CA1059316A - Camouflage cloth or sheet with hole patterning - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A camouflage sheet is perforated in such a way that the perforations produce or contribute to the camouflaging effect.
The holes which together form the perforations are arranged in positions corresponding to the points in a triangular raster or matrix, so that three adjacent holes form the vertices of an equilateral triangle. The edge portions of known sheets for camouflage in monotonous terrain, e.g. fields, desert, snow, lakes or the sea may be provided with the above-mentioned perforations in such a way that the perforations become sparser from the edge of the sheet towards the center.

Description

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The invention relates to a pliable, flexible or stiff :~
camouflage sheet with hole patterning which contribu-tes to or produces the camouflaging effect.
The designation "camouflage sheet" as employed below : : .: .
for the subject of the invention comprises any fabric and/or ;i~ ~ -plastic foil with or without a supporting net, a tarpaulin, a pliable or completely stiff sheet, plate or the like. ~;
As is well known, it was and still is qui-te common tha-t camouflage sheets and the like are made as nets with applied plastic or fabric pieces, so-called appliqué garniture, and -thus do not form a closed surface. I-t is also known -to furnish a sheet wi-th normally irregular apertures -to increase the camouflaging effec-t, bu-t primarily to make i-t possible -to look i -through the camouflage shee-t wi-thou-t being seen. In addition it is desirable that precipita-tion not form pools, rivulets, ice-coatings or shiny surfaces as a result of the camouflage acting as a closed roof. A sheet having numerous apertures is, ~-in addition, less likely to flutter from wind or from pressure ;
waves eminating from projectile explosions or projectile firings. ;~ ;
For each -type of camouflage shee-t or the like there is a certain range wi-thin which -the camouflage is ineffective, .
i.e. -the eye can register the camouflage details without their merging with the surroundings. This close-up range should be ;
small and is dependent on several factors, but it does happen ~. .
that a camouflage is chosen where this range is relatively large, but where the camouflage effect is even better at , considerably greater range. Camouflage can also have ano-ther ~

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function, namely rendering aiming difficult in -the shooting of 'a camouflaged target. This function is particularly well-known in the drastic camouflaging of vessels with camouflage rich in -contrast and easy to recognize but which, to a high degree, hinders or precludes subjective estimation and, to a certain ';~extent, even objective measurement of the vessel range, speed, ~
class and size. ~as-t, accurate aiming is, in addition, psycho- ~-logically and physiologically hinde're'd",often to a significan-t degree, by camouflage which can appear irritating or distrac-t- ' ing, some-thing not to be underrated in combat situations. What 'was said above in connection with vessels often also applies on '' land, e.g. to phan-tom targets. '~' An o-therwise eEfective camouflage encounters consider- -able difficul-ties in smooth -terrain such as meadows, deser-t, s-teppe, snow-covered fields and frozen or unfrozen lakes and streams. In such cases one generally uses unpa-tterned or slightly patterned camouflage having the same color as the surroundings, but the camouflage shee-t seldom has the exact same color and essentially always forms folds and surface -sections which - according to the lighting - produce shadows or varying degrees of brightness which con-trast with -the sur- i roundings -to a cer-tain ex-tent. This can be alleviated by using `;
camouflage shee-t having aper-tures, e.g. a shee-t consis-ting of a '~
camouflage net with appliquéd garniture, whereby even the 'i~
background of the sheet becomes visible to a certain degree '' through the apertures in the sheet, which is often a known ;~
advan-tage. Such sheets, however, have disadvantages precisely in said "monotonous" surroundings, are more expensive and the r~~

;~ .~' ' ' ' ' ' garniture can relatively easily be torn away during transport i and dragging along the ground unless it is attached in a ~ `;
special way which further increases the cost.
If, on the other hand, the sheet is furnished with numerous, preferably punched apertures, so distributed that a camouflage pattern is formed by these apertures, it is possible to avoid said disadvantages to a degree, in addition to which -~
the sheet is relatively light and nearly as durable as a closed `
coherent sheet, i.e. a sheet without apertures. This also has a certain significance in -that it is possible -to avoid a , ;
supporting net for the ac-tual sheet, or to use a supporting ne-t ~-which is both ligh-ter and less expensive -than a ne-t Eor appliquéd garniture, Providing a shee-t wi-th aper-tures of :~;
varying dimensions and varying dis-tribu-tion encoun-ters purely ;~
practical difficulties, however, if the sheet is not to be too expensive and, additionally, is not to display a pattern repeat i which is too small. As is well-known, pattern repeat is reIated ; ;-to the distance at which a given pattern is repea-ted on the sheet, since machine pattern printing, appliquéing, hole punching, e-tc. is usually carried ou-t wi-th -tools (prin-ting j plates or -the like) of limited size. This can, indeed, be A
avoided with successively opera-ting -tools which are controlled by paper tapes, computers or the like, but production thereby becomes expensive and complicated, i.a. because it is not only pattern repeats which are too small which are to be avoided, but also pattern sections which are unsuitable for the intended camouflage effect. `
It is simplest to produce camouflage sheets having a )593~
.`, , camouflage pattern formed entirely or in part by apertures, using a plate or ~-rotatable cylinder fitted with hole punches. ~ole punching of an entire `
pattern section on the sheet is effected in a way similar to printing, in that said plate ~or cylinder) punches holes instead of printing. It should, however, be possible to shift the individual hole punches on the plate so that the plate can be used for different patterns. This implies that the plate must be furnished with mountings for removable hole punches at all places, i.e. at so-called positions, where hole punches are to be attached.
The mountings thus form an imaginary grid array or matrix on the plate.
Alternatively the mountings can form one or a small number of arrays on a type of bar whereby the pattern section is hole punched row by row and whereby certain hole punches are made operative or inoperative under the control of a program by per se known mechanical, pneumatic or electrical means each time ~or nearly 0ach time) a new row of holes is punched, so that the distribution of the holes changes during the punching of the entire pattern section. In this case the hole punches must be program controlled, which means that the punched holes will be located at intersections in a matrix-forming grid. In hole punching by means of said plate it is likewise obvious to arrange each `~
hole punch mounting in its own intersection in the grid. For reasons pre-viously mentioned the possibility if distributing the holes entirely irregular-ly without contemplated imaginary grid arrays or the like is here ignored.
The holes should be circular, elliptical or oval, and the edges ~ i should not show indications of tearing, such as sharp edges or other dis-continuities. Furthermore, the holes should be neither too large nor too small, both with respect to the desired camouflage effect at the range and for the target in question and to practical demands.
In connection with the creation of the invention it was recognized that a rectangular imaginary grid array, i.e. an imaginary grid array based on the Cartesian coordinate system with square or at least rectangular matrix grids, resulted in a relatively large close-up range or "sight range", i.e.
the minimum range at which the hole groups are only just perceived as being artificial. The polar coordinate system is of little value for various reasons, ; ' ' '''' ' ' .. .. , .. .~.:.. . . .. ; . ~ ,., .... . :, .. . ..

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~ : , i.e. from the standpoint of camouflage and manufacturing.
By making the sheet in accordance with the characteri~ing clause of the main claim, on the other hand, it is possible to significantly reduce said sight range and to also obtain a somewhat greater freedom of choice in .. . .
the placement of the holes and somewhat greater sheet durability compared to a sheet whose holes are placed according to a rectangular coordinate system or imaginary grid array. ~ `~
In accordance with this invention, there is provided a camouflage sheet having a predetermined size and an exposed surface for presenting an appearance similar to a predetermined environment, said sheet having means for defining a plurality of non-uniformly distributed groups of circular or substantially oval punched holes in said surface~ said holes in each of said groups being arranged so that the centers thereoP lie at selected vertices of adjacent substantially equilateral, triangles, said exposed surface being of at least one color selected to match a color characteristic of said environment, and said holes contributing to the camouflage effect.
Figure 1 shows examples of imaginary grid arrays for holes in a camouflage sheet according to the invention, and Figure 2 shows an example of a hole pattern section in simplified form in that, in reality, the imag-inary grid array for a pattern according to Figure 2 must be significantly finer and the number of holes greater than that which is shown.
Figure 1 shows an imaginary grid array according to a per se known tow-dimensional coordinate system having three coordinate axis which form 60 angles with one another. This system is called "triangular". The thusly obtained grid according to Figure 1 therefore consists of numerous equilater-al triangles, but can also consist of regular hexagons arranged as in a honeycomb. The equilateral triangles or hexagons need not be equally large within the entire pattern section, i.e. the field which with pattern repeat may be repeated on the sheet. ~t the top of Figure 1 is shown a triangular B ~ `:

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imaginary grid array or matrix having larger triangles than these at the bottom of Figure 1.
Mountings for hole punches are arranged on a hole punch plate at those points which coincide with the vertices of the triangles according to Figure 1. This does not necessarily mean that the mountings must be located '' i: ::
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at all such vertices, and the mountings need not coincide exactly with the ~ `' vertices. The discrepancies should not, however, be so large that a signifi- .
cant number of triangles are right-angled triangles or otherwise deviate markedly from the form of a substantially equilateral triangle. The equiva-lent applies to rotary punching with a hole punch cylinder, and also to the program control in the above-mentioned method of punching row by row ~or column by column). '."!.
The holes may be of various sizes, that is various diameters for circular holes. Figure 2 shows an example of a hole pattern section having two different hole sizes, but having a single common triangular imaginary '.
grid array, while Pigure 1 shows two such imaginary grid arrays jaining one another within the entire pattern or within a pattern section. The two arrows 1 indicate separate regions within which small holes have the densest possible ~i dlstribution, namely so that every vertex in the triangular imaginary grid ;`
array is occupied by a hole, as indicated by the broken lines below the tip of the left-hand arrow 1. The arrow 2 indicates a region with small holes in ;-sparser distribution so that the holes coincide with the vertices of hexagons ~.
which together form a triangular imaginary grid array resembling a honeycomb. ;-The arrows 3 indicate separate regions having larger holes in the densest possible distribution in the same way as the small holes in the regions indicated by the arrows 1. The arrow 4 indicates a region having large holes in a distribution sparser than the densest possible.
According to the fineness ~vertex spacing) of the imaginary grid array and to requirements pertaining to the camouflage in question, it is ~-also possible to choose a single hole size or to use more than two hole sizes, but preferably not more than three. ~ ~
It is easily seen that the specific hole density, i.e. the ratio , between the combined surface area of the holes within a given reglon and the total area of this region, may be chosen within very broad limits. The lower limit is, of course~ zero, i.e. nG holes in the region, while the upper limit . .
depends primarily on the demands on the durability and on the construction ;
of the sheet, e.g. whether it is furnished with a supporting net or not.

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l~S93~6 Taking region 3 as an example, it can be seen that adjacent vertical hole groups (columns) are offset by one-half the distance between hole centers.
In a corresponding rectangular (Cartesian) imaginary grid array a similar -offset would not result in equilateral triangles, which means that for the same number of holes per unit area the minimum distance between two adjacent holes is markedly smaller than in the triangular imaginary grid array accord-ing to Figures 1 and 2, and that the sheet durability is considerably greater with the triangular imaginary grid array than with a rectangular imaginarygrid array (and even significantly greater still than for a polar coordinate imaginary grid array.) A camouflage sheet according to the invention may easily be furnished with a normally imprinted camouflage pattern, and may be executed for infra-red camouflage and for radar camouflage. For radar camouflaging according to U.S. paten~ 3,733,606 tor Dl' 2151349 or GB 1,314,624) it must be observed that the requirements for radar camouflaging disclosed therein must be met by the hole-punched sheet, but not by the sheet pr1or to punching, and that the indicated coefficient of reflectivity of at least 10% should be at least 25-40%. According to the composition, design, hole size and hole distribution of the sheet, the hole edges and/or interspaces between the holes can entail certain high frequency effects and therefore a finished sheet ~ -(preferably a prototype) according to the present invention intended for radar camouflaging according to the above-mentioned patent should be tested by means of practical tests of its radar camouflaging effect, particularly with respect to background reflections in the camouflaging of vehicles, artillery, etc. -~
The invention can also be used for a camouflage sheet with drastic camouflaging in accordance with what was previously mentioned and/or camou- -flage patterns composed of square or rectangular pattern sections of relatively appreciable size and, possibly, of varying degrees of brightness, that is varying specific hole density for different sections. Favorable results :
have been attained using two hole diameters of 32 and 42 mm on one and the same sheet for winter camouflage. In certain other cases two sizes of 25 and .. . . , , ., . . ., , i. , . - , . ~ ~ , ~

l~S93~1L6 40 or 45 mm have proved to be appropriate. For camouflaging very large ~ :
objects larger hole sizes may be appropriate. In simpler cases, e g. `
camouflage sheets for individual persons, a single hole size has proved to be sufficient. ~r' '' The camouflage sheet is preferably made from plastic film, optional-ly fabric such as plastic-impregnated fabric, whereby the film or fabric can be glued or welded to a supporting net. If the sheet is furnished with a supporting net it is normally of no significance for ~he camouflage effect if the net threads extend over the holes or a portion of the holes, even i :
the net is a different color from the sheet surface. It is thus simple to attach the net since the holes can be disregarded. In the event one wishes to attain the greatest possible strength using the weakest possible net, i.e. `~
to increase the pliability of the sheet, it is, however, feasible to join the net to the film or fabric in such a way that the net threads everywhere extend between the holes and thus not across the holes. This can be accomplished by choosing a net, if it is assumed to be a common net having rectangular meshes~ ^
with a net size, i.e. a rectangular coordinate system imaginary grid array, ~
that it can be adapted to the triangular hole pattern, or vice-versa. ~"
Alternatively, the net can be made in accordance with the triangular imaginary grid array with triangular meshes whose side length is preferably a multiple of the side length of the hole imaginary grid array triangles, whereupon the net is fitted to the foil or fabric in a suitable way upon attachment. A net made in this way is per se more expensive than a normal net, but on the other hand it is per se stronger and, in addition, provides considerably increased ~- -support to the sheet and can therefore be made with relatively thin net threads and has low weight.
It is also possible to reinforce the hole-patterned foil or fabric `
of the sheet by attaching parallel threads thereto which extend in a single direction, approximately like the strings of a harp.
A camouflage sheet according to the invention can be made with different colors on its two sides in a particularly simple manner so that, for example, one side is white for winter camouflage and the other side is color-r p~, l ' 1~)59316 .
patterned or sand yellow or camouflaging in normal terrain and in sand regions, respectively.
Existing camouflage sheets with closed surfaces whose camouflage pattern is for some reason no longer usable, e.g. because of sharp discolor-ation or bleaching, can be made usable again by means of hole patterning forming a sheet according to the invention.
An important possible use for the invention is that a common - i camouflage sheet having per se known camouflage patterns, but particularly an essentially single-colored camouflage sheet for use in snow, fields, -10 pastures, desert or the like is furnished with hole patterning at one or more -edge portions, normally on all edges, so that hole-punched sheet regions of ' preferably irregular form are obtained; starting from the edges of the sheet, the hole density becomes more and more sparse towards the center. At least the majority of the holes nearest the edge or edges of the sheet may or should have greater diameter than the majority of the holes further rom the edge.
By furnishing a common camouflage with such hole regions around its edges, a contrast-leveling and mechanically smoother transition to the ~;;
surrounding terrain may be attained so that any contrast between the camou- i; `
flage color or pattern and the color or pattern of the surroundings is lessen-ed or blurred. In addition, said step provides convenient sight holes and allows that the edge portions of the sheet can more easily be fastened with j ~
ropes, straps, hooks or the like, since these can be threaded through the ~, ;
holes. It may therefore be an advantage if a number of holes near the edge of ~1 ;
the sheet are furnished with a known hole reinforcement of plastic or metal.
Within a given region from the edge of the sheet the size and distribution density of the holes may very well be so large that a considerable portion of the background behind the sheet, i.e. normally the terrain under the edge ;~ -portions of the sheet, is visible through the holes so that a somewhat uniform ~;
transition between the ground appearance and the sheet appearance is obtained.
In this ~ay any contrast, normally already negligible, is reduced.
At least in normal cases the distribution density and size of the `~

holes should vary, not only in the direction from the edge of the sheet towards _ g~
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the center, but also along the edge and edge portions of the sheet, e.g.
according to Figure 2, Thus, if a rectangular camouflage sheet is assumed to lie directly on the ground, its edges should not be accentuated by having -a row of equally large holes with equal distribution extending parallel to the edges. Uneven hole size and/or uneven dis~ribution (density) of the holes should therefore be sought, even in the circumferential direction of the sheet.
For this reason i.e. extra holes can be arranged which are not incorporated into the triangle imaginary grid array of the remaining hole patterning and which, in addition, can serve in the securing of the sheet.

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Claims (11)

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

1. A camouflage sheet having a predetermined size and an exposed sur-face for presenting an appearance similar to a predetermined environment, said sheet having means for defining a plurality of non-uniformly distributed groups of circular or substantially oval punched holes in said surface, said holes in each of said groups being arranged so that the centers thereof lie at selected vertices of adjacent substantially equilateral, triangles, said exposed surface being of at least one color selected to match a color char-acteristic of said environment, and said holes contributing to the camouflage effect.

2. A sheet according to claim 1 wherein a first plurality of said holes are circular and are of equal diameter and wherein a second plurality of said holes are of equal diameter, the diameter of said second plurality of holes being between about 25% and about 100% larger than the diameter of said first plurality of holes, and wherein the triangles defining the centers of said first plurality of holes are of a different size than the triangles defining said second plurality of holes, the groups of holes consisting of said first and second pluralities being located in separate regions of said sheet.

3. A sheet according to claim 2 wherein at least one side of the sheet is white for winter camouflage.

4. A sheet according to claim 3 which further comprises a supporting net for supporting said camouflage sheet with said holes, and wherein the threads of said net extend in uninterrupted fashion over the sheet, independ-ently of its holes, which holes may thus be traversed by the threads.

5. A sheet according to claim 3 wherein the holes of said sheet are placed such that they coincide with net meshes, whereby said holes are not traversed by net threads, the mesh size of the meshes in said net being at least twice as large as the side length of the -triangles defining the centers of said holes.

6. A sheet according to claim 4 wherein one layer of electrically conductive material for radar camouflage is incorporated in the sheet whereby the finished hole-patterned sheet provides radar reflection higher than 25%.

7. A sheet according to claim 6 wherein said plurality of holes ex-tends substantially over only the edge portions of the sheet and not over the entire sheet, said exposed surface of said sheet having a second color.

8. A sheet according to claim 7 wherein in said edge portions the ratio between the total area occupied by all of the holes and the total area remaining between the holes diminishes from the edge of the sheet towards the center of the sheet.

9. A sheet according to claim 8, wherein said ratio varies non-uniformly in a direction parallel to the edges of the sheet.

10. A sheet according to claim 9 wherein sheet regions within which said ratio is constant have irregular form, at least a portion of such re-gions having a form different from a portion of the other regions.

11. A sheet according to claim 10 wherein, in addition to said plural-ity of holes, said sheet further includes additional holes not defined by said triangles and which are situated near the sheet edges, characterized in that at least said means defining said plurality of holes includes means for reinforcing the edges of said hole for carrying attachment lines or hooks for securing the edge portions of the sheet.