Abstract:
Hair trimmers, for example hair trimmers particularly suited for trimming nose hair. One aspect includes at least one movable blade and at least one shell having an interior surfaces at least one hole extending through the shell, and an interior cutting edge. The movable blade is hingedly connected to a movable blade hinge comprising a longitudinal axis. The shell, movable blade hinge and movable blade are positioned such that the cutting edge of the blade travels close to or along a portion of the interior surface of the shell and precedes the hinge such that resistance to the movement of the blade edge, such as that provided by a hair contacting the blade edge, will tend to wedge the blade more tightly between the hinge and the shell thereby increasing the contact pressure between the movable blade and the stationary surface. The cutting edge can also be urged toward the interior surface by centrifugal force.

Description:
RELATED APPLICATION DATA  
       [0001]     This application claims the benefit of related U.S. Provisional Patent Application Ser. No. 60/661,645 filed on Mar. 14, 2005. 
     
    
       [0002]     The present invention is directed to a hair trimmer and is particularly suited for use as a nose hair trimmer.  
       BACKGROUND  
       [0003]     Various devices have been previously disclosed for trimming hair including, for example, nose hair trimmers. Previously disclosed nose hair trimmers include devices having one or more openings through which hairs can extend into an area where they are cut. Some previous devices include movable blades driven by rotary motors which act in cooperation with stationary surfaces defining cutting areas to cut hair extending into the cutting areas. Those skilled in the art will appreciate that as movable blades are used for cutting, their cutting edges will tend to become dull over time due to the contact between the cutting edge of the movable blade relative to a static cutter. Some prior art devices rely upon springs to provide constant contact pressure between a rotating cutter and a static cutter. The constant contact pressure between the two cutters, even at times when hair is not being cut, tends to decrease the useful life of the blades. Therefore, it would be desirable to minimize the contact and/or the contact pressure between a movable blade and a stationary surface which cooperates with the movable cutting edge during a cutting step, particularly when hair is not being cut.  
         [0004]     It would also be desirable to provide a hair cutter which minimizes the contact and/or the contact pressure between a movable blade and a stationary cutting surface, at least when the blade is not cutting hair.  
         [0005]     It would further be desirable to provide a hair cutter with increased blade life and which decreases the amount of noise generated when the blades are moving.  
         [0006]     It would be particularly useful to provide a hair cutter, for example, a nose hair trimmer, which minimizes the contact and/or the contact pressure between at least one movable blade and at least one other surface when the blade is moving but not cutting hair. It is also desirable to provide a hair cutter which increases the contact pressure between a movable blade and a stationary surface when the cutting edge of the blade encounters resistance, such as when the blade edge encounters hair.  
       SUMMARY OF THE INVENTION  
       [0007]     Various embodiments of the present invention comprise hair trimmers, for example hair trimmers particularly suited for trimming nose hair, comprising at least one movable blade and at least one shell having an interior surface, at least one hole extending through the shell, and an interior cutting edge. The movable blade is hingedly connected to a movable blade hinge comprising a longitudinal axis. The blade hinge is moved in a manner such that the longitudinal axis moves along a path, preferably a circular path, thereby urging a movable cutting edge of the movable blade into contact with the interior cutting edge of the shell.  
         [0008]     The shell, movable blade hinge and movable blade are positioned such that the cutting edge of the blade travels close to or along a portion of the interior surface of the shell and precedes the hinge such that resistance to the movement of the blade edge, such as that provided by a hair contacting the blade edge, will tend to wedge the blade more tightly between the hinge and the shell thereby increasing the contact pressure between the movable blade and the stationary surface.  
         [0009]     According to one preferred embodiment of the present invention, at least one blade has a cutting edge which contacts the cooperating cutting surface of the shell forwardly (in a rotational direction) of the center of gravity of the movable blade. This results in an increased cutting pressure applied between the rotating blade and the cooperating stationary shell caused by a wedging action of the rotating blade into the hair or whiskers being cut.  
         [0010]     Various embodiments of the present invention utilize one or more blades hingedly connected to a movable blade hinge. As used herein, the term “hinge” and its various forms are used to indicate that the position of the cutting edge of the movable blade is not fixed relative to the movable blade support. As described in further detail below, the movable blade support can be fairly described as a hinge support, including but not limited to a movable shaft on which the movable blade is freely rotatable. The hinge connection between one or more movable blades and the respective blade supports can be mechanical and/or can take the form of a living hinge which relies upon the flexibility and/or resiliency of material used to manufacture one or more of the elements of the device, such as the movable blade support or the movable blade. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is an exploded view of one preferred embodiment of the present invention in the form of a nose hair trimmer.  
         [0012]      FIG. 2  is an assembled view of the nose hair trimmer illustrated in  FIG. 1 .  
         [0013]      FIG. 3  is a top plan view of the hair cutter shown in  FIG. 1 .  
         [0014]      FIG. 4  illustrates another embodiment of the present invention in the form of a multi-cutter comprising three movable blades in a single shell.  
         [0015]      FIGS. 5-8  illustrate another embodiment of the present invention in the form of a multi-blade shaver.  
         [0016]      FIG. 9  illustrates a further embodiment of the present invention wherein the cutting edge of a movable blade is not parallel to the longitudinal axis of the blade support.  
         [0017]      FIG. 10  illustrates an alternative embodiment of the present invention comprising a segmented stationary cutter assembly.  
         [0018]      FIG. 11  illustrates a still further embodiment of the present invention comprising a resilient blade support. 
     
    
     DETAILED DESCRIPTION  
       [0019]     Various embodiments of the present invention are directed to hair cutters comprising at least one movable blade connected to a movable blade support. The devices of the present invention also comprise a stationary blade which can be in the form of a shell within which the movable blade is moved. For purposes of cutting hair it is important that there is relative movement between the cutting edge of the movable blade and the stationary blade. While in the preferred embodiments described herein, the “stationary” surface is actually stationary relative to the hand of the person shaving or a housing on the motor, according to other embodiments the surface and/or cutting edges which cooperate with the movable blade can be movable either in a direction opposite to movement of the movable blade or in the same direction but at a slower rate. Therefore, as used herein, the term “stationary blade” is used to indicate a surface comprising at least one edge which is relatively movable to, and acts in cooperation with, the edge of the movable blade to cut hair.  
         [0020]     In each of the embodiments of the present invention described below, at least one movable blade is moved relative to a cooperating cutting surface or edge while centrifugal force is applied to the movable blade in the direction of the cooperating surface or edge. The cutting edge of the movable blade is positioned such that when resistance to its movement is encountered, for example by a hair, a wedging action will result tending to cause contact or, more preferably, to increase the contact pressure between the movable blade and the cooperating stationary blade.  
         [0021]     One preferred embodiment of the present invention is in the form of a nose hair trimmer and is illustrated in  FIGS. 1-3 . This illustrated nose hair trimmer comprises an electric motor  10  having a rotatable motor shaft  12 , a motor coupling  15 , a rotor coupling  20 , a bearing  25 , a rotor  30  which is fixed to a rotor coupling  20  with rotor fixing pin  22 . Rotor  30  which is rotated through the cooperation of the various parts and driven by motor  10 , comprises an eccentrically mounted blade support connector  32 . In this illustrated embodiment, blade support connector  32  is advantageously in the form of an eccentrically mounted bore dimensioned to securely receive a movable blade support  40  in the form of a shaft. A rotating blade  50  is movably supported on movable blade support  40  within a stationary blade  70 . Though not shown, the devices of the present invention can have suitable controls such as on/off switches and additional switches, knobs, or the like to control the rotational speed of the motor. Those skilled in the art will appreciate that as the motor speed is increased, the centrifugal force of the cutting edge on the interior surface of the shell will increase.  
         [0022]      FIG. 2  is an assembled view showing motor  10 , rotating motor shaft  12 , motor coupling  15 , rotor coupling  20 , rotor fixing pin  22 , blade support  40 , rotating blade  50 , static blade  70 , and a hair bristle H.  
         [0023]     In this illustrated embodiments, rotating blade  50  is freely rotatable on movable blade support  40 . From the present description, those skilled in the art will appreciate that advantages of the present invention can be obtained without requiring the rotating blade to rotate freely around the movable blade support  40 . It is only required that the blade edge move through a very small angle so that the contact pressure and/or position of the blade edge relative to the interior surface of the shell can change. For example, the angle of the cutting edge to the interior surface can hinge within about a few degrees or greater. From the present description and drawings, those skilled in the art will appreciate that the eccentric position of movable blade support  40  in rotating rotor  30  will move the longitudinal axis of movable blade support  40 , which has a longitudinal axis substantially parallel to the longitudinal axis of motor shaft  12 , through a generally circular path. This circular movement of movable blade support  40  will cause centrifugal force to act upon rotating blade  50 , e.g. in a direction perpendicular to a tangent to the path of movable blade support  40 , thereby causing rotating blade  50  to move outwardly and toward stationary blade  70 .  
         [0024]     The actual cutting operation of this embodiment of the present invention is best illustrated in  FIG. 3 . With reference to  FIG. 3 , when motor  10  is actuated movable blade support  40  is moved so that its longitudinal axis passing through the center of the movable blade support  40  moves in a circular path indicated by dotted lines P in a clockwise direction. This causes centrifugal force to act upon rotating blade  50  as indicated by arrow F.  FIG. 3  is merely for purposes of illustration and is not meant to indicate the exact position of forces acting upon rotating blade  50 . The centrifugal force F will tend to keep the rotating blade  50  of this illustrated embodiment in contact with the interior surface of stationary blade  70 . In the manner illustrated, cutting edge  52  of rotating blade  50  moves along the interior surface  71  of blade  70  and cooperates with cutting edges  72  of stationary blade  70  in order to cut hair. When a hair H is contacted by cutting edge  52 , as shown in  FIG. 2 , the resistance to the movement of the cutting edge  52  will tend to wedge the entire rotating blade  50  more tightly between movable blade support  40  and stationary blade  70  thereby increasing the contact pressure between rotating blade  50  and stationary blade  70 . Greater contact pressure reduces the likelihood that the cutting edge  52  will slide over a hair and not cut the hair as desired.  
         [0025]     From  FIG. 3 , it will also be appreciated that cutting edge  52  precedes or is generally positioned ahead of the center of gravity of rotating blade  50  relative to the rotation of the blade around the interior of stationary blade  70 . The cutting edge  52  also contacts the stationary blade  70  forwardly of the point of shortest distance between the center of rotating blade shaft  40  and stationary blade  70 . This forward or preceding positioning of cutting edge  52 , results in greater contact pressure between rotating blade  50  and stationary blade  70  when cutting edge  52  encounters resistance, e.g. from hair.  
         [0026]      FIG. 4  illustrates an alternative embodiment of the present invention comprising three rotating blades  150  movably disposed within a stationary blade shell  170  having cutting edges  171 . This embodiment is similar to the embodiment shown in  FIGS. 1-3  with the exception that it comprises three movable blades  150  connected to three rotating blade supports  140  for movement within stationary blade shell  170 .  
         [0027]     An alternative embodiment comprising a plurality of movable blades  250  in a form suitable for a shaver is illustrated in  FIGS. 5-8 . In this illustrated embodiment, rotating blade support  240  comprises three integrated hinges  242  for hingedly supporting movable blades  250 . As best shown in  FIG. 6 , in this illustrated embodiment each hinge  242  supports a plurality of movable blades  250 . While six blades are illustrated, a greater or lesser number of blades can be used. Unlike the arrangement of rotating blade  50  and movable blade support  40  shown in  FIG. 1 , from the present drawings it will be appreciated that blades  250  are not free to rotate entirely around each blade support hinge  242 . Nonetheless, blades  250  can rotate sufficiently on hinge supports  242  as rotating blade support  240  is moved when longitudinal axis L′ is moved in a circular path within shell  270 . Hinging blades  250  are advantageously positioned on hinge supports  242  in a generally balanced manner to minimize vibration of the entire device as blades  250  are moving within stationary shell  270 .  FIG. 10  illustrates a partially exploded view of a further embodiment, similar to the embodiment shown in  FIGS. 5-8 , but wherein the shell comprises multiple shell segments  470 .  
         [0028]      FIG. 9  illustrates a still further embodiment of the present invention wherein the cutting edge  352  of rotating blade  350  is disposed at an angle to longitudinal axis L″. Those skilled in the art will appreciate that it is preferable to have the cutting edge of the rotating blade contact a cutting edge of the stationary blade at an angle to provide a more scissor-like cutting action to hair rather than at a straight angle to provide a chopping action. This, of course, can be accomplished by having cutting edges of the stationary blade disposed at angles to the longitudinal axis of the blade support while keeping the cutting edge of the movable blade substantially parallel to that longitudinal axis, by having the cutting edge of the movable blade at an angle other than parallel to the longitudinal axis with the cutting edges of the stationary shell substantially parallel to the longitudinal axis, or having the cutting edges of both the movable blade and stationary cutting edges disposed at angles to each other.  FIG. 9  also illustrates a feature of the present invention wherein slots  375  having cutting edges  377  are provided in the distal end  378  of shell  370 .  
         [0029]     While the previously illustrated embodiments can provide the desired hinging or rotating action with elements formed of rigid materials, according to other embodiments, the hinging action which results in greater contact pressure between the movable blade and stationary blade is provided, at least in part, by utilizing flexible and/or resilient materials in the construction of the movable blades and/or movable blade supports.  FIG. 11  illustrates an example of an embodiment of the present invention comprising a resilient blade support. According to this illustrated embodiment, a rotating blade having blade edge  552  is connected by a resilient arm  542  to movable blade support  540 . As movable blade support  540  is moved around the interior of this illustrated shell, centrifugal force urges blade edge  552  into contact with the shell. As in the other disclosed embodiments, resistance to the movement of blade edge  552  along the interior surface of the shell will tend to increase the contact pressure between the blade edge  552  and the shell. As used herein, the phrase “contact pressure” is used to indicate that there is pressure exerted in a direction which would create and/or increase the pressure between the cooperating cutting edges and/or surfaces. The term “contact pressure” as used herein is not limited to times when the blade edge, for example  552 , is in actual contact with the illustrated shell. In certain circumstances, it is possible that a hair would cause a movable blade edge to move off of the interior surface of the shell, though this could result in less than optimum performance. The resilient arm  542 , blade and/or blade support  540  can be formed using metallic, polymeric and/or other suitably resilient material(s).  
         [0030]     By providing designs with a lower contact pressure between the movable blade(s) and the opposing cutting edge, e.g. “stationary” cutting edge, when the devices are not cutting hair, the various embodiments of the present invention reduce noise, and increase battery life and blade edge life. The described wedging action is designed to provide a more reliable cutting action and is less likely to result in a blade edge slipping over a hair and consequently exerting an uncomfortable pulling action.