Abstract:
An instrument for cutting hair comprises first and second members extending longitudinally in a direction generally parallel to a hinge axis  19  of a hinge that connects the two members. Each member has an arm and a leg. The legs have sockets in which tools are received. The arms comprise grip portions for grasping and actuating by a user&#39;s hand. During use, the actuation of the arms moves the legs in an arcuate path of a common circle about the hinge axis  19.  The legs and the tools disposed in the sockets of the legs have straight features that remain parallel to each other and to the axis  19  of the hinge during movement along the arcuate path. The instrument has a closed pinching or clamping position in which the tools meet each other in abutting relation. The method of using the instrument includes selecting tools from the group comprising razor blades, thinning blades and back guards, disposing selected tools in the sockets of respective legs, separating the legs, placing a lock of hair between the legs, clamping the tools on the lock of hair, and pulling or pushing the tool in a direction along the length of the hair to progressively cut hairs of the lock of hair.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to haircutting instruments and methods of using the same primarily in barbershops and beauty salons.  
           [0003]    2. Description of the Related Art  
           [0004]    It is well known to use a straight blade in cutting and thinning hair. In the past this has been accomplished by placing an instrument with a blade on one side of a lock of hair and the user&#39;s finger on the opposite side of the lock of hair. The user thus pinches or clamps the lock of hair between the blade and his or her finger. This is a tedious operation and requires great skill to prevent cutting one&#39;s finger with the blade. The user must take care to avoid being cut while maintaining the proper amount of pressure and the proper angle of the blade with respect to the individual hairs in the lock of hair.  
           [0005]    This procedure of pinching or clamping a lock of hair between the finger and a blade has the advantage of slicing the individual hairs at an acute angle which provides a softer feel at the hair ends and also inhibits the problem of the hair breaking. Another benefit of cutting the hair ends in this way is that it causes each individual hairs to lie more nicely within the lock of hair.  
           [0006]    It can be seen that there is a need in the art for a device and a method that assures the safety of the user and provides a consistency in the angle of cut. There is a further need to provide an instrument and a method for cutting hair with a straight blade that is easy to use. Still further, there is a need to provide the above stated needs with an instrument that has easily replaceable tools including blades.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    The instant invention overcomes these deficiencies with an instrument that is easy to use, safe, and provides consistency in the angle of the cut.  
           [0008]    The instrument is comprised of two pieces or members that are coupled by a hinge having an axis. Each piece has an arm and a leg that are substantially parallel to each other and the axis of the hinge. The arm has grip portions and the leg has sockets for receiving tools. This allows the user to actuate the legs by manipulating the grip portions of the arms.  
           [0009]    In use, the leg portions are separated by manipulating the grip portions. A lock of hair is placed between the tools that are positioned in sockets of the legs. The legs are then clamped onto the lock of hair by a gripping action and the instrument is pulled or pushed in a direction along the length of the lock of hair. This pulling or pushing action cuts individual hairs of the lock in the progressive manner as the instrument is moved away from the person&#39;s head.  
           [0010]    The legs have jaws that are substantially parallel to each other. The jaws in a fully clamped position are spaced apart to enable a lock of hair to slide between them. The jaws of the legs have sockets which receive tools. The tools comprise at least one cutting blade which can be a razor blade, a knife or a thinning tool. Tools also may include one back guard. Thus, the hair is clamped between two blades or a blade and a back guard so that when the instrument is pulled or pushed in a direction away from the person&#39;s head, the hairs of a lock of hair clamped between the jaws are pinched by the tools and progressively cut as the instrument is moved away from the person&#39;s head. The edges of the tools that engage the lock of hair are parallel to each other so that the lock of hair receives even pressure along the length of the tools.  
           [0011]    In one aspect of the invention, the arms and legs of each member of the instrument are spaced radially with respect to the axis of the hinge. In another aspect the arms and legs are generally parallel to the axis of the hinge. Expressed another way, each arm and each leg extends along a line parallel to the hinge axis. With this construction, the arms and legs remain generally parallel to each other and to the hinge axis during the hinging action.  
           [0012]    The tools may be two razor blades which meet in a parallel fashion at their distal edges. Alternatively, the tools may be two thinning blades which have teeth. These teeth meet each other similarly to the two blades. However, with the thinning blades there are spaces between the teeth through which individual hairs may pass as the instrument is pulled or pushed away from the person&#39;s head. Thus, only some of the hairs are cut. Another alternative is to have one razor blade in the socket of one of the legs, and a back guard in the socket of the other leg. In this way the back guard and the razor blade meet in a pinching manner on the lock of hair. In practice, any combination of tools may be used in the instrument as long as one of the tools comprises a blade.  
           [0013]    In another aspect of the invention, the instrument may be constructed such that the arms of the instrument are spaced at any preferred distance of comfort to the user. This spacing may be provided by the structure of the arms adjacent to the hinge wherein the arms abut each other and thereby space the finger loops from each other at a comfortable distance. Alternatively, stops may be provided at any location on the arms to mutually abut each other and provide the desired spacing.  
           [0014]    As with a regular pair of scissors, the grip portion of the present invention may be provided by finger loops that lie generally in a common plane. However, it is contemplated that the grip portions may be angled to that regular plane by plus or minus 70 degrees about the hinge axis. The selection of these angles can be especially important because of the different manner in which this instrument is used as compared with regular scissors. That is, the forces required when pulling or pushing the instrument along the lock of hair are different from the forces required when using a regular pair of scissors. The forces required with the instant invention, in turn, affect the gripping requirements. Because of the gripping requirements of the instant invention, having finger loop angles different from those of regular scissor finger loops is desirable in at least some cases.  
           [0015]    In use, a lock of hair may be placed between the tools in the instrument legs and the legs may be clamped onto the lock of a hair with light pressure. Depending on the angle of the tools, little or no pressure may be required to continue the cutting action along the length of the lock of hair, cutting the hair is effected by pushing or pulling the instrument away from the person&#39;s head. The user may selectively apply more pressure to cut the individual hairs more rapidly or completely sever a lock of hair. Also a user may grasp the lock of hair between the instrument and the person&#39;s head to minimize pulling on the hair at the scalp during the use of the instrument.  
           [0016]    These and other features and advantages of the invention will become apparent with the following description of the preferred embodiments and reference to the associate drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a perspective view of the instrument being used to cut hair;  
         [0018]    [0018]FIG. 2 is a perspective view of the instrument;  
         [0019]    [0019]FIG. 3 is a top plan view of the instrument;  
         [0020]    [0020]FIG. 4 is a side elevation view of the instrument;  
         [0021]    [0021]FIG. 5 is a cross section view taken along lines V-V of FIG. 2;  
         [0022]    [0022]FIG. 5A is a detailed top view of a cut away portion of tools similar to FIG. 3 showing alternative tools edges;  
         [0023]    [0023]FIG. 5B is a cross section view similar to FIG. 5 showing the range of angles at which the sockets can be disposed;  
         [0024]    [0024]FIG. 6 is a detailed end view of section VI of FIG. 5 showing how the tools meet at distal edges;  
         [0025]    [0025]FIG. 6A is a detailed end view similar to FIG. 6, but showing the razor blade and a back guard tool combination meeting at their distal edges;  
         [0026]    [0026]FIG. 7 is a cross section view taken along lines VII-VII of FIG. 2;  
         [0027]    [0027]FIG. 7A is a detailed top view of portion Vila shown in FIG. 3;  
         [0028]    [0028]FIG. 7B is a top view similar to FIG. 7A showing alternative embodiments of the finger loops of FIG. 7A;  
         [0029]    [0029]FIGS. 8A and 8B are end views showing alternative embodiments including tension and compression springs, respectively;  
         [0030]    [0030]FIG. 8C is an end view showing selectively alternative embodiments locating finger loops at varying distances from the hinge axis;  
         [0031]    [0031]FIG. 9 is a cross section view similar to FIG. 5 depicting the actual cutting during use of the instrument;  
         [0032]    [0032]FIG. 9A is a side elevation view of the cutting process similar to that shown in FIG. 9;  
         [0033]    [0033]FIGS. 10 and 11 are side elevation views showing alternative embodiments of the instrument of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0034]    A haircutting instrument  10  of the instant invention is used in cutting the hair  11  of a person  12  as shown in the example of FIG. 1. The haircutting instrument  10  has first and second members  14 , 16  pivotally connected together by a hinge  18  having an axis  19 . The members  14 , 16  have arms  20 ,  21  and legs  22 ,  23 . The arms  20 ,  21  are separated from the legs  22 ,  23  of the members  14 , 16  by a hinge portion, respectively.  
         [0035]    As shown in FIG. 2, the hinge  18  pivotally couples the first and second members  14 , 16  together in a non-crossing configuration. Each of the two members  14 , 16  remains on its own side of the hinge axis  19  during operation of the hinge  18 . The arms  20 ,  21  have respective grip portions  24 ,  25  and the legs  22 ,  23  have respective sockets for receiving a razor blade  29  or other tool  28 .  
         [0036]    [0036]FIG. 2 shows an important aspect of the invention. This aspect is related to the orientation and position of the hinge  18 . The hinge  18  has its axis  19  generally aligned with a length of the instrument  10 . The important aspect shown in FIG. 2 is that the grip portions  24 ,  25  of the members  14 ,  16 , respectively are offset from the hinge axis  19 . The legs  22 ,  23  are also offset from the hinge access. The difference between the offsets of the grip portions  24 ,  25  and the legs  22 ,  23  determines the amount of mechanical advantage that is afforded to the user when using the instrument  10 .  
         [0037]    Another important aspect of the present invention is that the two members  14 , 16  each extend lengthwise in a longitudinal direction. Each of legs  22 ,  23  and arms  20 ,  21  have straight features which extend lengthwise in the longitudinal direction. These straight features are generally parallel to each other and to the hinge axis  19  so that they remain parallel to each other and parallel to the hinge axis  19  during the operation of the hinge  18 . As such, these straight features comprise pairs of straight features on respective members  14 , 16 . These pairs of straight features are disposed to sweep out respective circumferential arcs of common circles that are concentric with the hinge axis  19 .  
         [0038]    As best illustrated in FIGS.  1 - 2  and  7 , the arms  20 ,  21  have the straight features referred to above provided by portions of the arms that extend in the same direction as the hinge axis  19  between generally radially extending portions of the arms  20 ,  21  and the grip portions  24 ,  25 , respectively.  
         [0039]    The figures show the first leg extending along a first line and the second leg extending along a second line. These lines are clearly parallel to each other. The embodiment of FIGS. 1 and 2 has arms  20 ,  21  with generally straight features extending in the same directions as the first and second lines. In fact, the straight features of the first and second arms  20 ,  21  may extend along the first and second lines defined by the first and second legs  22 ,  23 . Alternatively, they may be offset from the first and second lines. In either case, the first and second lines are spaced from a third line defined by the hinge axis  19  of hinge  18 .  
         [0040]    It can be seen from FIG. 2 that the portions of the arms  20 ,  21  that extend radially away from the hinge axis  19  may serve as stops to define one end of the range of motion of the members  14 ,  16  with respect to each other. In this case, no additional structure is required. Alternatively, stops  30  may be provided in order to determine an end of a range of motion of the members  14 ,  16  relative to the each other in a closed, pinching or clamping configuration. It can be seen that in the pinching or clamping configuration that legs  22 ,  23  remain spaced apart such that a lock of hair  31  is permitted to slide between legs  22 ,  23 . On the other hand, tools  28  abut each other and will pinch and cut individual hairs  32  of the lock of hair  31  when the instrument  10  is clamped thereon and pulled in a direction along the length of the lock of hair  31 .  
         [0041]    [0041]FIG. 3 clearly shows that the tools  28  not only approach each other in pinching or clamping configuration, but that they also approach each other in a parallel relationship. The legs  22 ,  23  also have respective jaws  33 ,  34  that remain parallel to each other during operation of the hinge  18 . When the jaws  33 ,  34  approach each other toward a clamping configuration, the opposing tools  28  eventually meet each other in parallel abutting relationship. This permits the lock of hair  31  to be pinched or clamped between the tools  28  for cutting action.  
         [0042]    The embodiment of FIGS. 3 and 4 is substantially similar to the embodiment of FIGS. 1 and 2 with the exception of the arms. FIGS. 3 and 4 have substantially no axially extending portion on their alternative arms  35 ,  36  between the radially extending portions and the grip portions. However, portions of the grip portions of alternative arms  35 ,  36  extend along lines parallel to or aligned with the lines defined by the straight features of the legs  22 ,  23 . Furthermore, portions  24   a ,  25   a  of the grip portions  24 ,  25  extending along lines parallel to or aligned with lines defined by the straight features of the legs can be considered as providing straight features themselves. Certainly, it is within the spirit and scope of the invention to construct these portions such that they have straight features.  
         [0043]    [0043]FIG. 4 is a side view that further shows the offsets of the grip portions  24 ,  25  and the legs  22 ,  23  from the hinge axis  19 .  
         [0044]    [0044]FIG. 5 is a section view taken along lines V-V of FIG. 2 and showing the jaws  33 ,  34  and their respective sockets  26 ,  27 . The sockets  26 ,  27  may be of any configuration, but are illustrated in the form of grooves  37 . Preferably the grooves  37  have an enlarged or reentrant base portion for receiving an enlarged portion  38  of the tool  28 . The enlarged base portion of the grooves  37  and the enlarged portion  38  of the tool  28  may be of any shape or configuration as long as they mate when the tool  28  is in a respective groove  37 . It is of particular interest to provide the enlarged portion  38  of the tool  28  larger than the non-enlarged portion of the groove  37  into which the tool  28  is inserted. In this way the tool  28  is prevented from leaving the groove in a generally radial direction along the groove. The directions that the tools  28  may be inserted and removed from the sockets  26 ,  27  are axial directions.  
         [0045]    The tools  28  that can be received in sockets  26 ,  27  are selected from the group comprising razor blades  29 , knives, thinning tools  40 , and back guards  41 . FIG. 5A is a detailed top view of a cut away portion of tools similar to FIG. 3, showing thinning tool  40  with edges  42 . These thinning tool edges  42  can be notched or comb shaped as illustrated in FIG. 5A.  
         [0046]    [0046]FIG. 5B shows that the instrument  10  can be made to accommodate tools  28  which are oriented at an angle measured relative to a plane  43  bisecting the instrument  10 . By way of example, this angle may be included within a range of 0 to 45 degrees when the instrument  10  is in a closed, pinching or clamping configuration. Expressed in another way, the instrument  10  can be constructed so that the angle between the tools  28  can vary in a range of 0 to 90 degrees. It should also be noted from FIG. 5B that the socket  45  may be of a modified form in order to receive a back guard  41 , which will typically be formed of a rigid material such as plastic.  
         [0047]    [0047]FIG. 6 is a detailed end view of portion VI of FIG. 5 and shows how the tools  28  abut each other. As is shown, the distal edge  45  of each tool  28  meets a distal edge  45  of the other tool  28  in mutually abutting relationship.  
         [0048]    [0048]FIG. 6A shows a detailed end view similar to FIG. 6 having the combination of a blade and a back guard  41  in respective jaws  33 ,  34 . With this combination the tips of the tools  28  will typically meet at their edges  45 ,  46 . The distal edge  46  of the back guard  41  should extend at least to a distal edge  45  of the razor blade  29  or beyond. Conceptually, the two razor blade configuration of FIG. 6 is similar to the configuration of FIG. 6A wherein one of the razor blades  29  in FIG. 6 serves as a back guard  41 .  
         [0049]    [0049]FIG. 7 is a sectional view taken along lines VII-VII of FIG. 2. This view emphasizes the possibility of selectively forming the arms  20 ,  21  in other than a planar configuration. Specifically, the arms  20 ,  21  may include grip portions  24 ,  25  or finger loops having grip portions  24 ,  25  defining planes at plus or minus 70 degrees from the flat plane defined by finger loops of a regular pair of scissors. Expressed another way, each of the finger loops may define a plane that is between 20 and 160 degrees relative to a bisecting plane that symmetrically bisects the two members  14 ,  16  of the instrument  10  when in its closed, pinching or clamping configuration.  
         [0050]    [0050]FIG. 7A is a detailed view of the portion of FIG. 3 encircled by the line VIIa. FIG. 7A shows the selectively variable way in which the alternative arms  35 ,  36  may be configured. Specifically, the alternative arms  35 ,  36  may be formed to define any of a variety of angles therebetween in order to meet the needs of a variety of users. It is of particular interest to locate the grip portions  24 ,  25  at a distance that permits the user to apply a force with ease. Locating the grip portions  24 ,  25  at the right distance is important for hairdressers or barbers who spend long hours utilizing instruments that they must grip. FIGS. 3 and 7A also show a variation from the embodiment shown in FIG. 2 in that the additional stops  30  are located along the portions of the alternative arms  35 ,  36  that extend radially away from the hinge  18 .  
         [0051]    [0051]FIG. 7B shows an alternative embodiment of the grip portions  24 ,  25  in the form of finger loops  47 ,  48 . As shown by the dashed lines in FIG. 7B the grip portions may be formed by finger loops  47  which extends inwardly or by finger loops  48  which extend outwardly from the remaining part of the arms. The finger loops  47 ,  48  may be selectively spaced similarly to the embodiment of FIG. 7A.  
         [0052]    [0052]FIGS. 8A and 8B are end views of the instrument  10  showing alternate embodiments which include springs  49 ,  50 . FIG. 8A shows a tension spring  49  that will hold the two members  14 ,  16  of the instrument  10  together in a clamping configuration. In this embodiment the user is required to force the jaws open by moving his or her fingers outwardly to expand the jaws against the bias of tension spring  49 . FIG. 8B, on the other hand, has a compression spring  50  that applies an outward force to the members  14 , 16 . In this embodiment, a user is required to force the members  14 , 16  inwardly together by squeezing the grip portions  24 ,  25  against the bias of spring  50 .  
         [0053]    [0053]FIG. 8C is an end view showing alternative locations of the grip portions  24 ,  25  in dashed lines. By selecting the distance of the grip portions  24 ,  25  from the axis  19  of the hinge  18 , the mechanical advantage is determined. It can be seen that if the grip portions  24 ,  25  are further away from the hinge axis  19  than are the distal edges  45  of  10  the tools  28 , a relatively small force applied to the grip portions  24 ,  25  will result in a larger force at the distal edges  45  of the tools  28  for pinching and cutting the lock of hair  31 .  
         [0054]    [0054]FIG. 9 shows the effect of clamping the tools  28  on a lock of hair  31  and pulling the instrument  10  in the direction of the large arrows. As can be seen by the half-diamond shape  52  of the cut ends of the individual hairs  32  in FIG. 9, both tools  28  act in a cutting function. By constructing the instrument so that the angles of the tools  28  are proper and by properly selecting blades having an angle of the taper of the cutting edges  45 , cutting a lock of hair  31  actually causes a slight inward force on the tools  28  and in turn on the jaws  33 ,  34  of the instrument  10  such that little or no clamping force is required during the pulling or pushing force along the length of the lock of hair  31 . Expressed in another way, when the tools  28  comprise two razor blades  29  with edges  45  having tapers which extend inwardly and away from the instrument  10 , a plowing effect pushes the tools  28  and thus the jaws  33 ,  34  together when the instrument  10  is  25  moved along the lock of hair  31  in a cutting action. The half-diamond shape  52  of the cut ends will only occur when a given individual hair  32  is cut by both blades. Most hairs  32  of a lock  31  will normally be protected on one side by other hairs  32  of the lock  31  and will only be cut by one blade.  
         [0055]    [0055]FIG. 9A shows a cutting action with the instrument  10  having a razor blade  29  for one of its tools  28  and a back guard  41  for the other of its tools  28 . In this embodiment the individual hairs  32  are cut to have a single flat severed surface  56 . Because of the angle of the razor blade  29  this single flat surface  58  forms an acute angle with respect to a lengthwise direction of the lock of hair  31  and the individual hairs  32  of the lock  31 .  
         [0056]    [0056]FIG. 10 is an alternative embodiment showing a haircutting instrument  57  in which arms  58  have been relocated to a position between hinge  60  and legs  61 . In this embodiment a user would position the hinge  60  in the palm of the hand or extending away from the palm of the hand with the fingers located in grip portions of the arms  58 . As can be seen by the dashed lines, the sockets  26 ,  27  and the tools  28  may be oriented such that the distal cutting edges  45  of the tools  28  may point in the same direction as the hinge  60  or away from the hinge  60 .  
         [0057]    [0057]FIG. 11 is a further alternative embodiment showing a haircutting instrument  67  in which the arms  70  of the instrument  67  are located on an opposite end of the legs  74  from the hinge  76 . In this embodiment it is contemplated that two hands would be used to pull or push the instrument  67  along the length of the lock of hair  31 . As can be seen by the dashed lines, the arms  70  comprising grip portions  78  may be located at the same distance from the axis of the hinge  76  or alternatively may be placed at a location closer to the axis of the hinge  76 . In this embodiment, similar to the embodiment of FIG. 10, the sockets  26 ,  27  and tools  28  can be made to face toward the axis of the hinge  76  or away from the axis of the hinge  76 .  
         [0058]    The method of using the haircutting instrument  10  of the instant invention is accomplished by a user cutting the hair  11  of a person  12   18 . The method results in a tapered cut, or a thinned and tapered cut. In accordance with this method, the user separates the legs  22 ,  23  of the instrument  10  by moving the arms  20 ,  21  in a first direction. Then the user places a lock of hair  31  between the legs  22 ,  23 . The user then clamps the legs  22 ,  23  on the lock of hair  31  by moving the arms  20 ,  21  in second direction. Then the user simultaneously maintains a clamping force on the lock of hair  31  and forces the instrument  10  in a direction generally perpendicular to the cutting edge  45 . This action severs individual hairs  32  of the lock by a clamping and pulling action. This method requires the placement of the instrument  10  with the tools  28  oriented transverse to the lock of hair  31 . Preferably the orientation of the instrument  10  is between 45 degrees and 135 degrees relative to the lock of hair  31 . In the preferred embodiment a longitudinal axis  19  of the instrument  10  coincides with the longitudinal extension of the blade edges  45  on the tool  28 . However it is contemplated that an instrument may be formed within the spirit and scope of this invention, which has an axis  19  which is longitudinal in a direction other than transverse to the blade edges  45 .  
         [0059]    Another aspect of the preferred embodiment is that in the method of using the instrument  10  an inward force on the jaws  33 ,  34  is maintained by virtue of the angle of the tapers on the blades disposed in the sockets  26 ,  27  in a clamping or pinching configuration. This inward force is caused by the shape of the blade tapers and the force of the instrument  10  moving in a direction along the length of the lock of hair  31 , wherein a plowing effect is achieved which causes the inward force on the blades and thus on the jaws  23  of the instrument  10 .  
         [0060]    The method of using further comprises a preliminary step of selecting the tools  28  from a group of tools. The group of tools comprises a razor  29 , a knife, a thinning tool  40  and a back guard  41 . In the present invention the terms razor and knife are used interchangeably. However, it is understood that a knife generally has a thicker blade and often is not of the disposable type, which are more commonly termed razor blades. The preliminary step of selecting the tools  28  and fitting them in the sockets  26 ,  27  may comprise selectively choosing either two razor blades  29 , a razor blade  29  and a back guard  41 , two thinning blades, or a thinning blade and a back guard  41 . Any combination of the tools  28  may be selected as long as one of the tools  28  selected has a blade for cutting hair  11 .  
         [0061]    While the method of using the haircutting instrument has been described relative to the embodiment of FIGS.  1 - 2  and  7 , it should be well understood that the method of use will typically apply equally to all of the embodiments. Analogous parts are readily apparent from one embodiment to another in applying the method of use.  
         [0062]    There may be other embodiments and variations of embodiments that are not set forth here, and which are within the spirit and scope of the instant invention. Furthermore, the instant invention is not to be limited by the description and terms used herein, but is only to be limited in accordance with the claims.