CA1156078A - Segmented projection screen construction - Google Patents

Abstract

Abstract The disclosure describes a new structure for making a large screen or mirror, such as used in a vehicle simulator, whereby such large structure is divided into a plurality of, preferably, identical segments. Each segment, then, is made on the same mold or pattern which ensures an accurate radius of curvature and that the edges of each segment will co-act with the adjacent segment in a laterally non-slipping relationship.
By this structure, the curved surfaces co-act together to define a smooth larger surface. Each segment is formed of expanded polyurethane foam with the two surfaces treated in different ways, depending on the use to which the structure is to be put.

Description

:~ 1S6078 SEG~ENTED SCREE~ CONSTRUCTION
BACKGROUND OF THE INVENTION

1. Field of the Invention _ This invention, generally, relates to projected-image vi~ual systems with screens and/or mirror3 having large radii for exhibiting pro~ected images and, more particularly, to a light-weight structure for a screen or mirror segment structure to cooperate with a plurality of similar segments in the construction of a larger project~d-image structure.
In the construc~ion of concave screens having large focal lengths, it is well known that it is important to avoid defects which can vary the focal point of the screen and become quite visible when an image is proJected onto these screens. It is particularly important in large focal length mirrors.
The screens or mirrors for exhibi~ing projec~ed images that have been used in the past, with curvatures o~ a large magnitude, have been difficult and quite expensive to produce.
This is because of the unusually heavy weight involved with each segment not only due to the weight of each segment but due also to the support structure required to maintain the curvature faithfully.
Although such large pro~ection ~tructures have most every conceivable curved configuration, even to the provision of a complete sphere, varying the curvature of ~uch structures has been neither convenient nor inexpensive. With present day emphasis on cost o~ conjtructlon, a screen or mirror constructed i~ accordance wlth the principles of the present invention will reduce the cQst dramatically and will provide a structure that is usePal, while provlding a ~ruc~ure whlc~
ad~ Oe ready sqrvicin~ ~o corr~ct de~ec~9 which develop ~o~ o ~ime.

; -~r~

1 156~7~

Such large curved-surface structures for exhibiting pro~ected ima8e~ are found to be uniquely adapted for use in vlsual display systems for vehicle simulators and will be described in this connection. An important improvement in flight simulation and in similar display sy~tems was achieved with the collimation of the displayPd image, i.e., by making all image points appear to be at infinity. The problem of providing collimation is complicated by any requirement for a wide field of view, and optical systems are ~nown which will provide collimated light for a wide field of view. However, such systems have not been capable of providing inexpe~sively collimated beams so wide that two or more trainees may view the scenes simultaneously.

2. Description of the Prior Art In the prior art, numerous training and 3imulator apparatus have been constructed which embody a position from which a trai~ee or pilot can manipulate control and observe a ~ response in a projected visual ima~e. For-example, the trainee or pilot i9 positioned in a mockup of a boat, submarlne, airplane, tank or other vehicle, and when he manipulates controls, such as a wheel, stick or ~hrottle, the observed visual scene responds in a manner which simulates corresponding movements of the training vehicle.
The prior art pa~ents~w~c~ a~ a~nown to~have relevant diqclosur2s are as follows~: 2,273,074, 3,6P07,584, 3,718,989

3,998,522 and 4,124,277.
However~ notwlthstanding the extensive efforts that have been made i~ this field, there has not yet been shown a segment structure to co-act with a plurality o~ segment structures to form a lar8er structure with the degree of accuracy in i~s curvature that is re~uired in the simulator ~ield in ordar ~o develop ~he required reali~ in the r,~roJec~e~ ~cene. In additlon, Xrom ~he prlor su~eations ~o divid~ a fnirror surPace into a l'series o~ ml~rors'~ or tha~ a 7 ~

"sc~een is composed of a number of small screen surfaces", there is not one disclosure of how it can be done or ho~ to do it lnexpenslvely.
SUM~RY OF THE INVENTION
A principal ob~ect of the i~vention is to provide a new and improved structure for a qegment which admits of co-acting with a plurallty of segment ~tructures to form a larger structure for exhibiting pro~ected images with suffici.ent realism ~or use in a proJected-image visual system of a sim~llator.
It i8 also an ob~ect oE the invention to provide such a segment structure that is inexpensive ~o manufacture, yet main-tains an unusually high degree of accuracy in the curvature of the assembled larger structure.
In a presently preferred form of the invention, a 15 synthetic porous material, such as polyurethene foam, is cured to a predetermined density and having two surfaces spaced apart a predetermined distance, one ~urface having a curvature that is defined as accurately as feasible. The i~vention includes several different forms of means to attach and 20 3upport a predetermined number of segment structures so that all of the accurately defined curved surfaces co-act together to form a smooth, continuous surface.
.

DESCRIPTION OF THE DRAWINGS
The foregoing, other and further obJects, features and 25 advantage9 will appear re ~ully fro~ the detailed de3cription of the presently preferred embodlments o~ the invention and ~rom the appended claims, both viewed in con~unction with ~he a co~panying drawing~J where:
FIG. 1 i3 a per~pqctlve view, partly ln cro~s section, 3~ Oe a ~egmen~ed s~ructu~5 const~ucted in accordance wi~h the p~incipl~s o~ the lnventlan.
PIG. 2 is a detailqd View o~ one end o~ FIG~ }.
FIG. 3 i~ a cross sectional view Oe a portlon o~ two sa~ma~l~s showing how they are at~ached and supported ~oga~her.

1 1~807~

FIG. 4 is a plan view taken along the line 4-4 in FIG. 3.
FIG. 5 is a view taken along the line 5-5 in FIG. 4.
FIG. 6 is a diagrammatic illustration of ho~ two I-beams at 90 to each other, are fitted together.
FIG. 7 is a top view of ~egments assemb}ed together in accordance with the present in~ention.
FIG. 8 i9 a view of the end of FIG. 7.
FIG. 9 is a view taken along the line 9-9 in FIG. 7.
FIG. lO is a front view taken along the line 10-lO in FIG. 7 shQwing slx matching ~egments assembled and attached together to form a curved section.
FIG. 11 is an illustration to a stand to assemble, align and test each section to ensure the smooth continuous curvature of a segment Rtructure is malntained for an 15 assembled section.
FIG. 12 i5 a vertical, perspective view showing par~ of a supporting structure for a plurality of segme~ts.
FIG. 13 is a view in perspective, partly in cross section, of an entire sphere constructed of the segment structures, in accortance with the principles of the present invention.
FIG. 14 is a diagrammatic illustration of a manner of forming oue segment structure, in accordance with the presently preferred form of the invention.
FIG. 15 is a diagra = tic illustration of a manner of forming another segment structure in accordance with the principles of ~he invention.
FIG. 16 is a diagrammatic illustrat~on of the formation of still another segment structure i~ accordance with the p~lnciple~ of the invention.
~0 FIG. 17 i~ a diagr~matic illu~ra~ion o~ ~he formation a~ ye~ another segment ~tructure in accordallce with the pre~ent in~en~ion.

11~6078 PRESENTLY PREFERRED EMBODIMENTS
While the description hereinafter relates to a structure whlch i~ unlquely adapted for wide-angle-dlsplay visual systems, particula~ly for slmulator use, they may have other use3, as one skilled in the art will readily appreciate.
In accordance with the present inveneion, a curved mirror-or screen structure is divided into any desired number of, preferably, equally sized segments. A reason for the present de3ire to have ea~h segment of the same size is that 1~ is contemplated that each segment is made from the same mald or on the same master, as will be explained in more detail presently, and the slze of each segment i8 determined by choice as to the particular weight that can be handled and manipulated conveniently.
Each segment structure, made in accordance with the invention, is unusually ~trong and rigid in configuration, and hav~ng a low weight, it provides an exceptional degree of fidelity for the geometric curvature of the entire segment surface. The features of construc~ion which contribute substantially to its low weight are the e~treme thinness of the segment skin and the light weight of the segment body.
Although each segment is made oE a tougher skin and, therefore, is more resistant to abuse, yet if the surface of a segment is da~aged in any way, the entire segment may be removed and replaced easily, because of the particular construction of the segment and bscause of the particular means for holding and adjusting each of the segments relative to ~ho~e ad~acent to lt.
Yet ano~her advan age Oè a cons~ruc~lon ln accordance wi~h the inven~lon i9 ~ha~ ~he uni~ue s~ructure o~ each ~e~men~ e~fec~ively i~olate8 ~he optical surface o~ a screen ~r~ the mou~in~ 3ur~ace, 8ince each Be~ment s~ruc~ure i8 made ~ro~ the 3ame mold or pa~ern, i~ will ma~ch the ~d~acen~
~e~ment per~ec~ly, and ~hu~, lt will adapt readilq to ~ 1 ~60~8 assembly into a larger configuration. On the other hand, each segment can be used as an entity if 90 desired.
In order to obtain maximum training value from vehlcle ~imulators, the trend is to provide such simulators with a 5 visual display ~ystem. Such a system can vary in complexity and sophistication from a fixed scene that is pro~ected in the pilot's field of vision to computer-controlled image ~lteration 3ystem~ with infinity image or CRT displays. ~ -In the training of an aircraft pllot, costly flight train-lng i9 avoided by providing a simulated cockpit of an aircraftwhereln there i~ a simulation of many aspects of the environ-ment within the cockpit of an actual alrcraft. A portion of the training includes the utilization of a ~imulated visual scene from an aircraft.
The pilot US2S the visual scene outside his cockpit most ; often during a take-off or a landing. Therefore, most simulators simNlate the vlsual scene near an airport. In one type of simulator, a motion picture is made of the visual scene from an actual aircraft during a landing or take~off. The motion picture thereafter i9 projected through a complex optical system to provide a simulated visual scene in realistic perspective.
Due to the increased use of the visual system in simulators today, there is a real need for a field-of-view a~
large a9 possible, yet of a new, lightweight structure for use with a simulator. A structure in accordance with the present invention, uniquely fulfills this need. The unit wei~ht of each segment oE a ~i~ror and/or screen that is conq~ruc~ed in accord~nce wi~h the prlnciple~ o~ ~he present inv~nclQn ~pprQxi~ates two ~o fivq po~mds per ~quare ~oo~.
It i~ con~e~plated tha~ only by the manu~acture o~
qac~ ~egment from Chq sa~q mold~ or ~ro~ the same master, can ~he po~ential of uni~o~mi~y and preciqion at a reasQn3ble cost 4e realized. Any proce~ o~ manu~ac~ure, ~hat re~ts 1 15~0~8 mainly on skilled labor to produce uniformity of geometry and finish, implies the risk of discontinuity in several aspects aside from probably prohlbieive costs ln producing a great number of segments. Moreover, the probability of mismatches when ~oini~g such variou~ly made segmen~s wGuld be very high in spite of the close dimensional tolerances.
The pre3ent inventlon, in its broadest aspect, contemplates the manufacture o~ segments of a screen of larger dimensions by formlng from the same mold individual segments of relatively large-area and substantially thin (when compared with its larger area), and o~ substantial strength, such as by the relatively new Reaction Injection Molding (RIM) technique.
Such polyurethane structural foam has a high strength-to-weight ratio, when used with RIM production process, and produces a segment structure with an integral, solid skin and a micro-cellular core.
The polyurethane structural foam is the result of a balanced chemical reaction between a polyol and an isocyanate.
In the reaction injection molding process, these liquid components are metered into a mixing chamber from which they are in~ected at atmospheric pressure into a closed mold. The mold i9 partially filled, depending upon the density of the finished product desired, and the mixture then expands to fill the entire mold space. The pressure developed during the foaming is relatively low, approximately 40 pounds per square inch.
Since polyurethane structural foam duplicates the mold surfaca, it i3 usual to have the mold surface as highly polished and s~ooth a~ posslble, It i~ already Light in color?
and therePore, P~r most use~, ~u~the~ ~eatmen~ ~or colq~ 1 unn~ceq8ary. ~or use~ whe~e loads mu~ be secured ~o ~he polyur~t~an~ s~ruc~u~al P~am seg~ent, local ~einPorcemen~
wl~h me~al i~ser~ may be necessary, I 1 5~;078 These inserts can be foamed in place. For foamed-in-place lnser~s, the insert i9 Eixed in place so that it does not move during the foaming phase. To improv~ adhesion between the segment and a metal insert, the metal surface ls roughened and degreased.
For a simple, one-time connection, wood or self-eapping screws can be inserted directly into the polyurethane structural foam after it is culed. The screw pull strength is dependant upon such factors as screw size and pilot hole dLameter. Screws should only be used in those segments with an overall density highPr than 25 pounds per cubic foot.
The mold temperature must be controlled closely and precisely to obtaln the results desired, i.e., the particular de8ree of density within the foa~ed material when it is cured.
This density of the foamed material is the primary factor i~
determining its weight as well as its strength, and therefore, it i9 desired to have a low density in the center of the material, which density becomes increasingly higher (or more dense) as one proceeds toward the surface of the material.
This temperature is controlled by maintaining its variations between two de8rees C., making it essential to use only good heat conducting molding materials. Tempered wa~er is used as - the best medium for controlling this mold temperature.
It i8 important to note that the lnformation concerning the polyurethane structure foam is ~urnished for the benefit o~ the artisan attempting to follow the teachings of tke present invention, and, in and o~ itself, forms no part o~ the present invention, It is ~he structuxe Oe the par~icula~
~e8men~ ~ha~ i9 the inven~ive ~eature here. Accordingly, the 30 lnven~lon ~hould in na way be limited to ~he par~icular pla~ic mate~ial usqd to ~o~m ~hq basis o~ ~he segment, ln tha~
o~her, dl~e~en~ and varlous materials may bq used, as bq~er within the p~view a~ an ar~i~an skilled ln that art.

1 1 58~78 For example, in place of polyurethane foamed structures, reinforcing with carbon rather than glass fibers may be More effective for some u3es, even though carbon fibers are much more costly. Another particular material is a percentage glass-rein-S forced polycarbonate, or a polyphenylene oxide structural foa~may be used.
Of course, many other materials may be known to an artisan skilled in this art which might be appropriate ~or use in a particulsr segment structure, and seill other and diEferent materlals mlght be available in the future.
Accordingly, it is understood that the present invention is in no way limited to the particular material described in this presently preferred embodiment.
One alternative arrangement of materials with which a construction in accordance with the principles of the inv~ntion is uniquely adapted to be effective utilizes a segment ~ormed of a suitable synthetic porous material with an appropriate ~etal, such as aluminum, nickel and the like, electro-formed on the optical surface in a very thin layer. There are companies today quite skilled in the electro-forming process.
Referring now to FIG. 1 of the drawings, the reference numeral 10 identi~ies one segment of a larger 3tructure, and the reference numeral 11 identifies a second segment of the same structure, the segment 11 being identical with the segment 10, having been formed on the same mold or paetern.
The optical surfaces 12 and 13 of the segments 10 and 11, respectively, are continuous and smooth, partlcularly at the line 14 where they ~oin, and have a large radlus of curvature.
~hQse 9urPaces 12 and 13 are appropriately fo~med to rePlect 3~ an ima~e which i9 pro~ec~qd ~h~reon a~ ln a normal si~ula~ian apparatu~.
~ IG. 2 Oe ~he drawings 1~ an enlar~ement o~ onq carner Oe thq ~qgmen~ 10 in order ~o reveal it~ cons~ruc~ion wlth ~ore pflrticularlty, ~or exa~ple, i~ may b~ see~ in FIG~ 2 ~ha~ the 3~ sur~acq l~ is actually ~or~ed by a sepa~a~e skln lS which is 1 15~78 ldentical to, in this particular embodiment of the invention st N cture, a second skin 16 spaced apart therefrom and sealed thereto by a plas~ic foam filler 17. The two skins 15 and 16 are relatively thin~ preferably a typical example ~ould be .031 inches max., as compared with a thickness of 2 inches between the inner surfaces of the skins 15 and 16. The plastlc foam filler 17, which i~ fo~med in place, bonds and, therefore, adheres readlly to the inner 3urfaces of these tw~ skins 15 and 16.
The two segments 10 and 11, as stated previously, are ~hown in FIG. 1 positioned approxima~ely correc~ly relative to each other to form a smooth, continuous surface, without there bein8 shown any means for holding the~ in this position.
In FIG. 3 of the drawings, there is shown a way, presently preferred, of attaching these two se~ments together to support them in this position.
Referring now to FIG. 3, a type of insert 21 shown imbedded in the foam 22 adjacent the upper edge of the upper-most segment is shown with a flange 23 which may be any de9ired configuration, such as circular, square, octagonal, etc. Moreover, the flan8e 23 may be perfora~ed with one or more rows of apertures 24 if desired, or it may be solid, it being a matter of the strength desired to be held by the insert 21.
The insert 21 also has a body 25 ~hich may be any desired configuration, and the body 25 may have a series of ralqed surPaces 26, like deep thread~, in order to give it mor~ re9i~tance t4 eXtrac~ion ~rom within the ~oam 22. ~he in~ert 21 ha9 a ~en~rally locatqd aper~ure 27 in whlch a bolt 2~ i~ threaded a~ainst a wa~her 29. Uisposed be~ween the head 30 o~ th~ bol~ 28 and ~he wa9hqr 29 is a lock wash 31 in ordqr ~o ~ur~her secure the bel~ 23 ~lrmly in place.
The body 32 of the bolt 23 ~i~8 within an enlarged clearanc~
openin~ 33 which pqrmi~s ad~ustmen~ oP po~ition Eor the s~ments, aq wlll be explained in mere detail presently.

- 1 15~078 The lowermost ~egment ~tructure, as viewed in FIG. 3, ha~ a ~olid skin 18 on the back or reverse ~ide thereof for the rigid, lightweigh~ porous core of synthetic foam 20, and it has, al~o, a skin 19 on the opposite surface which may be of a different material from that of the solid skin 18, but the ski~ 19 mu~t be solid and tough, as must be the skin 18.
In this view of the inventive structure, the ~kin 19 is highly polished, more reflective, mlrror-like finish, such as aluminum with a protective coating thereon. Alternatively, it can be a very thin glass plate, or it can be plaQtic, in order to achieve a hlghly reflective quality.
An lnsert 34 tha~ is shown near the edge of the lowermost segment in FIG. 3 ha~ a body 35 wlth a plurality of dull or rounded ~errations 36 along its length to increase it3 r2sistance to extraction from the foam 20. An aperture 37, located centrally ~ithin the insert 34, opens externally through the skin 18 to receive a threaded end 38 of a bolt 39. The bolt 39 has a head 40 which squeezes and firmly grips a lock washer 41 against a plain washer 42.
The bolt 39 has a main body 43 which extends from the head 40 to the threaded end 38 and which fits within an enlarged clearance opening 44, the purpose of which wlll be explained in more detail presently. Both of the clearance openings 33 and 44 are located in a flange 45 of the I-beam 46, with a matchlng flange 47 ~paced a predetermined distance from the fla~ge 45.
A pluraLity of U-~haped spacer washers, indlcated by the reference numeral~ 48 and 49, serve to space the flange 45 ~rom ~he ~klns 18 and 18', which may vary from p~int to point 3~ becau~ th& skins 18 ~nd 18' are curved lnto a predetcr~ined ~hapq, as viewed be~ ln FIC. 1 a~ ~he drawing~. Accordi~ly, ~inc~ ~he I~bea~ 46 19 contemplated as being only ~ htly cuXv~d and not nqceqsarily curved to match ~he configurations oP the 9e~qn~? ~he elangq 45 will vary in dis~ance grom 3S ~he ~kin ~' at varioua polnt~ aero~s i~s length.

l 156078 It is impo~tant to note a space 50 located between the flange 23 of the insert 21 and the inside surface of the skin 19'. One reason for thi~ space is to permit the foam ~2 to enter and seal the insert adhesivaly to both the inside surface of the skin 19' and, thereby, fixedly positlon the insert 21.
However, an even more lmportant resson for this space 50 is to prevent any distortion in the surface of the thln skin 19', which would occur if it touched on the inside surEace, because the skin 19' is so thin that any ob~ect touching on the inside gurface would be vlsible through it and would cause optical aberrations on the face vlewed.
Another i~portant feature seen in this FIG. 3 is the space 51 between the adjacent edges of the skins 19 and 19', which is typical of the gap between adjacent 3kins all the way around each segment. The space 51 is small, in the arder of .030 inch ~ .003 inches, and is for the purpose of preventing any chipping as would occur if the skins 19 and 19' are glass and they touched.
To fixedly position adjacent segments with the spacing, as indicated by the space 51, a suitable resilient separator, preferably a silicone plastic, is injected into a space 52 and molded in place upon the completion of the assembly, as will be deqcribed in more detail presently. This will fixedly secure the two segments adjacent each other, preventing their touching with a solid impact sufficient to chip the edge o~ a surface.
As better seen in FIGs. 4 and 5, a dowel pin 53 fits snugly into a hole 54 drilled all the way through the flange 4S Oe each I-beam, ~he spa~ers 48 and into the body 25 a~ t~le 30 insert 21. The manne~ ~ eixlng these dowel pinq, such as t:he pin 53, pre~erably tw~ per ~e~ment, will be described in ~o~e de~ail presen~ly. However, Ju8t b~ie-Ely, once the seg~en~8 h~ve been ad~u~tqd care~nlly t4 Xix the space 51 between them, a~ in ~cco~d~nce wi~h ~he dasired dimen~ion given above, ~he b~lt 28 and ~he bolt 39 Are tlghtened. Then, while the segments are being thus held in place, a hole is drilled such as the hole 54, in FIG. 5, and the dowel pin 53 i9 driven into place, thus fixedly securing the dimension 51.
A similar pin 55 i9 shown for the insert 34, in FIG. 4.
The I-beam 46 extends continuously past the two sides 56 and 57, respectively, is best shown in FIG. 4 of the ~rawing~. The fillet weld 58 is shown on each side of the side 56 and also on each side of the side 57 to ~oin these two to the I-beam 46. In FIG. 5, the fillet weld 59 is shown to ~oin the side 56 also to the horizontal flange 45 of the continuou~ I-beam 46.
In FIG. 6 of the drawings, there i9 shown how two I-b~ams are Joined together perpendicularly. The bottom flange 60 of the l-beam 62 is cut off along a line 63, and in like manner, the top flange 64 is sut off along a line 65, le~ving a pro~ecting extension 66, which is that portion of the body 62 that extends past a line drawn between the line 63 and 65.
As best seen in FIG. 6 of the drawings, an extension 66 is formed by that part of the body 62 which remains after the upper and lower flanges, 64 and 60, respectively, are cut off back to the respective lines 65 and 63. The edge 67 will touch against the surface 6~ of the I-beam 46 ~ust when the line 63 touches the end 69 and the line 65 touches the end 70.
Thereaftcr, firm ~oints may be made by suitable welding, or any other suitable attaching means.
Referring now to FIGS. 7, 8 and 9 of the drawings, it is shown how a plurality of segments are Joined together to form a "~ection" havin~ a desired number of segwents. FIG. 7 shows more par~lctllarly a top viqw of a ~ection having ~hre~ ~eg~en~
3q 71l 7~ and 739 r~pec~ively. However, hlso vl~ible in FIG. 7, i~ a por~ion o~ ~hrqc additional segment3 74, 7S and 76? ~oined al~o to the segmqn~s 71, 72 and 73 along a line indicat~d by ~hQ re~erence nume~al 51, identified more par~icularly in F~G, 3 of ~he drawln~ hi~ same re~er~nce n~m~ral Sl 1~
3S n~ed he~e ~o indicate that the ~pacln~, in ~he o~der of .030 ~ .
I

inches, ls common between all segments, generally. In addition, the same refarence numeral 51 is used to indicate the spacing between ad~acent segments 71 and 72; and be~ween ad~acent segments 7Z and 73.
While I-beams are utilized in these respective Figures for the purposes of this illus~ration, therle are available alternative forms of construceion to affix iad~acent segments to each other rigidly and ~o provide the neces~ary overall support. Such an alternative is shown in FIG. 8 of the drawings as being an alternative to that end referred to and lden~ified in FIG. 7.
In ~IG. 8, two channels 77 and 78 are bolted together as illustrated by the straight lines 79 and 80, respectively.
With the channels 77 and 78 firmly affixed to each ~ther, the resemblance to an I-beam is present.
~ owever, having the so-called I-beam in this form of structure, i.e., the two channels 77 and 78, admits of another means to space the tw~o segments with respect to each other in order to accurately obtain the spacing 51. By way of example, the channels 77 and 78 may be affixed at the borders of the respective segment structure~, and then, when the rwo segments are positioned next to each other and when the ~pacing 51 is established, a washer or other suitable spacer may be placed within the gap 81, before the channels 77 and 78 are bolted together ac 79 or 80.
FIG. 9 is a side view of this section, but taken aIong the line 9-9 ln ~IG. 7. It illustrates the effectiveness o~ the I-beam supe~s~uc~u~e ~o~ 9upp4rting the lndividual seg~ent s~ruc~ures 73 and 76 in rela~ion to aach other ln 4rder tQ ~ ly a~ix tha 9pacq Sl. In ~his side view o ~he sec~i4~, ~he spac~ 82 i9 clearly vislblq between the lowq~m4st flang~ 83 o~ the bo~to~-to-top I-bea~ 84.
I~ is con~emp1ated, ~l~hough no~ e~sen~ial, ~h~t ~he ve~tical I-bea~ 84 is the contlnuou~ one, whereas the ~ide-~4-side I-beams are arranged to abutt in a manner as shown in FIG. 6. In this FIG. 9, the lowermost I-beam i~ identlfled by the reference numeral 85, whereas the uppermo~t I-beam is identiied by the reference numeral 86 and the i~termediate I-beam i~ 87. Al~o as ~hown in FIG. 9 are ~our spaces identifled from top to bottom as 88, 89, 90 and 91.
Whereas the view in FIG. 9 includes approximately 40 degrees, the top view shown in FIG. 7 includes approximately 60 degrees.
FIG. 10 is a full frontal view o~ the assembled section ~s shown in FIG. 7 or the drawings, taken along a line 10-10 in FIG. 7. In this view, each segment is identified by reference numbers 71, 7Z, 73, 74, 75 and 76. It is contemplated that the vertically positioned I-beams, identified by reference numerals 92, 93, 94 and 95, in ~IG. 10, are continuous, as viewed in this Figure, as contrasted with the horizontally arranged I-beams 96, 97 and 98, from top to bottom, which are intermediate of the vertical I-beamR and are attached together as illus~rated in FIG. 6.
Also shown in FIG. 10, for the segment 75, there are indicated four crossline~ and identified by the reference numeral 99 to illu~trate that in each of these positions, a cast-in-place in3ert i~ positioned during formation of the segment structure and used to facilitate carrying by tempor~rily attachin~ a suitable handle (not shown). It is contemplated that each segment structure, man d actured in accordance wlth the invention, that iq o~ su~ficient ~ize to make handling otherwise awkward, such cast-in-place inqerts may be. 90 included.
Sinee each of the segment structures are c~nstructed and eormqd ~o~ the samq identical mold, ~hey are id~n~ical ln ~lze and in arc~e qh~p~. A p~deter~ined ~umbe~ o~ such ~e~m~nCq a~e a~qmbled together tQ Eorm a ~hape s~mewhak 3S la~gq~ (~uch as tha~ ~ho~n ln FIG. 10) and is called a 1 1 560~8 - 16 ~

"section", for the purposes oE this description. A "section"
i9 assembled of a deslred number oE the "segments", and any convenient method may be used in such asgembly.
As shown in FIG. ll of the drawings, a convenient way of as~embling these segments is on a large table lO0, having an upper surface lOl in or~er to support the s1:ructure being a3sembled. By a series of vertically positioned members 102 wi~h suitable braces 103, the table lO0 ls supported in an elevated -position relative to a floor surface 104.
In ~his illustration, there are three segment structures vlsible on the table lO0, they being segments 105, 106 and 107, in order to form a section 108. By a suitable gauge ~not shown), the space Sl is set by adjusting the position of ad~acent segments. Ihen, a suitable resilient separator lS (such as a fluid silicone mixture) i8 injected and molded in place, as described in connect~on with FIG. 3. Since each of these segments are supported vertically on the table lO0, once the silicone mixture is set, the gauge may be remo~ed because there are no forces acting upon each segment structure to alter the spacing.
Various I-beams, or other segment support structure, are arranged within the space identified by the reference numeral lO9 and supported appropriately on the upper surface lOl of the table lO0. Then, a plurality of individual segments (three bein8 visible in this view, 105, 106 and 107) are attached to the I-beams, a~ explained in connection with FIG. 3, supra.
A~ is well known, an important factor in the cost of any ~aterial ordered from a vendor is dependent directly upon the de&ree of tolerance speci~ied when ordarin~ the material.
There~ore, whiIe ~he I-bqa~q are ord~r~d ~o a desired cu~vatu~e, the ~alera-ncq m~y 4e in ~ha order o~ inch~
and the d~viation9 ~ro~ the deqired curvature a~ co~pen~ated Eor by qpaeer~, indicated by the re~erence numerals 4~ and

4~ in ~IC. 3 and ~he sp~cerq 48 an~ 49 bain~ ITY~haped perm:l~s 1 1561)'~8 the~ to be slipped into place about the resp2ctive bolt without removing the bolt.
By any suitable structure, a hook indicated by the reference numeral 110 is located and fixedly positioned A distance from ~he surface of the section 108 equal to tbe radius of its curvature. A suitable radius gauge is formed by having a non-extensible member 111 to accurately position a plumb 112, having a plastic or other soft tip, an accurate distance above the surface of curvature for the section 108. Then, by moving the plumb 112 about the surface in any desired direction, any deviation ln the curvature of the section 108 will become apparent immediately.
A atructure ldentified generally by the numeral 113 selves to provide the non extensible member 11 with the desired length.
It is important that the hook 11~ be fixed positively, as well as accurately~ and to accomplish this, the structure 113 has surfaces 114 and 115 which are flared apart upwardly until they reach a surface 116, such as a ceil$ng or, as seen in this view, as formed by a horizontally arranged beam 117. The beam 117 is braced by diagonally arranged braces 118 and 119 attached between the beam 117 and the downwardly flared apart support legs 120 and 121, positioned on pedestals 122 and 123, respectively.
In FIG. 12 of thte drawings, there i9 shown, by way of illustration onlyl one structure ~or superstructure) 124 for supporting a plurality of sections embodying more than one Yegment each. The particular number of segments that ate ~oined at ehe factory prior to shipping ls dictated by such considerations as welght, convenience and ease of handling the section. If the surface of the segments is that of highly rePl~ctlve macerial, such as polished metal or even a glass mi~r~ ~urface, then the weighc mi~h~ be expected to be sub~tantiaLly more than iP only a scrqen surface is lnvol~ed, For the heavler weighlng segments, perhaps only four segments might be Joined to form a section, such as segments 125, 126, 12g and 130, or alternatively, 125, 126, 127 and 128. The segments 131 and 132 ~ight be ~oined together at the factory as a cwo-segment section, or alternatively, these two segments 131 and 132 mi8ht be combined at the factory with segment~ 129 and 130 or with segments 127 and 128, it largely being a matter of choice, dictated by convenience.
The particular supporting supPrstructure, illustrated by way of example only in FIG. 12, is depicted in sufficient detail that a description thereoE is not believed to be necessary, because the particular superstructure is not an aspect of the present inventlon, but rather, goes to illustrate another use for the invention.
In FIG. 13 of the drawings, the particular invention is shown in an environment in which it is believed to be a particular benefit in the simulator art. Here, the invention is used to form a complete sphere with a screen-type of surface, indicated by the reference numeral 133. A plurality of identical segment structures 134 are ~oined in a manner as has been deYcribed already in order to form a sphere, indicated generally by the reference numeral 135.
The particular suparstructure to support the individual sections, each composed of a plurality of segments 134, i9 not shown because it can be removed once such a spher~ 135 is completed. Of course, if the simulator is not a fixed-base type, but rather is a mation-base type, the supportive super~tructure may be retained in place. With the support structure removed, however, each segment structure supports the adJacent segments, making a superstructure unneces~ary.
A small opening 136 i~ left in this structure to provide a~ceq~ ~o a 3i~ula~4r ~pp~ratus 137 located wl~hln thi~ sphere 13S in ~uch a mann~r as ~he qyepoln~ 13~ will be at ~he geo~ecrlc cen~er o~ the ~pherq ~or ~aximum r~l1sm of an 1mage 3S p~o~ected upon ~hq scrqen 133. ~he openlng a~ the very ~op of the sphere 135 is small and i9 filled by a single 3egment made to fit that opening.
To illustrate a pre~ently preferred method of making each segment structure with either 8 screen or a mirror surface, in accordance with the present invention, reference is mate to FIG. 14 of the drawings. In this view, a fixed mold is indicated by the reference numeral 139 and has a plurality of openings 140 for the circula~ion of either heating or cooling medium, such as tempered water, to contol the temperatu e of the upper surface 141 precisely. The surface 141 is the critical part of this mold 139, because it is of the same radlus as the flnished screen or mirror. By using the same surface to form each 3egment, clearly the curvature of the final product will be the desired curvature.
The total area of a desired display surface is divided into an equal number of segments of equal dimensions, preferably rectangular, but, however, they m~y be s~uare, which is a speclal form of a rectangle. Then, knowing the rectangular dimensions of each segment, an angle 142 is formed of a suitable material and is joined at its ends to form a generally rectangular border to match the desired shape of each segment structure.
Then, the ~oined form of angle 142 is laid upon the mold surface 141 to define the border, as described, and in FIG. 14, it 19 contemplated that ehe border definlng angle 142 will become part of the segment structure. However, this need not be the case in every instance. For example, the means to deflne a suitable border can be attached to either the mold 139 or, preerably, to an upper platen 143. It can be at an appropriate angle ~o form a V-shaped trough with the border o~ an ad~acen~ aegmen~ atruc~ure, as ~hown in FIG. 3 by ~he re~qrence nume~al 52, 11~607~

The upper platen ~43, being movable vertically, is ad~usted ~o ~ust touch the rectangular configuration for~ed by the an$1e 142. This defines a cavity 144 between the lower surface 141 and a surface 145 on the movabl~ upper platen 143.
S The temperature of the surface 145 is controlled, like the temperature of the 3urface 141, by a plurality of holes 146 in order to circulate either a heating or a cooliI~g medium from a sultable source 141.
With the space 144 accurately defined as described above, predetermined quantitles of a polyol and an isocyanate are metered into the space 144, which can serve now as a mi~ing ch~mber, partially filling the spacq 144, depending upon the density of the finished product desired, the mixture reacts and expands to fill the entire space. During the curing process, the temperature of the mixture is controlled closely and precisely to obtain the desired results. The foam material i3 in~ected from a suitable supply 148 through any convenient access opening 149 into the space 144.
A segment constructed in the manner just described lmmediately above is the presently preferred form, i.e., where the foam itself forms the surface to be used as a screen.
The polyurethane structural foam segment formed in this manner ~ay have a density sufficiently dense along its concave surface formed against the mold surface 141 to permit it to be highly 2S poli3hed and, preferably, coated with a highly reflective material by any of the present-day known processes, such a~
electro-forming an ultra-thin but highly reflective coating of aluminum, nickel or the llke.
In addition, the surface of the segment qtructure that is formed a8ainst the surface 145 also is the denser foam su~f~ce and is e~tirely sultable, in many instanceq, to attach lt ln pl~ce with o~dl~ry w~od screwa~ ~or examplq, quppor~ ~or ~he se~men~ qt~uc~ure may be provlded by inse~ing directly i~t~ thi~ dqnser Poam ~art o~ the ~e8m~nt s~ructure a ~ui~able self-tappin~ ~crew.

The above description suggests a modificaeion which i~
illustrated diagrammatically in FIG. 15 of the drawings. In thl9 view, the sa~e mold 139 may b~ used wLth its upper conYex surface 141 and a plurality o~ hole3 or tubular opening~ 140 to receive the heating ant coolin~ medium.
A positioning s~op 150 is located ad~acent one edge of the mold 139 to position accurately each part to be formed on the surface 141. In thi~ view, a lower skin 151 is laid directly on the mold surface 141 with one edge against the po~itionlng stop 150, and then, an identical upper skin 152 ~ith suitable end angles 153 and 154 attached is posltioned over the skin 151 and again~t the positioning stop 150, forming a generally rectangular space 155.
The stop 150 has a surface 156 against which the angle 154 is positioned to give the angle 154 the correct position relative to the lower skin 151 for the finished segment. By way of illustration, the angle 154 as well as the angle 153 and the other ends (not ~isible) may be positioned wi~h a desired tilt to form a somewhat V-shaped opening between adjacent segments for filling with the desired resilient material, as the space 52 qhown and described in connection with FIG. 3 of the drawings.
In FIG. 15, two inserts 157 and 158 with respective flanges 159 and 160 are shown held in position by short screws 161 and 162 against the upper skin 152 in order to define a space 163 and 164 between each respective flange 159 and 160 of the inserts 157 and 158 and the lower skin 151. It has been found tbat the space~ 163 and 164 are required in order to prevent a disto~tion being vi~ible th~ough ~he lower skin 151. Therefo~e~
~he ~paces 163 and 164 are iu~t su~icient for a layer o~ ~he ~oamed ma~erial ~o flow between the ~langes lS9 ~nd 160 and the lower skin 151, ~hereby makin8 the ~lan~es 159 and 16~, re~pectively, invlsible a~ vlewed through the lower skln 151.

A suitable 3ynthet~c porous ~aterial is injected, as illustrated diagrammatically by the reference numeral 165, into the spsce 155 at about the upper~ost point ln order to prevent air being trapped as the synthetic porous material expands during the curing process. The material, for example, polyurethane ~tructural foam, is cured in place in the chamber 155 and is sufficlently strong to miake the entire segment structure unusually strong and rigid.
Therefore, after the polyurethane i9 cured, the temporary screws 161 and 162, as well as any otherY that might be holding foamed-in-place inserts in their proper posi~ion, are removed to permit either ~he temporary attachment of a handle fo~
manipulating the segment structure or for the attachment of an I-beam, as illustrated in FIG. 3 of the drawings. By attaching to the upper skin 152 the two inserts 157 and 158 as well as the angles 153 and 154, all of this activity i9 benchwork, ~hare it can be done much faster and with a much higher degree of accuracy than at the manufacturing site.
As clearly visible in FIG. 15, each of the two angles 153 and 154 is not illustrated as being fixedly attached to the lower skin 151. In practice, the lower skin 151 is placed upon the mold surface 141, and since the lower skin 151 is relati~ely thin and flexible, it will immediately assume the configuration of the surface 141.
Thereafter, the assembled unit of the upper skin 152 with all of the inserts (such as the inserts 157 and 158) and the surrounding angles ~such as the angles 153 and 154) is placed over tha lower skln 151 and i9 positioned against the qtop surface 156. After the polyurethane structural foam i5 cured 3~ withl~ th~ ~pac~ lSS, the synthetic porqus ma~erial eorm~ a ri~ld attach~ent adhasively ~ixin~ the lower skin 151 to the upper ~kln 152, as well a~ wi~hin the spaces 163 and 164 and within thq channels o~ the a~gles 1S3 and 154, making ~ur~her ~ach~n~ unnecqs~ary in order to lift the lqwer ~kin lSl wi~ the upper skin 152~

1 1 ~6078 Referring now to FIG. 16 of the drawings wherein lt is shown a further embodlment of a seg~ent constructed in accordance with the principles of the inventlon. Here a very thin mirror skin 166 is laid over the surface 141 of ~he mold 139 and is positioned againgt the stop lS0.
An upper skin 167, then, with all of its attachments, such as the angle~ 168 and 169 and the inserts 170 and 171, is positioned against the stop surface 156 over the lower skin 166, as illustrated in FIC. 16 of the drawings. As explained above, the angles 168 and 169 are not attached to the mirror skin 166 becau~e they would be visible through the skin.
Each angle member 168 and 169 is sharpened at one end to a fine line ed8e as illustrated by the reference nu~eral 172 in FIG. 16 in order to minimlze contact area with the 15 - surface of the skin 166. Because of this characteristic of a surface against the lower mirror skin 166, ~he two inserts 170 and 171 are maintained out of contact with the mirror skin 166, as illustrated by the spaces 173 and 174 and as explained in detail above.
The inserts 170 and 171 are fixedly attached to the upper skin 167 by mean~ of a Ionger threaded member with a nut 175 and 176, respectively, intermediate of this threaded ~ember, to leave extending from the upper skin 167 a substantially longer threaded end 177 and 178, respectively.
Z5 By this means, the foa~ed-in-place inserts 170 and 171 are fixedly attached to the upper skin 167 and need not be touched further because the extended threaded ends 177 and 178 are used to insert through a larger hole in the flange of a sultable I-bea~ for attachin~ ad~acent segment edges. Of course, by 3~ a~aching ~he se~ment s~ructures in ~hi~ manner ~o an ~-beal~, ~h~ ~hreaded qxt~nded end~ 177 and 178 need only have a 3uitable spacer washer inserted and then a nut threaded over each end ~o malce ~hem opera~lve. A9 illustra~ed 4y the rq~erence numeral 179, a suitable syn~he~ic porous material i~ inJected within the cavity 180.

1 1 5~078 Yet ano~her embodiment of a ~egment, constructed ln accordance with the princlples of the present invention, is illustrated by the diagrammatic view in FIG. 17. A thin glass sheet 166 is laid on the curved surface 141 of a mold 139 with thz border angles 142 carefully positioned thereover so that the edges will match the ed8e~ of the glass ~Ikin 166, as illustrated by the reference numeral 181, fo~ing a line contact with the skin 166.
Then an upper pla~en 182, which is movable vertically, is lowered to touch the edges of the borde~ angles 142 thereby defining a space 183. From a suitable sGurce 184, a polyrethane structural foam is inJected into the space 183S so that as lt is cured, it will expand to touch the upper surface 185.
From a suitable source 186 of heating and cooling, a suitable fluid is circulated through the openings 187 in order to control the curing of the polyurethane that has been in-jected into the space 183. Since no foamed-in-place inserts are illustrated in this view, the foamed polyurethane may be cured to a degree that makes it more dense than usual by controlling its temperature, and the segment structure is attached to a 3uitable support and to each other by wood screws, as described prevlously.
In view of the above detailed descrlption of the presently preferred form of the invention and in view of the detailed description of various modifications thereto, other and still further modificatons, variation~, advantages and uses will occur to one skilled in this art. Accordingly, the description and ~odifications pre~en~ly presented hereinabove are ~o he considered ~9 illus~ra~iYq only, ~h~ ~rue ~pirl~ and scope o~
the inv~io~ beiny tha~ deEined by ~he claims appended hereto.

Claims (13)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:

1. In a projected-image visual system for a simulator, a segment structure for co-acting with a plurality of segment structures to form a larger structure for exhibiting projected images, said segment structure comprising:
a synthetic porous material cured to a predetermined density and having two surfaces spaced apart a predetermined distance, at least one surface of said two surfaces having an accurately defined curvature, border means positioned around the periphery of each in-dividual segment structure and formed in a manner to fit with the border means of adjacent segment structures in a laterally non-slipping relationship, and means to support said segment structure with accurately defined spacing between adjacent segment structures, so that all of said one surfaces co-act together to define a smooth, substantially continuous surface for exhibiting said projected images.

2. A segment structure as claimed in claim 1, character-ized in that said two surfaces include sheets of the same material.

3. A segment structure as claimed in claim 1, character-ized in that said one surface is different from the other of the said two surfaces in a highly polished, more reflective, mirror-like quality, to enhance realism in its reflection of said projected images.

4. A segment structure as claimed in claim 1, char-acterized in that said one surface is different from the other of said two surfaces in a diffuse light reflective quality to enhance its function as a screen on which projected images are exhibited.

5. A segment structure as claimed in claim 1, 2, or 3, characterized in that a predetermined number of insert means are embedded within said cured synthetic porous material to enable a plurality of segment structures to be attached together rigidly.

6. A segment structure as claimed in claim 4, charac-terized in that a predetermined number of insert means are embedded within said cured synthetic porous material to enable a plurality of segment structures to be attached together rigidly.

7. A segment structure as claimed in claim 1, 2, or 3, characterized in that a predetermined number of insert means are embedded within said cured synthetic porous material to enable a plurality of segment structures to be attached together rigidly, and further characterized in that each of said insert means includes surface means to increase its resistance to extraction.

8. A segment structure as claimed in claim 6, charac-terized in that each of said insert means includes surface means to increase its resistance to extraction, and further characterized in that said surface means to increase the distance of extraction of said insert means from said cured synthetic porous material is in the form of an annular flange of a predetermined size and shape.

9. A segment structure as claimed in claim 1, 2, or 3, characterized in that a predetermined number of insert means are embedded within said cured synthetic porous material to enable a plurality of segment structures to be attached together rigidly, further characterized in that each of said insert means includes surface means to increase its resistance to extraction, and still further characterized in that said surface means to increase the resistance to extraction of said insert means from said cured synthetic porous material is in the form of an annular flange of a predetermined size and shape.

10. A segment structure as defined in claim 8, character-zed in that said surface means to increase the resistance to extraction of said insert means from said cured synthetic porous material is in the form of an annular flange of a predetermined size and shape.

11. A segment structure as claimed in 1, 2, or 3, characterized in that a predetermined number of insert means are embedded within said cured synthetic porous material to enable a plurality of segment structures to be attached together rigidly, further characterized in that each of said insert means includes surface means to increase its resistance to extraction, and still further characterized in that said surface means is in the form of a plurality of serrations arranged along the length of the body to increase its resistance to extraction.

12. A segment structure as claimed in claim 8, char-acterized in that said surface means is in the form of a plurality of serrations arranged along the length of the body to increase its resistance to extraction.

13. In a projected-image visual system for a simulator having a trainee's position and a larger structure for exhibiting projected visual images, a segment structure for co-acting with a plurality of segment structures to form said larger structure for exhibiting projected visual images, said segment structure comprising;
a synthetic porous material cured to a predetermined density, and having a boundry formed by edges of a predetermined configuration;
said edges of a predetermined configuration being formed to fit matching edges of adjacent segment structures, so that said edges are unobtrusive to a trainee in said trainee's position in said simulator;
said synthetic porous material also having two surfaces spaced apart a predetermined distance;
at least one of said two surfaces having an accurately defined curvature; and means to attach a plurality of said segment structures with the surface of each segment structure, having said accurately defined curvature, co-acting together to define a smooth substantially continous larger surface of predetermined dimensions, for exhibiting said projected visual images to a trainee in said trainee's position with substantially the same realism as that obtained with a surface of said predetermined dimensions which is formed of a single, unitary, one-piece structure.