Umted States Patent
`
`[19]
`
`[11] Patent Number:
`
`5,692,821
`
`Rodriguez, Jr. et al.
`[45] Date of Patent:
`Dec. 2, 1997
`
`
`USOOS692821A
`
`[54] METHOD AND SYSTEM FOR THERMAL
`MANAGEMENT WITHIN A DISPLAY
`DEVICE
`
`......................... 362/373
`5/1995 Ahlgreu et a].
`5,420,769
`1/1996 Suganuma et a].
`....................... 345/87
`5,483,253
`FOREIGN PA'I'ENT DOCUMENTS
`
`[75]
`
`Inventors: Ernesto Melquiades Rodriguez, Jr.;
`Xiaowei Zhao, both of Round Rock,
`Tex.
`[73] Assignee: Minnesota Mining and
`Manufacturing, Saint Paul, Minn.
`
`8—22074 of 1996
`Japan .
`8-22075 of 1996
`Japan .
`Primary Examiner—William Dowling
`Attorney, Agent, or Firm—Nestor F. Ho
`[57]
`ABSTRACT
`
`[21] APPI- No.: 673,292
`
`6
`
`Jun. 28, 1996
`[22] Filed:
`353/5233]??? 21/14
`""""
`[5:]
`[[1]]; (2:1;
`
`E8} F: 1d fS-ereln-
`’ 353/5; $335773
`ea
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`0
`,
`,
`,
`353/60’ 61’ 529 1199 362/373, 294’ 3457
`264
`
`[56]
`
`References Cited
`US. PATENT DOCUMENTS
`
`5/1986 Emura ....................................... 353/66
`4,588,271
`
`
`. 353/60
`11/1988 Ogawa .....
`4,787,737
`5/1990 Ogawa et a1.
`. 353/57
`4,925,295
`
`..... 353/31
`7/1990 Miyatake et a1.
`4,943,154
`
`1/1991 Endo ........
`3691373
`4,985,815
`
`2/1994 Meuse ......
`362/293
`5,285,363
`
`5,374,969 12/1994 Kyhl et al.
`.............................. 353/119
`
`Athermal management system is for utilization in a compact
`display device. A duct is provided within the lamp housing
`of the display device and a high-wattage light source is
`mounted Within the duct Multiple cooling fins are mounted
`to at least one inner surface ofthe duct and extend into the
`duct. A thermal radiation absorbent coating, such as black
`anodization, covers the interior of the duct and the cooling
`fins and provides for an increased surface absorption of
`thermal radiation. Aport within the duct, which is transpar-
`ent to visible light, is utilized to direct visible light through
`a display assembly. An infrared filter, which is reflective or
`absorptive of infrared radiation, such as a so-called “hot
`mirror” is utilized to maintain thermal radiation within the
`duct and a fan is then utilized to pass cooling fluid through
`the duct, passing the cooling fluid- over the cooling fins and
`removin th
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`US. Patent
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`Dec. 2, 1997
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`Sheet 1 of 5
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`’ US. Patent
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`Dec. 2, 1997
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`Sheet 2 of 5
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`5,692,821
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`US. Patent
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`Dec. 2, 1997
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`Sheet 3 of 5
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`5,692,821
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`5,692,821
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`1
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`2
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`5,692,821
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`METHOD AND SYSTEM FOR THERMAL
`MANAGEMENT WITHIN A DISPLAY
`DEVICE
`
`CROSS—REFERENCE TO RELATED
`APPLICATION
`
`This application is related to us. Ser. No. 08/623,729,
`filed Mar. 29, 1996, Attorney Docket No. 52539USA1A,
`which is assigned to the Assignee of the present application.
`BACKGROUND OF THE INVENTION
`
`1
`
`1. Technical Field
`
`15
`
`The present invention relates in general to projection
`systems and, in particular, to thermal management systems
`for use within a projection system. Still more particularly,
`the present invention relates to an improved method and
`system for thermal management in a compact display device
`having a high-wattage lamp.
`2. Description of the Prior Art
`Overhead, slide and video projectors, as have been his-
`torically configured, occupy a considerable volume of space
`when ready for use. This is due to the fact that the needed
`components are large but also to limitations of optical
`technology and the amount of space within the device which _
`is needed to accommodate light cones and ventilation ducts.
`This bulky space can be regarded as a nuisance, or at least
`as an inconvenience, to a user, and as a result, considerable
`etfort has been devoted to features that result in a smaller
`stored unit.
`
`Examples of efiorts to downsize such projectors may be
`seen in US. Pat No. 5,374,969, which discloses an over-
`head projector having a collapsible base and a folding lens
`arm. Another unit that folds for transforation and storage,
`having a different folding mechanism, is exemplified by the
`overhead projector sold by Minnesota Mining and Mann-
`facturing Company (3M) under model no. 2770, where the
`folding and unfolding mechanism, while complex,
`is
`extremely simple to operate. US. Pat. No. 4,588,271
`describes yet another projector which will collapse for
`storage.
`In recent years, liquid crystal display (LCD) panels have
`been added to the traditional overhead projector, introducing
`a new use for an established technology. Such panels are
`electronically addressable, i.e., the appearance of the final
`image is controlled by electronic signals which are sent to
`the liquid crystal display panel. The electronic signals may
`come from a computer or maybe a standard video (NTSC)
`signal or from other suitable devices.
`'
`Initially, these liquid crystal display panels were designed
`as an addition to a conventional overhead projector and were
`added or removed at will, according to the desired mode of
`use of the unit. As the convenience of electronically gener—
`ated and stored representations became more appreciated, a
`new class of presentation device appeared, often referred to
`as an “integrated projector.” Such a unit is capable of taking
`input from a computer, or other signal source, and projecting
`an image onto a screen. Modern integrated projectors are
`capable of projecting useful images even in high ambient
`light conditions. Such units have developed a patent litera-
`ture of their own, a few examples of which are outlined
`below.
`
`us. Pat. No. 4,943,154 discloses a projector which has
`three “light valves” (a particular form of an addressable
`liquid crystal display) and a complicated optical path
`intended to allow the output of a white—light source to be
`
`split into red, green and blue components, imaged within the
`three light valves and then recombined for projection
`through a single lens. Such optical systems are complicated
`to manufacture, assemble and maintain, occupy a consider—
`able space, weigh a substantial amount and have potential
`efficiency problems.
`An alternate design approach is the utilization of a single
`liquid crystal display panel, optical path and lens and
`interpose in succession red, green and blue filters. As each
`0 filter moves into the optical path,
`the appropriate color
`image is formed on the liquid crystal display. Such units
`have been limited by the ability of a liquid crystal display to
`rapidly respond to changing input signals.
`In devices of a compact nature such as laptop computers
`and related devices, as exemplified by US. Pat. No. 5,483,
`253, a liquid crystal display panel is provided which is
`hinged at its rear edge so that it may be folded down to
`become coplanar with the keyboard for storage and trans-
`portation. However, these units are normally reflective in
`nature. sometimes backlit and sometimes have been made
`detachable so that the panel may be used on an overhead
`projector. Recently, so—called “palm-top” organizers have
`also become available. These devices combine a small
`computer, keyboard and LCD panel and are even smaller
`than laptop computers mentioned above.
`A problem in modern display units is efiective manage—
`ment of thermal energy resultant from the utilization of
`high-energy light sources. For example, US. Pat. No. 5,285,
`363 discloses a heat transfer unit constructed utilizing a
`plurality of overlapping wire grids deployed behind a cold
`mirror which reflects visible light and transmits infrared
`radiation into the overlapping wire grids for removal via a
`ventilation system. Such as system provides enhanced effi-
`ciency in the removable of heat from the area adjacent to a
`reflector, but does not address the cooling of the light source,
`which is necessary for light source life span enhancement.
`Consequently, it would be desirable and advantageous to
`design a compact display device which includes an
`improved thamal management system such that a high-
`wattage lamp may be utilized within a compact display
`device.
`
`20
`
`30
`
`35
`
`SUMMARY OF THE INVENTION
`
`45
`
`50
`
`55
`
`60
`
`65
`
`It is therefore one object of the present invention to
`provide an improved projection system.
`It is another object of the present invention to provide an
`improved thermal management system for use within a
`projection system.
`It is yet another object of the present invention to provide
`an improved method and system for thermal management in
`a compact display device having a high-wattage lamp.
`The foregoing objects are achieved as is now described.
`A thermal management system is provided for utilization in
`a compact display device. A duct is provided within the lamp
`housing of the display device and a high-wattage light
`source is mounted within the duct. Multiple cooling fins are
`mounted to at least one inner sm‘face of the duct and extend
`into the duct. A thermal radiation absorbent coating, such as
`black anodization, covers the interior of the duct and the
`cooling fins and provides for an increased surface absorption
`of thermal radiation. A port within the duct, which is
`transparent to visible light, is utilized to direct visible light
`through a display assembly. An infrared filter, which is
`reflective or absorptive of infrared radiation, such as a
`so-called “hot mirror,” is utilized to maintain thermal radia-
`tion within the duct, and a fan is then utilized to pass cooling
`
`XLNX-1009
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`3
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`5,692,821
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`4
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`fluid through the duct, passing the cooling fluid over the
`cooling fins and removing thermal energy from the display
`device in a highly eflicient manner.
`
`All objects, features and advantages of the present inven-
`tion will become apparent in the following detailed written
`description.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The invention itself, as well as a preferred mode of use,
`further objects and advantages thereof, will best be under—
`stood by reference to the following detailed description of an
`illustrative embodiment when read in conjunction with the
`accompanying drawings, wherein:
`FIG. 1 is a perspective view of one embodiment of a
`compact integrated liquid crystal display projector incorpo—
`rating the thermal management system of the present inven-
`tion;
`
`10
`
`15
`
`.
`
`FIG. 2A is a sectional View of the compact integrated
`liquid crystal display projector of FIG. 1 depicted in a
`storage/transportation state;
`
`20
`
`FIG. 2B is a sectional view similar to FIG. 2A showing
`the compact liquid crystal display projector of the present
`invention in a deployed state;
`
`FIG. 3 is a top-plan view of the compact integrated liquid
`crystal projector of FIG. 1 with the upper surface thereof
`removed, also depicted in a deployed state; and
`FIG. 4 is a perspective view of the novel thermal man-
`agement duct utilized within the compact integrated liquid
`crystal display projector of the present invention.
`
`DETAILED DESCRIPTION OF PREFERRED
`EMBODIMENT
`
`With reference now to the figues and, in particular, with
`reference to FIG. 1, there is depicted one embodiment 10,
`the compact integrated liquid crystal display projector of the
`[resent invention. Exterior features of projector 10 include
`a case or body 12, two upper retracting doors 14 and 16, an
`actuation button 18, a rear foot adjustment knob 20, a
`receptacle 24 for a power supply cable, a power onlolf
`switch 26 and one or more ports providing various types of
`electrical connectivity (such as video and data drivers), each
`indicated at reference number 28.
`
`In the depicted embodiment body 12 is box-like, and its
`upper surface (which includes doors 14 and 16) is planar and
`generally parallel with its lower planar Sin-face when the
`device is in the storage/transportation state. This shape
`provides a particularly low profile, but as those skilled in the
`art will appreciate, other profiles can be provided which are
`not as rectangular as projector 10. Body 12 may be con-
`structed of any durable material, preferably a lightweight
`polymer such as acrylonilrile butadiene styrene (ABS) or
`polycarbonate.
`
`Referring now to FIGS. 2A and 213, there are depicted
`longitudinal cross-sections of projector 10 depicting its
`storage/transportation state and its deployed state,
`respectively, which illustrate that projector 10 is additionally
`comprised of a light source 30 which is mounted within
`genaally rectangular duct 32. As illustrated, two of the inner
`surfaces of generally rectangular duct 32 include a plurality
`of cooling fins 33. In a preferred embodiment of the present
`invention, the inner surface of duct 32 and the surface of
`each cooling fin 33 is coated with a thermal radiation
`absorbent coating such as a black anodization or black
`oxidation in a manner well-known in the prior art. A
`collimator (parabolic reflector) 34 and a condenser lens 36
`
`3O
`
`35
`
`45
`
`55
`
`oppositely disposed about light source 30, an infrared filter
`(hot mirror) 38 which is approximate to condenser lens 36,
`a display assembly 40 and a projection lens 42 are also
`depicted within projector 10.
`All of these components are located within body 12,
`although as depicted in FIG. 2B, display assembly 40 and
`projection lens 42 may protrude from body 12 when pro-
`jector 10 is deployed in a projection mode. Display assembly
`40 is pivotally or rotatably attached to the inside of body 12
`in a manner such that, in the deployed state, display assem-
`bly 40 is generally perpendicular to the light path, but while
`in a storage or transportation state, display assembly 40 is
`generally parallel to the light path, occupying the space that
`is reserved for the light cone during operation.
`In referring to the cross—sectional views of FIGS. 2A and
`2B, the term “longitudinal” is utilized to describe a direction
`of the projector which coincides with the projection access,
`i.e., the generally straight line between light source 30 and
`projection lens 42. This term is appropriate for the particular
`embodiment depicted, but should not be construed in a
`limiting sense. Other embodiments may employ folded
`optical paths such as by the use of mirrors, catadioptric
`Fresnel lenses, etc., and (while these components might add
`to the cost of the device and be less desirable for other
`reasons) such a device could still benefit from the thermal
`management system of the present invention.
`For example, while it is certainly preferable in the
`depicted embodiment of the present invention to have the
`light strike the display assembly 40 at a generally normal
`angle during use, this is not a critical requirement since
`substantial space savings can be achieved without a full 90°
`rotation of the panel assembly. Further, a “keystone” cor—
`rection option which modifies the shape of the image can be
`obtained through selection of the angle of rotation of the
`display panel. A stop pin or block formed on the inside of
`body 12 can be utilized to prevent display assembly 40 from
`rotating beyond a desired position.
`Light source 30 is preferably a high—intensity source such
`as an EVD (halogen) lamp or a series of high-output metal
`halide lamps (e.g., 250 watt, 400 watt or 575 watt) available
`from Osram (a subsidiary of Sylvania & Company of
`Germany or Philips Electronics of The Netherlands). Light
`sauce 30 is preferably connected to a 12-volt DC power
`supply 44 which is located within body 12 (see FIG. 3). In
`the depicted embodiment, duct 32 is preferably constructed
`of 5052 aluminum extrusion. Condenser lens 36 is prefer-
`ably plano-convex and is constructed of a borosilicate glass
`such as Pyrex (a trademark of Coming, Inc.). Inflated filter
`38 is preferably a conventional hot mirror such as those
`available from Bausch & Lomb.
`
`Display assembly 40 can take on various forms, such as
`a transmissive liquid crystal display panel, a light valve or
`a micromirror array. In the depicted embodiment of projec-
`tor 10, display assembly 40‘includes a liquid crystal display
`panel 46, such as the 6.4" panel available from Sharp of
`Japan or Liesegang of Germany, and further, two Fresnel
`lenses 48 and 50 are provided within display assembly 40
`and are secured within housing 52. A fan 55 (see FIG. 3) is
`also mounted within housing 52 to cool
`liquid crystal
`display panel 46. The entire display assembly is arranged to
`pivot about a horizontal access, in the center of the assembly.
`Display assembly 40 can then be rotated to occupy the voids
`needed for expansion and contraction of the optical beams
`when the projector is in use. Such voids have no useful
`function when the projector is not in operation, and are thus
`generally available for component storage. Such a feature
`enables saving a substantial volume of space.
`
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`Along with the pivoting of display assembly 40, means
`may be provided to ensure protection of the display while it
`is in storage or in use. This means may consist of movable
`flaps or doors that provide a substantially contiguous exte-
`rior form when the unit is in use or in storage. As seen in
`FIGS. 2A and 2B, these doors include doors 14 and 16, as
`well as lower doors 54 and 56, all of which are pivotally
`attached to body 12. When display assembly 40 is rotated for
`use, these doors move aside to allow passage. The doors not
`only project the display assembly and provide more aes-
`thetically appealing design, but also reduce light leakage.
`Each of the aforementioned doors is preferably spring-
`loaded so as to automatically retract upon rotation of display
`assembly 40 to the stowed position. Projection lens 42 may
`also be coupled to display assembly 40, such as by linkages
`58, so as to automatically retract projection lens 42 when
`projector 10 is configured in the storage state, and to
`automatically extend projection lens 42 outside of body 12
`when projector 10 is configured in the deployed state.
`Display assembly 40 itself is preferably biased by an over—
`center spring which is engaged by a latch attached to button
`18. This latch also locks the apparatus when stowed by
`locking doors 14, 16, 54 and 56 and maintains projection
`lens 42 in the retracted position. An iris or lens cover (not
`shown) may also be provided to impart additional protection
`to projection lens 42 when it is retracted. A lever (not visible
`in the figures) attached to the side of body 12 and attached
`to display assembly 52 may be used to simultaneously move
`all parts to the stowed position.
`FIGS. 2A and 2B also depict a rear foot assembly 60
`which, with feet 62 formed on lower retractable door 54,
`completes a tripod approach to levelling the unit. As can be
`seen. while in the deployed position, display assembly 40
`rests on feet 62 and so supports body 12 and also eliminates
`the need to lock the LCD module in an open position in case
`the projector slides across a tabletop. Foot assembly 60
`includes an adjustment knob 20 which is fastened to a worm
`gear or threaded member 64, and a rack or travel guide 66
`that has one end 68 fashioned into a foot. The rear end of
`projector 10 may thus be raised by twisting knob 20 clock-
`wise to adjust the pitch angle of the projection axis when the
`projector is resting on a support surface in order to adjust the
`height of the projected image. While twisting of the knob
`counterclockwise will lower the rear end of projector 10,
`foot assembly 60 is advantageously provided with a feature
`that allows a quick release of travel guide 66 and retraction
`of foot 68 into body 12. Travel guide 66 is fitted into a cavity
`or holder formed in or attached to body 12, but is not rigidly
`attached thereto. Rather, it is provided with sufficient toler-
`ance to allow it to pull away from worm gear 64. A spring
`attached to travel guide 66 then automatically retracts it.
`Friction from the spring actually holds guide 66 against gear
`64, preventing guide 66 from retracting under normal
`circumstances, but the user can push knob 20 laterally to
`displace guide 66 away from gear 64 and allow the spring to
`retract it
`With further reference to FIG. 3, other components of
`projector 10 may be seen. These components include a
`second fan 70 for cooling power supply 44 and a third fan
`72 which is coupled to one end of duct 32 for cooling the
`optical module which is surrounded by duct 32, for which
`conduction and convection thermal cooling occurs, and an
`optional speaker 74. Additional electronics provided for
`liquid crystal display may be conventional and/or beyond
`the scope of the present invention except that, consistent
`with the goal of compactness, the electronic components are
`preferably packaged in a relatively small subassembly. An
`
`appropriate package is available from Neo Systems under
`model no. MDI—0344, and includes functionality for data
`and video to drive the liquid crystal display panel.
`Finally, referring to FIG. 4, there is depicted a perspective
`view of duct 32 which may be utilized within the compact
`integrated liquid crystal display projector depicted within
`FIG. 1. As illustrated, duct 32, in the depicted embodiment
`of the present invention, comprises a generally rectangular
`metallic duct, preferably constructed of a thermal conduc-
`tive material such as 5052 aluminum. A plurality of cooling
`fins 33 are formed on the inner surface of two of the surfaces
`of duct 32 and extend inward into the interior volume of duct
`32. The interior surfaces of duct 32 and the surfaces of
`cooling fins 33 are all preferably coated with a thermal
`radiation absorbent coating such as black anodization or
`black oxidation in order to greatly enhance the absorption of
`thermal energy by the surfaces within duct 32.
`In the depicted embodiment of duct 32, cooling fins 33 are
`generally straight and extend into duct 32 in a generally
`perpendicular fashion from the inner surface of duct 32. The
`length, spacing and shape of cooling fins 33 may be varied
`to optimize the reflection of infrared radiation within duct
`32, greatly enhancing the absorption of infrared radiation by
`duct 32 and cooling fins 33. Cooling fins 33 may be oblong,
`curved or ribbed in shape in order to maximize the reflection
`of infrared radiation within duct 32, dependent upon the
`size, shape and configuration of duct 32. Further, cooling
`fins 33 are disclosed as aligned parallel to the flow of cooling
`fluid through duct 32; however, cooling fins 33 may also be
`advantageously arranged to provide turbulent flow of cool—
`ing fluid to further distribute and manage thermal energy
`within duct 32.
`As further illustrated within FIG. 4, a cooling fan 72 is
`mounted to one end of duct 32 and is utilized to draw cooling
`fluid through duct 32, eliminating excessive heat within duct
`32 by passing that cooling fluid over the surface of cooling
`fins 38 and the inner surface of duct 32. Further, a port is
`provided Within one surface of duct 32 which is transparent
`to visible light. That port is filled with infrared filter 38
`which, as described above, may be provided utilizing a
`conventional hot mirror.
`
`45
`
`55
`
`65
`
`Thus, as described herein, the compact integrated liquid
`crystal display projector of the present invention includes a
`novel thermal management system comprising a duct having
`a plurality of cooling fins mounted to the inner surface
`thtn'eof which extend into the interior volume of the duct and
`which are coated with a thermal radiation absorbent coating
`such that thermal radiation is readily absorbed by the inner
`surface of the cooling duct. In this manner, cooling fluid may.
`be forced through the cooling duct to efficiently remove
`excessive thermal energy from within the duct, greatly
`enhancing the efficiency and life of the light source. In this
`manner, a high-wattage light source may be utilized within
`a relatively compact integrated liquid crystal display pro-
`jector.
`While the invention has been particularly shown and
`described with reference to a preferred embodiment, it will
`be understood by those skilled in the art that various changes
`in form and detail may be made therein without departing
`from the spirit and scope of the invention.
`What is claimed is:
`1. A thermal management system for use in a display
`device having a latnp housing, said thermal management
`system comprising:
`a duct within said lamp housing for passing a cooling fluid
`through said lamp housing;
`
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`7
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`5,692,821
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`8
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`a light source mounted within said duct;
`a plurality of cooling fins mounted to an inner surface of
`said duct; and
`
`a thermal radiation absorbent coating disposed upon said
`inner surface of said duct and said plurality of cooling
`fins.
`
`5
`
`2. The thermal management system according to claim 1
`further including a fan for forcibly passing cooling fluid
`through said duct.
`3. The thermal management system according to claim 1
`wherein said duct is generally rectangular in shape and
`wherein said plurality of cooling fins are disposed along at
`least two sides of said inner surface of said generally
`rectangular duct.
`'4. The thamal management system according to claim 1
`whaein said duct further includes a port disposed therein
`which is transparent to visible light.
`5. The thermal management system according to claim 4
`wherein said port is reflective of infrared radiation.
`6. The thermal management system according to claim 4
`wherein said port is absorptive of infrared radiation.
`7. The thermal management system according to claim 1
`wherein said thermal radiation absorbent coating comp-ises
`black anodization.
`
`8. The thermal management system according to claim 1
`wherein said plurality of cooling fins are constructed of a
`metallic material.
`
`9. The thermal management system according to claim 8
`wherein said metach material is aluminum.
`10. The thermal management system according to claim 1
`wherein said cooling fluid comprises air.
`11. The thermal management system according to claim 1
`wherein said light source comprises a halogen lamp.
`12. The thermal management system according to claim 2
`wherein said plurality of cooling fins are arranged in an
`orientation parallel to the flow of cooling fluid through said
`duct.
`
`13. A display device having an enhanced thermal man-
`agement system comprising:
`a lamp housing;
`
`10
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`15
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`20
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`25
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`a thermal radiation absorbent coating disposed upon said
`inner surface of said duct and said plurality of cooling
`fins;
`
`a display assembly having means for creating an image;
`means for directing light from said light source to said
`display assembly, defining a light beam direction; and
`a projection lens positioned to receive the image created
`by said display assembly.
`14. The display device according to claim 13 further
`including a fan for forcibly passing cooling fluid through
`said duct.
`
`15. The display device according to claim 13 wherein said
`duct is generally rectangular in shape wherein said plurality
`of cooling fins are disposed along at least two sides of said
`inner surface of said generally rectangular duct.
`16. The display device according to claim 13 further
`including means for moving said display assembly fiom a
`storage position in which said display assembly is generally
`parallel with said light beam direction, to a deployed posi-
`tion in which said display assembly is disposed at an oblique
`angle with respect to said light beam direction.
`17. The display device according to claim 13 wherein said
`means for directing light from said light source to said
`display assembly includes:
`
`a reflector located adjacent said light source, opposite said
`display assembly; and
`
`a condenser lens interposed between said light source and
`said display assembly.
`18. The display device according to claim 13 wherein said
`duct further includes a port disposed therein adjacent to said
`light source which is transparent to visible light.
`19. The display device according to claim 18 wherein said
`port is reflective of infrared radiation.
`20. The display device according to claim 18 wherein said
`port is absorptive of infrared radiation.
`21. The display device according to claim 13 wherein said
`thermal radiation absorbent coating comprises black anod-
`izau’on.
`
`a duct within said lamp housing for passing a cooling fluid
`through said lamp housing;
`a light source mounted within said duct;
`a plurality of cooling fins mounted to an inner surface of 45
`said duct;
`
`22. The display device according to claim 14 wherein said
`plurality of cooling fins are arranged in an orientation
`parallel to the flow of cooling fluid through said duct.
`*
`*
`*
`*
`*
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`USOOS692821B1
`(12) REEXAMINATION CERTIFICATE (4460th)
`United States Patent
`US 5,692,821 C1
`
`(45) Certificate Issued:
`Oct. 16, 2001
`Rodriguez, Jr. et al.
`
`(10) Number:
`
`(54) METHOD AND SYSTEM FOR THERMAL
`MANAGEMENT WITHIN A DISPLAY
`DEVICE
`
`(75)
`
`Inventors: Ernesto Melquiades Rodriguez, Jr.;
`Xiaowei Zhao, both of Round Rock,
`TX (US)
`
`('73) Assignee: Minnesota Mining and
`Manufacturing Company, St. Paul,
`MN (US)
`
`Reexamination Request:
`No. 90/005,386, Jul. 7, 1999
`
`Reexamination Certificate for:
`Patent No.:
`5,692,821
`Issued:
`Dec. 2, 1997
`Appl. No.2
`08/673,292
`Filed:
`Jun. 28, 1996
`
`Int. Cl.7 ...................................................... B03B 21/14
`(51)
`
`(52) US. Cl.
`.. 353/52; 353/61; 362/373
`(58) Field of Search .................................. 353/52, 54, 56,
`353/57, 60, 61, 119, 362/264, 294, 345,
`373
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4,219,371 *
`
`8/1980 Larrimore ............................ 362/264
`
`4,419,716 * 12/1983 Koo ........................................ 362/96
`
`....... 353/55
`4,453,810 *
`6/1984 Curiel
`
`5/1995 Wiggs ......
`.. 60/641.15
`5,419,135 *
`........................... 353/119
`5,669,688 *
`9/1997 Baar et a1.
`
`FOREIGN PATENT DOCUMENTS
`
`0035526 *
`
`3/1983 (JP).
`
`* cited by examiner
`
`Primary Examiner—William Dowling
`
`(57)
`
`ABSTRACT
`
`Athermal management system is for utilization in a compact
`display device. A duct is provided Within the lamp housing
`of the display device and a high-wattage light source is
`mounted Within the duct. Multiple cooling fins are mounted
`to at least one inner surface of the duct and extend into the
`
`duct. A thermal radiation absorbent coating, such as black
`anodization, covers the interior of the duct and the cooling
`fins and provides for an increased surface absorption of
`thermal radiation. Aport Within the duct, which is transpar-
`ent to visible light, is utilized to direct visible light through
`a display assembly. An infrared filter, which is reflective or
`absorptive of infrared radiation, such as a so-called “hot
`mirror” is utilized to maintain thermal radiation Within the
`
`duct and a fan is then utilized to pass cooling fluid through
`the duct, passing the cooling fluid over the cooling fins and
`removing thermal energy from the display device in a highly
`efficient manner.
`
`t:
`
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`US 5,692,821 C1
`
`1
`REEXAMINATION CERTIFICATE
`ISSUED UNDER 35 U.S.C. 307
`
`THE PATENT IS HEREBY AMENDED AS
`INDICATED BELOW.
`
`2
`a plurality of cooling fins mounted to an inner surface of
`said duct, the inner fins being directly exposed to the
`light source; and
`a thermal radiation absorbent coating disposed upon said
`inncr surfacc of said duct and said plurality of cooling
`fins.
`
`10
`
`15
`
`Matter enclosed in heavy brackets [] appeared in the
`patent, but has been deleted and is no longer a part of the
`patent; matter printed in italics indicates additions made
`to the patent.
`
`AS A RESULT OF REEXAMINATION, IT HAS BEEN
`DETERMINED THAT:
`
`Claims 1 and 13 are determined to be patentable as
`amended.
`
`Claims 2—12 and 14—22, dependent on an amended claim,
`are determined to be patentable.
`
`1. A thermal management system for use in a display
`device having a lamp housing, said thermal management
`system comprising:
`a duct Within said lamp housing for passing a cooling fluid
`through said lamp housing;
`a light source mounted Within said duct;
`
`13. A display device having an enhanced thermal man-
`agement system comprising:
`a lamp housing;
`a duct Within said lamp housing for passing a cooling fluid
`through said lamp ho