Patent Publication Number: US-2019183223-A1

Title: Hair Straightening Device

Description:
FIELD OF THE INVENTION 
     Current products and devices that are designed to relax, straighten, or lengthen the curls of hair employ chemicals or electronic heating (e.g., a flat iron, heated hair brush, hot air brush, etc.). 
     Heating devices, whether they be professional grade or drug-store home-use grade, frequently cause forehead and hand burns—such as flat or tubular heat irons. Heat irons and other heating devices often heat up to 300 degrees for thinner finer hair and up to 350-400 degrees for treating thick curly hair. Hair burns at 450 degrees. 
     There are hundreds of relaxing or straitening serums and chemicals on the market to apply to hair. But a heat conducting tool is still needed to truly reduce the volume and severity of curly hair. And many of the chemicals in these products can cause a reaction—especially for users with allergies or sensitivities. Plus, there is always the danger of leaving electric styling tools in the power-on mode—causing a fire hazard. 
     And since mechanically straightening hair needs to be done on a daily basis to maintain the desired results—especially after showering or washing hair—traveling presents additional problems. In particular, electronic heating devices for straightening hair like flat irons—even those specifically designed for traveling—are bulky and take up valuable luggage space. These devices are also heavy, which makes the luggage more difficult for a user to carry and transport, and can lead to increased fees if the luggage is checked during a flight. In addition, electronic heating devices require an electrical converter when traveling internationally. 
     There are strictly mechanical devices designed to straighten hair, such as hook-and-loop (e.g., Velcro®) and foam rollers. But these often undesirably rip out hair. 
     Hot rollers require electricity, and don&#39;t come in a large enough circumference for the purpose of straightening hair. In addition, they create curls by design and so are difficult to use to straighten hair. 
     Hair can also professionally straightened, such as with a salon “blow out”. But these procedures also use heat, and so have all the risks listed above. And such professional straightening is expensive and lasts only a day. Even if hair is not washed, the straightening effect is frequently lost during the tossing and turning of sleep. 
     Moreover, using chemicals and/or heat to straighten hair damages the hair itself, drying it out, making it more brittle and frizzy, and reducing its luster and sheen. 
     SUMMARY OF THE INVENTION 
     As such, it is desirable to provide a new device that can relax, straighten, or lengthen the curls of hair without using heat or chemicals. It is also desirable for such a new device to be of a size, shape, and weight that it can be easily packed in luggage for travel without taking up much space or increasing the weight of the luggage significantly. 
     Upon cutting her hair short, the inventor realized that her hair was less curly and more straight when it was longer, and was more curly with more volume when it was shorter. The inventor realized that it was the increased weight of longer hair made it more difficult for the hair to spring back upwards into curls. This increased weight of longer hair resulted in less time being needed to straighten it. The inventor then realized that what was needed to relax, straighten, or lengthen the curls of hair without using heat or chemicals was a device that could attach to the end of hair to add weight without damaging the hair or deforming it shape (e.g., crimping or bending). 
     According to the present invention there is therefore provided a hair straightening device as described by way of example below and in the accompanying claims. 
     In one embodiment of the invention there is provided a hair straightening device including a first arm, a hinge connected to the first arm, and a second arm connected to the hinge. The first arm, the second arm, or both are rotatable around the hinge between an open position where the first arm and the second arm do not contact each other and a closed position where the first arm and the second arm contact each other. The second arm comprises protrusions extending away from an interior surface of the second arm that faces the first arm of when the hair straightening device is in the closed position. The first arm may include:
         holes that correspond to the protrusions of the second arm and in which at least a portion of the protrusions of the second arm are arranged when the hair straightening device is in the closed position;   a first deformable material that is contacted and deformed by the protrusions of the second arm when the hair straightening device is in the closed position;   a first non-deformable material that is contacted but not deformed by the protrusions of the second arm when the hair straightening device is in the closed position; or   a combination thereof.       

     In another embodiment, the first arm comprises both the holes and the first deformable material. 
     In yet another embodiment, the holes are formed in a non-deformable material that is different from and covers the first deformable material, and which is not deformed by the protrusions of the second arm when the hair straightening device is in the closed position. 
     In a further embodiment, the first arm comprises the holes, which are formed in a non-deformable material that is not deformed by the protrusions of the second arm when the hair straightening device is in the closed position. 
     In yet a further embodiment, the protrusions comprise a deformable material so that ends of the protrusions are deformed by an interior surface of the first arm that faces the protrusions when the hair straightening device is in the closed position. 
     In another embodiment, the interior surface of the first arm is formed from a non-deformable material that is not deformed by the protrusions of the second arm when the hair straightening device is in the closed position and the protrusions contact and are deformed by the interior second surface. 
     In yet another embodiment, each protrusion has a width that decreases as the protrusions extends from the interior surface of the second arm. 
     In a further embodiment, each protrusion is shaped as a cone or pyramid. 
     In yet a further embodiment, each protrusion has a width that is constant as the protrusions extends from the interior surface of the second arm. 
     In another embodiment, the device weighs from 5-60 grams. 
     In yet another embodiment, each of the first and second arms comprises a hair-side surface configured to contact hair when hair is arranged between the first and second arms and the device is in the closed position. Each hair-side surface has a length extending from the hinge to an end of the respective first or second arm that is in a range of from 1-6 inches, and a width perpendicular to the length that is in a range of a 1-6 inches. 
     In a further embodiment, the length of each hair-side surface is greater than or equal that the width of that hair-side surface. 
     In yet a further embodiment, the length of each hair-side surface is less than the width of that hair-side surface. 
     In another embodiment, at least one arm of the first and second arms comprises a port through which a mass of material can be added, removed, or both, to the inside of the one arm to adjust the weight of the device. 
     In yet another embodiment, the at least one arm further comprises a cover configured to open and close the port. 
     In a further embodiment, a spring that applies a spring force to bias the first and second arms towards each other to maintain the device in the closed position. 
     In yet a further embodiment, one arm of the first and second arms comprises a magnet generator that generates a magnetic field, and the other arm of the first and second arms comprises a magnetic attractor that is attracted to the magnetic generator by the magnetic field so as to bias the first and second arms towards each other to maintain the device in the closed position. 
     In another embodiment, the magnet generator is a permanent magnet. 
     In yet another embodiment, the magnet attractor is a permanent magnet. 
     In a further embodiment, the magnet attractor is a piece of metal. 
     In yet a further embodiment of the invention there is provided a hair straightening device that includes a first arm, a hinge connected to the first arm, and a second arm connected to the hinge. The first arm, the second arm, or both are rotatable around the hinge between an open position where the first arm and the second arm do not contact each other and a closed position where the first arm and the second arm contact each other. The first arm comprises a deformable first material that forms an interior deformable surface of the first arm that faces the second arm when the hair straightening device is in the closed position. The interior deformable surface of the first arm is deformed by the second arm when the hair straightening device is in the closed position. 
     In another embodiment, the second arm comprises a deformable second material that forms an interior deformable surface of the second arm that faces the interior deformable surface of the first arm when the hair straightening device is in the closed position. The interior deformable surface of the second arm is deformed by the first arm when the hair straightening device is in the closed position. The deformable second material is the same as or different from the deformable first material. 
     In yet another embodiment, the second arm comprises a non-deformable material that forms an interior non-deformable surface of the second arm that faces the interior deformable surface of the first arm when the hair straightening device is in the closed position. The interior non-deformable surface of the second arm is not deformed by the first arm when the hair straightening device is in the closed position and the deformable surface of the first arm contacts and presses against the non-deformable surface of the second arm. The non-deformable material is different from the deformable first material. 
     The device can be used by individuals of almost any age. It takes less than a minute each to apply, and can be left on the ends of the sections of hair until the hair is completely dry or can be removed earlier for a less straight surface. The device is portable and weighs far less than a blow dryer or flattening iron. The device can be used with or without a blow drying. Because the device provides a “head start” in relaxing the hair, a small low-powered hotel blow dryer will suffice and large home hair driers can be used at a lower setting, thereby reducing the chance of damaging the hair. The device can be used by professional stylists to aide and speed up the process of blowing hair dry. 
     It is noted that the features of the above-described embodiments are not exclusive to each other, and that any one of the above embodiments/features can be combined with one or more of the other embodiments/features to arrive at further embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  show an embodiment of the hair straightening device  1  in a closed state. 
         FIG. 3  shows an embodiment of the hair straightening device  1  in an open state. 
         FIG. 4  shows an embodiment of the hair straightening device  1  with a 180° opening. 
         FIG. 5  shows another embodiment of the hair straightening device  1 . 
         FIGS. 6 and 7  show yet another embodiment of the hair straightening device  1 . 
         FIG. 8  shows an embodiment of the hair straightening device  1  where the arms  2 , 3  have nonuniform varying widths. 
         FIGS. 9 and 10  show an embodiment of the hair straightening device  1  where the arms  2 , 3  have nonuniform varying thicknesses. 
         FIGS. 11 and 12  show yet again another embodiment of the hair straightening device  1 . 
         FIGS. 13-17  show another embodiment of the hair straightening device  1 . 
         FIGS. 18A-18D  show various shapes for the toothed surface. 
         FIGS. 19 and 20  show yet another embodiment of the hair straightening device  1 . 
         FIGS. 21A  shows the hair straightening device  1  with arms  2 , 3  in a straight state. 
         FIG. 21B  shows the hair straightening device  1  with arms  2 , 3  in a bent state. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, many other elements which are conventional in this art. Those of ordinary skill in the art will recognize that other elements are desirable for implementing the present invention. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein. 
     The present invention will now be described in detail on the basis of exemplary embodiments. It is noted that any numerical ranges disclosed herein are included to individually disclose every sub-range and number, both whole integer and partial fraction, within the disclosed range. For example, a disclosed range of 1-100 is intended to individually disclose 20-90, 40-80, 30.5-50.2, 20, 67.3, 84.512924, and every other range and number that falls within the recited range. 
       FIGS. 1-3  show an embodiment of the hair straightening device  1  that has a first arm  2  and a second arm  3 . The two arms  2 , 3  come together to clamp or clip onto the bottom portion of damp hair that has been combed straight. Each of the first and second arms  2 , 3  has a corresponding hair-side surface  4 , 5 . The damp hair is sandwiched between the two hair-side surfaces  4 , 5 , when the straightening device  1  is closed. The clip  1  is designed so as to have a weight sufficient to hold hair down and straight, and prevent the hair from springing or curling back up, regardless of the length of the hair or strength of the curl force of the hair. The device  1  is left attached to the hair until it becomes dry, at which point the first and second sides  2 , 3  are separated from each other and the clamp  1  is removed from the hair. In this manner, the hair is held straight until it dries, at which point it remains straight even when the device is removed. 
     The two arms  2 , 3  have ends  6 , 7  that come together securely by way of magnetic attraction, clamp, clip, or spring (e.g., compression spring, extension spring, torsion spring, constant force spring). The other ends  8 , 9  of the arms  2 , 3  can also be held together by way of magnetic attraction, clamp, clip, or spring. In this way, the ends  8 , 9  can be permanently connected to each other, or can be removably connected like the ends  6 , 7  so that so that the arms  2 , 3  are completely detachable from each other. 
     Alternatively or additionally, the ends  8 , 9  can be attached to each other via a hinge  10  so that the arm  2  rotates around the hinge  10 . The hinge  10  can be integral to and a part of the arm  3 , or can be a separate component that is attached to the arm  3 . The end  8  of the arm  2  can be permanently attached to the hinge  10  for ease of use, or can be designed to be separated from the hinge  10  for portability. 
     One or both of the hair-side surfaces  4 , 5  may be made from a non-slip material that provides friction against hair so that the device  1  does not slide off the hair after being clipped around the hair. Examples of such a material includes elastomers like silicone, natural rubber, synthetic rubber, latex, and the like, as well as foams like latex foam, polyurethane non-memory foam, polyurethane memory foam, soy memory foam, neoprene foam, foam rubber, silicone foam and the like. 
     In a preferred embodiment, one of the hair-side surfaces  4 , 5  is a tooth-lined or fiber-grabbing surface and the other hair-side surfaces is a smooth non-slip surface that has an impression potential (e.g., silicone). When the two surfaces  4 , 5  come together, they grab onto the ends and don&#39;t slip off the hair strands. The tooth-lined or fiber-grabbing surface, side one, submerges into or gently penetrates the soft and smooth non-slip surface, side two, to securely grab the hair. The size of the device  1  may vary depending on the texture, thickness, and amount of hair a particular clip  1  is designed to collect for the purpose of creating a taut smooth surface. 
     In the embodiment shown in  FIG. 3 , the ends  6 , 7  coming together by way of magnetic attraction via two magnetic pieces—a magnet generator  11  (e.g., a magnet) that is incorporated into or on one of the ends  6 , 7 , and a magnetic attractor  12  (e.g., a magnet, a piece of magnetic metal) that is attracted to the magnetic generator and which is incorporated into or on the other of the ends  6 , 7 . If a magnetic piece  11 , 12  is incorporated on a hair-side surface  4 , 5 , then it is preferably covered with a material that has a soft, pliable surface—like fabric, cloth, neoprene, wet-suit material, spongy material (e.g., a piece of natural or synthetic sponge), a foam material, a plastic, or any of the non-slip materials listed above for the hair-side surfaces  4 , 5 —so that the soft, pliable material is arranged between the magnetic piece  11 , 12  and the hair. For example, the magnetic piece  11 , the magnetic piece  12 , or both, may be covered by the non-slip materials listed of the respective hair-side surface  4 , 5  itself. Such a soft, pliable surface has more give than the hard magnetic pieces, and prevents harsh lines being left in the hair from the magnetic pieces. Weight distributed slightly unevenly keeps strands from kinking. 
     While  FIG. 3  show the magnetic pieces  11 , 12  arranged on the ends  6 , 7  of the arms  2 , 3 , the magnetic pieces  11 , 12  can be arranged anywhere along the arms  2 , 3 . The magnetic pieces  11 , 12  can also extend from the ends  6 , 7  to the ends  8 , 9 , or any length in-between. Furthermore, more than two magnetic pieces  11 , 12  can be used—such as multiple magnetic pairs  11 , 12  arranged along the arms  2 , 3 , one long magnetic generator  11  paired with multiple magnetic attractors  12 , multiple magnetic generators  11  paired with one long magnetic attractor  12 , or any combination thereof. 
     In the embodiment shown in  FIG. 3 , protrusions or teeth  13  line one of the surfaces  4 , 5 , and holes  14  line the other of the surfaces  4 , 5  into which the protrusions or teeth  13  submerge when the device  1  is closed. This increases the surface area of the device  1  in contact with the hair, thereby increasing the frictional force and making for a more secure grip on the hair. 
     The clip  1  may also adhere to the tips of the strands of hair by simple tension from a clamp or other tension coil system creating a tight grip (e.g., a torsion spring arranged near or around the hinge  10 ). The one or more hair-side surfaces  4 , 5  of the clip could be a spongey or giving surface  16  that would keep the hair from crimping but also create a non-slip gripping surface to ensure the weighted device does not fall down the length of the strands eventually falling off. 
     As shown in  FIG. 4 , the device may have a 180° opening allowing the arm  3  that is covered in rigid or flexible protrusions or teeth  13  to comb through, manipulate, and untangle hair by running the length of the strands before clamping the hair between the arms  2 , 3  to sandwich and hold onto the hair. 
     As shown in  FIG. 5 , the interior hair-side surface of the arm  2  can be formed by a resilient material or padding  16 , which can be comprise felt, velvet, cushioning (e.g., an elastomeric or foam material such as those listed above for the hair-side surfaces  4 , 5 ), thermoplastic polyurethane (TPU), or the like. The protrusions or teeth  13  on the arm  3  submerge into the padding  16  when the device  1  is closed. Because the padding  16  is a resilient material that deforms when the protrusions or teeth  13  are pushed into it, there is no need for holes  14  to be formed in the interior hair-side surface of the padding  16 . However, holes  14  for the protrusions or teeth  13  can be formed in the padding  16  to provide a more secure contact between the protrusions or teeth  13  and the padding  16 , and strengthen the grip of the clip  1  on hair. 
     The protrusions  13  can be formed from a rigid material—like hard plastic, resin, metal, wood, etc.—to enable the flexible teeth  13  to comb through, manipulate, and untangle hair. The protrusions  13  can also be formed from a deformable and resilient material—like one an elastomer or foam—to provide additional force against the hair and increase the surface area of the clip  1  that actually squeezes the hair. If the teeth  13  are formed from a deformable and resilient material, then there is no need for holes  14  to be formed in the interior hair-side surface  4  of the arm  2 . However, such holes  14  for the protrusions  13  can of course be formed in the hair-side surface  4 —be it deformable or rigid—to provide a more secure contact between the teeth  13  and the hair-side surface  4 , and strengthen the grip of the clip  1  on hair. 
     As shown in  FIGS. 6 and 7 , the device may be made up of two arms  2 , 3  that come together through a coiled tension clamp where the interior hair-side surface areas  4 , 5  of arms  2 , 3 , are made up of felt, velvet, or cushioning (e.g., a foam material)  16  that grasps to the strand ends. 
     While the above embodiments have frequently been described as using some soft, deformable padding material to form one or both of the hair-side surface  4 , 5 , one or both of these surfaces can instead be formed from a rigid, non-deformable material, like plastic, metal, resin, or wood. For example, in a variation of the embodiment shown in  FIGS. 6 and 7 , the felt, velvet, or cushioning (e.g., a foam material)  16  of one of the arms  2 , 3  can be replaced or overlaid with a rigid, non-deformable material. This creates a smooth, taut surface to protects hair from creases and dents. 
       FIGS. 1-7  show the two arms  2 , 3  as being of a uniform width and thickness. But the two arms  2 , 3  may be of different widths, different thicknesses, or both. For example, as shown in  FIG. 8 , the first arm  2  may include a first portion  2   a  having a width W 2a , and second portion  2   b  having a width W 2b  that is wider than the width W 2a . The second portion  2   b  is configured to contact the hair of a user when the hair straightening device  1  is in a closed state.  FIG. 8  shows a second portion  2   b  with a length L 2a  that is greater than the width W 2b . But the second portion  2   b  can also be designed with a with a length L 2a  that is equal to or less than the width W 2b . Similarly, the second arm  3  may include a first portion  3   a  having a width W 3a , and second portion  3   b  having a width W 3b  that is wider than the width W 3a . The first and second portions  2   a , 2   b  may be formed from two different pieces that are attached to each other, or may be formed from a single integral piece. Similarly, the first and second portions  3   a , 3   b  may be formed from two different pieces that are attached to each other, or may be formed from a single integral piece. 
     In addition, the two arms  2 , 3  may have the same thicknesses, or different thicknesses. For example, as shown in  FIGS. 9 and 10 , the first arm  2  has a thickness T 2  that is greater than a thickness T 3  of the second arm  3 . This configuration can of course be reversed so that the first arm  2  has a thickness T 2  that is less than a thickness T 3  of the second arm  3 . Furthermore, the thickness of the two arms  2 , 3  from the ends  6 , 7  to the respective ends  8 , 9  can be constant or varied. For example, as shown in  FIG. 10 , the thickness of each of the arms  2 , 3  can decrease from the ends  6 , 7  to the respective ends  8 , 9  so that the ends  8 , 9  can be squeezed together by a user against a spring arranged near, in, or around the hinge  10 . to separate the ends  6 , 7  from each other so that hair can be placed between the arms  2 , 3  before the user releases the ends  8 , 9  so that the spring can close the ends  6 , 7  together to grasp the hair. 
     As shown in  FIGS. 11 and 12  the device may be made up of two sides that clamp together by way of a first portion  18  that engages with and is held to a second portion  19 . This can be accomplished by hook-and-loop fasteners, snaps, buttons and button holes, interlocking knobs, and the like. In one embodiment, the first portion  18  is a magnetic attractor  12  (e.g., a magnet, a piece of magnetic metal) and the second portion  19  is a magnetic generator  11  (e.g., a magnet) to which the first portion  18  is attracted and held when the device  1  is closed. In this embodiment, the hinge  10  is formed from a flexible material—such as flexible plastic, rubber, an elastomeric material (e.g., TPU), fabric, cloth, felt, and the like—to allow the first arm  2  to bend or rotate around the hinge  10  and move between the open position shown in  FIG. 11  and the closed position shown in  FIG. 12 . 
     In the embodiment shown in  FIGS. 11 and 2 , the first arm  2 , second arm  3 , and hinge  10  are formed from a single material. The first and second arms  2 , 3  include a spongey or giving material  16 , such as that described above. Teeth  13  extend from the hair-side surface of the padding  16  of the second arm  3 , and push into the hair-side surface of the padding  16  of the first arm  2  when the device  1  is closed. Including protrusions  13  all alone the surface of the arm  3  (e.g., as shown in  11 - 17 ) rather than just in a row (e.g., as shown in  FIGS. 1-5 ) further increases the surface area of the device  1  in contact with the hair, making for a more secure grip on the hair. 
     The device  1  is heavy enough to lengthen hair or “pull” curls out without damaging the hair or injuring the user—preferably 5-60 grams. The device can be of a fixed weight or of an adjustable weight. For example, a port  15  can be incorporated into one of both of the ends  6 , 7  so that the corresponding arm  2 , 3  can be filled with a substance (e.g., water, sand, etc.) to add or remove weight. The weight creates a smooth surface in the hair without slack that does not permit the hair to recoil upwards. The hair-side surfaces  4 , 5  are preferably 1-6 inches long and a 1-3 inches wide; therefore creating a surface area of 1-18 square inches. 
       FIGS. 13-17  show an embodiment of the device  1  where the hinge  10  is formed has ends  10 A, 10 B and a shaft  10 C. At least one of the two arms  2 , 3  slides along the shaft so that the arms can move between an open state shown in  FIG. 16  and a closed state shown in  FIG. 17 . The shaft  10 C is formed of any of the flexible materials mentioned above. For example, the shaft  10 C may be formed of a resilient and elastic material so as to act like a flat spring. As another example, the shaft  10 C may be malleable and bendable without any resilience or elasticity (e.g., formed by a fabric material). This allows that shaft  10 C to bend as shown in  FIGS. 14 and 15 . Rows of protrusions  13  are formed along the hair-side surface  5  of the arm  3 . The arms  2 , 3  are held in the closed position by any of the mechanisms discussed above, including hook-and-loop fasteners, snaps, buttons and button holes, magnets, and the like. For example part of the one or both of the arms  2 , 3  may be formed by a magnetic material. Similarly, each of the arms  2 , 3  may be formed multiple layers, one of which is formed by a magnetic piece (i.e., a magnetic generator or a magnetic attractor as described above). This would allow for a magnetic field to be generated across the entire hair-side surface of at least one of the arms  2 , 3 —ensuring a more secure closure of the two arms  2 , 3  than if the magnetic field was localized to just a portion of one of the hair-side surfaces. 
     The protrusions  13  may be formed in a variety of shapes. For example, each tooth can be formed to have a width that decreases as the tooth extends from the interior surface of the second arm—such as in the shape of a cone or pyramid. Alternatively, each tooth can have a width that is constant as the tooth extends from the interior surface of the second arm—such as a column or pillar. The cross section of such a straight-sided column or pillar may be circular, triangular, rectangular, or the like. The protrusions  13  can have pointed, rounded, or flat ends. 
     Each tooth or protrusion  13  has a height H P  that extends perpendicular from a hair-side surface of the respective arm  2 , 3 , and has a length and a width that are both perpendicular to the height. While many of the embodiments of the protrusions  13  shown in the drawings have widths and lengths that are equal to each other, this does not need to be the case. For example, the protrusions  13  can each be formed to have a length L P  that is greater than a width W P . 
     Any shape can be used for such protrusions  13 , with some examples of such shapes shown in  FIGS. 18A-18D . For example,  FIG. 18A  protrusion may be formed to have wave-like cross section with a curved peak.  FIG. 18C  shows another example where the protrusions  13  have a trapezoidal cross section with a flat peak. And  FIG. 18D  shows the protrusions  13  having a triangular cross section with a pointed peak. 
     As mentioned above, the length L P  of each protrusion  13  may be equal to or greater than the corresponding width W P . Furthermore, the length direction of each protrusion  13  may be parallel to the length direction and perpendicular to the width direction of the corresponding arm  2 , 3 . In another embodiment, the length direction of each protrusion  13  is parallel to the width direction and perpendicular to the length direction of the corresponding arm  2 , 3 . In yet another embodiment, the length direction of each protrusion  13  intersects with both the length direction and the width direction of the corresponding arm  2 , 3 . 
     The length L P  of each protrusion  13  may be substantially equal to the length or width of the arm  2 , 3 , on which the protrusion is arranged. For example, the entire hair-side surface  4 , 5  of one or both of the arms  2 , 3  may contoured with protrusion  13  formed as ribs or ridges with peaks  21  and troughs  22 . If both hair-side surfaces  4 , 5  of the arms  2 , 3  are contoured with ribs/ridges, preferably the peaks  21  of the hair-side surface  4  fit in the troughs  22  of the hair-side surface  5  and the peaks  21  of the hair-side surface  5  fit in the troughs  22  of the hair-side surface  4  with the device  1  is in the closed state. 
     The hair-side surfaces of the troughs  22  may be smooth as shown in  FIGS. 18A, 18C, and 18D , or may include mini protrusions  23  as shown in  FIG. 18B . Preferably, the height of the mini protrusions  23  is less than the height H P  of the protrusions  13  so that the peaks of the mini protrusions  23  do not extend past the peaks  21  of the protrusions  13 . While the mini protrusions  23  have only been shown with regard to a wave-like cross section, such mini protrusions  23  can be included in any cross-sectional shape (e.g., the trapezoidal cross section of  FIG. 18C , the triangular cross section of  FIG. 18D , etc). 
       FIGS. 19 and 20  show an embodiment of the device  1  where the two sides/arms  2 , 3  clamp together by way of corresponding knobs  20  that interlock as shown in  FIG. 20  to hold the device  1  in the closed state. 
     The arms or sides  2 , 3  may be rigid so as to have a cross section in the length or width direction that is curved, straight, or a combination thereof. Alternatively, the arms or sides  2 , 3  may be malleable so that they can be bent by a user into the desired shape. This would allow the hair to be shaped as each user desires.  FIG. 21A  shows a hair straightening device  1  with bendable arms  2 , 3  in a straight state.  FIG. 21B  shows the hair straightening device  1  after the arms  2 , 3  have been bent by a user. The arms  2 , 3  will stay in that bent shape until it is changed by the user. Such arms can be bent and shaped before the device  1  is applied to the hair, or after it is applied. While  FIG. 21B  shows arms  2 , 3  with both bent portions and straight portions, the entire length of each arm  2 , 3  may of course be bent or curved. 
     It is noted that the embodiments described above are not exclusive to each other. 
     In particular, any feature from any embodiment may be used in another embodiment. Similarly, the any of the features of a given embodiment may be combined with any of the features in any of the other embodiments. 
     It is also noted that the terminology used above is for the purpose of reference only, and is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, “below”, “rightward”, “leftward”, “clockwise”, and “counterclockwise” refer to directions in the drawings to which reference is made. As another example, terms such as “inward” and “outward” may refer to directions toward and away from, respectively, the geometric center of the component described. As a further example, terms such as “front”, “rear”, “side”, “left side”, “right side”, “top”, “bottom”, “horizontal”, and “vertical” describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology will include the words specifically mentioned above, derivatives thereof, and words of similar import. 
     While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the inventions as defined in the following claims. 
     In addition, it is noted that citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.