- BACKGROUND OF THE INVENTION
This application claims the benefit of U.S. Provisional Patent Application No. 61/560,781, entitled Temperature Sensitive Bi-Layer Films and Composite Substrates, filed Nov. 16, 2011.
1. Field of the Invention
In general, the present invention relates to the structure of bi-layer films that change shape as a function of temperature. More particularly, the present invention relates the use of bi-plastic films in the manufacture of composite products that change shape as they experience changes in temperature.
2. Prior Art Description
Artificial flowers are an enduring tradition, going back perhaps thousands of years. The earliest artificial flowers were simple wrapped bundles of wood, feathers and other natural materials. Over the centuries, much more elaborate flowers have been made from exotic materials, such as jade, ivory, silver, and gold. In modern times, artificial flowers are typically made from silk, molded plastic and decorative fabrics. Using such modern materials, artificial flowers can be made so realistic that they must be touched in order to determine if they are real.
In the prior art, no matter how realistic or detailed an artificial flower is formed, the vast majority of artificial flowers are static. Due to the materials used to create artificial flowers, most artificial flowers do not grow, change shape, bloom, or respond to the sun in the way of actual living plants. In an attempt to make artificial plants more lifelike, some prior art attempts have been made to create artificial plants from materials that are not static. Such prior art is exemplified by U.S. Pat. No. 2,561,217 to Muir, entitled Simulated Flower With Thermo Static. The Muir patent discloses a rudimentary artificial flower in the shape of a crown. The petals are made from a laminate of metal and paper. When heated by a lamp or the sun, the paper expands faster than the metal, and the tips of the crown bend. However, the paper will also expand if exposed to humid air, reducing or eliminating the intended effect due to heating. Additionally, the metal film can easily crease, permanently damaging the petal and preventing future motion. Furthermore, the paper can “creep” (i.e. change in length due to stress), reducing its reliable range of operation. The range of motion is also quite limited.
Later inventions, such as is exemplified by U.S. Pat. No. 6,966,812 to Blonder, entitled Thermally Movable Plastic Devices And Toys, describes a more versatile construction that is responsive to changes in temperature. The Blonder patent describes a bi-layer laminate of two plastics with a specified difference in thermal expansion coefficient. This causes the material to change shape when heated. However, there are fundamental limits to the performance of a petal made from a bi-layer film.
In a bi-layer film, typically two plastic films are joined together that have different coefficients of expansion. As such, one material will expand with temperature more than the other. This causes the bi-layer film to curve as temperature changes. Plastic films are manufactured as sheets that are wound onto rolls. The stretching and heating during the extruding, drawing, rolling and curing steps of manufacture alters certain characteristics of a plastic film. Due to the manufacturing steps that are needed to create plastic films, plastic films typically have a coefficient of expansion along the length of the plastic roll that is significantly larger than the coefficient of expansion across the width of the roll. That is, the length of the film will expand significantly with temperature, but the width of the film will not. In the plastic film industry, the direction in which a film expands is referred to as the low-temperature expansion-coefficient direction, or “LEXD”.
In a bi-layer film, the temperature at which a bi-layer film is completely straight is called the “layflat” temperature. Above this temperature the bi-layer film curls away from the higher expansion coefficient side. Below this temperature the bi-layer film curls away from the lower expansion side. Accordingly, at temperatures below the layflat temperature, the bi-layer film will curl in the direction of the LEXD. For example, if a bi-layer film is at a temperature below the layflat temperature and the low expansion side of the bi-layer is on the outside of a roll, then the bi-layer film will curl more tightly on the roll.
It will be understood that at temperatures below the layflat temperature, the lowest energy solution is for the bi-layer film to curl along the direction of the slightly higher expansion coefficient axis, in a direction parallel to the LEXD. No curvature occurs in the direction perpendicular to the LEXD because of the stiffness provided to the bi-layer film by its primary direction of curvature. Conversely, at temperatures below the layflat temperature, the bi-layer film only curves in a direction perpendicular to the LEXD. This limits the movements of any artificial flower petal made solely from bi-layer films.
To make prior art bi-layer film appear more realistic, different artificial petals and leaves are cut from bi-layer films at different orientations, such as parallel to the LEXD, perpendicular to the LEXD and at various angles in between. However, combining petals cut at different angles relative to LEXD still produces many undesirable behaviors in an artificial flower. For example, if the flower is moved into the shade after the blossom opened in the sun, the petals start to close. But, since the bi-layer films are relatively stiff and do not close in precise sequence, the petals can interfere with each other and often “lock-up”, preventing the blossom from fully closing. This is especially true if the artificial flower becomes inadvertently deformed by a user's hand, or by being compressed while stored.
In nature, real petals exhibit complex motions as they open and close. The outer perimeter of the petal may curl backwards, while the inner section may curl inward. Simple bi-layer films cannot move in both directions at once. Furthermore, real petals contain ribs, veins and other significant non-planar features. If these features were embossed into a thick bi-layer film, the texture would stiffen the bi-layer film preventing it from bending properly when exposed to heat.
- SUMMARY OF THE INVENTION
A need therefore exists for a device and method of producing the petals and leaves for an artificial flower that better mimic the bloom and contraction characteristics of natural plants. This need is met by the present invention as described and claimed below.
The present invention is a composite structure that changes shape as temperatures change. The composite structure is highly useful in forming flower petals and leaves for artificial flowers. In this manner, the artificial flowers can be caused to bloom and spread as they are placed in light and receive warmth.
The composite structure used to make the artificial petals utilizes a flexible substrate. The flexible substrate is static and does not change shape by itself in response to changes in temperature. The flexible substrate is made from highly flexible material and can be provided with a color scheme that makes the flexible substrate mimic the coloration of a flower petal or leaf.
BRIEF DESCRIPTION OF THE DRAWINGS
A supports structure is affixed to the flexible substrate. The support structure is made from bi-layer films that change shape in response to changes in temperature. The support structure is formed into a complex shape that is smaller than the flexible substrate it support. As a result, when the support structure is affixed to the flexible substrate, the support structure causes the flexible substrate to buckle, bend and twist as the support structure changes shape with temperature. The support structure can be designed so as to cause the changes in the flexible substrate to mimic the natural blooming movements of a flower petal or leaf. The result is that artificial flowers can be created that are dynamic and bloom when warmed by light.
For a better understanding of the present invention, reference is made to the following description of exemplary embodiments thereof, considered in conjunction with the accompanying drawings, in which:
FIG. 1 is a perspective view of an exemplary embodiment of an artificial petal made in accordance with the present invention;
FIG. 2 is an exploded view of the exemplary embodiment shown in FIG. 1;
FIG. 3 shows the embodiment of FIG. 1 changed in shape by a change in temperature;
FIG. 4 shows a methodology used to form part of the artificial petal shown in FIG. 1 and
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 5 shows an alternate embodiment of an artificial petal.
Although the present invention can be used to make a variety of novelty products that change shape in correlation to changes in temperature, the present invention is particularly useful in the formation of artificial petals for artificial flowers. Two embodiments of artificial petals are illustrated and described. These embodiments are selected in order to set forth some of the best modes contemplated for the invention. The illustrated embodiments, however, are merely exemplary and should not be considered a limitation when interpreting the scope of the appended claims.
Referring to FIG. 1 in conjunction with FIG. 2, an artificial petal 10 is shown for use in the construction of an artificial flower. The artificial petal 10 utilizes a flexible substrate 12 that has the shape of a petal from the type of plant being simulated. The flexible substrate 12 is preferably fabric, such as silk, or a thin plastic netting. The flexible substrate preferably provides very little resistance to being flexed, bend and/or folded. Furthermore, it is preferred that the flexible substrate 12 be fairly translucent so that some light or radiant heat energy can pass through the artificial petal 10 and reach other artificial petals deeper within the artificial flower being formed.
The flexible substrate 12 is preferably ornamented with a color scheme that matches the natural color scheme of the petals of the flower being simulated. As such, it would be understood that the flexible substrate 12 would be primarily red if it were being used to create an artificial red rose. However, the flexible substrate 12 can have many other color schemes. For instance, it a novelty artificial flower were being created, the flexible substrate 12 can be printed with the same color scheme as money, the colors of a school, or the colors of a professional sports team.
The flexible substrate 12 is thin and pliable. The flexible substrate 12 is static and does not change appreciably in shape or size as changes in temperature occur. However, the flexible substrate 12 does have to be substantial enough that the flexible substrate 12 does not sag or flop over due to the everyday forces of gravity.
A bi-layer support structure 14 is attached to the flexible substrate 12. The bi-layer supports structure 14 is an assembly that includes a first film layer 16 bonded to a second film layer 18. The first film layer 16 and the second film layer 18 have different coefficients of thermal expansion. In this manner, the bi-layer support structure 14 is only planar at the layflat temperature of the bi-layer support structure 14. The bi-layer support structure 14 is preferably formed as a vein structure that includes a central vein 20 and branching veins 22. The branching veins 22 can be made at different lengths and at different widths so that each presents a unique shape change profile as temperatures change. The LEXD of the bi-layer support structure 14 may be uniform across the bi-layer support structure 14. However, as will later be explained, the LEXD within each of the branching veins 22 and the central vein 20 can be selectively altered.
The bi-layer support structure 14 is also preferably colored with the color scheme of the flower petal being simulated. As such, when the bi-layer support structure is attached to the flexible substrate 12, the overall artificial petal 10 has the appearance of a real flower petal.
Referring to FIG. 3, it can be seen that as temperature changes, the shape of the bi-layer support structure 14 also changes. More specifically, the central vein 20 and the branching veins 22 all bend and twist in unique patterns. The change in shape of the bi-layer support structure 14 causes the flexible substrate 12 to bend, buckle, and fold. To the extent there are multiple branching veins 22 attached to the flexible substrate 12, different sections of the flexible substrate 12 can move in different directions at the same time. This creates a myriad of complex contours within the flexible substrate 12 that present a petal appearance that is much closer to that found in nature.
When multiple artificial petals 10 are attached together to form an artificial flower, the flexible substrates 12 of the various artificial petals 10 will touch and slide against one another as temperatures change. Since the flexible substrates 12 are highly pliable, this contact does not create forces sufficient to hinder the movement of the smaller bi-layer support structures 14. The areas occupied by the bi-layer support structures 14 are less than half the areas occupied by the flexible substrates 12. Artificial flowers can therefore be created with dense petals 10. However, the bi-layer support structures 14 never come close enough together to touch. The result is an artificial flower that can efficiently open and close without the individual petals 10 ever binding together. This ability to avoid binding persists even when the artificial flower is slightly deformed or damaged from being stored. The result is an artificial flower that reliably opens and closes with changes in temperature regardless to how the artificial flower is positioned and regardless to whether or not the artificial flower is initially deformed. The artificial flower is therefore highly robust as compared to prior art flowers that are nearly always adversely affected by deformation damage.
Referring now to FIG. 4, a method of altering the LEXD in the branching veins 22 and central vein 20 of the bi-layer support structure 14 is described. The bi-layer support structure 14 is stamped or otherwise cut from a larger sheet of bi-layer material. As such, the initial direction of the LEXD is uniform. In the shown embodiment, the LEXD is shown to be parallel to the length of the central vein 20.
The branching veins 22 do not travel in the same direction as the central vein 20. As such, the LEXD does not travel in the same direction along the lengths of the various branching veins 22, but rather in a direct initially set on the larger sheet of plastic. To alter the directions of the LEXD, the bi-layer support structure 14 is placed under a die head 24 in a press 26. The press 26 compresses the bi-layer support structure 14 against the die head 24. The die head 24 may be heated. The stresses in the bi-layer support structure 14 caused by the die head 24 causes the direction of the LEDX to selectively change into new directions. As a result, the bi-layer support structure 14 can be provided with multiple LEDX directions depending upon the area of the bi-layer support structure 14 being examined. By way of example, in FIG. 4, the bi-layer support structure 14 is altered by the press 26 so that each of the branch veins 22 and the central vein 20 have an LEDX that is aligned with its direction of travel.
Referring to FIG. 5, an alternate embodiment of an artificial petal 30 is shown. In this embodiment, separate and distinct bi-layer supports 32, 34, 36 are attached to a flexible substrate 40. Some of the bi-layer support structures 32, 34 can be attached to one side of a flexible substrate 40 while other bi-level support structures are attached to the opposite side. Since the bi-layer support structures 32, 34, 36 are separate and distinct, each can be formed from a different bi-layer material. Likewise each can be configured with a different size and shape. The result is an artificial petal 30 that can be caused to change into many different shapes across a wide range of temperatures. Furthermore, the flexible substrate 40 can be caused to bend in both forward and backwards directions simultaneously. Such shapes are required to mimic many natural flower blooms.
It will be understood that the embodiments of the present invention that are illustrated and described are merely exemplary and that a person skilled in the art can make many variations to those) embodiments. For instance, the shape of the flexible substrate, the coloration of the overall petal, and the shape of the support structure can be varied to mimic the shape, color and bloom characteristics of any flower petal or plant leaf. Furthermore, in the shown embodiments, the bi-layer supports structures are shown being attached to the exterior of a single flexible substrate. It will be understood that the bi-layer support structures can be placed inside of an artificial petal made from two flexible substrates. In this manner, the bi-layer support structures will be hidden from view. All such embodiments are intended to be included within the scope of the present invention as defined by the claims.