Abstract:
A hair cutting head  605 , for use in a hair cutting apparatus  500  comprising: an elongated heated wire  260  suitable for shaving, cutting or burning hair growing from a skin surface; and a blunt debris removal element  650 , situated and configured to remove debris or scorched hair residue from the skin after shaving, cutting or burning by the heated wire.

Description:
RELATED APPLICATIONS 
       [0001]    The present application is a continuation-in-part of PCT/IL03/00219, PCT/IL03/00220, and PCT/IL03/00221 all filed on Mar. 13, 2003, the disclosures of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to removing hair with a heat element. 
       BACKGROUND OF THE INVENTION 
       [0003]    The removal of unwanted hair from the body can be accomplished with mechanized means, for example razors, tweezers or wax, all of which are uncomfortable to use, irritate the skin and/or cause damage to the skin. 
         [0004]    The use of heated wires or other structures to cut hair from a skin surface has been proposed. However, a heat generator that generates heat of a sufficient magnitude to cut hair and is offset from the skin to prevent skin damage, often leaves behind unwanted stubble. 
         [0005]    In Peterson, U.S. Pat. No. 3,934,115, parallel metal strips on the upper side of ceramic facing that contacts the skin, are used to cut hair. Hills, in U.S. Pat. No. 2,727,132 and P. Massimo in IT 1201364, use a continuously heated element to burn hair. P. M. Bell in U.S. Pat. No. 558,465, D. Seide in U.S. Pat. No. 0,589,445, G. S. Hills in U.S. Pat. No. 2,727,132, G. L. Johnson in U.S. Pat. No. 3,093,724, Hashimoto in U.S. Pat. No. 5,064,993 and U.S. Pat. No. 6,307,181 B1, F. Solvinto in FR 2531655 and EP 0201189, and E. Michit in 2612381, use a continuously heated wire to burn hair. J. F. Carter in U.S. Pat. No. 3,474,224, provides a circular comb device for burning nose hairs. These references do not appear to provide a means of reducing the hairs to the level of the skin. 
         [0006]    Vrtaric, in U.S. Pat. No. 4,254,324, provides a heat hair cutting system that is applied only to the tips of the hair to remove the split ends. 
         [0007]    Iderosa, in U.S. Pat. No. 5,065,515, describes a heating element that preheats hair before cutting it with a blade coupled to the heating element. However, since the heating element is permanently in contact with the skin, it is believed that its temperature is limited to a temperature which does not damage the skin, for continuous exposure and which is not uncomfortable for the user. 
         [0008]    The present applicants have disclosed a heat-generating system for cutting hair in PCT publications WO 03/009977 and WO 03/009976. The disclosures of these applications are incorporated herein in their entirety by reference. These applications describe methods and devices in which a wire providing pulsed or non-pulsed heat is used to cut hair. As used herein, a heat-generating wire refers to one or more of: metal wires, ribbons or any other type of heat-generating elements capable of generating heat of sufficient magnitude and/or duration to cut hair from an area of skin. In general, all of the configurations of wires, etc. disclosed in either of the above referenced applications are applicable to the present invention. In addition, the structures and methods described herein are usable in or in conjunction with the structures disclosed therein. 
         [0009]    In the above referenced PCT applications, the hair is severed close to the skin by heating the hair. This severing of the hair may also destroy at least a portion of the hair below the skin. As used herein the term “cut” is used to describe this type of severing or shaving of the hair. 
       SUMMARY OF THE INVENTION 
       [0010]    An aspect of some embodiments of the invention relates to a structure adapted for cutting hair with a removable cutting head. The removable cutting head comprises a wire that generates heat that is sufficient to cut hair, optionally with the aid of a blade. In an exemplary embodiment of the invention, the removable cutting head is positioned in the structure between two supports that position the surface of the skin with respect to the wire. 
         [0011]    Optionally, one of the supports is adapted to sense motion of the structure across the skin from which the hair grows, for example using a movable roller, an optical motion detector or an inertial motion detector. In some embodiments of the invention, the cutting head is activated responsive to the motion. In some embodiments of the invention, the cutting head is positioned to contact the skin and is activated to cut hair by heating the wire. Alternatively, the cutting head is normally positioned below the supports (out of contact with the skin) and when activated, is moved to the level of the supports to interface the skin. 
         [0012]    In some embodiments of the invention, the wire is heated only when motion is detected by the support sensor, in order to prevent the skin from being burnt by contact with the wire for a long time. Alternatively, the wire is distanced from the skin when not in motion across the skin. In the latter case, the heating need not be controlled by the sensing of motion. 
         [0013]    An aspect of some embodiments of the invention relates to a removable cutting head for cutting hair by heat that comprises a debris removal element, such as a blunt scraper, to remove debris resulting from the cutting process. In an exemplary embodiment of the invention, the cutting head burns hairs near their roots leaving carbonized residue in the hair pores and on the skin surface. The scraper, optionally attached to the cutting head, scrapes away the carbonized residue and any other debris (e.g. small hairs) produced during the cutting process. 
         [0014]    An aspect of some embodiments of the invention relates to a removable cutting head for cutting hair by heat, which additionally comprises a blade mounted on one side of the cutting head. In some embodiments of the invention, the wire in the cutting head is not hot enough to cut hair, or is not hot enough to cut hair with a thickness above a certain value. In this case, the blade cuts the hair. However, heating of the hair makes the cutting action faster and smoother even without shaving cream or the like. Optionally, the blade mounted on the cutting head complements the heated wire in cutting hair, leading to a smoother result. In some embodiments of the invention, the heated wire softens the hair before it is cut, in order to allow use of a duller blade. In an embodiment of the invention, the wire is heated to a temperature 50 to 100° C., optionally between 100 to 150° C., 150 to 250° C., 250 to 500° C. or 500 to 600° C. While this aspect of the invention is usable with wires that are not hot enough to burn and cut the hair, it is also usable with hotter wires which do cut some or all the hairs and is then used as a back-up to avoid multiple passes for cutting uncut or partially cut hairs. 
         [0015]    There is thus provided, in accordance with an embodiment of the invention, a hair cutting head, for use in a hair cutting apparatus comprising: 
         [0016]    an elongated heated wire suitable for shaving, cutting or burning hair growing from a skin surface; and 
         [0017]    a blunt debris removal element, situated and configured to remove debris or scorched hair residue from the skin after shaving, cutting or burning by the heated wire. 
         [0018]    Optionally, the head comprises a row of skin depressing elements on at least one side of said elongated heated wire. Optionally, the at least one side is opposite a side on which the blunt debris removal element is situated. 
         [0019]    Optionally, the wire has a diameter between 10 to 1000 micrometers, optionally, between 10 to 500 micrometers or between 500 to 1000 micrometers. 
         [0020]    There is further provided, in accordance with an embodiment of the invention, a hair cutting device comprising: 
         [0021]    a hair cutting head according to any of the preceding claims; wherein said wire is heated when said cutting head comes in contact with a skin surface. 
         [0022]    In various embodiments of the invention, the wire is heated to a temperature between 700 and 800° C., 800 and 1000° C. or more than 1000° C. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Exemplary non-limiting embodiments of the invention described in the following description, read with reference to the figures attached hereto. In the figures, identical and similar structures, elements or parts thereof that appear in more than one figure are generally labeled with the same or similar references in the figures in which they appear. Dimensions of components and features shown in the figures are chosen primarily for convenience and clarity of presentation and are not necessarily to scale. The attached figures are: 
           [0024]      FIG. 1A  is a schematic diagram of a structure supporting a heat-generating wire adapted for cutting hair, in accordance with an exemplary embodiment of the invention; 
           [0025]      FIG. 1B  is a schematic diagram of an alternative structure of  FIG. 1A , in accordance with an exemplary embodiment of the invention; 
           [0026]      FIG. 2  is a schematic diagram of the structure of  FIG. 1A  including position adjusters, in accordance with an exemplary embodiment of the invention; 
           [0027]      FIG. 3  is a partly sectioned isometric view of a vibrating hair cutting unit, in accordance with an exemplary embodiment of the invention; 
           [0028]      FIG. 4  is a side cross-section of the vibrating hair cutting unit of  FIG. 3 , shown while cutting a hair, in accordance with an exemplary embodiment of the invention; 
           [0029]      FIG. 5A  is a schematic diagram of a hair cutting unit without a shaving head according to an exemplary embodiment of the invention; 
           [0030]      FIG. 5B  is a schematic diagram of a hair cutting unit with a removable shaving head deployed to contact the skin, according to an exemplary embodiment of the invention; 
           [0031]      FIG. 5C  is a schematic diagram of a hair cutting unit with a removable shaving head deployed at a distance from the skin, according to an exemplary embodiment of the invention; 
           [0032]      FIG. 6A  is a schematic diagram of a removable shaving head, according to an exemplary embodiment of the invention; 
           [0033]      FIG. 6B  is a schematic diagram of an alternative removable shaving head, according to an exemplary embodiment of the invention; and 
           [0034]      FIG. 6C  is a schematic diagram of an additional alternative removable shaving head, according to an exemplary embodiment of the invention. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0035]      FIG. 1A  is a simplified schematic diagram of a heat-generating wire  260  suspended on a frame  200 , comprising two posts  240  and  242 , in accordance with an exemplary embodiment of the invention. In an exemplary embodiment, posts  240  and  242  comprise wire guideways  120  and  122 . Heat-generating wire  260  is optionally centered in guideways  120  and/or  122 . 
         [0036]    In an exemplary embodiment, posts  240  and  242  are held in position by a strut  244 , for example substantially perpendicular to posts  240  and  242 . Heat-generating wire  260 , for example, is attached at wire ends  270  and  272  to posts  240  and/or  242 . 
         [0037]    In an exemplary embodiment, a conduction post  290  is electrically conductive and is attached to an electrically conductive area  190  while a conduction post  292  is electrically conductive and is attached to an electrically conductive area  192 . Further, tension-providing posts  240  and  242  are electrically conductive and connected to conductive areas  190  and  192  respectively so that power provided through posts  290  and  292  causes wire  260  to generate heat. 
         [0038]    In an exemplary embodiment, one or both of tension posts  240  and  242  are manufactured from a springy electrically conductive material so that when properly positioned, they serve to keep heat-generating wire  260  taut during motion across a skin surface. Optionally, posts  240  and/or  242  are relatively flexible so they bend when subjected to a force pushing them towards each other. Optionally, posts  240  and/or  242  are relatively inflexible so they do not bend when subjected to a force pushing them perpendicular to the axis of wire  260 . 
         [0039]    In an exemplary embodiment, tensioning of wire  260  during manufacture is accomplished, for example, in the following manner, when one or both of the posts are springy. 
         [0040]    With the wire placed in guides  120  and  122 , wire ends  270  and/or  272  are pulled in a direction  208 , with sufficient force and/or at an appropriate angle, with respect to (horizontal) wire  260 , to cause posts  240  and  242  to bend toward each. Wire  260  is then attached to posts  240  and/or  242 , for example at points  276  and  278  respectively, using solder, electrically conductive glue (such as conductive epoxy), brazing, laser brazing and/or other connection means known in the art. Mechanical connection such as clamping can also be used. Optionally the clamp is copper or gold coated to provide a slightly conforming and highly conductive mechanical electrical connection. It should be noted that posts guideways  120  and/or  122  may be continually bent toward each other by the tension of wire  260 . After attachment to the posts, free ends of the wires may be removed. 
         [0041]    A similar method may be used if only one post is springy (or even if both are springy). In this case, wire  260  is optionally permanently attached to the inflexible post (or optionally to the frame), before or after tensioning. Then the other end of the wire is tensioned as aforesaid and then attached to the frame or post on which it is mounted. Optionally, especially when the wire is pre-attached to one of the posts, that post does not need a guide. 
         [0042]    Optionally, additional tension to wire  260  is provided by one or more coiled springs between posts  240  and/or  242  and wire  260 . 
         [0043]    Tensioned wire  260  will remain in tension even in the presence of longitudinal expansion that occurs due to heating of wire  260  and/or due to pressure as wire  260  moves in a direction  402  against a hair  404  ( FIG. 4 ). 
         [0044]    One method of pulling wire ends  270  and/or  272  in direction  208  is by attaching wire ends  270  and/or  272  to one or more tension-providing wheels (not shown), positioned, for example on strut  244 . By rotating the one or more wheels, wire ends  270  and  272  are pulled in direction  208  to tension wire  260 . Other methods for pulling wire  260  in direction  208  are known in the art and include, for example, attaching a spring mechanism and/or pneumatic tensioning device to wire ends  270  and/or  272 . 
         [0045]    In an exemplary embodiment, conductive post  290  fits into a socket  180  and conductive post  292  fits into a socket  182 . A friction fit between sockets  180  and  182  and posts  290  and  292  is provided, for example to allow easy removal of frame  200  from sockets  180  and  182  for replacement of the entire frame or for cleaning and/or repair of wire  260 . Sockets  180  and  182 , for example, are conductive and capable of transmitting power from a power source, thereby providing electrical current to heat-generating wire  260  via posts  290  and  292 , connection area  190  and  192  and tension posts  240  and  242 . It is generally envisioned that the wire, posts and strut mechanism will be replaced when the wire breaks. 
         [0046]    In an exemplary embodiment, post supports  160  are positioned against posts  240  and  242  to prevent undue motion in a direction  168 . Alternatively or additionally, posts supports  162  are positioned against posts  240  and  242  to prevent undue motion in a direction  166 . This assures that motion applied to frame  200  results in desired motion of the wire. 
         [0047]      FIG. 1B  is a schematic diagram of an alternative structure of  FIG. 1A , in accordance with an exemplary embodiment of the invention. In this embodiment, wire  260  passes through rings  150  and  152  in posts  240  and  242  prior to tensioning and attachment to the posts. 
         [0048]      FIG. 2  is a schematic diagram of heat-generating wire  260  on frame  200  of  FIG. 1A , mounted in vibrating compartment  300  that projects from vibrator posts  130  and  138 . In an exemplary embodiment, a vibrator  350  connected to posts  130  and  138 , comprises a motor  234  having an off-center weight  232  that causes vibration of vibrator  350  as motor  234  revolves in a direction  230 . Alternatively or additionally, vibrator  350  is connected to posts  130  and  138  with a transverse connector  354 . 
         [0049]    An optional cross pin  132  passes through vibrator posts  130  and  138 , allowing their movement around pin  132 . As vibrator  350  vibrates, it imparts vibration to vibrator posts  130  and  138 , thereby causing heat-generating wire  260  and/or compartment  300  to cyclically move in directions  402 . 
         [0050]    In cutting hair  404  ( FIG. 4 ), vibration of wire  260 , frame  200  and/or compartment  300  facilitates heat-generating wire  260  to make multiple passes over hair  404  while held against a given area of skin  400 . Multiple passes of wire  260  increase the cutting efficiency of heat-generating wire  260  during each period it contacts area of skin  400  (i.e., as it is moved, by the user, across the skin surface). The excursion of the wire is, for example, between 0.05 and 2 mm, optionally between 0.3 and 1 mm. 
         [0051]    In an exemplary embodiment, vibrating compartment  300 , for example comprises a snap-together structure and/or is removably attached to vibrator posts  130  and  138  so that it can be removed for cleaning and/or to allow removal of frame  200  from sockets  180  and  182 . 
         [0052]    As shown more clearly in  FIG. 3 , in an exemplary embodiment, compartment  300  comprises a row of skin-depressing elements  312 . Skin-depressing elements  312  serve to depress and/or tighten area of skin  400  ( FIG. 4 ), allowing heat-generating wire  260  to cut hair  404  without sinking into skin  400  and possibly dissipating its heat so that it cuts less efficiently and/or burns skin  400 . 
         [0053]    In an exemplary embodiment of the invention, two rows of skin-depressing elements are provided on either side of heat-generating wire  260 . Rows of skin depressors are shown in the PCT publications described above, for example, posts or the like. However, the skin depressors shown in the present embodiments differ from those shown in that they comprise elongate elements that whose long axis points generally toward the wire. The present inventors have found that the elongate elements shown herein provide for smoother and more comfortable travel of the shaver along the skin. Other configurations of skin-depressing elements  312 , for example, comprising skin-depressing elements  312  at varied heights, angles, and/or planes with respect to skin  400  ( FIG. 4 ), wire  260  and/or compartment  300 , are also contemplated in exemplary embodiments of the invention. In preferred embodiments of the invention the long axis of the elongate elements is parallel to the plane of the opening (and thus of the skin) or are at a small angle (5, 10, 15 or 20 degrees) with respect to the plane. 
         [0054]    Alternatively or additionally, post protectors  340  and  342  extend beyond posts  240  and  242  and/or skin-tensing and depressing elements  312 . In an exemplary embodiment, post protectors  340  and  342  prevent the heat and/or vibrations from posts  240  and  242  from damaging skin  400  ( FIG. 4 ) or vice-versa, by offsetting the proximate area of skin  400  proximal away from posts  240  and  242 . 
         [0055]    In an exemplary embodiment, wheels  318 ,  320  and/or  330  are juxtaposed against strut  244  and are rotatable so that flats  388 ,  390  and  392  respectively adjust the position of strut  244 . Positional adjustments of strut  244  affect the position of wire  260  with respect to skin-depressing elements  312  and hence against area of skin  400 . By rotating wheels  318 ,  320  and/or  330 , an operator, for example, controls the closeness of heat-generating wire  260  to skin-depressing elements  312 , adjusting the position of wire  260  in a direction  248 . Alternatively or additionally, the operator adjusts the angle of wire  260  to skin-depressing elements  312 , for example in directions  284  and/or  286 . 
         [0056]    Using wheels  318 ,  320  and/or  330  an operator can optimally position an angle of the wire with respect to the plane of the ends of depressors  312  (or the opening, if rows of depressors are not used). 
         [0057]      FIG. 3  is a cross-section of a vibrating hair cutting unit  100  having vibrating compartment  300  and a relatively non-vibrating structure  106 , with wire  260  positioned within a gap  328 . Optionally, skin-depressing elements  312  are elongate elements, positioned on one side of wire  260 , pointing toward gap  328 . As indicated above, a row of skin depressing elements  314  may comprise elongate elements on the opposite side of wire  260  gap that point toward gap  328 . Optionally, post supports  160  and  162  are positioned against posts  240  and  242  to prevent wire  260  from contacting skin depressing elements  312  and/or  314 . 
         [0058]    Structure  106 , for example, comprises a mechanical motion detector wheel or roller  110  that rotates along a surface, for example area of skin  400  ( FIG. 4 ) and signals a controller  118  that unit  100  is moving in relation to skin  400 . In an exemplary embodiment, controller  118  turns vibrator  350  on or off in response to movement, thereby causing vibrator  350  to selectively provide vibrations. 
         [0059]    Optionally, motion detector wheel  110  switches vibrator  350  on when unit  100  moves above a minimum speed in relation to skin  400  and switches vibrator  350  off when unit  100  moves below the minimum speed. In exemplary embodiments of the invention, the minimum speed is between 0.2 to 1 cm/second optionally about 0.5 cm/sec. In some embodiments of the invention, the motion detector also indicates when the speed is above a value to cause proper hair removal. In general, this speed is above 1-3 cm/sec. However, this value may vary depending on the diameter and temperature of the wire. Alternatively or additionally, mechanical motion detector  110  comprises an optical motion detector that directs controller  118  to switch vibrator  350  on or off. Optionally, in addition to controlling vibrations, motion detector  110  functions to switch heat generated by wire  260  on or off in response to motion of unit  100  on skin  400 . Optionally, the system includes a visual indication of whether the heat and/or vibration are activated, as for example a light. In an embodiment of the invention, the light is green when the velocity is in a desired range and red when it is outside this range. 
         [0060]    In an exemplary embodiment, a battery  114 , for example, provides power to vibrator  350  and/or wire  260 . Optionally, battery  114  is rechargeable and, for example, linked by a power input  116  to an external power source, for example a power converter and/or an AC electric power receptacle (not shown). Alternatively or additionally, power input  116  is directly connected to wire  260  and/or vibrator  350  without battery  114  intervening and wire  260  is powered, for example, by AC current. 
         [0061]    For clarity of presentation, in these embodiments, connections, for example between tension posts  240  and  242 , and/or vibrator  350 , and battery  114 , are not shown. However in an exemplary embodiment, a simple arrangement of electrical connectors is used to electrify heat-generating wire  260 , vibrator  350  and/or other components associated with unit  100 . 
         [0062]    In an exemplary embodiment, cross pin  132  has end pins  134  and  136  that attach to structure  106 , allowing vibrating compartment  300  to vibrate on posts  130  and  138  in relation to structure  106 . One or more movement limiters  332  that abut post  130  and/or  138  to limit excursion of posts  130  and  138  during vibration of compartment  300  optionally project from housing  106 . In an exemplary embodiment, movement limiters  332  comprise compressible material, for example a silicone. In an alternative exemplary embodiment, frame  200  is connected directly to vibrator  350  and compartment  300  and structure  106  remain stationary while heat-generating wire  260  vibrates in relation to skin  400 . 
         [0063]    In an exemplary embodiment, compartment  300  comprises a container  140  adapted for receiving a fluid and/or solid deodorant  142 . Container  140 , for example, is joined to a passage  146  having a venturi opening  148 . Deodorant  142  atomizes as compartment  300  vibrates and is distributed through venturi opening  148  to the area around wire  260  and/or to skin  400 . 
         [0064]    Alternatively or additionally, deodorant  142  vaporizes in response to heat provided by heat-generating wire  260 . Alternatively or additionally a cover  310  is provided on passage  146  and a user-operated trigger  308  is provided on structure  106  that opens cover  310  to release vapors and/or aerosol from deodorant  142 . 
         [0065]    No matter what type of dispensation means is used, though, as deodorant  142  atomizes and/or vaporizes, it passes through communication passage  146  to the general area of heat-generating wire  260  and skin  400 , thereby masking and/or neutralizing odors generated during cutting of hair. The deodorant (which can be a perfume that masks the smell of the burnt hair), can be provided in different popular scents 
         [0066]    In still another alternative exemplary embodiment shown in  FIG. 1A , a smoke and/or odor-removing filter  280  is located over ventilation holes  380  in strut  244 . A rotatable ventilator prop blade  236  (or other pumping mechanism) rotates to cause odors to be drawn through filter  280 . A ventilator passage connecting an input of filter  280  to holes  380  may be provided to allow flow of the air containing the burnt odor to filter  280   
         [0067]    Optionally, filter  280  comprises a porous material that absorbs a deodorant, for example a liquid deodorant and an operator places liquid deodorant on at least one area of filter  280 . As odors pass over filter  280 , they are neutralized and/or replaced with a pleasant fragrance. Optionally, odor-removing filter  280  is located in or adjacent a receptacle  374  that additionally collects cut hair  460  ( FIG. 3 ). 
         [0068]    Optionally, blade  236  is activated together with the heat and/or vibration. Optionally, it is deactivated at the same time as one or both of these elements or operates for a somewhat longer time to provide additional odor removal. 
         [0069]      FIG. 4  is schematic cross-sectional view of vibrating hair cutting unit  100  cutting hair  404  that is growing from area of skin  400 , in accordance with an exemplary embodiment of the invention. 
         [0070]    In an exemplary embodiment, an electrostatic outcropping  370  is incorporated into unit  100 , for example near motion detector wheel  110  and electrostatically attracts a cut hair  460  cut by heat-generating wire  260 . Electrostatic outcropping  370 , for example, of Teflon material will self charge, by friction with the skin, to an extent suitable for attracting the hair. Other charging means and materials can also be used. 
         [0071]    Optionally, hair collection receptacle  374  is juxtaposed near outcropping  370  to collect cut hair  460  that accumulates on outcropping  370 . Optionally, receptacle  374  has a collection aid  378 , comprising a comb or brush, that brings cut hair  460  in proximity of outcropping  370 . 
         [0072]    In an exemplary embodiment, wire  260  is manufactured from Kantaal D, (an alloy of nickel chromium and other metals manufactured by Kantaal Group). Alternative materials for wire  260  include Nichrome, other wire resistance materials or other alloys suitable for high temperature operation. For lower temperatures other spring steel (SS) alloys are suitable. For higher temperatures platinum tungsten wire (such as PtW wire manufactured by Johnson Matthey (UK), Precious Metals Division or Goodfellow (UK)) may be used. Other high temperature wires materials such as pure platinum and platinum/iridium alloy can also be used. However, such wires are very flexible. 
         [0073]    In an exemplary embodiment, the current through wire  260  is 0.5 A, though it may vary, depending on the dimensions and/or materials comprising wire  260 . In order to cut efficiently, wire  260 , for example, reaches a peak temperature of between 700 and 1200° C., when wire  260  is held against hair  404  for 0.1-100 milliseconds, optionally 1-10 milliseconds, depending on the mass and temperature of the wire used. In some embodiments of the invention, the temperature of the wire is even higher than 1200° C. 
         [0074]    Lower temperatures, for example 500° C., can be used to cut hair  404  when wire  260  is held against hair for longer periods of times, for example, 50-150 milliseconds. Higher temperatures, for example 1000° C., can be used to cut hair  404  when wire  260  is held against hair  404  for shorter periods of time, for example, 5-15 milliseconds. 
         [0075]    Battery  114 , for example, produces between 3 and 30 volts and between 0.030 and 5 amperes, depending on the dimensions of wire  260 . 
         [0076]    In exemplary embodiments, wire  260  has a circular cross section with a diameter of 0.01-0.25 millimeters. Alternatively, wire  260  has a diameter of above 0.25 millimeters (e.g between 0.25 mm-0.5 mm or even up to 1 mm), when manufactured from a less flexible and/or weaker material and below 0.25 millimeters when manufactured from a more flexible and/or stronger and/or higher temperature material. 
         [0077]    In some embodiments of the invention, wire  260  is shaped as a ribbon with a rectangular cross section or another geometrical shape, instead of a circular cross section as described above. Optionally, the width of the cross section is similar to the diameter of wire  260  with a circular cross section. In some embodiments of the invention, wire  260  has a sharpened head which serves as a blade to assist in removing hairs which did not burn from the heat. 
         [0078]    Wire  260  has a length, for example, of 25-30 millimeters though it could have a length greater than 30 millimeters or less than 25 millimeters, based upon, for example, the amount of hairs  404  that it is designed to cut on each pass. 
         [0079]    Examples of springy electrically conductive materials used in manufacturing posts  240  and/or  242 , include spring steel (SS  302 ) and beryllium copper. Optionally, the posts are plated with a material such as tin, which improves conductivity to the wire and solderability of the posts. 
         [0080]    Skin-depressing elements  312  are shown as being straight comb-like pieces, though their shape could vary. Alternatively or additionally, rows of skin-depressing elements  312  with varied designs could be included in a kit provided with unit  100 . For example, rows of skin-depressing elements  312  included in the kit could be curved along their length, semi circular or even end in round balls. Use of the various designs of rows of skin depressors  312  could be based on, for example hair density and/or preference of the operator. 
         [0081]      FIG. 5A  is a schematic diagram of a hair cutting unit  500  without a shaving head according to an exemplary embodiment of the invention. In an exemplary embodiment of the invention, hair cutting unit  500  comprises an encasement  530  with two support elements ( 510 ,  110 ) installed on the top end that interface the user&#39;s skin  400 . In an exemplary embodiment of the invention, a socket  540  is provided between the two support elements. Optionally, as shown in  FIG. 5B  a removable shaving head  600  is deployed into socket  540  between the supports in order to cut hair. In an exemplary embodiment of the invention, one of the supports comprises motion detector wheel  110 , which senses movement of the head across a surface with hair and activates hair cutting unit  500 . Optionally, the second support comprises a balance roller or fingers  510 , which balances hair cutting unit  500  so that removable shaving head  600  will be held tangent to the surface of skin  400  while hair cutting unit  500  is pressed against skin  400  to cut hair. Optionally roller or fingers  510  have only a small contact area (in the transverse direction) with skin surface  400 , so that the hair can pass freely to the cutting head. 
         [0082]    In an exemplary embodiment of the invention, socket  540  comprises two or more conduction posts  520  upon which removable shaving head  600  is mounted. Optionally, conduction posts  520  supply electrical current to shaving head  600  to heat wire  260 . Optionally, the posts can be non-conducting with electrical connection to the cutting head provided by other means. 
         [0083]      FIG. 5C  shows hair cutting unit  500  with shaving head  600  in a retracted position. As indicated above motion detector wheel  110  is used to detect motion (or other means, for example, an optical motion detector or an inertial motion detector, as known in the art or described in the present inventor&#39;s previous PCT publications). When motion is detected, a controller optionally, instructs shaving head  600  to be brought to the position shown in  FIG. 5B . When motion is not detected, the shaver head is in the retracted position shown in  FIG. 5C . 
         [0084]      FIG. 6A  is a schematic diagram of removable shaving head  600 , according to an exemplary embodiment of the invention. As shown in  FIG. 6A  shaving head  600  comprises two or more connection sockets  630  which match conduction posts  520  (shown in  FIG. 5A ). Optionally, when deployed conduction posts  520  form electrical contact with a connection wire  620  that electrically connects between connection sockets  630  to wire  260 . 
         [0085]    In some embodiments of the invention, socket  540  and removable shaving head  600  are designed so that removable shaving head  600  is aligned with balance roller  510  and motion detector  110 . Optionally, in use of hair cutting unit  500 , balance roller  510  and motion detector  110  are pressed against the surface of skin  400  and moved along skin  400  to cut hair. Optionally, motion detector  110  senses the motion and causes hair cutting unit  500  to supply current to heat, wire  260 . Skin depressing elements  312  glide along the surface and position the skin surface with respect to wire  260 , while the hair is ignited at the point of contact with wire  260 . Optionally, when hair cutting unit  500  is not in motion, current is not supplied to wire  260  on order to prevent damage to skin  400  from the heat at the parking position. 
         [0086]    In some embodiments of the invention, socket  540  is positioned so that removable shaving head  600  is below the supports (as shown in  FIG. 5C ), balance roller  510  and motion detector  110 . Optionally, when motion detector  110  senses motion socket  540  rises up to align the top of shaving head  600  with balance roller  510  and motion detector  110 , in order to cut hair. Optionally, when the motion ceases socket  540  sinks down to the original position which prevents contact between wire  260  and skin  400 . 
         [0087]    In some embodiments of the invention, current is continuously supplied to wire  260 , since skin  400  is protected by withdrawal of head  600 , when hair cutting unit  500  is not in motion. 
         [0088]    In some embodiments of the invention, the current is turned off, for safety sake. It should be understood that in the shavers described in the inventors&#39; prior publications, the thickness (mass) of the wire is limited by the need to cool the wire quickly when the current is turned off, so that the skin does not burn. However, in accordance with the present embodiment of the invention, a thicker wire  260  (e.g. with a diameter of 100-200 micrometers), can be used as compared with the disclosures, since it is taken out of contact with the skin when there is no motion. In addition, the wire can be heated to a higher temperature, since head  600  withdraws when not in motion along the surface of skin  400 , thus preventing any specific position from getting burnt. Alternatively or additionally, current may be supplied to the wire as pulses, which are sufficient to burn hair but are short enough to prevent the skin from getting burnt. 
         [0089]    In some embodiments of the invention, a Led hole  670  is created at the bottom of removable head  600  to mount a Led or other light source  570  (shown in  FIG. 5A ) to illuminate the wire and skin, for example to indicate that hair cutting unit  500  is in use and/or that wire  260  is hot. 
         [0090]    In some embodiments of the invention, socket  540  is vibrated during use in order to enhance the cutting process as described above. However, it should be understood that vibration and other particular features of the described embodiments need not be present in an actual embodiment. In general, each of the features of the present invention may be used with prior disclosed embodiments and can be individually implemented without others of the new features described herein. 
         [0091]      FIG. 6B  is a schematic diagram of an alternative removable head  605 , according to an exemplary embodiment of the invention. In an exemplary embodiment of the invention, the cutting process using a heated wire  260  may leave debris on the skin and/or in the pores of the hairs, for example as a result of igniting the hairs causing carbonization of the base of the hair in the pore and/or around it. In an exemplary embodiment of the invention, a removable head  605  with a debris removal element  650  (such as a preferably blunt scraper) is used during the cutting process to scrape away debris. Optionally, element  650  is positioned in any other position at which it can scrape the skin after the hair is cut. As used herein, the term “blunt” element means that the element is incapable of cutting hair. 
         [0092]      FIG. 6C  is schematic diagram of an additional alternative removable head  610 , according to an exemplary embodiment of the invention. In this embodiment of the invention, a removable head  610  with a blade  660  is used in order to cut the hair after wire  260  has heated it and enhance the speed of the cutting process. Depending on the wire temperature and mass, wire  260  can cut all or some of the hair, with blade  660  completing the process. Alternatively, for lower temperature of the wire, the hair is not cut through by the wire. However, the heat from wire  260  prepares the hair for cutting (e.g., it softens the hair) so that it is more easily cut. Unlike the prior art device described in the background of the invention, the heated wire can be hot enough to heat the hair to a temperature substantially higher than a temperature that would damage the skin, due to one or more of the low mass of the wire, pulsing of the wire, heating of the wire only when motion is detected and/or the removal of the wire from skin contact when motion is not detected. In some embodiments of the invention, wire  260  may reach temperatures higher than 50° C., 100° C., 150° C. or even as high as 1000° C. 
         [0093]    A variety of numerical indicators have been utilized to describe the dimensions or temperature of the heat-generating wire. Additionally, a variety of numerical indicators have been utilized to describe structures besides heat-generating wire, including length, diameter and position of skin depressors in relation to the heat-generating wires. It should be understood that these numerical indicators could vary even further based upon a variety of engineering principles, materials, intended use and designs incorporated into the invention. The reader is further referred to the above referenced PCT applications, which contain numerous variations on many of the features described herein. 
         [0094]    It should be further understood that the individual features described herein can be used together, in the manner above, in a single shaving device. Alternatively, each of the features (or some combination of them) can be used separately, for example, by being added to one of the devices shown in the above referenced PCT publications. Furthermore, it should be understood that the examples given above are exemplary in nature and are not intended to limit the scope of the invention or the claims. 
         [0095]    The terms “include”, “comprise” and “have” and their conjugates as used herein mean “including but not necessarily limited to”.