United States Patent
`Loban et al.
`
`[i9]
`
`US005612741A
`[li] Patent Number:
`[45] Date of Patent:
`
`5,612,741
`Mar. 18, 1997
`
`[54] VIDEO BILLBOARD
`
`[75]
`
`Inventors: Jerry M. Loban, Grapevine, Tex.;
`Henry D. Ryng, Phoenix, Ariz.
`
`[73] Assignee: Curtis Mathes Marketing
`Corporation, Dallas, Tex.
`
`[21]
`
`[22]
`
`[51]
`[52]
`[58]
`
`Appl. No.: 148,048
`Nov. 5, 1993
`
`Filed:
`Int. CI.6
`H04N 5/66; H04N 9/12
`348/383; 348/840
`U.S. CI
`348/383, 744,
`Field of Search
`348/745, 748, 750, 751, 756, 758, 761,
`766, 778, 779, 781, 790, 794, 806, 807,
`839, 840; 345/13, 10; 340/815.4, 815.47,
`815.49, 815.53; 359/455-460; H04N 9/12,
`7/12, 5/66, 7/18
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,295,159 10/1981 Carollo et al
`1/1984 Gagnon et al. .
`4,425,028
`3/1987 Koda et al. .
`4,650,286
`
`348/761
`
`4,715,684 12/1987 Gagnon .
`4/1988 Cardin
`4,739,567
`6/1988 Ledebuhr .
`4,749,259
`4,786,146 11/1988 Ledebuhr.
`9/1989 Kalver
`4,866,530
`5/1990 Clausen et al
`4,923,280
`4,951,131
`8/1990 Lindahl
`4/1991 Morin
`5,005,950
`5,061,921 10/1991 Lesko et al
`5,257,017 10/1993 Jones et al
`3/1994 Mitano et al
`5,296,922
`
`359/460
`
`348/799
`359/456
`348/747
`348/383
`340/815.83
`348/744
`359/457
`
`Primary Examiner—Michael Lee
`Attorney, Agent, or Firm—Akin, Gump, Strauss, Hauer &
`Field, L.L.P.
`
`[57]
`
`ABSTRACT
`
`A video billboard 10 includes one or more projection units
`12utilizing aliquidcrystal light valve projector 32 to project
`images onto a lenticulated lens screen 34. The types of
`images to be displayed, along with the time of day inwhich
`the images are to be displayed, are controlled from a remote
`master transmitter 24. A plurality of projectionunits 12(a-d)
`can be mounted together to provide an enlarged image
`display area.
`
`31 Claims, 4 Drawing Sheets
`
`MASTER
`COMPUTER
`
` IPR2016-01869 Ex. 1008
`Broadsign International, LLC Petitioner
` 1
`
`

`
`U.S. Patent
`
`Mar. 18, 1997
`
`Sheet 1of 4
`
`5,612,741
`
`46
`
`12a
`
`58
`
`T
`
`12b
`
`MASTER
`COMPUTER
`
`22
`
`24
`
`12c
`
`12d
`
`58
`
`48
`
`RCU
`
`38
`
`FIG. I
`
`48
`
`42) 52ÿl2a
`
`42
`
`32
`
`J2b
`
`44
`
`50'
`
`54
`
`FIG. 3
`
` 2
`
`

`
`U.S. Patent
`
`Mar. 18, 1997
`
`Sheet 2 of 4
`
`5,612,741
`
`20
`COMMUNICATIONS LINK
`(CELLULAR TELEPHONE SATELLITE)
`
`22
`
`VIDEO CLIP STORAGE
`28ÿ NTSC FORMAT
`U-(PC CONTROLLED)
`
`30
`
`NTSC LINE DOUBLER
`
`38
`
`40
`
`24
`
`26
`
`MASTER
`COMPUTER
`
`32
`
`LIGHT VALVE
`PROJECTOR
`
`FIG. 2.
`
`36
`
`34
`
`FIG. S
`
` 3
`
`

`
`U.S. Patent
`U.S. Patent
`
`Mar. 18, 1997
`Mar. 18, 1997
`
`Sheet 3 of 4
`Sheet 3 of 4
`
`5,612,741
`5,612,741
`
`68
`
`so /mwrz 70
`
`FIC17
`
`Vlléfifllfé
`
`F-‘lC5.8
`
` 4
`
`

`
`U.S. Patent
`
`Mar. 18, 1997
`
`Sheet 4 of 4
`
`5,612,741
`
`10
`
`32
`
`54
`
`82
`
`84
`
`FIG. 9
`
`54
`
`10 "
`
`FIG. IO
`
` 5
`
`

`
`5,612.
`,741
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`1
`VIDEO BILLBOARD
`
`BACKGROUND OF THE INVENTION
`
`5
`
`to
`
`1. Technical Field
`This invention relates to display devices and, more par-
`ticularly, to displays utilizing liquid crystal light valves.
`2. Discussion
`Billboards are used to display various messages typically
`consisting of a combination of text and graphics. Tradition-
`ally, the message has been provided by way of fixed sheets
`which are pasted to a backing. This traditional approach
`suffers from the inability to quickly change the displayed
`message since it requires the use of a crew to change the
`message. Electronic billboards provide the advantage inthat 15
`it is easier to change the displayed message.The Department
`of Transportation Management Systems have introduced a
`relatively new fiber optic message signs. Other electronic
`billboards include the dot matrix type utilizing many indi¬
`vidual bulbs. Within stadiums, arenas and auditoriums there 20
`presently are electronic dot matrix display devices used for
`instant replays, advertising and customer information. While
`these electronic billboards are easily changed, they suffer
`from a variety of problems such as lack of good graphics
`capabilities, poor contrast ratios and/or requiring a signifi- 25
`cant amount of power.
`The present invention is drawn to solving one or more of
`these problems.
`
`SUMMARY OF THE INVENTION
`
`30
`
`Inaccordance with the teachings of the present invention,
`a liquid crystal light valve provides an intense video light
`source for a rear projection screen of a video billboard. Inthe
`preferred embodiment, display information is communi¬
`cated from a master computer to a receiver in the billboard 35
`housing which, in turn, controls the light valve. Commands
`may also be communicated via shared or dedicated land-
`lines. The billboard is capable of providing complex video
`graphics with high contrast ratios. It can provide message
`changes on command through landline, cellular phone, 40
`satellite relay or other wireless communication links. Within
`the commercial advertising billboard industry it will allow
`the use of computer video control to change graphics easily
`and quickly, as desired. Advertisements, public service
`announcements or traffic conditions can be displayed in near 45
`real time from remote locations since images can be down¬
`loaded via the communication links and displayed at pre¬
`programmed time slots, if desired.
`Preferably, a lenticulated screen structure using multiple 5Q
`optical elements is employed to increase the gain of the
`projected light. One of the elements is a vertical black stripe
`lenticular lens whereas the other element is a combined
`Fresnel and horizontal lenticular optical element. The out¬
`side surface of the screen is in the form of a protective sheet 55
`which includes horizontal louvers.
`It is envisioned that the billboard may be constructed of
`a plurality of substantially identicalprojection unit modules.
`As a result, the size of the ultimately constructed billboard
`can be easily modified, as desired, by utilizing a different 50
`number of projection unit modules.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The various advantages of the present invention will
`become apparent to those skilled inthe art after studying the 65
`following specification and by reference to the drawings in
`which:
`
`2
`FIG. 1is a perspective view of a video billboard made in
`accordance with the teachings of the present invention;
`FIG. 2 is a combination perspective view and block
`diagram useful in understanding the general concept of this
`invention;
`FIG.3 is a cross sectional view taken along the lines 3—3
`of FIG. 1;
`FIG. 4 is a perspective view of a projection unit module
`made inaccordance with the teachings of the present inven¬
`tion;
`FIG. 5 is a cross sectional view of a projection unit
`module taken along the lines 5—5 of FIG. 3;
`FIG. 6 is an exploded perspective view of the screen
`construction in accordance with the teachings of the pre¬
`ferred embodiment;
`FIG.7 is a cross sectional view of a segment of the middle
`plate of the screen looking downwardly along the lines 7—7
`of FIG. 6;
`FIG. 8 is a cross sectional view of a segment of the inner
`plate of the screen looking along the lines 8—8 of FIG. 6;
`FIG. 9 is a cross sectional view of an alternative embodi¬
`ment of a projection unit module having both front and rear
`screens; and
`FIG. 10 is a view looking down on another embodiment
`of a billboard having front and rear projection screens.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`It should be understood from the outset that, while this
`invention is being described in connection with its preferred
`embodiments and best mode of practicing the invention, it is
`not intended that these particular teachings are to restrict the
`scope of this invention. With that caveat in mind, the
`reader's attention is first directed to FIG. 1where a video
`billboard 10 is shown as including four (4) substantially
`identical projection unit modules 12(a-d) cooperating
`together to present an enlarged image area for projecting a
`textual or graphic messages. Since,
`in this
`variety of
`embodiment, each of the projectionunit modules is substan¬
`tially identical, only one of them will be described in detail.
`Suffice it to say that the general teachings of this invention
`are applicable to a single projection unit module or a
`multiplicity of units which are mounted together to form an
`image display area of desired size. Of course, when a
`multiplicity of units are used, suitable multiplexing circuitry,
`well known in the art, would also be used in order to
`coordinate the segments of the overall message to be dis¬
`playedby each individualunit. Inthe preferredembodiment,
`each module is approximately 144" wide xl08" high and
`96" deep. In the illustrated embodiment, the modules are
`bolted together to form a single unit which is 288" wide
`x216" high x96" deep with a combined image area of
`18'x24'. The modules are designed so that they may be
`stacked four high and in an unlimited number horizontally.
`The modules 12 are supported by two hollow masts 14
`and 16. Masts 14 and 16 contain maintenance access within
`their hollow structure as well as the power and signal cabling
`such as cables 15 (FIG. 3). With additional reference to
`FIGS. 2 and 3, the masts 14 and/or 16 can also enclose a
`suitable receiver electronics package which is generally
`designated by the reference numeral 18. The receiver elec¬
`tronics package 18 includes a communications link 20 that
`communicates wirelessly via antenna 22 with a transmitter
`in the form of a master computer 24 via antenna 26. The
`
` 6
`
`

`
`5,612,
`741
`
`3
`communications link 20 can be provided by cellular tele¬
`phone, satellite relay or other wireless transmission schemes
`known in the art. The billboard electronics package 18
`further includes a video clip storage memory 28. Preferably,
`video clip storage memory 28 is a PAL, SECAM or NTSC 5
`format video storage device which serves as a graphic
`generator containing a plurality of programs for generating
`different messages to be displayed in the image area of the
`billboard 10. For example, clip storage memory 28 can
`contain programs for generating messages such as multiple
`advertisements, static and dynamic graphics or emergency
`information. The message generating programs can be
`downloaded from master computer 24 over link 20, along
`with sufficient information to determine when the message
`should be displayed, for how long and other pertinent data.
`A video line doubler 30 serves to take advantage of the 15
`full resolution of the projection devices by effectively dou¬
`bling the number of scan lines for driving the cathode ray
`tubes of the LCLV projectors, as discussed below.
`The output of line doubler 30 is connected to a liquid 2Q
`crystal light valve projector 32 which, in FIG. 2, is shown
`projecting an image onto a screen 34 via mirror 36. A liquid
`crystal
`light valve (LCLV) is utilized as the projector
`because it provides an extremely high contrast ratio and is
`bright enough that it can be used for outdoor signage in 2S
`bright sunlight. Contrast ratios of at least 80:1 are supplied
`to the rear projection screen and an overall brightness is
`provided which is equal or greater than new fiber optic
`technology. As is known in the art, an LCLV projector
`utilizes an internal cathode ray tube (CRT) to control the 3Q
`transmissive characteristics of a liquid crystal device which,
`in turn, modulates light from a high intensity source to
`define the image projected onto the screen. Representative
`examples of literature describing LCLV projectors include
`U.S. Pat. Nos. 4,425,028; 4,786,146; 4,715,684; 4,749,259 3J
`and 4,650,286, all of which are hereby incorporated by
`reference. LCLV projectors of these general types are com¬
`mercially available from Hughes-JVC Technology Corpo¬
`ration under the model designation 335S or Ampro-Grey-
`hawk under model designation 7000S. Preferably,
`the 4Q
`projector contains a light source that provides an intensity of
`at least 4,000 lumens so as to generate an image of extremely
`high contrast ratio and intensity. For example, a 2500 watt
`arc lamp can be used for the light source.
`A remote control unit (RCU) 38 provides an operator at 45
`the site of billboard 10 with sufficient controls to enable
`initial alignment of the projection system and to allow
`periodic realignment thereof as may become necessary.
`RCU38 can, for example, include an infraredtransmitter for
`transmitting control signals to a photo detector 40 mounted 50
`on one of the masts 14-16.
`An environmental control system (ECS), represented by
`the reference numeral 42, is providedineach projection unit
`12. The environmental control system 42 takes the form of
`an isolated heat pump system so that no external air is 55
`dispensed into the projection volume 44 of each module 12
`which is sealed against adverse environmental conditions.
`ECS 42 is capable of maintaining an operating temperature
`of 70° F. ±15° F. with an external skin temperature of -40°
`F. to +140° F. ECS 42 also serves to maintain a non- 60
`operating temperature of greater than -25° F. and less than
`+140° F. with an external skin temperature range of —40° F.
`to +150° F. ECS 42 exhausts air via ducts 46, one of which
`is shown on mast 14. Supply air employs a combination of
`external ambient and air from within the mast which will 65
`allow some of the conditioned air from a positive pressure
`system to be used for heat exchange. The positive pressure
`
`4
`system includes a fan and a filter (not shown) such that exit
`air flow is about 40% of the inlet air flow. The air flow inlets
`and exits are located within the support masts 14,16to allow
`access only to maintenance personnel.
`Each mast has a maintenance access door 48 and internal
`ladder (not shown) to allow maintenance personnel to have
`sufficient access to allow removal and replacement of pro¬
`jector 32, if necessary. The projector 32 is approximately 21"
`high x28" wide x52" long, weighing a maximum of 359
`pounds. It is positioned at the bottom center of each module
`12 and attached to a common structure with the screen and
`fold mirror, as will be discussed.
`FIGS. 3-5 illustrate the preferred optical system for the
`LCLV projector 32. Light from projector32 is reflected from
`a first fold mirror 50 upwardly and at an angle back towards
`a second fold mirror 52 which inturn reflects the image onto
`screen 54.
`Screen 54 is illustrated in more detail in FIGS. 6-8.
`Screen 54 is made up of three sheets which are laminated
`together to form a composite structure. Outer sheet 56 is a
`0.250" thick polycarbonate shield with an ultraviolet inhibi¬
`tor and a non-reflective outer surface that serves as a bullet
`proof shield to protect the internal lens sheets. The outer face
`of sheet 56 includes louvers 58 on 4" centers at a 5°
`downward pitch angle. Louvers 58 may be a black textured
`polycarbonate strips which are ultrasonically welded to the
`outer face of sheet 56.
`Sheet 60 and sheet 62 contain multi-element lenses that
`provide illumination gain for the image projected on the rear
`of screen 54 by LCLV projector 32. Middlelens sheet 60 has
`an outer face 64 providing a combined black stripe and a
`lenticular lens structure. The lenticular lens is provided by a
`plurality of vertically extending spherical rib surfaces 66.
`Vertically extending black stripes 68 are interposed between
`the lenticular rib surfaces 66. The inner face 70 also includes
`a complementary lenticular ribbed lens structure 72. Lens
`sheet 60 provides a black stripe lenticular of 1.5 mm
`(0.059") acrylic which will provide a horizontal half gain
`angle of ±50° and have a reflectivity at normal incidence of
`less than 5.0%. It has a lenticulation pitch of 1.2 mm center
`to center of black stripe, with a backside lenticulation at the
`same pitch to gather light for horizontal dispersion.
`The front face 74 of the inner lens sheet 62 includes a
`horizontally disposed lenticular structure provided by ribs
`76 which are spaced about 0.5 mm apart to provide a ±30°
`vertical spread of the projected light. Rear face 78 includes
`a spherical Fresnel lens pattern 80 having a focal length of
`about 150". The Fresnel lens pattern 80 serves to collimate
`the light.Inthe preferred embodiment, lens sheet 62 is about
`6.0 mm thick.
`The three sheets are preferably bonded together with a
`suitable high viscosity adhesive such as cyanoacrylate.
`In operation, the operator uses the remote control unit 38
`to perform initial set up and alignment procedures. Once set
`up, the master computer 24 transmits sufficient information
`to video billboard 10 so that the message to be displayed can
`be changed at a moment's notice. Billboard 10 can be used
`by traffic management systems in metropolitan areas to
`communicate traffic instructions to vehicle operators. In
`commercial advertising,
`the video billboard 10 allows
`advertising by the minute, hour, day, month, during prime
`time commuter periods, as well as any other times. This
`provides tremendous flexibility to advertisers as to the cost
`and implementation of video advertisements. The combina¬
`tion of the liquid crystal
`light valve and lens structure
`provided by the present invention cooperate to provide very
`
` 7
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`

`
`5,612,741
`
`high visibility while using comparatively little power, less
`than 4,000 watts.
`Various modifications of
`this invention will become
`apparent to those skilled in the art. For example, FIG. 9
`shows a dual projection system 10' which employs a 50%
`beam splitter 82 to reflect half of the beam intensity from
`projector 32 to a rear projection screen 54', while the
`remaining half of the beam passes through splitter 82 and is
`reflectedfrom mirror 84 onto the front screen 54. Inthe FIG.
`10 embodiment,
`individual projection modules 12' are
`mounted back-to-back to provide images on the front and
`rear of the billboard 10". The module housings are tapered
`to provide a space for receiving additional masts (e.g., 19)
`for supporting the modules and through which cabling and
`air from a centralized environmental control system 42' can
`be ducted into the modules through vents 17.
`Still other modifications will become apparent to one
`skilled in the art after studying the following claims.
`What is claimed is:
`1. A video billboard system comprising:
`a plurality of projection unit modules connected together,
`each projection unit module comprising a hollow hous¬
`ing having an interior projection volume;
`a liquid crystal light valve projector mounted in each of
`said housings, said projector having a cathode ray tube
`for controlling characteristic of a liquid crystal device,
`said liquid crystal device modulating light from a high
`intensity source;
`a screen for each of said projection unit modules, said
`screens arranged to define an enlarged image area for
`said billboard system and for receiving the modulated
`light from each of said projectors, respectively;
`a receiver coupled to said projectors, respectively;
`transmitter means for transmitting commands to the
`receivers for controlling images to be projected onto
`said screens;
`said screens each comprising an outer protective trans¬
`parent sheet, a middle lens sheet having a lenticular
`lens structure and an inner lens sheet having a Fresnel
`lens structure; and
`a remote control unit wirelessly coupled to said projectors
`for aligning images projected by said projectors onto
`said screens to provide an enlarged image for said
`billboard system.
`2. The video billboard system of claim 1wherein:
`said projection unit modules are supported by a plurality
`of masts.
`3. The video billboard of claim 2 wherein the masts are
`hollow and wherein cabling from the receiver to the pro¬
`jector runs at least partially within the hollow mast.
`4. The video billboard system of claim 1which further
`comprises:
`an environmental control system, located within the hous¬
`ing of each of the projection unit modules, for main¬
`taining the air within each of the projection volumes
`within predefined criteria.
`5. A video billboard system comprising:
`a plurality of projectionunit modules, each projectionunit
`module having a hollow housing with a liquid crystal
`light valve projector disposed in an interior projection
`volume of said housing and for projecting light having
`a contrast ratio of at least 80:1 onto a rear surface of a
`screen, said screen forming a wall of said housing;
`said projection unit modules being mounted together so
`that the screens of the projection unit modules provide
`a substantially flush enlarged image area;
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`a plurality of hollow masts supporting the projection unit
`modules above ground level;
`an electronics package within at least one of said hollow
`masts, said electronics package including a video clip
`storage memory for storing a plurality of prepro¬
`grammed instructions for generating different messages
`to be displayed on the image area of the billboard;
`cabling connecting the electronics package to each of the
`projectors, said cabling being routed at least partially
`through a hollow mast;
`an environmental control system comprising an isolated
`heat pump for regulating the environment within said
`projection volume of the projection unit modules,
`respectively, without dispensing external air into said
`projection volume; and
`transmitter means, located remotely from the billboard,
`for transmitting commands to the video clip storage
`memory for selecting images to be displayed, and the
`time period for which the images are to be displayed,
`on the image area of the billboard.
`6. The billboard of claim 5 wherein the transmitter means
`communicates over a wireless communication link with the
`video clip storage memory.
`7. The billboard of claim 5 wherein the screen comprises:
`an outer protective sheet having a plurality of angled
`louvers on an outer face thereon; and
`a middle sheet and an inner sheet, one face of a sheet
`having a combined vertically extending black strip and
`lenticular lens structure, a second face of one of the
`sheets having a horizontal lenticular lens structure, and
`a third face on one of the sheets having a Fresnel lens
`structure thereon.
`8. A video billboard system comprising:
`plural projection units;
`a liquid crystal light valve projector disposed in each of
`said projection units, said projector having a cathode
`ray tube for controlling characteristics of a liquid
`crystal device, said liquid crystal device modulating
`light from a high intensity source;
`a screen for receiving the modulated light from said
`projector;
`a receiver coupled to said projector;
`transmitter means for transmitting commands to said
`receiver for controlling images to be projected onto
`said screen; and
`each projectionunit includes front and rear screens, along
`with optical means for directing images from said
`projector onto said front and rear screens, respectively.
`9. A video billboard system comprising:
`a plurality of projection unit modules mounted back-to-
`back to provide front and rear image areas for the
`billboard, each projection unit module having a screen
`and a housing with a liquid crystal light valve projector
`for projecting light having a contrast ratio of at least
`80:1 onto a rear surface of said screen;
`said projection unit modules being mounted together so
`that said screens of said projection unit modules pro¬
`vide a substantially flush enlarged image area;
`a plurality of hollow masts supporting said projectionunit
`modules above ground level;
`an electronics package within at least one of said hollow
`masts, said electronics package including a video clip
`storage memory for storing a plurality of prepro¬
`grammed instructions for generating different messages
`to be displayed on the image area of the billboard;
`
` 8
`
`

`
`7
`cabling connecting the electronics package to each of the
`projectors, said cabling being routed at least partially
`through a hollow mast;
`an environmental control system for regulating the envi¬
`ronment within said projection unit modules; and
`transmitter means, located remotely from said billboard,
`for transmitting commands to said video clip storage
`memory for selecting images to be displayed, and the
`time period for which the images are to be displayed,
`on the image area of said billboard.
`10. A large scale video display apparatus comprising:
`a generally hollow housing having a screen defining one
`wall of said housing and a projector disposed within a
`projection volume within said housing for projecting a
`video image onto said screen from a light source;
`said screen comprising an outer protective transparent
`sheet, a middle lens sheet having a lenticular lens
`structure and an inner lens sheet adjacent said projec¬
`tion volume having a Fresnel lens structure for colli-
`mating and projecting a video image on said screen
`generated by said projector, said middle lens sheet and
`said inner lens sheet each include major inner and outer
`faces, said inner faces facing said projection volume
`and said outer faces facing the exterior of said housing,
`said Fresnel lens structure being located on an inner
`face of said inner lens sheet and said lenticular lens
`structure comprising a horizontal lenticular lens struc¬
`ture disposed on an outer face of said inner lens sheet
`and a vertical lenticular lens structure disposed on an
`outer face of said middle lens sheet.
`11. The video display apparatus set forth in claim 10
`including:
`a plurality of horizontally extending louvers on an outer
`face of said outer protective sheet.
`12. The video display apparatus set forth in claim 10
`wherein:
`said outer protective sheet is formed of a polycarbonate
`having an ultraviolet inhibitor therein and a non-reflec¬
`tive outer surface, said outer protective sheet being
`operable to protect said middle lens sheet and said inner
`lens sheet.
`13. The video display apparatus set forth in claim 10
`wherein:
`said middle lens sheet
`includes generally vertically
`extending rib surfaces forming said vertical lenticular
`lens structure on said outer face and vertically extend¬
`ing black stripes interposed between said rib surfaces.
`14. The video display apparatus set forth in claim 13
`wherein:
`the other face of said middle lens sheet includes comple¬
`mentary lenticular rib surfaces.
`15. The video display apparatus set forth in claim 10
`wherein:
`said inner face of said inner lens sheet includes a spherical
`Fresnel lens pattern.
`16. A video display apparatus comprising:
`a hollow housing including a closed projection volume
`disposed therein, one wall of said housing comprising
`a video display apparatus screen;
`a video projector disposed in said projection volume for
`projecting a video image on said screen, said video
`projector being operable to modulate light from a high
`intensity source; and
`an environmental control unit disposed in said projection
`volume comprising an isolated heat pump for control-
`
`25
`
`35
`
`40
`
`45
`
`S5
`
`65
`
`5,6
`
`l2,741
`
`5
`
`10
`
`15
`
`20
`
`8
`ling the temperature within said projection volume
`within a predefined range without exchanging external
`air into said projection volume.
`17. A video display apparatus comprising:
`a plurality of projection unit modules, each module
`including a hollow housing and each module having a
`closed projection volume, one wall of each of said
`housings comprising a video display apparatus screen;
`a video projector disposed in each of said projection
`volumes for projecting a video image on said screen,
`said video projector being operable to modulate light
`from a high intensity source, said projection unit mod¬
`ules being mounted back to back to provide front and
`rear image areas for said video display apparatus, and
`an environmental control unit disposed in each of said
`projection volumes comprising an isolated heat pump
`for controlling the temperature within said projection
`volumes within a predefined range without exchanging
`external air into said projection volumes.
`18. The video display apparatus set forth in claim 17
`wherein:
`said projection unit modules are mounted on spaced apart
`masts and a portion of said environmental control
`system is disposed in at least one of said masts and is
`operable to conduct heat exchange air through duct
`means disposed in said one mast.
`19. A video billboard system comprising:
`at least one projection unit module comprising a hollow
`housing having an interior projection volume;
`a liquid crystal
`light valve projector mounted in said
`housing, said projector having a cathode ray tube for
`controlling characteristics of a liquid crystal device,
`said liquid crystal device modulating light from a high
`intensity source;
`a screen for receiving the modulated light from said
`projector;
`a receiver coupled to said projector;
`transmitter means for transmitting commands to the
`receiver for controlling images to be projected onto
`said screen; and
`said screen comprising an outer protective transparent
`sheet, a middle lens sheet having a lenticular lens
`structure and an inner lens sheet having a Fresnel lens
`structure, said sheets having respective inner faces
`facing said projection volume and outer faces facing
`the exterior of said at least one module, said Fresnel
`lens structure is located on an inner face of the inner
`lens sheet; and
`said lenticular lens structure comprises a horizontal len¬
`ticular lens structure located on an outer face of the
`inner lens sheet and a vertical lenticular lens structure
`located on an outer face of the middle lens sheet.
`20. The video billboard structure of claim 19 which
`further comprises:
`a plurality of black stripes vertically spaced along the
`outer face of the middle lens sheet.
`21. The video billboard system of claim 20 which further
`60 comprises a plurality of horizontally disposed louvers on an
`outer face of the outer protective sheet.
`22. A large scale video display apparatus for projecting
`video images onto opposed screens comprising:
`a projection unit module comprising a hollow housing,
`opposed walls of said housing forming image project¬
`ing screens, each of said screens being made up of an
`outer protective sheet and at least one inner lens sheet
`
` 9
`
`

`
`5,612
`
`9
`defining at least one of a lenticular lens structure and a
`Fresnel lens structure, said hollow housing defining a
`projection volume;
`a projector disposed in said projection volume for gener¬
`ating a modulated light image from a high intensity 5
`source;
`a beam splitter disposed in said projection volume for
`reflecting approximately half of a beam generated by
`said projector toward one of said screens while the
`remaining half of said beam passes through said beam 10
`splitter; and
`a mirror disposed in said projection volume for receiving
`said remaininghalf of said beam and for projecting said
`remaining half of said beam onto the other of said 15
`screens.
`23. The video display apparatus set forth in claim 22
`wherein:
`said projector comprises a liquid crystal light valve pro¬
`jector for projecting modulated light onto both of said 20
`screens by way of said beam splitter and said mirror.
`24. The video display apparatus set forth in claim 22
`wherein:
`said at least one inner lens sheet includes a Fresnal lens
`structure formed on an inner face thereof and a hori- 25
`zontal lenticular lens structure formed on an outer face
`thereof.
`25. The video display apparatus set forth in claim 24
`wherein:
`each of said screens includes a middle lens sheet disposed 30
`between said inner lens sheet and said outer protective
`sheet and comprising a vertical lenticular lens structure
`formed thereon.
`26. The video display apparatus set forth in claim 22
`including:
`an environmental control system disposed in said projec¬
`tion volume for controlling the temperature within said
`projection volume within a predefined range without
`exchanging external air into said projection volume.
`27. The video display apparatus set forth in claim 26 40
`wherein:
`said environmental control system includes an isolated
`heat pump disposed at least partially in said projection
`volume.
`28. The video display apparatus set forth in claim 22
`wherein:
`said video display apparatus includes a plurality of pro¬
`jection unit modules connected together such that their
`respective screens define an enlarged image area for 50
`said apparatus.
`29. A video display apparatus comprising:
`a hollow housing including a closed projection volume
`disposed therein, said housing including opposed walls
`each comprising a video display screen;
`a video projector disposed in said projection volume for
`projecting a video image, said video projector being
`operable to modulatelight from ahighintensity source;
`
`55
`
`35
`
`45
`
`10
`a beam splitter disposed in said projection volume for
`receiving a beam from said projector and for splitting
`said beam to reflect half of sa