Note: Descriptions are shown in the official language in which they were submitted.
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= ' . . '
Fluid cooied.disp[ay
. = .
Cross-Reference to Related Applications
[0001] This application is a provisional patent application and' does not
claim priority
to any co-pending applications.
Technical Field
[0002] This invention generally relates to cooling systems and in particular
to cooling
systems for electronic displays..
Background of the Art
[0003J Conducfive and convective heat transfer systems for electronic displays
are
known. These systems of the past generally attempt to remove heat from the
electronic
components in a display through as many sidewalls of the display as possible.
In order
to do this, the systems of the past have relied primarily, on fans for moving
air past the
components to be cooled and out of the display. In some cases, the heated air
is
moved into convectively thermal communication with fins. 'Some of the past
systems
also utilize conductive heat transfer from heat producing components directly
to heat
conductive housings for the electronics. In these cases, the housings' have a
large
- .
surface area, which is in convective communication with ambient air outside.
the
housings. Thus, heat is transferred convectively or conductively to the
housing. and is
then transferred into the ambient air from the housing by natural convection.
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[0004]. While such heat transfer systems have enjoyed a measure of success in
the
=
past, improvements to displays require even greater cooling capabilities.
Summary of the Invention .
[0005] In particular, cooling devices for electronic displays of the past have
generally
used convective heat dissipation systems that function to cool an entire
interior of the.
display by one or more fans and fins, for example. By itself, this is not
adequate in
many climates, especially when radiative heat transfer from the sun through a
display window becomes a major factor.. In many applications and locations 200
Watts or more
of power through such a display window is common. Furthermore, the market is
demanding larger screen sizes for displays. With increased electronic display
screen
size and corresponding display window size more heat will be generated and
more heat
will be transmitted into the displays.
[0006] In the.past, many displays have functioned satisfactorily with ten or
twelve inch
screens. Now, many displays are in need of screens having sizes greater than
or equal
to twenty-four inches that may require improved cooling systems. For example,
some
outdoor applications call for sixty inch screens and above. With increased
heat
production with the larger screens and radiative heat transfer from the sun
through the
display window, heat dissipation systems of the past, which attempt to cool
the entire
interior of the display with fins and fans, are no longer adequate.
[0007] A large fluctuation in temperature is common in the devices of the
past. Such
temperature fluctuation adversely affects the electronic components in these
devices.
Whereas the systems of the past, attempted to remove heat only through the non-
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display sides and rear components of the enclosure surrounding the electronic
display
=
components, a preferred embodimenfi of the present invention causes advective
heat
transfer from the face of the display as well. By the aspects described below,
the
.
present irivention has made consistent cooling possible for electronic
displays having
screens of sizes greater than or equal to twelve inches. For example, cooling
of a 55
. .
inch screen can be achieved, even in extremely hot climates. Greater cooling
capabilities are provided by the device and method described and shown in more
detail
below.
100081 A preferred embodiment of the present invention relates to a cooling
system
and a method for cooling an electronic display. A preferred embodiment
includes a
transparent liquid cooling chamber, a reservoir tank, and a pump. The
components in
. the systerrt are preferably housed within the electronic display housing.
The cooling
chamber defines a fluid compartment that is anterior to and coextensive vrrith
the
electronic display surface. The pump causes coolant fluid to move through the
cooling
chamber. The reservoir tank provides the system with a constant supply of
coolant and
also provides surface area to conduct heat away from the coolant fluid
contained
therein. The circulating coolant removes heat directly from the electronic
display
surface by advection. In order to view the display, the coolant fluid is
transparent or at
least semi-transparent. The. image quality of an exemplary embodiment remains
essentially unchanged, even though coolant is flowing over the visible face of
the
electronic display surface.
[0009] In.certain embodiments, the system,may also include a filter. The
filter may be
included to remove contaminants that collect in the coolant fluid.
Additionally, the
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system may also be provided with a radiator. The addition of a radiator may
further.
assist in radiating heat contained in the liquid coolant. If included, the
filter and the
radiator may be in fluid communication with the cooling chamber, the reservoir
tank,
and the pump.
[0010] Optionally, a fan unit may also be included within the housing of the
display if
further cooling capability is desired. The fan unit may be positioned to
provide a near
laminar flow of air within the interior of the housing. Thus, excessive heat
in the
housing interior may be transferred outside of the housing.
[0041]. Provided a fan is included, the display and system may further include
an
optional air curtain device to reduce the amount of heat on the surface'of the
display.
The air curtain system redirects exhaust air generated by the fan so that it
passes over
the face of the display to provide a supplemental cooling mechanism.
[0012I: The display and system may include sensors. The display and system may
also be a first display and system of a plurality of displays with respective
systems.
Alternatively, the present invention may include a plurality.of electronic
displays and
respective cooling systems.
[0013] In a preferred method, the system is supplied with a predetermined
amount of
coolant fluid. The coolant fluid is then pumped through the interconnected
components
of the cooling system. As the fluid moves through the system, heat is
transferred away
from the electronic display surface. Preferably, the reservoir tank provides
an occasion
for the retumed coolant fluid to cool before the fluid is- re-circulated
through the cooling
chamber.
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[0014] The foregoing and other features and advantages of the present
invention will
be apparent from the following more detailed description of the particular
embodiments
of the invention, as illustrated in the accompanying drawings.
Brief Description of the Drawings
[0015] A better understanding of an exemplary embodiment, will be obtained
from- a.
reading of the following detailed description and the accompanying drawings
wherein
identical reference characters refer to identical parts and in which:
[0016] FIGURE 1 is a perspective view of an exemplary -errrbudirnerrt irr cot
j~rrn;tion -- --- ---
~
with an exemplary electronic display.
[0017]. FIGURE 2 is a perspective view of an exemplary embodiment of the
cooling
chamber.
[001:8] FIGURE 3 is a side view of an exemplary embodiment of the cooling
chatnber.
[0019] FIGURE 4 is an explanatory schematic showing various components that
may
be included in.a preferred'embodiment:
[0020] FIGURE 5 is a cross-sectional side view through the center of the
display.
Detailed Description of a Preferred Embodiment
[0021] Embodiments of the present invention relate to a cooling system for an
-electronic display and to combinations of the cooling system and the
electronic display:
[0022] Fig. I shows an exemplary embodiment of the present invention. As may
be
appreciated, when the display 15 is exposed to outdoor elements, the
temperatures
inside the display 15 will vary greatly without some kind of cooling device.
As such, the
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electronics including the display screen (e.g., LCD screen) will have a
greatly reduced
life span. By implementing certain embodiments of the cooling system disclosed
herein,.
temperature fluctuation is greatly reduced. This.cooling capability has been
achieved in
..
spite of the fact that larger screens generate more heat than smaller screens.
[0023] Because the display 15 has an innovative cooling system, it may be
placed in
direct sunlight. Although the cooling system may be used on smaller displays,
it is
especially useful for larger LCD, LED, or organic light emitting diodes (OLED)
displays.
These screens, especially with displays over 24 inches, face signifi:cant
cooling issues
in outdoor environments.
~. . .
[0024] In Fig. 1, the display area 49.of electronic display 15 is completely
covered by
a transparent fluid coolant contained within a narrow ftuid compartment that
is anterior
to and. coextensive with the electronic display surface (see 128 in Figs. 2
and 3). The
, . .
display shown also is equipped with an optional air curtain device 114 which
is the
subject matter of co-pending U.S. Application No. 11/941,728, incorporated by
reference herein. Optionally, the display also has a reflection shield 119, to
mitigate
;. . .
reflection of the sunlight on the display surface. Additionally, in outdoor
environments
where sun exposure is an issue; housing 75 is preferably white or cream in
color. A
color which is light reflective will help to reduce the solar radiation
absorbed by the
housing 75.
[0025] It is to be understood that the spirit and scope of the disclosed
embodiments
includes cooling of displays including, but not limited to LCDs. By way of
example and
not by way of limitation, the present invention may be used in conjunction
with displays
selected from, among LCD (including TFT or STN type), light emitting diode
(LED),
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organic light emitting diode (OLED), fleld emitting display (FED), cathode ray
tube
(CRT), and. plasma displays. Furthermore, embodiments of the present invention
may
be used with displays of other types including those not yet discovered. In
particular, it
is contemplated that the present invention.may be well suited for use with
full color, flat
panel OLED displays. While the embodiments described herein are well suited
for
outdoor environments, they may also be appropriate for indoor applications
(e.g.,
. . factory environments) where thermal stability of the display may be at
risk.
[0026] In a preferred embodiment, the fluid used to cool the display is non-
flammable.
An exemplary coolant fluid includes 30% isopropyl alcohol, 20% distilled
water, and
50% ethylene glycol. Preferrably, the coolant fluid is resistant to freezing
and will also
inhibit the growth of harmful microorganisms. However, depending on the
environmental conditions, many transparent fluids may be substituted with
acceptable
results.
[0027]. Using a non-flammable liquid to cool the dispta.y has some Important
advantages. One advantage is that doing so permits the present invention to be
used in
applications-that have restrictions on the use of flammable matedals. For
example,
flammable liquid cooling systems would typically not be approved for
gasoiine.disp[ay
pumps because of the obvious fire hazards associated with that environment.
However, it should be recognized that any number of transparent or semi-
transparent
fluids may be used, including flammable fluids, if the environment so permits.
[0028] As shown in Fig. 2 a significant feature of a preferred embodiment is
the
-cooling chamber 4. The cooling chamber 4 comprises the electronic display
surface
128 (e.g., the anterior surface of an LCD stack), a front glass 44 mounted in
front of the
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electronic display surface, the entrance manifold 59, the exit manifold 60,
and the
spacing members 39. The spacing members 39 extend vertically along the side
edges
of the cooling chamber 4. In this way the spacers forrri interior sidewalls of
the fluid
compartment 202 and prevent coolant from leaving. the, chamber. Together, the
entrance manifold 59, the exit manifold 60, and the spacing members 39 define
the
fluid compartment 202. The thickness of the fluid compartment 202 corresponds
to the
thickness of spacers 39 and the manifolds 59, 60. The thickness of the fluid
compartment 202 may be adjusted as required for the particular application.
[0029) Although fluid coolant may conceivably move in either direction within
the
cooling system 22, it is preferable to pull the fluid in from the bottom
through manifold
~. ,
59 of the cooling chamber. 4. Preferably, the fluid exits the cooling chamber
4 through
exhaust manifold 60. While filling the chamber, it is best to fill.the chamber
from the
~. .
bottom-up to inhibit air pocket formation which may negatively affect the
display image.
. _. ,
Filling the chamber 4 from the bottom up allows trapped air to efficiently
evacuate the
fluid compartment 202 through outlet 99.
[0030] During operation of the cooling system 22, a pump (not shown) causes
the
fluid to move through an inlet 98 at the entrance of manifold 59. 'Preferably,
manifold
59 extends along the base of the narrow cooling chamber 4. The entrance
manifo[d 59
includes a plurality of apertures from which the fluid coolant enters the
fluid
compartment 202. The presence of the entrance manifold 59 causes a uniform
flow of
coolant to enter and flow through the chamber 4. This helps to reduce the
presence of
air bubbles and flow disturbances that may negatively affect the display
picture.
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f _
.
[0031] Preferably, the transparent coolant fluid is pulled upwards across the
viewable
face of the electronic display surface 128 (see the dash arrows). As the fluid
travels
across the display, the liquid conducts heat away from the surface of the
display. The
fluid exits the display through an exhaust manifold 60 which extends along the
upper
edge of the cooling chamber: The exhaust manifold 60 also includes a plurality
of
apertures from which the fluid coolant exits the fluid compartment 202.
Preferably, the
apertures along exhaust manifold 60 are smaller than the apertures along
entrance
manifold 59. This relationship helps to prevent curvature of plates 44, 128
caused by
fluid pressures on the glass. Curvatures in these plates may negatively
distort the
display image.
[0032] The fluid coolant exits the exhaust manifold 60 through an outlet 99.
Preferably the fluid, which has absorbed heat from the display, travels to the
reservoir
tank 37 where it is received into the return port 14 of the reservoir tank 37.
By
contacting the cooling fluid directly to the electronic display surface 128,
maximal heat
transfer will be achieved. As it moves across the electronic display surface
128, the
coolant fluid may conduct heat away from the electronic display surface 128.
[0033] As shown in Fig 3, the cooling chamber requires only one additional
front glass
44. Advantageously, the preferred embodiments of the present invention utilize
the
electronic display surface 128 as the posterior surface of the cooling chamber
4.
Therefore, in this context, the term "electronic display surface" means the
front surface
.
of a typical electronic display (in the absence of the embodiments disclosed
herein).
The electronic display surface 128 of typical displays is glass; however,
neither plate 44
nor plate 128 need necessarily be glass. By utilizing the electronic display
surface 128
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=
as the posterior surface wall of the fluid compartment 202, there may be fewer
surfaces
to impact the visible light traveling through the display. Furthermore, the
entire device
will be lighter and cheaper to manufacturer_
[0034] Although the embodiment shown utilizes the electronic display surface
128,
certain modiftcations and/or coatings (e.g., index matching dielectrics) may
be added to
the electronic display surface 128, or to other components of the system in
order to {
. .
accommodate the fluid' coolant or to improve the optical performance of the
device.
In the embodiment shown, the 'electronic display surface 128 may be the= front
glass
plate of a liquid crystal display stack. However, almost any display surface
may be
suitable for embodiments of the present cooling system.
10035] Fig. 4 is an explanatory schematic illustrating an exemplary cooling
system
embodiment. As may be appreciated from the drawing, the cooling system 22
includes
various components ih fluid communication. Preferably, this may be
accomplished by
connecting the components with a series of tubes or pipes (illustrated
conceptually as
dotted lines in Fig. 4). The cooling system 22 components include a. reservofr
tank'37,
a pump 47, and a cooling chamber 4 in fluid communication. Preferably, the
system
also includes a filter 83 and a r=adiator 72, also in fluid communication.
Optionally, the
system may also include a fan unit 94. However, the optional fan unit is
preferably not
in fluid communication with the other components.
40036] Reservoir tank 37 holds the primary volume of coolant fluid and
provides
surface area to conduct heat away from the fluid while it is contained in the
tank 37.
The tank has at least 2 openings, an exit port 13 and a return port 14.
Optionaily, the,
reservoir tank includes a ventilation port 66. Pump 47 causes the coolant
fluid to move
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through the system 22. As may be appreciated by those skilled in the art, pump
47
may be located at a number of locations along the cooiant fluid pathway with
suitable
resufts. However, in order to minimize curvature of plates 44 and 128, it is
preferable to
. .
position pump 47 after the cooling chamber 4 so that the pump actually pulls
iiquid
. s
coolant from the bottom to the top of coofing chamber 4. If the pump is so
positioned,
as shown in Fig. 4, engaging the pump creates an area of low pressure at the
top of the
cooiing chamber 4. In this way fluid flows through the cooing chamber 4
according to
the arrows. Due to the "siippenne.ss" of some coolant fluids, pump 47 is
preferably a
positive displacement pump.
'[00371 In order to regulate the flow of coolant fluid through the cooling
chamber, a
bypass line with a valve 634 may be provided. The bypass line provides a
bypass route
i. =
for cooiant fluid to bypass the cooling chamber 4. The valve 634 is adapted to
facilitate
, =
control over the amount of coolant fluid diverted through the bypass line. The
bypass
line and valve 634 allow a predetermined portion of coolant fluid to be
diverted away
from the flow directed to the cooling chamber 4 and thereby facilitate control
over the
flow rate through the cooling chamber itself. In this way, the flow rate
'through the
cooling chamber may be regulated.
[0038] As one skilled in the art will appreciate, other methods and devices
may also
, ..
be used to regulate the flow through the cooling chamber. For example, the
size and
pump speed of pump 47 rnay be optimized for a-given application. Altemativeiy,
a
variable speed pump may also be used. Preferably, the variable speed pump may
be
in electrical communication with at least one pressure transducer (not shown).
Preferably, a pressure transducer may be placed upstream of the cooling
chamber 4
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-
and another pressure transducer may be placed downstream of the cooling
chamber 4:
The pressure information provided by the at least one pressure transducer may
be
utilized to set the operating speed of the variable speed pump. In that, way,
the flow
rate through the cooling chamber 4 may be adjusted to maintain appropriate
pressures
in the device. Maintaining appropriate pressures in- the cooling chamber 4 is
important
. .i
for preventing deformation or breakage of the display glass.
[0039] An 'optional 'tilter 83 may be added to remove contamination in the
fluid.
Preferably, a radiator 72 and fan unit 94 may also be included to provide even
greater
thermal stability. Optionally, a spigot (not shown) may be provided to
facilitate the
process of filling and emptying-the coolant fluid from the system.
[0040] As shown in Fig. 4 and optional radiator 72 is positioned to receive
fluid exiting
the cooling chamber 4. The radiator helps to further dissipate heat in the
coolant fluid
which has traveled across display surface 128. An op#ional fan unit 94 may be
positioned to work in conjunction with the radiator 72.
[0041] In operation, fluid exits the reservoir tank V fnom an output port 13
whlch may
be located beneath the tank 37_ On its way to the cooling chamber 4, the-
fluid. passes
through optional filter 83. From the filter 83, the fluid next enters the
cooling chamber 4
through inlet 98 of manifold 59. The fluid coolant travels up through the
fluid
compartment of the cooling chamber 4 in the direction indicated (dash arrows).
The
coolant fluid exits cooling chamber 4 through outlet 99 of the upper manifold
60.
Preferably, the fluid is then received by an optionaf radiator 72. While
traveling through
the optional, radiator 72, an optional fan unit 94 may force air past the
radiator 72 to
assist in transferring heat away from the coolant fluid. Fan unit, 94 also
helps to
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exchange the heated air inside the display housing 75 with the ambient air
outside the
display housing 75. Pump 47, which may be positioned after the radiator 72 in
Fig. 4,
can pull the fluid toward the reservoir tank: The fluid is received into the
reservoir tank
37 through return port 1.4. Preferably, return port 14 may be disposed at a
location that
is relatively distant from exit port 13 so as to allow the retuming fluid the
maximum
opportunity to cool before It exits the reservoir tank.37 through port 13.
. .
[0042] If desired, fan units may be located at the base of the housing 75 just
behind
the cooling chamber 4 of display--15::--F-an -units--rnay- provide;-a-laminar -
faow- of- air--- : -=
through the interior of the housing 75. Preferably, the airflow will be
directed across at
least one extemal surface of reservoir tank 37. As , described in Copending
U.S.
Application No. 11/941,728, which is incorporated by reference, the air
exhaust flow
. .
may ultimately be redirected onto the oooling chamber surface 44 by way of an
optional
air curtain system 114 (see Figs. I anc} 4).
[0043] If desired, a temperature sensor (not shown) and a switch (not shown)
may be
incorporated within the electronic display. 15. The temperature sensor may be
used to
detect when temperatures have reached a predetermined threshold value. In such
a.
case, the pump -can be selectively engaged when the temperature in the display
meets
a predetermined value. Predetermined thresholds may be selected and the system
may be configured with a thermostat (not shown) to advantageously keep the
display at
a relatively constant temperature, or at least within a range of acceptable
temperatures.
Altematively, to avoid the need for a thermostat, the pump 47 may run
continuously
when the electronic dispiay 15 is operational. 13
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[0044] Fig. 5 is a side cross-sectional view of an exemplary embodiment
showing the
preferred location of certain components. Advantageously, the reservoir tank
37, the
pump 47, the cooling chamber 4, the radiator 72, the fan unit 94, a filter
(not shown),
.
. .
may all be mounted within housing 75. In the figure, the interconnecting
tubing is
hidden for clarity.
100451 Preferably, reservoir tank 37 may be located near the top corner of the
housing
75 of the display 15. The tank 37 may also have a triangular shape. This will
allow the
upper and posterior surfaces of the tank to conform to the housing. of the
tank. This
position facilitates efficient heat transfer of the heat in the coolant fluid.
to the external
surfaces of the display housing 75. Although.this arrangement provides
acceptable
results, many other arrangements would also provide suitable cooling.
[0046]: In the arrangement shown in Fig. 5, fan unit 94 forces a laminar flow
of air into
the display housing 75. In the embodimerit shown, the air will travel upward
toward
reservoir tank 37.. Because tank 37 extends across the top of the housing and
it has a
triangular shape, the tank 37 will cause the 'moving. air to exit toward the
front of the
display. An optional air curtain device 114. may be included to direct the
exhaust air
across the front glass 44 of the cooling chamber. The stream. of air will also
assist in
the removal of heat from the electronic display surface 128.
[0047] Having shown and described a preferred, embodiment of the invention,
those
skilled in the art will realize that many variations and modifications may be
made to
affect the described invention and still be within the scope of the claimed
invention. For
~ example, the order of.many of the components mentioned In Figure 4 is not
critical and
may be switched without substantially sacrificing the 'devices performance.
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Additionaliy, many of the elements indicated above may be altered or replaced
by
different elements which will provide the same result and fall within the
spirit of the
claimed invention. It is the.intention, therefore, to limit the invention only
as indicated
by the scope of the Gaiins.
, , . .
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