference C, Tar Remover, Power Steering Fluid,
Antifreeze, and windshield washer fluid). The coating material may or may not
be UV or
thermally cured. Some alternative coating materials are Momentive PHC 587,
Momentive AS 4700, and Red Spot 620V.
Wire heating element 305 is actively controlled in order to increase
performance
and efficiency of the wire heating element 305. A heating element circuit
board 320 is
attached to the headlamp circuit board, as discussed in detail below. As shown
in FIGS.
and 11, a recess 322 is provided in lens 300, as shown formed in inner surface
312 of
lens 300, to accept heating element circuit board 320. In the embodiments
shown,
heating element recess 322 and circuit board 320 are positioned in the inboard
corner of
lens 300 so as to not obstruct the photometric pattern of the low beam or high
beam
functions, to improve aesthetic appearance, and to provide a convenient
location for
attachment to a mating harness for electrical connection to a main driver
circuit board.
However, circuit board 320 could be positioned in other locations of lens 300.
Thermal
compression bonding or welding is utilized to attach heating element circuit
board 320 to
lens 300. For example, heating element circuit board 320 may be affixed to
lens 300
using a two component, 1:1 mix ratio epoxy from Star Technology (Versabond
ER1006LV). Alternate adhesives may be used based on temperature range,
adhesive
strength/durability, out-gassing properties, chemical reactivity, flexibility,
application
method, cure time, appearance, availability, and cost. Acceptable adhesives
include non-
cyanoacrylate based adhesives.
FIG. 12 illustrates heating element circuit board 320 affixed to inner surface
312
of lens 300 at recess 322. As illustrated, heating element 305 contacts
heating element
circuit board 320. FIGS. 13A and 13B illustrate first and second sides of
heating
element circuit board 320. In general, heating element circuit board 320
includes a
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thermistor 350 on the outward facing or first side 352 for heater control
feedback
purposes. Heating element circuit board 320 also includes two conducting pad
areas 325
and 326 on an inner or second side 354 to which wire heating element 305 is
soldered.
Heating element circuit board 320 and thermistor 350 are placed into lens 300
such that
the distance between an outer surface thermistor 350 and an outer surface of
the lens
does not exceed 1/10 the distance from the outer surface of thermistor and an
inner
surface of the lens at any one point for the purpose of minimizing the thermal
impedance
between thermistor 350 and outer lens surface and maximizing the thermal
impedance
between the thermistor and the inner lens surface. Thermal impedance is
therefore
manipulated by varying the thermistor's distance from the inner and outer
surfaces of the
lens, represented by the equation: Do < (1/10)Di where Do = the distance from
the
thermistor to the outer lens and Di = the distance between the thermistor and
inner lens.
Therefore, the resistance to heat transfer is at least 10 times more from the
thermistor to
the inside air compared to the resistance to heat transfer between the
thermistor and the
outside of the lens.
The resistance of thermistor 350 may be used to accurately predict lens
surface
temperature wherein the ratio of distances versus the desired accuracy of the
control
system feedback is calculated and validated empirically. Thermal impedance is
the
resistance to transfer heat from any one point to any other point (if the
thermal
impedance is high, less heat transfer will occur and vice versa). Thermistor
350 is
sensitive to temperature changes on the lens surface since that is the surface
from which
water-based contamination such as snow and ice is removed. Therefore, it is
necessary
to have a very low thermal impedance from thermistor 350 to lens outer surface
311. In
this case, the lens material and outer lens coating are the thermal barriers
between the
thermistor and the outer lens. In addition, it is important to maximize the
resistance
from the thermistor to the inside of the lamp so the inside lamp temperature
does not
affect the temperature reading sensed by the thermistor.
The thermistor is essentially a surface mount resistor having approximate
dimension: .03 x .065 x .03 inches (width, length, height) that is comprised
mainly of
CA 02910816 2015-10-29
alumina. The thermistor operates under a programmable logic sequence in order
for the
heating wire to be activated/deactivated automatically in order to melt snow
and ice on
the lens. The thermistor is used to provide feedback to the micro-controller
in the form of
a resistance. This resistance is correlated to a temperature that the micro-
controller stores
and uses to decide whether the heater should be on or off and at what level of
power. The
resistance/conductivity of wire heating element 305, as well as that of the
actual
thermistor 350 and heating element circuit board 320, is factored-in to
optimize the
operation of the thermistor. In one embodiment, wire heating element 305 is
adapted to
activate at 10 degrees C and deactivate at 15 degrees C. However, the micro-
controller
may also be programmed to activate or deactivate wire heating element 305
based on a
resistance that is stored in the microcontroller from current and voltage that
is associated
with a specific temperature. The thermistor manufacturer provides the data to
make the
correlation between the resistance and temperature.
In particular, the heater control is a closed loop controller comprised of a
programmable micro controller (already existing in headlamp main PCB), the
lens
thermistor, a current sensing resistor, a voltage sensor, a mosfet, and the
heater wire
circuit. The micro-controller monitors the outer lens temperature by
calculating the lens
thermistor's resistance at regular clock intervals, which has a known
correlation to
temperature. When the temperature is determined to be at or below a set
activation
temperature (programmed into the micro-controller), the micro-controller
provides a
signal to the mosfet which connects one leg of the heater circuit to lamp
power (the other
leg is connected to ground), therein powering the heater. If the temperature
is determined
to be above a set deactivation temperature (also programmed into the micro-
controller),
it provides a signal to the mosfet to disconnect the leg of the heater circuit
from power,
therein removing any power in the heater circuit. The micro-controller can
also modulate
power for the purpose of power regulation. Further, the microcontroller
calculates heater
wire temperature and will regulate heater power to prevent the heater wire
from
exceeding the melt or softening temperature of the lens material as needed.
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Heating element circuit board 320 contains conductive pads 325, 236 to
facilitate
heater circuit leads in consideration of the circuit configuration plus two
thermistor
control leads. The conductive pads may be formed of copper covered nickel
coated with
gold to provide a non-corroding, malleable surface that is conducive to
welding or
thermal compression bonding of wire heating element 305, as well as additional
electrical
attachment via spring containing (pogo) pins. In general, thermal compression
bonding
includes applying high temperature and pressure (locally) to mechanically fuse
two
materials together. Typically, a hard material is superimposed onto the end of
a pressing
mechanism capable of high pressure with a heating element used to heat the
hard
material. The two materials desired to be bonded together are pressed together
with
substantial force while the hard material on the end of the press is heated
causing the
two materials to bond together at the molecular level. The process can be used
to bond
similar materials (metal to metal) or dissimilar materials (metal to ceramic)
together
effectively.
Heating element circuit board 320 also includes a circuit board connector 355
for
engaging a mating connector 360, as shown in FIG. 12, for connecting heating
element
circuit board 320 and thermistor 350 to the lamp main driver board. In
particular, as
shown in FIG. 15, electrical connection between heating element circuit board
320 and
main driver board is achieved through pigtail wires 365 which exit driver
board heat
sink module 240 and are routed along a back of housing 35 and through aperture
302 in
housing 35 behind heating element circuit board 320. A wire seal 370 is used
to route
wires 365 through hole while maintaining an environmental seal. Individual
wire seals
are also formed around each wire.
As illustrated in FIGS. 14A and 14B, wire seal 370 includes three holes 375
through which wires 365 pass. Wire seal 370 also includes a circumferential
groove 380
for tightly engaging aperture 302 in housing 35. Wire seal is formed of an
elastomeric
material and is suitable for acting as a moisture barrier.
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Figure 15 is a back perspective view of housing 35. In general, housing 35
includes a drive circuit module 240, shown in detail in Figure 16, with an
interior portion
245 adapted to contain a circuit board, such as a FR4 circuit board.
Electrical leads 246
and connector 247 are adapted to connect the circuit board to a power source.
Interior
portion 245 is surrounded by a rim track 249 having a gasket positioned
therein (not
shown). Drive circuit housing 242 is formed of a thermally conductive material
and acts
as a heat sink. In addition, drive circuit housing 242 includes a back portion
250 having
fins 252 formed therein for heat dissipation. Attachment tabs 255 with
apertures 256
extend from drive circuit housing 242 for attaching drive circuit module 240
to headlamp
housing 35. Drive circuit module 240 is mounted to headlamp housing 35 at a
circuit
board module receiving opening. As shown, wires 365 connect drive circuit
module 240
and drive circuit board (not shown) to heating element circuit board 320.
Heating of lens 300 by wire 305 is activated based on lens temperature.
Initially,
the temperature of the lens is measured by thermistor 350. A decision is then
made by
logic in a microcontroller, processer, FPGA, other integrated circuit, or by
analog
circuitry whether to activate heating wire 305. A power converter, such as a
SEPIC
topology switch mode power supply, may be used to boost or step down power
source
voltage to match heater wire resistance. If such a power converter is used, a
microcontroller will is used to decide what temperature to engage the heating
wire and
how much to engage the heating wire. If a power converter is not used, heater
wire
resistance is matched to power source voltage. Heating wire is then activated
to heat lens
300.
Several factors are considered when determining when and how much heat is
required to remove water based condensation from a lens. The area of the lens
to be
heated is first determined by considering the area(s) of the lens that light
passes through
for the lamp function(s) that will be active (or desired) when lens heating is
necessary.
From this data, the required heater power is determined using ambient
temperature set to
the lowest defined operating temperature of the lamp, an assumed water based
contamination layer on the lens exterior (approximately 2 mm thick), lens
material and
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thickness, and required wire spacing (assuming uniform and non-segmented
heating is
desired). Other considerations include lamp internal air temperature
prediction based on
the previously listed parameters and heat dissipation from active lamp
functions (CFD
used for this), time desired/required to remove the water based contamination,
assumed
air convection coefficient inside and outside of the lamp, latent heat of
fusion of ice,
density of ice, and heat capacity of all material in the heat transfer paths
(including the
ice). This information is used to mathematically express heat transfer from
the wire to the
air (both inside and outside of the lamp) and the amount of energy to raise
the
temperature of the ice to zero degrees C and convert the ice to water as a
function of
time. The mathematical expressions are combined and solved to determine the
amount of
power required from the heater wire to melt the ice in the desired/required
time period so
that once the ice is melted, the water runs off the lens due to gravity.
When multiple operating voltages are required, multiple heating element
circuits
are used and configured in series, parallel, or a combination of series and
parallel in order
to attain uniform heater power at any of the prescribed input voltages for a
linear type
heater driver. Alternately, a switcher type driver may be used with a single
heater circuit.
The inherent resistance of the control system components including the
thermistor in the
lens must be offset in one of the heating element circuits for systems with
multiple
heating element circuits to ensure uniform heating between circuits (unless
otherwise
desired), because that resistance adds to the heating element circuit, therein
reducing the
amount of current that flows through it compared to other circuits. This is
readily
achieved by modifying the length of each circuit such that the resistances
balance when
the control system net resistance is added to one circuit. Straight paths of
the heater
circuit as embedded into the lens are minimized to reduce the appearance of
light
infringement within the optical pattern in order to produce a clearer more
vivid shape that
is more easily perceived by the human eye. Additionally, the embedding process
creates a
meniscus of lens material along the heater wire. The shape of this meniscus
bends light
around the wire such that, for a curved path, light bent away from the wire
which leaves a
void at angle A, will be bent toward a void at angle B, thus reducing the
clarity or even
eliminating such void.
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It will be understood by those skilled in the art that the above disclosure is
not
limited to the embodiments discussed herein and that other methods of
controlling
heating element, thermal transfer fluid circulating device, or Peltier heat
pump may be
utilized. These methods may include manual activation and deactivation of
heating
element, thermal transfer fluid circulating device, or Peltier device via an
on/off switch.
Other alternative embodiments include continuous activation of the elements so
that
LED lamp temperature is high enough to prevent accumulation of water-based
contamination but low enough to prevent inadvertent thermal deterioration of
the LED
lamp and its components.
While description has been made in connection with embodiments and examples
of the present invention, those skilled in the art will understand that
various changes and
modification may be made therein without departing from the present invention.
It is
aimed, therefore to cover in the appended claims all such changes and
modifications
falling within the true spirit and scope of the present invention.
