Note: Descriptions are shown in the official language in which they were submitted.
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System and Method for Thermally Controlling an Electronic Display
Technical Field
[0001] Exemplary embodiments generally relate to heating/cooling systems for
electronic displays.
Background of the Art
[0002] Electronic displays are typically used in indoor, temperature-
controlled
environments. Although the temperature surrounding the display might be
relatively
stable (near room temperature), the components of the display may generate a
large
amount of heat. If not properly removed, this heat could damage the display or
shorten
its lifetime. Conductive and convective heat transfer systems have
traditionally been
used to remove heat from the electronic components in a display through as
many
sidewalls of the display as possible. While such heat transfer systems have
enjoyed a
measure of success in the past, today's electronic displays require even
greater cooling
(and in some case heating) capabilities.
[0003] Modern electronic displays are now being used in outdoor environments
as
well as other situations where the surrounding. temperature may extend above
and
below room temperature. In addition to heat transfer from the surrounding air,
radiative
heat transfer from the sun through a display surface may also become a major
factor.
In some applications and locations, 200 Watts or more of power through such a
display
surface is common. Furthermore, the market is demanding larger and brighter,
sometimes high definition displays. With increased electronic display size
more heat
will be absorbed from the sun and more heat will be transmitted into the
displays. To
compete with the ambient light from the sun as well as reflections off
surrounding
surfaces, displays must produce more light, which also typically results in
more heat
generated by the display and/or its backlight assembly.
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[0004] Further, in some applications the temperature may drop well below room
temperature. Some components of an electronic display may malfunction or may
be
permanently destroyed by exposure to such low temperatures. For example, the
performance of the liquid crystal material in a liquid crystal display (LCD)
may be
effected by low temperatures.
Summary of the Exemplary Embodiments
[00051 In an aspect, there is provided a thermally controlled electronic
display. The
display comprises a display stack; a backlight assembly positioned posterior
to said
display stack and having a posterior surface; a constricted convection plate
in close
proximity to the posterior surface of said backlight assembly, the space
between the
convection plate and the posterior surface of the backlight assembly defining
a gap
configured to constrict air to travel between the posterior surface and the
constricted
convection plate; one or more constricted convection fans adapted to draw air
through
said gap; a first plate of anti-reflective glass positioned anterior to said
display stack, the
space between said anti-reflective glass and said display stack defining an
insulating
gap; a linear polarizer positioned anterior to said first plate; and a second
plate of anti-
reflective glass positioned anterior to said linear polarizer.
WU] In an aspect, there is provided a thermal control system for an electronic
display having a display surface and a backlight assembly. The system
comprises a
first gas chamber positioned anterior to the electronic display surface, said
first gas
chamber having an entrance, exit, and exterior surface; a second gas chamber
in
gaseous communication with the entrance and exit of said first gas chamber and
positioned posterior to the electronic display surface, said second gas
chamber having
interior and exterior surfaces; one or more chamber fans within said second
gas
chamber to propel gas around the first and second gas chambers; and one or
more
exterior fans adapted to force air over the exterior surfaces of the second
gas chamber
and between the backlight assembly and an exterior surface of the second gas
chamber_
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room In an aspect, there is provided a method for thermally controlling an
electronic
display having a display surface and a backlight assembly, comprising the
steps of:
providing an isolated gas system comprising a first gas chamber which includes
the electronic display surface and a second gas chamber in gaseous
communication
with said first gas chamber, the second gas chamber having exterior surfaces
and
placed adjacent to a rear surface of the backlight assembly;
forcing isolated gas into the first gas chamber;
directing the isolated gas into the second gas chamber;
forcing cooling gas over the exterior surfaces of the second gas chamber and
between the rear surface of the backlight assembly and an exterior surface of
the
second gas chamber; and
reintroducing the isolated gas into the first gas chamber.
[0008] In an aspect, there is provided a gas cooling system for an electronic
display
enclosed within a housing, said electronic display having a display surface
and a
backlight having a rear surface. The system comprises a first gas chamber
positioned
anterior to the electronic display surface; a second gas chamber in sealed
gaseous
communication with said first gas chamber and positioned posterior to the
electronic
display surface; a. cooling chamber fan within said second gas chamber to
propel
circulating gas around the first and second gas chambers; and a second fan
positioned
to force ambient air from outside of the housing over the rear surface of the
backlight.
Nom In an aspect, there is provided a thermally regulated electronic display,
comprising an electronic display contained within a housing and having a
display
surface; a first gas chamber positioned anterior to the display surface of the
electronic
display; a second gas chamber in gaseous communication with said first gas
chamber
and positioned posterior to the electronic display, said second gas chamber
comprising
exterior surfaces; a cooling chamber fan to propel circulating gas around the
first and
second gas chambers; and a second fan adapted to force ambient air from
outside the
housing between the first and second gas chambers_
[0010] In an aspect, there is provided an isolated gas cooling system for a
liquid
crystal display (LCD) enclosed within a housing, said LCD having a display
surface arid
a LED backlight panel, the system comprising a first glass plate; a second
glass plate
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laminated to the first glass plate and placed in front of the LCD display
surface, the
space between the glass plates and LCD display surface defining a channel; an
anti-
reflective coating applied to any one of the following: first glass plate and
second glass
plate; a cooling plenum in gaseous communication with the channel to form an
isolated
closed loop; a first fan positioned so as to circulate gas through the channel
and cooling
plenum; and a second fan positioned so as to force ambient air from outside of
the
housing between the cooling plenum and the backlight panel.
[0011] In an aspect, there is provided a gas cooling system for an electronic
display
having a display surface and a rear surface, the system comprising a first gas
chamber
positioned anterior to the electronic display surface; a second gas chamber in
gaseous
communication with said first gas chamber and positioned posterior to the rear
surface
of the electronic display, the space between the rear surface and the second
gas
chamber defining a gap; a cooling chamber fan within said second gas chamber
to
propel gas around the first and second gas chambers; and a fan positioned to
draw
ambient air through said gap.
[0012] In an aspect, there is provided a thermally regulated electronic
display
comprising a housing having an exhaust; a liquid crystal stack having a
display surface;
an LED backlight with a thermally conductive rear surface positioned posterior
to the
liquid crystal stack; a first gas chamber positioned anterior to and
containing the display
surface; a second gas chamber in gaseous communication with said first gas
chamber,
said second gas chamber positioned adjacent to the rear surface of the LED
backlight,
the space between the second gas chamber and rear surface of the LED backlight
defining a gap; a cooling chamber fan which propels gas around the first and
second
gas chambers; and a fan which forces ambient air into the housing, through the
gap,
and out the exhaust.
[0013] In an aspect, there is provided an isolated gas cooling system for a
liquid
crystal display (LCD) having a display surface and a LED backlight panel, the
system
comprising a first glass plate; a second glass plate laminated to the first
glass plate and
placed in front of the LCD display surface, the space between the glass plates
and LCD
display surface defining a channel; an anti-reflective coating applied to any
one of the
following: first glass plate and second glass plate; a cooling plenum in
gaseous
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communication with the channel and positioned behind the LED backlight panel,
the
space between the cooling plenum and backlight panel defining a gap; a first
fan
positioned so as to circulate isolated gas through the channel and cooling
plenum; and
a second fan positioned so as to force cooling gas over the cooling plenum and
through
the gap.
[0014] In an aspect, there is provided a method for cooling an electronic
display
having a rear surface, comprising the steps of:
placing a substantially planar surface adjacent to the rear surface of the
electronic display to define a gap between the planar surface and the
electronic display;
placing a closed loop of circulating gas around the display;
forcing a circulating gas around the closed loop; and
forcing cooling air through said gap.
[0015] In an aspect, there is provided a method for cooling an electronic
display
having a front surface and a gap defined between a rear surface of the
electronic
display and a second posterior surface, comprising the steps of:
circulating gas around the display in a closed loop;
allowing the gas to contact the front surface of the electronic display; and
forcing cooling air through the gap
where the cooling air is not permitted to mix with the circulating gas.
[0016] In an aspect, there is provided a method for cooling an LED backlit
liquid
crystal display where the LED backlight contains a rear surface and the LCD
contains a
front viewing surface, and a posterior surface is spaced apart from the rear
surface of
the LED backlight to define a gap, the method comprising the steps of:
circulating gas around the LCD and backlight in a closed loop;
forcing cooling air through the gap; and
preventing the circulating gas from mixing with the cooling air.
[0017] In an aspect, there is provided a gas cooling system for an electronic
display
having a display surface and a rear surface, the system comprising a closed
loop of
circulating gas positioned to surround the electronic display; and an open
loop of cooling
air travelling along the rear surface of the electronic display without mixing
with the
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circulating gas; wherein the open loop cooling air flows through the center of
the closed
loop of circulating gas.
[0018] In an aspect, there is provided a thermally regulated electronic
display
comprising a housing having an entrance and an exhaust; a liquid crystal stack
having a
display surface; an LED backlight with a thermally conductive rear surface
positioned
posterior to the liquid crystal stack; a closed loop of circulating gas
positioned to
surround the liquid crystal stack and LED backlight; and an open loop of
cooling air
travelling through the entrance, along the rear surface of the LED backlight,
and
exhausting out of the display.
[0019] In an aspect, there is provided a thermally regulated liquid crystal
display
assembly, the system comprising a liquid crystal stack having a display
surface; an LED
backlight with a thermally conductive rear surface positioned posterior to the
liquid
crystal stack; a glass plate placed in front of the display surface, the space
between the
glass plate and display surface defining a channel; a closed loop of
circulating gas
positioned to surround the liquid crystal stack and LED backlight where
circulating gas
flows through the channel; and an open loop of cooling air contacting the rear
surface of
the LED backlight.
[0020] In an aspect, there is provided a system for cooling an electronic
display
having a posterior display surface and contained within a housing, the system
comprising a constricted convection plate placed posterior to the posterior
display
surface; two side panels placed adjacent to the constricted convection plate
and the
posterior display surface, defining a constricted convection channel having an
entrance
and an exit; and a fan placed to draw air from outside of the housing through
the
constricted convection channel.
[0021] In an aspect, there is provided a liquid crystal display (LCD)
comprising a liquid
crystal stack;
a backlight assembly behind the liquid crystal stack and comprising:
a metal core printed circuit board (PCB) having front and back sides;
a plurality of LEDs mounted on the front side of the PCB;
a posterior surface on the rear side of the PCB;
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a constricted convection plate placed behind the posterior surface of the PCB,
defining a constricted convection channel having an entrance and an exit;
and
a fan positioned to draw air through the constricted convection channel.
[0022] In an aspect, there is provided a system for cooling an electronic
display
comprising an electronic display comprising a front display surface and a
posterior
surface; a constricted convection plate and a pair of sidewalls behind the
posterior
surface of the display, defining a constricted convection channel having an
entrance
and exit; a gaseous closed loop traveling across the front display surface,
behind the
constricted convection plate, and returning to the front display surface; a
means for
propelling gas around the closed loop; a means for cooling the gas in the
closed loop;
and a means for forcing air through the constricted convection channel.
[0023] In an aspect, there is provided a system for cooling an electronic
display
having a posterior display surface and contained within a housing, the system
comprising a constricted convection plate placed posterior to the posterior
display
surface covering the majority of the posterior display surface; at least one
bracket which
connects the posterior display surface with the constricted convection plate;
and a fan
placed to draw ambient air between the constricted convection plate and the
rear
posterior.
[0024] In an aspect, there is provided a liquid crystal display (LCD)
comprising:
a liquid crystal stack;
a backlight assembly behind the liquid crystal stack and comprising:
a printed circuit board (PCB) having front and back sides;
a plurality of LEDs mounted on the front side of the PCB;
a posterior surface on the rear side of the PCB;
a constricted convection plate placed behind and substantially parallel with
the
posterior surface of the PCB; and
a fan positioned to draw air between the constricted convection plate and the
posterior surface.
[0025] In an aspect, there is provided a system for cooling an electronic
display
comprising:
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an electronic display comprising a front display surface and a posterior
surface
where no electronics are mounted to the posterior surface of the electronic
display;
a constricted convection plate behind the posterior surface of the display
covering a majority of the posterior display surface; and
'a means for forcing air between the constricted convection plate and the
posterior surface of the electronic display.
[0026] In an aspect, there is provided a system for cooling an electronic
display
having a posterior display surface and contained within a housing, the system
comprising a constricted convection plate placed posterior to the posterior
display
surface and covering the majority of the posterior display surface; a channel
formed
between the constricted convection plate and the posterior display surface;
and a fan
placed to draw ambient air through the channel; wherein the constricted
convection
plate thermally isolates electrical components from the posterior display
surface.
[0027] In an aspect, there is provided a liquid crystal display (LCD)
comprising:
a liquid crystal stack;
a backlight assembly behind the liquid crystal stack and comprising:
a printed circuit board (PCB) having front and back sides;
a plurality of LE Ds mounted on the front side of the PCB;
a posterior surface on the rear side of the PCB which does not have any
electronic devices attached directly thereto;
a constricted convection plate placed behind the posterior surface of the PCB;
and
a fan positioned to draw air between the constricted convection plate and the
posterior surface.
[0028] In an aspect, there is provided an electronic display assembly
comprising:
an electronic display comprising a front display surface and a posterior
surface
where no electronics are mounted directly to the posterior surface of the
electronic display;
a constricted convection plate behind the posterior surface of the display;
and
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a fan positioned to force ambient air between the constricted convection plate
and the posterior surface of the electronic display;
wherein the constricted convection plate isolates the posterior surface from
electronic devices for operating said electronic display.
[0029] In an aspect, there is provided a gas cooling system for an electronic
display
having a display surface and a rear surface, the system comprising a closed
loop of
circulating gas positioned to surround the electronic display; and an open
loop of
ambient gas travelling along the rear surface of the electronic display; where
the
circulating gas and ambient gas are two separate flows of fluid.
[0030] In an aspect, there is provided a thermally regulated electronic
display
comprising a liquid crystal stack having a display surface; an LED backlight
with a rear
surface positioned posterior to the liquid crystal stack; a closed loop of
circulating gas
positioned to surround the liquid crystal stack and LED backlight; and an open
loop of
ambient gas travelling along the rear surface of the LED backlight.
[0031] In an aspect, there is provided a thermally regulated electronic
display
assembly, the system comprising an electronic display having a display surface
and a
rear surface a glass plate placed in front of the display surface, the space
between the
glass plate and display surface defining a channel; a closed loop of
circulating gas
positioned to surround the electronic display where circulating gas flows
through the
channel; and an open loop of ambient gas contacting the rear surface of the
electronic
display.
[0032] Exemplary embodiments may contain one or more of the thermal control
features disclosed herein. A plurality of thermal control features are
disclosed and
these features may be utilized alone or in any combination. The precise
combination of
features would depend upon the particular cooling/heating needs of the display
at issue,
which would depend upon the type of display, size of the display, and its
particular
environment. The embodiments may be practiced with any form of electronic
display,
including but not limited to: LCD, light emitting diode (LED), organic light
emitting diode
(OLED), field emitting display (FED), cathode ray tube (CRT), plasma, and
projection
displays. An exemplary embodiment would be practiced with LCD displays.
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[0033] One thermal feature relates to an isolated gas cooling system. The gas
cooling
system is preferably a closed loop which includes a first gas chamber
comprising a
transparent anterior plate and a second gas chamber comprising a cooling
plenum.
The first gas chamber is anterior to and coextensive with the viewable face of
the
electronic display. The transparent anterior plate may be set forward of the
electronic
display surface, defining the depth of the first gas chamber. A cooling
chamber fan, or
equivalent means, may be located within the cooling plenum and may be used to
propel
gas around the isolated gas cooling chamber loop. As the gas traverses the
first gas
chamber it contacts the electronic display surface, absorbing heat from the
display
surface. Because the gas and the relevant surfaces of the first gas chamber
are
transparent, the image quality remains excellent. After the gas has traversed
the
transparent first gas chamber, the gas may be directed into the rear cooling
plenum
where it is cooled.
[0034] Another thermal feature may utilize the isolated gas system as a
heating
device, either instead of or in addition to its cooling abilities. An isolated
gas heating
system would also be a closed loop system with a first gas chamber anterior to
the
display surface and a second chamber comprising a heating plenum or
cooling/heating
plenum. Heating elements may be placed within the plenum in order to heat the
gas
within the second chamber. As the gas is forced into the first chamber it may
transfer
its heat to the display surface. The gas may then return to the plenum for
another
heating cycle. The plenum may function as a cooling plenum only, heating
plenum only,
or a combination heating/cooling plenum; all depending upon the particular
display and
its particular operating environment.
[0035] Some embodiments may place electronic components used to operate the
electronic display within the plenum of the isolated gas chamber. The
electronic
components may include, but are not limited to: transformers, circuit boards,
processors, resistors, capacitors, batteries, motors, power supplies,
illumination
devices, wiring and wiring harnesses, and switches. If the plenum is being
utilized as a
cooling plenum, the cool gas within the plenum can further aid in the cooling
of the
electronic components, which will naturally generate heat during operation.
Further, if
the plenum is being utilized as a source of heat for the display, the natural
heat from the
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electronic components can also heat the gas in the plenum, reducing the amount
of
energy which needs to be applied to the heating elements.
[0036] A linear polarizer may be used in some embodiments to further reduce
the
solar loading on the electronic display. This polarizer can be used in
combination with
the isolated gas chamber, or may simply be placed anterior to the electronic
display with
an insulating gap between the polarizer and the display. The insulating gap
reduces the
amount of heat that is transferred between the polarizer and the display.
[0037] Some electronic displays, such as LCDs for example, require a backlight
assembly to produce an image upon the display surface. The backlight
assemblies are
typically a large source of heat for the display. Thus, some embodiments may
utilize a
constricted convection system to cool the backlight unit for the display. The
constricted
convection system may comprise a constricted convection plate which is placed
in close
proximity to the backlight assembly in order to define a gap. Gas is forced
through the
gap in order to facilitate more efficient cooling of the backlight assembly.
In some
embodiments a wall of the plenum may constitute the constricted convection
plate.
[0038] Some embodiments may also utilize an air curtain device which forces
air
(either warm or cold) over the exterior surface of the display assembly.
[0039] Finally, some embodiments may use a fluid assembly which contacts a
fluid
against the display surface in order to cool it. The fluid may be a
substantially clear
form of coolant fluid which is pumped through an anterior cavity which
includes the
display surface.
Brief Description of the Drawings
[0040] A better understanding of the exemplary embodiments 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:
[0041] FIGURE 1 is a perspective view of an exemplary embodiment in
conjunction
with an exemplary electronic display.
[0042] FIGURE 2 is an exploded perspective view of an exemplary embodiment
showing components of the isolated gas cooling system.
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[0043] FIGURE 3 is top plan view of an exemplary embodiment of the cooling
chamber.
[0044] FIGURE 4 is a front perspective view of an embodiment of the isolated
cooling
chamber, particularly the transparent anterior surface of first gas chamber.
[0045] FIGURE 5 is a rear perspective view of an embodiment of the isolated
cooling
chamber, showing optional electrical components placed in the plenum.
[0046] FIGURE 6 is a rear perspective view of an embodiment of the isolated
cooling
chamber showing surface features that may be included on the plenum
[0047] FIGURE 7 is a top plan view of an exemplary embodiment of the cooling
chamber showing surface features that may be included on the plenum.
[0048] FIGURE 8 is a front perspective view of an embodiment of the isolated
cooling
chamber with included thermoelectric modules.
[0049] FIGURE 9 is a top plan view of an exemplary embodiment of the cooling
chamber with included thermoelectric modules.
[0050] FIGURE 10 is an exploded perspective view of an exemplary embodiment
showing components of the isolated gas cooling system.
[0051] FIGURE 11 is a top plan view of an exemplary embodiment of the heating
chamber.
[0052] FIGURE 12 is a rear perspective view of an embodiment of the heating
chamber, showing optional electrical components and heating elements.
[0053] FIGURES 13 and 14 are cross-sectional views of exemplary embodiments
for
utilizing a linear polarizer with the isolated gas system or an insulating
gap.
[0054] FIGURES 15A and 15B are side views of exemplary embodiments of the
constricted convection cooling system with a constricted convection plate.
[0055] FIGURE 16 is a top plan view of an exemplary embodiment where the
cooling
plenum is utilized as the constricted convection plate.
[0056] FIGURES 17A-17C are cross-sectional views of embodiments where the
cooling plenum is utilized as the constricted convection plate.
[0057] FIGURE 18 is a front plan view of a display utilizing an air curtain
device.
[0058] FIGURE 19 is a cross-sectional view of a display utilizing an air
curtain device.
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[0059] FIGURE 20 is an illustration showing the components for a liquid cooled
display.
Detailed Description
[0060] It is to be understood that the spirit and scope of the disclosed
embodiments
includes thermally controlling displays including, but not limited to LCDs.
For simple
explanation purposes, embodiments may be described with respect to the
components
for LCD displays. By way of example and not by way of limitation, embodiments
may
be used in conjunction with displays selected from among LCD, light emitting
diode
(LED), organic light emitting diode (OLED), field emitting display (FED),
cathode ray
tube (CRT), plasma, and projection displays. Furthermore, embodiments may be
used
with displays of other types including those not yet discovered. In
particular, it is
contemplated that embodiments may be well suited for use with full color, flat
panel
OLED displays. Further, it is particularly contemplated that embodiments may
be used
with relatively large, high definition LCD displays. While the embodiments
described
herein are well suited for outdoor environments, they may also be appropriate
for indoor
applications (e.g., factory environments, coolers/freezers, etc.) where
thermal stability of
the display may be at risk.
Isolated Gas Cooling System
[0061] As shown in FIGURE 1, when the display 10 is exposed to outdoor
elements,
the temperatures inside the display 10 may vary greatly without some kind of
cooling
device. As such, the display 10 may not function properly or may have a
greatly
reduced life span. Direct sunlight is especially problematic in causing
increases in the
internal temperature of the display 10.
[0062] In Figure 1, the display area of the electronic display shown includes
a narrow
gas chamber that is anterior to and coextensive with the electronic display
surface. The
display shown is also equipped with an optional air curtain device 114. The
air curtain
device 114 is discussed in detail below. Optionally, the display may have a
reflection
shield 119, to mitigate reflection of the sunlight on the display surface.
Additionally, in
outdoor environments, housing 70 is preferably a color which reflects
sunlight.
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[0063] As shown in FIGURE 2, an exemplary embodiment of the electronic display
10
includes an isolated gas cooling chamber 20 contained within a display housing
70. A
transparent first gas chamber is defined by spacers 100 and transparent front
plate 90.
A second transparent front plate 130 may be laminated to front plate 90 to
help prevent
breakage of front plate 90 and protect the interior of the display. Cooling
chamber 20
surrounds a display stack 80 and associated backlight assembly 140.
[0064] The display 10 may include means for cooling gas contained within the
second
gas chamber. This means may include one or more fans 60 which may be
positioned at
the base of the display housing 70. The fans 60 may ingest cool air and force
the
cooler ingested air over at least one external surface of a posterior cooling
plenum 45.
If desired, an air conditioner (not shown) may also be utilized to cool the
air which
contacts the external surface of plenum 45. Alternatively, the fans 60 may
simply ingest
ambient air.
[0065] Referring to FIGURE 3, embodiments of the isolated gas cooling chamber
20
may comprise a closed loop which includes a first gas chamber 30 and a second
gas
chamber 40. The first gas chamber includes a transparent plate 90. The second
gas
chamber comprises a cooling plenum 45. The term "isolated gas" refers to the
fact that
the gas within the isolated gas cooling chamber 20 is essentially isolated
from external
air in the housing of the display. Because the first gas chamber 30 is
positioned in front
of the electronic display surface 85, the gas should be substantially free of
dust or other
contaminates that might negatively affect the display image. An optional
filter (not
shown) may be utilized to assist in preventing contaminates and dust from
entering the
first gas chamber 30.
[0066] The isolated gas may be almost any transparent gas, for example, normal
air,
nitrogen, helium, or any other transparent gas. The gas is preferably
colorless so as not
to affect the image quality. Furthermore, the isolated gas cooling chamber 20
need not
necessarily be hermetically sealed from the external air. It is sufficient
that the gas in
the chamber is isolated to the extent that dust and contaminates may not
substantially
enter the first gas chamber.
[0067] In the closed loop configuration shown in Fig. 3, the first gas chamber
30 is in
gaseous communication with the second gas chamber 40. A cooling chamber fan 50
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may be provided within the cooling plenum 45 and utilized to propel gas around
the
isolated gas cooling chamber 20. The first gas chamber 30 includes at least
one front
glass 90 mounted in front of an electronic display surface 85.
[0068] Referring to FIGURE 4, the front plate 90 may be set forward from the
electronic display surface 85 by spacing members 100. The spacing members 100
define the depth of the narrow channel passing in front of the electronic
display surface
85. The spacing members 100 may be independent or alternatively may be
integral
with some other component of the device (e.g., integral with the front plate
90). The
electronic display surface 85, the spacing members 100, and the transparent
front plate
90 define a first gas chamber 30. The chamber 30 is in gaseous communication
with
plenum 45 through entrance opening 110 and exit opening 120.
[0069] As shown in Fig. 3, a posterior surface of the first gas chamber 30
preferably
comprises the electronic display surface 85 of the display stack 80. As the
isolated gas
in the first gas chamber 30 traverses the display it contacts the electronic
display
surface 85. Contacting the cooling gas directly to the electronic display
surface 85
enhances the convective heat transfer away from the electronic display surface
85. In
exemplary embodiments the electronic display surface 85 comprises the
posterior
surface of the first gas chamber 30. Accordingly, the term "electronic display
surface"
refers to the front surface of a typical electronic display (in the absence of
the
embodiments disclosed herein).
[0070] In an exemplary embodiment, the electronic display surface 85, front
plate 90,
and optional second front plate 130 may be comprised of a glass substrate.
However,
neither display surface 85, nor transparent front plate 90, nor optional
second
transparent front plate 130 need necessarily be glass. Thus, the term "glass"
may be
used herein interchangeably with the term plate, but a glass material is by no
means
required. Further, electronic display surface 85 does not have to comprise the
posterior
surface wall of the front gas compartment 30. An additional plate may be used.
However, by utilizing the electronic display surface 85 as the posterior
surface wall of
the gas compartment 30, there may be fewer surfaces to impact the visible
light
traveling through the display. Furthermore, the device will be lighter and
cheaper to
manufacturer.
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[0071] Although the embodiment shown utilizes the electronic display surface
85,
certain modifications and/or coatings (e.g., anti-reflective coatings) may be
added to the
electronic display surface 85, or to other components of the system in order
to
accommodate the coolant gas or to improve the optical performance of the
device. In
the embodiment shown, the electronic display surface 85 may be the front glass
plate of
a liquid crystal display (LCD) stack. However, almost any display surface may
be
suitable for embodiments of the present cooling system. Although not required,
it is
preferable to allow the cooling gas in the first gas chamber 30 to contact the
electronic
display surface 85 directly. In this way, the convective transfer of heat from
the display
components to the circulating gas will be maximized.
[0072] Referring to Fig. 4, the front plate 90 of the first gas chamber 30 is
transparent
and is positioned anterior to the electronic display surface 85. The arrows
shown
represent the movement of the isolated gas through the first gas chamber 30.
As
shown, the isolated gas traverses the first gas chamber 30 in a horizontal
direction.
Although cooling system 20 may be designed to move the gas in either a
horizontal or a
vertical direction, it is preferable to propel the gas in a horizontal
direction. In this way, if
dust or contaminates do enter the first gas chamber 30, they will tend to fall
to the
bottom of chamber 30 outside of the viewable area of the display. The system
may
move air left to right, or alternatively, right to left. After the gas
traverses the first gas
chamber 30 it exits through exit opening 120. Exit opening 120 defines the
entrance
junction into the rear cooling plenum 45.
[0073] FIGURE 5 shows a schematic of the rear cooling plenum (illustrated as
transparent for explanation). One or more fans 50 within the plenum may
provide the
force necessary to move the isolated gas through the isolated gas cooling
chamber.
Whereas the first gas chamber 30 was designed to collect heat from the surface
85 of
the display, the second gas chamber 40 is designed to extract the heat from
the gas
and remove the heat from the cooling chamber 20. The second chamber 40 may
have
various contours and features to accommodate the internal structures within a
given
electronic display application.
[0074] If desired, various electronic components 200 can be placed anywhere
throughout the second gas chamber 40. The electronic components 200 may
include,
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but are not limited to: transformers, circuit boards, processors, resistors,
capacitors,
batteries, motors, power supplies, illumination devices, wiring and wiring
harnesses, and
switches. These components can be mounted directly on the walls of the chamber
or
supported on rods or posts 209. Thus, the cooling plenum can be designed to
not only
extract heat from the first gas chamber 30 but also to cool these various
electronic
components 200. (Additionally, as discussed below, if the isolated gas system
is used
to heat the display, the electronic components can assist in heating the
isolated gas.)
[0075] Referring now to FIGURES 6 and 7, various surface features 150 may be
added to improve heat dissipation from the plenum 45. These surface features
150
provide more surface area to radiate heat away from the gas within the second
gas
chamber 40. These features 150 may be positioned at numerous locations on the
surface of the plenum 45.
[0076] Referring now to FIGURES 8 and 9, one or more thermoelectric modules
160
may be positioned on at least one surface of the plenum 45 to further cool the
gas
contained in the second gas chamber 40. The thermoelectric modules 160 may be
used independently or in conjunction with surface features 150.
Alternatively,
thermoelectric modules 160 may be used to heat the gas in the plenum if the
isolated
gas system is utilized to heat a display in a cold environment.
[0077] FIGURE 10 shows an exemplary method for removing heat in the gas
contained in the rear plenum 45. Fan 60 may be positioned to ingest air and
blow that
air across the anterior and posterior surfaces of the plenum 45. Again, fan 60
may
ingest air conditioned air into the display housing 70 or may simply ingest
ambient
surrounding air. Furthermore, in this configuration, fan 60 may also force air
past the
heat generating components of the electronic display (e.g., the display stack
80 and the
backlight assembly 140) to further improve the ability to cool the entire
display. It
should be noted that this embodiment can be combined with the constricted
convection
cooling method discussed in detail below. The heated exhaust air may exit
through one
or more apertures 179 located on the display housing 70.
Isolated Gas Heating System
[0078] As mentioned above, the isolated gas system can be utilized to also
heat the
electronic display. Referring to FIGURES 11 and 12, heating elements 220 may
be
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located within the second gas chamber 40 and operate to warm the gas as it
passes
through the second gas chamber 40. These heating elements can be any one of
the
many commonly available heating elements or thermoelectric modules. Many
times,
these elements are simply a material which contains a high electrical
resistance, and
thus generates heat when current flows through it. The heating elements can
be, but
are not limited to, any one of the following: nichrome wire or ribbon, screen
printed
metal/ceramic tracks deposited on ceramic insulated metal (generally steel)
plates,
CalRod (typically a fine coil of nichrome wire in a ceramic binder, sealed
inside a tough
metal shell), heat lamp, and Positive Thermal Coefficient (PTC) of resistance
ceramic.
[0079] As discussed above, the plenum 45 may contain electrical components 200
which power and control the electronic display. The electrical components may
be any
one of the following: transformers, microprocessors, printed circuit boards,
power
supplies, resistors, capacitors, motors, wiring harnesses, and connectors. The
electrical
connections for the electrical components 200 may pass through a wall of the
plenum
45. The electrical components 200 can be located anywhere within the plenum
45. The
electrical components 200 may be mounted on the posterior or anterior surface
of the
plenum and may be mounted directly on the surface of the plenum or may be
suspended by mounting posts so that gas may pass all around the component.
[0080] While the display is operational, the isolated gas cooling system may
run
continuously. However, if desired, a temperature sensor (not shown) and a
switch (not
shown) may be incorporated within the electronic display. Thus, a thermostat
may be
used to detect when temperatures have reached a predetermined threshold value
and
the isolated gas system may be selectively engaged when the temperature in the
display reaches a predetermined value. Predetermined temperature thresholds
may be
selected and the system may be configured to heat, cool, or both heat and cool
the
display to advantageously keep the display within an acceptable temperature
range.
Linear Polarizer with Optional Insulator Gap
[0081] FIGURE 13 is a cross-sectional view of another exemplary embodiment for
another thermal control feature. In the arrangement shown, the front plate 90
and a
second front plate 130 may be comprised of glass and may be laminated
together. The
first and second front panels 130 and 90 may be fixed to one another with a
layer of
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index matched optical adhesive 201 to form a front glass unit 206. The display
stack 80
may comprise a liquid crystal assembly 212 interposed between a front
polarizer 216
and a rear polarizer 214. In other embodiments, the display stack 80 may be
any other
type of assembly for any other type of electronic display. The space between
the
display stack 80 and the front glass unit 206 defines an insulator gap 300.
The insulator
gap 300 serves to thermally separate the front glass unit 206 from the LCD
stack 80.
This thermal separation localizes the heat on the front glass unit rather than
allowing
solar loading of the LCD stack. If used in combination with the isolated gas
system, the
insulator gap 300 may comprise the first gas chamber 30. In other embodiments,
the
insulator gap 300 may be used without the isolated gas system simply as a
layer of
insulation from both the ambient air as well as solar loading.
[0082] The second front panel may have a first surface 202 and a second
surface
208. The first surface 202 may be exposed to the elements; while the second
surface
208 may be fixed to the first front plate 90 by the index matched optical
adhesive 201.
The first front plate 90 may have a third surface 209 and a fourth surface
204. The third
surface 209 may be fixed to the second front plate 130 by the index matched
optical
adhesive 201; while the fourth surface may be directly adjacent to the
insulator gap 300.
In some embodiments, to decrease the solar loading of the display stack 80 and
improve the viewable image quality, an anti-reflective coating may be applied
to the first
surface 202 and the fourth surface 204. In other embodiments, the anti-
reflective
coating may only be applied to at least one of the first, second, third, or
fourth surface
202, 208, 209, and 204, respectively.
[0083] FIGURE 14 is a cross-sectional view of another exemplary embodiment of
the
front glass unit 206. In the arrangement shown, the front glass unit 206
comprises a
second front plate 130, a layer of index matched optical adhesive 201, a
linear polarizer
400, and a first front plate 90. The linear polarizer 400 may be bonded to at
least one of
the first, second, third or fourth surfaces 202, 208, 209, and 204,
respectively. Again,
anti-reflective layers may be applied to at least one of the first, second,
third or fourth
surfaces 202, 208, 209, and 204, respectively. The linear polarizer 400 may be
aligned
with the front polarizer 209 found in the LCD stack 85. The inclusion of a
linear
polarizer 400 in the front glass unit 206, further decreases the solar load on
the display
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stack 80. The
reduction in solar loading may significantly reduce the internal
temperature of the electronic display. The linear polarizer 300 may also cause
a
reduction in specular reflection of the front glass unit 206 and the display
stack 80. As
discussed above, if used in combination with the isolated gas system, the
insulator gap
300 may comprise the first gas chamber 30. In other embodiments, the insulator
gap
300 may be used without the isolated gas system simply as a layer of
insulation from
both the ambient air as well as solar loading. Again, it should be noted that
the display
stack 80 may be an LCD stack, but it can also be any other type of electronic
display.
[0084] It should also be noted that the second front plate 130 is not
required.
Embodiments may utilize only the first front plate 90 with a linear polarizer
attached to
either the posterior or anterior surface of the front plate 90. An anti-
reflective layer may
also be attached to either the anterior or posterior surface of the front
plate 90. The
front plate 90 may be tempered for additional strength if using only the front
plate 90
without the second front plate 130.
Constricted Convection
[0085] Some types of electronic displays require a backlight assembly in order
to
generate an image upon a viewable screen. LCDs are one type of display that
requires
a backlight assembly. Other types of displays, such as plasma displays and
OLEDs, do
not require a backlight assembly as they generate light themselves. However,
these
types of displays still generate a significant amount of heat. Thus, in the
foregoing
description, the constricted convection system will be described with regard
to a
backlight assembly, but it should be noted that the embodiments can be
practiced with
other types of displays. Therefore, when a backlight or backlight assemblies
are
discussed, these assemblies could also be the rear surfaces of other heat-
generating
displays and the constricted convection system would facilitate more efficient
cooling of
these alternate displays. It should also be noted that Figures 15A-15B and
Figures
17A-17C are not necessarily drawn to scale. The relationship between the
elements
may be exaggerated for explanatory purposes.
[0086] FIGURE 15A shows a cross-sectional view of the backlight 140 with the
constricted convection plate 300, the space between the posterior surface of
the
backlight 140 and the constricted convection plate defines a narrow gap 305 to
constrict
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air to travel between them. The dimensions of the gap may vary depending on
several
factors including the size of the display, its operating conditions, the type
of backlight
assembly and its posterior surface material, and the number and power applied
to the
various constricted convection fans. Some exemplary embodiments may utilize a
gap
distance of approximately 0.25-3.5 inches. Other embodiments may utilize a
slightly
larger gap. It has been found that forcing air through this gap 305 increases
the ability
to cool the backlight 140. One or more constricted convection fans 310 may be
used to
pull air through the gap 305. FIGURE 15B shows a cross-sectional view of
another
embodiment for the constricted convection system where one or more constricted
convection fans 310 push air through the gap 305.
[0087] FIGURE 16 shows a top view of the isolated gas system as discussed
above.
The cross-section line 17-17 is shown passing through the isolated gas system.
[0088] FIGURES 17A-17C show cross-sectional views of the 17-17 section that is
shown in Figure 16. Referring first to Figure 17A, towards the front of the
display is the
first gas chamber 30 which abuts against the electronic display 80. Anterior
to the first
gas chamber 30 is the front plate 90. Towards the rear of the display, the
backlight 140
is placed in close proximity to the second gas chamber 40. In this
arrangement, the
outer wall of the second gas chamber 40 may function as the constricted
convection
plate. This embodiment does not utilize a constrictive convection fan, but
instead uses
the fan 60 which ingest air from outside the display housing and forces it
over the
surfaces of the second gas chamber 40. As noted above, this air may simply be
ambient air or alternatively this air may come from a conditioning unit (not
shown). To
facilitate the flow of air between the backlight 140 and the cooling chamber
40, a
guiding device 320 may be used.
[0089] Referring now to Figure 17B, the cooling chamber 40 contains a guiding
feature 41, which is used in combination with the guiding device 320 to
facilitate the flow
of air between the backlight and the cooling chamber. Figure 170 shows another
embodiment, where both the external fan 60 and the constrictive convection fan
310 is
used. This embodiment could also utilize a version of the guiding devices
shown in
Figures 17A and 17B.
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[0090] The backlight 140 may comprise a printed circuit board (PCB) with a
plurality of
lights mounted to the side facing the electronic display 80. The lights in the
backlight
may be any one of the following: LED's, organic light emitting diodes (OLED),
field
emitting display (FED), light emitting polymer (LEP), or organic electro-
luminescence
(OEL) lights. In an exemplary embodiment, the backlight 140 would ideally have
a low
level of thermal resistance between the side facing the electronic display 80
and the
side facing the second gas chamber. To accomplish this low level of thermal
resistance, the backlight 140 may be built using metal printed circuit board
(PCB)
technology to further transfer heat away from the lights. The rear surface of
the
backlight 140 may also be metallic, or some other thermally conductive
material, to
further enhance the convective heat transferring properties. The surface may
even
have a plurality of surface features such as fins to further enhance the
convective heat
transferring properties. The constrictive convective fan 310 may then send the
warm air
out of an exhaust 179 (shown in Figure 2) so that it may exit the display
housing
entirely.
[0091] While the display is operational, the external fan 60 and the
constrictive
convection fan 310 may run continuously. However, if desired, a temperature
sensor
(not shown) and a switch (not shown) may be incorporated within the electronic
display.
This effective thermostat may be used to detect when temperatures have reached
a
predetermined threshold value. In such a case, the various fans may be
selectively
engaged when the temperature in the display reaches a predetermined value.
Predetermined thresholds may be selected and the system may be configured with
a
thermostat (not shown) to advantageously keep the display within an acceptable
temperature range. This would save on both energy costs as well as the useful
lifetime
of the devices.
Air Curtain
[0092] In addition to the various thermal control features discussed above, an
air
curtain device can also be used. The air curtain device may be used alone, or
in
combination with any of the other thermal control features discussed above.
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[0093] FIGURE 18 shows an electronic display 10, having a housing 70 and a
front
plate 90. The air baffles 114 for the air curtain can be seen as a broken line
in the
figure. Cross-section line 19-19 can also be seen in this figure.
[0094] FIGURE 19 shows the cross-sectional view from the line 19-19 shown in
Figure 18. This figure shows the circulation of air through the housing 70
when fans 60
are actuated. As discussed above, fans 60 ingest air into the housing 70
through
entrance 51. This air may be ambient air or alternatively may be air
conditioned air.
The flow of ingested air is shown as arrow 111. Once inside the display
housing 70, the
air may flow upwards along flow arrow 121. This air may be utilized with any
of the
above mentioned thermal control features. For example, this air may be used to
cool
the isolated gas within the second chamber (plenum) or may be used with the
constricted convection system described above.
[0095] For explanatory purposes, the details of the internal components of the
display
have been omitted from this figure and only a cavity 61 is shown. It should be
noted,
that the air curtain can be practiced with any type of electronic display and
with any
combination of the thermal control features described above. Various internal
features
(not shown) may be placed within the cavity 61 to direct the air towards the
baffles 114.
The ingested air may continue through the cavity 61 along arrow 121 until it
reaches the
baffles 114 which may direct the air against the exterior display surface.
This exterior
surface may be the first front plate 90, or alternatively, any of the
additional front plates
which are described in detail above (ex. second front plate 130).
[0096] Thus, the air curtain can be used as an exhaust for the cooling of
internal
components of the display. Alternatively, the cool air from the air curtain
can be used to
further cool the exterior front surface of the display which may be subjected
to
significant solar loading or heat transfer from ambient hot air.
Fluid Cooling System
[0097] FIGURE 20 is an explanatory schematic illustrating another thermal
control
feature. As may be appreciated from the drawing, the cooling system 22
includes
various components in fluid communication. Preferably, this may be
accomplished by
connecting the components with a series of tubes or pipes (illustrated
conceptually as
dotted lines). The cooling system 22 components include a reservoir tank 37, a
pump
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47, and a cooling chamber 4 in fluid communication. Preferably, the system
also
includes a filter 83 and a radiator 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.
[0098] 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 two openings, an exit port 13 and a return port 14.
Optionally, the
reservoir tank includes a ventilation port 66. Pump 47 causes the coolant
fluid to move
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 coolant fluid pathway with
suitable results.
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 liquid
coolant from
the bottom to the top of cooling chamber 4. If the pump is so positioned,
engaging the
pump creates an area of low pressure at the top of the cooling chamber 4. In
this way
fluid flows through the cooing chamber 4 according to the arrows. Due to the
"slipperiness" of some coolant fluids, pump 47 is preferably a positive
displacement
pump.
[0099] 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
for coolant 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.
[00100] 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 may be optimized for a given application. Alternatively,
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 and
another
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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 for
preventing
deformation or breakage of the display glass.
[00101] An optional filter 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.
[00102] In operation, fluid exits the reservoir tank 37 from an output port 13
which 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 optional 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. Pump 47, which may be
positioned after the radiator 72, can pull the fluid toward the reservoir
tank. The fluid is
received into the reservoir tank 37 through return port 14. Preferably, return
port 14
may be disposed at a location that is relatively distant from exit port 13 so
as to allow
the returning fluid the maximum opportunity to cool before it exits the
reservoir tank 37
through port 13.
[00103] If desired, fan units may be located at the base of the housing 75
just behind
the cooling chamber 4 of display 15. Fan units may provide a laminar flow of
air
through the interior of the housing 75. Preferably, the airflow will be
directed across at
least one external surface of reservoir tank 37. As described above, the air
exhaust
flow may ultimately be redirected onto the cooling chamber surface 44 by way
of an
optional air curtain system 114.
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[00104] If desired, a temperature sensor (not shown) and a switch (not shown)
may be
incorporated within the electronic display. 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.
Alternatively, to avoid the need for a thermostat, the pump 47 may run
continuously
when the electronic display is operational.
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