Real electric shaver

RELATED APPLICATIONS

The present application is a U.S. national application of PCT/IL02/00604, filed on Jul. 21, 2002. The present application claims the benefit under §119(e) of U.S. provisional application No. 60/306,892 filed on Jul. 23, 2001, and U.S. provisional application No. 60/354,019 filed on Feb. 5, 2002, the disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to removing hair with periodically applied heat without damaging the skin.

BACKGROUND OF THE INVENTION

The removal of unwanted hair from the body can be accomplished with non-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.

Mechanized cutting means for cutting hair, for example dry shavers, in addition to being uncomfortable to use, are limited to cutting hair of a specific length. Beard trimmers, for example, cut facial hair stubble, but cannot cut longer hairs on the scalp.

Alternate devices that use an electrical or electromagnetic source, for example electrolysis and photothermolysis, are effective but usually require an experienced operator to ensure proper administration without untoward side effects.

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 that cuts the hair close to the skin, often damages the skin. Alternatively, since the heat generator is offset from the skin to prevent skin damage, unwanted stubble is left behind.

In Peterson, U.S. Pat. No. 3,934,115, parallel metal strips on the upper side of a 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. 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 FR 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. Aside from physically separating the skin from the heated element, these references do not appear to provide other protection against burning of the skin.

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.

A prior art system for depilation, based upon photothermolysis is shown in U.S. Pat. No. 6,187,001, the disclosure of which is incorporated by reference. In this method, radiant energy is used to heat the air surrounding the skin to remove hair. EP publications EP 0 736 308 and EP 0 788 814, the disclosures of which are incorporated herein by reference, utilize radiant energy to selectively heat the hair, destroying it.

SUMMARY OF THE INVENTION

According to an aspect of some embodiments of the present invention, a device comprises a heat generator that generates continuous heat of sufficient temperature to cut hair while contacting the skin. However, during the process of cutting hair, the heat generator is prevented from damaging the skin by controlling the period of time during which heat continuously contacts a given area of skin. In some embodiments of the present invention, a heat generator continually contacts the skin and the period of its heat generation is limited to prevent skin damage. In some embodiments of the present invention, the generator remains hot throughout its duty cycle and is removed from contacting a section of skin to limit the period of time in which heat is applied, thereby preventing skin damage.

According to an aspect of some embodiments of the present invention, pulsed heat is applied through a heat generator containing one or more heat elements that contact the skin at least intermittently. In an exemplary embodiment, a pulsed heat generator provides pulsed heat at the heat elements wherein the pulses of heat are short enough so that although the temperature is high, the amount of heat transferred to the skin does not damage the skin. On the other hand, hair that contacts the heat element is destroyed, due to the lower heat capacity of the hair. Such a device may contact the skin substantially continuously.

As used herein, a heat generator is defined as a unit containing one or more heat elements heated to a temperature sufficient to cut hair during a given period of time in which it is in contact with the hair. It should be understood that current applied to the heat element at the line frequency (50-60 Hz) is to be considered continuous current, since it provides substantially constant heat.

Unless specified, further embodiments apply to both pulsed heating aspects and non-pulsed heating aspects of the present invention. Furthermore, while either pulsed or continuous heating may be described in reference to an embodiment of the invention, pulsed heating is generally usable in all the embodiments that are described with continuous heating. Additionally, embodiments that are described as using pulsed heating can use continuous heating if means for avoiding overheating of the skin as described herein are provided.

The cutting of a hair is dependent upon the magnitude of heat absorbed by the hair, whether a low temperature over a long period of time or a high temperature over a short period of time, whether pulsed or non-pulsed heat. Hence, the heat generator may generate heat at a lower temperature for a longer period of time or at a higher temperature for a shorter period of time in order to cut hair.

Heat builds in a specific area of a given hair and reaches a sufficient magnitude to cut the hair substantially independent of the hair length. In an exemplary embodiment of the present invention, a single apparatus cuts hair of a variety of lengths, from facial stubble to long hair on the scalp, in a variety of persons. Additionally or alternatively, the present invention allows a single apparatus to cut hair of a variety of lengths without exchanging, for example, cutter accessories. Further, the heat element used to cut hair, provides a sterile cutting environment, preventing the transmittal, for example, of scalp bacteria from one user to the next.

In some embodiments of the present invention, a heat generator provides heat of sufficient temperature to cause cessation of hair regrowth through destroying a hair growth regulatory mechanism as identified by R. L. Rusting in “Hair—Why it grows, Why it stops”,

Scientific American

248:6 June 2001, pp. 56-63. Alternatively, a heat generator provides heat at a lower magnitude to cause delay of hair regrowth through partial destruction of the hair growth regulatory mechanism.

In an exemplary embodiment of the invention, the heat generator contains one or more heat elements, for example a heated wire and/or heated strip that contacts the hair and, optionally, the skin. Additionally or alternatively, the one or more heat elements consist of one or more of a wire, a ribbon, or a conductive coating on a non-conductive surface, for example a ceramic material in the form of a bar. Optionally, the one or more heat elements contain, at least in part, a metal. Alternatively, they do not contain any metal.

In other embodiments of the invention, the heat generator comprises two or more heat elements. The hair is cut, for example, with absorption of an appropriate amount of cumulative heat by each hair. Two or more heat elements promote faster transfer of the necessary cumulative heat than, for example one heat element, allowing faster movement of the unit while cutting the hair.

Additionally or alternatively, two or more heat elements allow each heat element in the heat generator to maintain a lower temperature while cutting hair as compared to a heat generator with a single heat element at a higher temperature.

Additionally or alternatively, the pulsed current is pulsed at different times through the two or more heat elements and is, for example, synchronized so that one heat element generates heat while another heat element does not generate heat or, optionally, generates heat at a lower temperature.

Optionally, the heat generator comprises one or more walls that are perpendicular to the skin comprising, for example, a slot through which hair passes. In an exemplary embodiment, the one or more heat elements are moved by the device in relationship to the slot during use to prevent damage from heat buildup in a given area of skin. For example, in some embodiments of the invention, the heat generator, or a portion of the heat generator, is mechanized to be periodically removed from an area of skin. The heat generator, for example lifts the one or more heat elements from the skin in a regular cycle or by moving them along the surface of the skin. When a mechanized heat generator contains two or more heat elements, the heat elements, for example, have an axis parallel to the skin and rotate around the axis that is parallel to the skin.

In an alternative mechanical embodiment, the mechanization provides for rotation of the heat elements about an axis perpendicular to the skin, such that the heat element moves along the surface of the skin. This provides for contact times with the skin that do not cause skin burns while providing for continuous cutting action, since all of the heat elements are adjacent to the skin with a high duty factor.

In some embodiments of the present invention, two or more heat elements are situated on a vertical plane in relationship to the skin surface, so that the hairs are cut successively closer to the skin as the heat elements sequentially pass an area of skin. Alternatively or additionally, the heat generator comprises two or more heat elements situated on a horizontal plane to the skin so that cumulative heat appropriate for cutting a hair may be provided sequentially as the multiple heat elements pass the same site.

In an exemplary embodiment, the heat generator comprises two or more heat elements of different cross sectional sizes, with the heat element of greater cross section providing greater transfer of heat to cut hair while at the same temperature as the heat element of lesser cross section. Optionally, heat elements of different cross sectional sizes are located in a cylinder about an axis that moves perpendicular to the skin. Additionally or alternatively, the heat elements of different cross sectional sizes are situated in a non-vertical plane in relationship to the skin with one heat element at a different height from the skin than another heat element. For example the thicker heat element is located further from the skin to provide faster coarse cutting of the hair. Additionally or alternatively, the heat elements of different cross sectional sizes are situated on a horizontal plane in relation to the skin with one behind the other. For example, the thicker heat element is located in front of the thinner heat element, so the thinner heat element is used to cut the relatively fewer hairs that may have been left uncut the larger first heat element.

Similarly, heat elements of different cross sectional sizes that are arranged in a cylinder or on a horizontal or non-horizontal plane, allow the thicker heat element to cut the bulk of the hairs in its path while the thinner heat element cuts the relatively few hairs missed by the first heat element.

In an exemplary embodiment, the heat generator cuts hair in conjunction with a cooling apparatus, for example a fan, to provide cooling to the skin during the cutting process. In addition, when pulsed heating is used, the fan helps to remove heat from the heat element during the “off” time, so that a higher repetition rate for the heat pulses and a higher duty cycle can be used.

In an exemplary embodiment, the hair cutting apparatus includes a grasping structure designed to be grasped by an operator to which the heat generator is attached. The heat generator is held by the grasping structure at a specific angle to the skin, for example, perpendicular to the skin. Optionally, the heat generator is held at a non-perpendicular angle to the skin. The angle of heat generator, whether perpendicular or non-perpendicular is varied, for example, according to the design of the grasper.

In an exemplary embodiment, one or more posts provide the connection between the grasping structure and the heat generator. These posts are, for example, flexible or spring loaded so that as the heat generator moves across the contour of the skin, the heat generator moves up and down and/or swivels on the flexible posts in relation to the grasper. This movement prevents, for example, the heat element from pressing with undue force into the skin surface, causing skin damage.

In an exemplary embodiment of the present invention, heat is applied through a heat element that contacts the skin while two or more skin depressors located in proximity to the heat elements hold the skin flat. The two or more skin depressors prevent the heat element from sinking into the skin and causing skin damage due to increased contact area between the skin and the heat element. Optionally, one or more rows of skin depressors touch the skin and the one or more heat elements are parallel to the one or more rows of skin depressors. Additionally or alternatively, two rows of skin depressors are provided and the one or more heat elements are located between the two rows of skin depressors, optionally parallel to the two rows of skin depressors. Optionally, the one or more heat elements are not parallel to the two rows of skin depressors.

In an exemplary embodiment, the one or more heat elements of the heat generator are held at one or both ends by a tension generator. The one or more tension generators comprise, for example, a spring-loaded mechanism, to tighten the one or more heat elements of the heat generator during longitudinal expansion that may occur during heat generation. Additionally or alternatively, said one or more tension generators tighten the one or more heat elements to prevent substantial deformation while pressing against hair during hair cutting.

In an exemplary embodiment of the present invention, the one or more skin depressors are designed so that the one or more tension generators do not cause skin damage during cutting. For example, the one or more skin depressors located near the tension generator protrude beyond the tension generator so the skin does not contact the tension generator, thereby preventing buildup of heat and resultant skin damage.

Additionally or alternatively, the one or more rows of skin depressors provide a cooling mechanism for the heat elements. As the pressure on the heat elements of the heat generator, caused by the hairs in its path, increases, the heat elements of the heat generator displace and touch one or more of the skin depressors and cool. This cooling of the heat elements of the heat generator prevents heat buildup that can cause damage to the skin. A second pass cuts the hairs in the path of the cooled heat generator that were not cut during a first pass.

Optionally, the one or more rows of skin depressors provide current to the one or more heat elements of the heat generator only when the heat generator is in motion. In an exemplary embodiment the heat elements contain, for example, a positive charge potential and the two or more rows of skin depressors are connected to an electrical ground. As the heat generator is moved along the skin and comes against hairs in its path, the cool heat elements remain stationary against the hairs. As the heat generator continues motion, the heat elements bend and touch a row of skin depressors, thereby completing the circuit so electricity flows through the heat elements to the grounded skin depressors and the elements heat up. Upon cessation of motion, the heat elements no longer press against hairs in their path and become straight, for example with the assistance of the tension generated by the tension generator, so they no longer touch a row of skin depressors. The current through the heat elements is thereby disrupted and the heat elements cool.

In an exemplary embodiment, heat is applied through a heat element controlled by a motion detector so the heat element provides heat only while the heat element moves in relation to the skin. Upon slowing of the heat generator's motion below a specific rate, or its cessation of motion, the motion detector stops the production of heat by the heat element. Additionally or alternatively, in response to reduction or cessation of motion, the temperature of heat, produced by the heat generator, is reduced.

In an exemplary embodiment, the temperature and (when a pulsed heat source is used) pulse rate, and/or pulse width in a single heat element is controlled by a velocity detector. One or more of these factors is raised or lowered responsive to the velocity of the heat generator. This control, for example, prevents damage to the skin by excessive heat at a lower velocity. Additionally or alternatively, a velocity detector controls one or more factors of temperature, pulse rate and/or pulse width in each heat element individually when there are, for example, two or more heat elements.

In an embodiment of the pulsed aspect of the present invention, the pulsed heat generator applies continuous current as it moves at a higher speed in relation to the skin and applies pulsed current optionally at a rate that is reduced as the heat generator moves at a lower speed.

There is thus provided a hair cutting apparatus comprising a structure, a portion of which being adapted for placement against a skin surface where hair is to be cut, a heat generator comprising one or more heat elements heated to a temperature sufficient to cut hair, at least one of said heat elements being juxtaposed with said portion and positioned to touch said skin and a controller that controls said heat generator to prevent heat from being applied continuously in a single area for sufficient time to cause skin damage.

Optionally said controller comprises a velocity detector and the velocity detector causes said heat generator to increase the temperature of said heat element when the velocity of said apparatus increases in relation to said skin and to decrease the temperature of said heat element when the velocity of said apparatus decreases in relation to said skin.

In an embodiment of the present invention, said heat generator provides pulsed heating of said one or more heat elements. Optionally, the one or more heat elements are heated for a period of between 10 and 100 msec for each on-off cycle. Optionally, the heating of the heat element is repeated at a pulse repetition rate of 1-100 Hz.

In an exemplary embodiment, said controller comprises a velocity detector. Optionally, the velocity detector causes said heat generator to increase its rate of repeated pulsing when the velocity of said apparatus increases in relation to said skin and to decrease its rate of repeated pulsing when the velocity of said apparatus decreases in relation to said skin.

Optionally, the velocity detector causes said heat generator to increase the width of each pulsation during said repeated pulsing when the velocity of said apparatus increases in relation to said skin and to decrease the width of each pulsation during said repeated pulsing when the velocity of said apparatus decreases in relation to said skin.

Optionally, the velocity detector causes said heat generator to generate continuous heating when the velocity increases above a specified velocity as sensed by said velocity detector. Additionally or alternatively, the velocity detector causes said heat generator to increase the temperature of said heat element when the velocity of said apparatus increases in relation to said skin and to decrease the temperature of said heat element when the velocity of said apparatus decreases in relation to said skin.

In an exemplary embodiment, said velocity detector comprises an optical velocity detector. Optionally, said velocity detector comprises a mechanical velocity detector.

In an exemplary embodiment, said controller comprises a motion detector. Optionally, the motion detector controls said heat generator, switching said heat generator on when said heat generator is in motion in relation to said skin and switching said heat generator off when said heat generator-is not in motion in relation to said skin. Additionally or alternatively, said motion detector comprises an optical motion detector. Optionally, said motion detector comprises a mechanical motion detector.

In an exemplary embodiment, the one or more heat elements comprise ribbon-shaped and a wide side of said ribbon-shaped heat elements are substantially perpendicular to said skin. Optionally, the one or more heat elements comprise a wire substantially parallel to said skin. Optionally, the one or more heat elements comprise two or more heat elements. Additionally or alternatively, a plane formed by the two or more heat elements is parallel to said skin. Optionally, the plane formed by the two or more heat elements is perpendicular to said skin. Optionally, the plane formed by the two or more heat elements is neither parallel nor perpendicular to said skin.

In an exemplary embodiment, the two or more heat elements have different cross-sectional areas. Optionally, the two or more heat elements have different cross-sectional configurations. Optionally, the heat applied by at least two of the two or more heat elements is applied at a different pulse rate. Optionally, the heat applied by at least two of the two or more heat elements is applied at a different pulse width or the temperature in at least two of the two or more heat elements is different.

In an exemplary embodiment of the present invention, at least one end of one heat element is attached to a tension generator. Optionally, the tension generator comprises a spring. Optionally, the tension generator comprises a spring-loaded wire. Additionally or alternatively, said portion that is adapted for placement against the skin comprises two or more skin depressors that contact said skin surface. Optionally said two or more skin depressors are perpendicular to said skin.

Optionally, said two or more skin depressors comprise one or more rows of skin depressing elements.

In an exemplary embodiment, said two or more skin depressors comprise at least two rows of skin depressing elements. Optionally, said two or more skin depressors comprise two parallel rows of skin depressing elements. Optionally, said one or more heat elements are located between said two rows of skin depressing elements.

Additionally or alternatively, at least one heat element is parallel to one or more rows of skin depressing elements. Optionally, said at least one heat element is not parallel to one or more rows of skin depressing elements. Alternatively, said at least one heat element is not parallel to said two or more rows of skin depressing elements. Optionally, at least one end of one heat element is connected to a tension generator and one or more of said skin depressing elements protrude beyond said tension generator.

In an exemplary embodiment, when the at least one heat element is so constructed that when it contacts one or more hairs during motion, it displaces opposite its direction of motion in relation to the skin. Optionally, when said heat element displaces in an amount sufficient to contact one of said skin depressors, it cools as it contacts the skin depressors. Optionally, when said heat element displaces in an amount sufficient to contact one of said skin depressors, it heats as it contacts the skin depressors.

In an exemplary embodiment, said portion adapted for placement against a skin surface is separate from said structure and said portion is mounted with one or more mountings on said structure. Optionally, said mounting comprises flexible posts. Additionally or alternatively, said mounting comprises spring-loaded mountings. Additionally or alternatively, said mountings are electrically connected to said heat elements.

In an exemplary embodiment, the controller comprises a motor that moves the heat elements along the skin, so that the temperature of the skin does not rise to a level that causes it to burn. Optionally, the heat elements are elongate heat elements arranged to form a discontinuous cylindrical surface having a rotation axis. Additionally or alternatively the heat elements rotate about the axis they are periodically brought into contact with and removed from contacting said skin surface. Optionally, the axes of the heat elements radiate from an axis, said axis being perpendicular to the axes of the heat elements. Optionally, the controller rotates the elongate heat elements about the axis.

In an exemplary embodiment, said apparatus includes a fan that provides cooling for at least one heat element.

There is thus further provided a method of cutting hair comprising providing a heat element touching the skin, said heat element being heated to a peak temperature high enough to cause the cutting of hair and the burning of skin at said position and interrupting the heating of the skin at said position before the skin is burned. Optionally, said interrupting comprises interrupting a supply of heat to the heat element. Optionally, said interrupting is accomplished by a motion detector when it detects a lack of motion of said hair cutting apparatus in relation to said skin.

In an exemplary embodiment, interrupting is accomplished by a velocity detector when it detects a reduction in velocity of said heat element in relation to said skin. Additionally or alternatively, interrupting comprises moving the heat element along the skin so that it does not remain in a position to bum the skin for a time sufficient to burn the skin.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary non-limiting embodiments of the invention are described in the following description, read with reference to the figures attached hereto. In the figures, identical and similar structures, heat 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:

FIG. 1

is a simplified schematic diagram of a wire cutting a hair, in accordance with an exemplary embodiment of the invention;

FIG. 2

is a simplified electrical schematic diagram of strip cutting a hair, in accordance with an exemplary embodiment of the invention;

FIG. 3

is a simplified schematic diagram, in accordance with an exemplary embodiment of the invention;

FIGS. 4A and 5

are respective orthogonal cross-sectional views of a hair cutting apparatus, in accordance with an exemplary embodiment of the invention;

FIG. 4B

is a cross sectional view of an alternative hair cutting apparatus, in accordance with an exemplary embodiment of the invention;

FIGS. 6 and 7

are cross-sectional and top perspective views, respectively, of an embodiment of a hair cutting device, in accordance with an exemplary embodiment of the invention;

FIG. 8

is a bottom perspective view of the device of

FIGS. 6 and 7

, in accordance with an exemplary embodiment of the invention;

FIGS. 9A-C

is respective partial side, end and perspective views of an alternative motorized example of a hair cutting apparatus, in accordance with an exemplary embodiment of the invention;

FIG. 10A

is a heat generator with an optical velocity detector, in accordance with an exemplary embodiment of the invention;

FIG. 10B

is a heat generator with a servo-velocity detector, in accordance with an exemplary embodiment of the invention;

FIG. 11A

is a hair cutting apparatus with a heat element situated between two parallel lines of skin depressors, in accordance with an exemplary embodiment of the invention;

FIG. 11B

is a side view schematic diagram of a hair cutting apparatus shown in

FIG. 11A

on a skin surface, in accordance with an exemplary embodiment of the invention;

FIG. 11C

is a schematic diagram of a heat element on a skin surface;

FIG. 11D

is a portion of a hair cutting apparatus of

FIG. 11A

taken along lines A—A, in accordance with an exemplary embodiment of the invention;

FIG. 11E

is a portion of a hair cutting apparatus of

FIG. 11A

taken along lines A—A, in accordance with an exemplary embodiment of the invention at a different time;

FIG. 12

is a partially exploded view of a hair cutting unit, in accordance with an exemplary embodiment of the invention;

FIG. 13

is an assembled hair cutting unit corresponding to the exploded view of

FIG. 12

, in accordance with an exemplary embodiment of the invention;

FIG. 14

is an electrical functional block diagram of a section of a hair cutting apparatus, in accordance with an exemplary embodiment of the invention;

FIG. 15

is an electrical schematic diagram of pulses from an optical mouse velocity detector on a hair cutting apparatus, in accordance with an exemplary embodiment of the invention;

FIG. 16

is an electrical schematic diagram of pulses from an electronic circuit on a hair cutting apparatus, in accordance with an exemplary embodiment of the invention; and

FIG. 17

is an electrical schematic diagram of voltage in response to a motion detector on a hair cutting apparatus, in accordance with an exemplary embodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1

is a schematic cross-sectional diagram of an embodiment of a wire

100

cutting a hair

102

, while optionally touching a portion of skin

104

, in accordance with an exemplary embodiment of the invention.

In a pulsed embodiment of the invention, the current through wire

100

is pulsed on for between 10 and 100 milliseconds. The length of current pulse, for example, is based upon the peak temperature of wire

100

, for example, or other factors such as the speed at which wire

100

passes over skin

104

. During this short period of time, wire

100

heats to the desired temperature. However, in the short time that the current is on, the amount of heat generated is not sufficient to heat skin

104

to a temperature at which it is damaged. Because the heat dissipates in skin

104

faster than in a hair, wire

100

does not have sufficient time to damage skin

104

, but cuts hair

102

. Generally, wire

100

moves in a direction

108

along a portion of skin

104

and if the movement is halted, absent the pulsing of the heat, wire

100

will burn skin

104

In non-pulsed embodiments of the present invention, for example, wire

100

is periodically removed from skin

104

to prevent skin damage. Additionally or alternatively, wire

100

remains in constant contact with skin

104

and the current through wire

100

is turned off to prevent skin damage when wire

100

is stationary with respect to skin

104

. Mechanisms, for example, that turn the current to wire

100

on or off while in contact with skin

104

or periodically remove wire

100

from skin

104

, will be explained below.

In an exemplary embodiment, the current through wire

100

is 0.5 A, though it may vary, depending on the dimensions and/or materials of wire

100

. In order to cut efficiently, wire

100

, for example, reaches a peak temperature of between 700 and 800° C., when wire

100

is held against hair

102

for 10-50 milliseconds. Lower temperatures, for example 500° C., can be used to cut hair

108

when wire

100

is held against hair for longer periods of times, for example, 50-100 milliseconds. Higher temperatures, for example 1000° C., can be used to cut hair

108

when wire

100

is held against hair

108

for shorter periods of time, for example, 5-10 milliseconds.

Optionally, a fan

106

is provided that cools skin

104

and wire

100

to avoid overheating skin

104

. The operating temperature of the device and/or the duration of heat application to a given area of skin

104

will likely change based upon whether or not a fan is used in conjunction with wire

100

. For example, temperatures of 1000° C. for a duration of more than 10 milliseconds are contemplated for cutting hair

108

in conjunction with fan

106

.

Additionally or alternatively, the color of wire

100

as it attains different temperatures, may be used as a determinate of hair cutting ability. For example, the power supply may be set to a level that causes wire

100

to become red hot at which it will cut hair

108

rapidly. Additionally or alternatively, the power supply may be set to a level that causes wire

100

to become yellow to yellow-red hot or a color indicating a temperature at which, for example, it will cut hair

108

less rapidly. Optionally, an operator can be apprised of these temperature-associated colors. By increasing and/or decreasing a current control to wire

100

, for example, the operator can cause wire

100

to glow at a specific color, indicating that an optimal temperature of wire

100

has been reached.

In an exemplary embodiment, wire

100

has a diameter of 0.070 millimeters, 0.01 millimeters or less, for example, when manufactured of a flexible material. A flexible material, for example, comprises, for example, a wire

100

manufactured from Kantaal D, (an alloy of nickel chromium and other metals manufactured by Kantaal Group). Alternative materials for wire

100

include Nichrome or other wire resistance materials. Alternatively, wire

100

could have a diameter of between 0.08 and 0.5 millimeters, when a less flexible material is used for its manufacture.

In an exemplary embodiment, wire

100

has a length, for example, of 10 millimeters, so that it cuts only a 10-millimeter swath of hair on each pass. Optionally, wire

100

has a longer length, for example 30 millimeters or more, providing a larger swath of hair cut with each pass.

An advantage of the present invention over prior art dry shavers, for example, is that heated wire

100

sterilizes skin surface

104

, or provides an aseptic environment, during cutting hair

108

. Additionally or alternatively, the heat of wire

100

suppresses and/or does not promote the spread of bacteria or other unwanted organisms during the cutting process. In contrast, for example, a dry shaver neither provides an aseptic environment nor suppresses the spread of bacteria during the cutting process. Hence, bacteria is often spread on skin

104

during cutting with a dry shaver, with a resultant infection, for example, when skin surface

104

is breached.

FIG. 2

is a schematic diagram of an alternative embodiment of a hair cutting device utilizing a ribbon

200

, shown in cross section (optionally touching the skin), cutting a hair

202

while moving in a direction

208

along a skin surface

204

, in accordance with an exemplary embodiment of the invention. A follicle

232

, the remains of a cut hair

230

, is, for example, cut below skin surface

204

.

R. L. Rusting in “Hair—Why it grows, Why it stops” by,

Scientific American

248:6 June 2001, pages 56-63, identifies the existence of stem cells within a bulge

234

that are part of the hair regulatory mechanism. In an exemplary embodiment, the heat of ribbon

200

radiates from skin surface

204

through hair follicle

232

to affect the cells of bulge

234

, thus providing a cessation of hair regrowth for a period of time, for example, a few days, a few weeks, a few months or even permanently.

In an exemplary embodiment of the present invention, a curved end

244

forms on a hair bulb

242

that has been cut with a heat element, for example ribbon

200

, that is more comfortable to shaved skin

204

. This is a distinct advantage over, for example most razors and electric shavers, that often leave a hair bulb

250

with a sharp point

252

that is uncomfortable to shaved skin

204

.

Ribbon

200

, for example, has a width, dimension a, of 0.05 millimeters or less, when manufactured from strong materials and/or the peak temperature is low. Alternatively, ribbon

200

could have a higher width dimension a, for example 0.2 millimeters or more, when manufactured from weaker materials and/or a higher peak temperature is maintained. Height, a dimension b, is not critical, except that excessive height results in high power consumption.

Ribbon

200

with a greater height dimension b, however, allows a large heated area to contact hair

202

, providing faster buildup of heat in hair

202

and faster rate of cutting. A narrow width dimension a, provides less heat transfer to skin

204

when using a ribbon

200

with a greater height b for rapid cutting. Other useful shapes, for example a sharp edge on the lower portion of ribbon

200

or an oval shape to ribbon

200

, provide other associated advantages as will be clear to persons of skill in the art.

In general the dimensions of ribbon

200

can be based on the amount of power available (whether the device run from batteries or from mains), and factors including whether the heat is pulsed or continuous, whether movement of ribbon

200

is mechanical or manual, whether fan cooling is provided and limitations on the heat capacity of the ribbon

200

so that skin damage is avoided. The values given above are typical for the particular material and are not to be considered as limiting.

FIG. 3

is a simplified schematic representation of an embodiment of a device

300

, in accordance with an exemplary embodiment of the invention. A power supply

310

, for example, produces between 3 and 30 volts and between 0.030 and 5 amperes, depending on the dimensions of a heat element

324

. Power from power supply

310

causes heat element

324

to heat to a temperature that is sufficient to cut hair, for example, between 700-800° C. when contact with a hair is between 10 and 50 milliseconds. An optional pulsar

320

(which can be part of power supply

310

) regulates the current produced by power supply

310

so that it, for example, produces pulsed heat for a period of 10-200 milliseconds such as 50 ms. The time between pulses is regulated, depending on the rest of the construction, to allow heat element

324

to cool sufficiently and to be off for a sufficient period to avoid burning of the skin and build-up of heat, even if heat element

324

is not moved. Generally, the pulse rate is between 1 and 100 Hz. However, as described below, if mechanical motion is provided to heat element

324

so that it does not continuously contact the skin, high duty cycles and even continuous heating may be provided.

Heat element

324

is optionally attached to a post

340

by a spring

332

and to a post

342

by a spring

330

. These springs maintain tension on heat element

324

even as it expands during the heating phase so that it remains taut against a hair

312

, shown in cross section.

FIGS. 4A and 5

are respective orthogonal cross-sectional views of a hair cutting apparatus

500

, with

FIG. 5

taken along lines V—V of

FIG. 4A

, in accordance with an exemplary embodiment of the invention. Apparatus

500

comprises one or more heat elements

514

,

516

and

518

stretched across a slot

504

in a housing

506

. Slot

504

is, for example, 1.0 centimeter wide to allow a small swath of hair to enter slot

504

for cutting. Alternatively, slot

504

may have a width of 0.5 centimeters or less, to cut an even smaller swath of hair or a width of 2.0 centimeters of more in order to cut a larger swath of hair on each pass.

Heat elements

514

,

516

and

518

, as shown in

FIG. 4A

, are on the same horizontal plane so that they are all, for example, in continuous contact with a portion of skin

524

. Additionally or alternatively, the heights of heat elements

514

,

516

and

518

can be set so that, for example, they are not in contact with skin

524

and cut hairs to a specific length. Alternatively or additionally, heat elements

514

,

516

and/or

518

can have different duty cycles, limiting, for example, the number of heat elements

514

,

516

and/or

518

providing heat at any given time.

A spring

544

(

FIG. 5

) is attached to each heat element

518

(only

518

is shown in

FIG. 5

) to keep it taut even as it expands during heating. Heat element

518

is attached to a power supply

510

, shown schematically. One way of placing heat element

518

so it contacts skin

524

is to provide rods

502

, mounted in walls

506

that are attached to heat element

518

and bring heat element

518

close to skin surface

524

. When heat element

518

is formed in a ribbon, for example, slots may be placed in rods

502

to position and orient ribbon heat element

518

.

FIG. 4B

shows an alternative exemplary embodiment of hair cutting apparatus

500

′ comprising heat elements

514

′,

516

′ and

518

′ that are of different heights in respect a skin surface

524

direction beneath slot

504

′ in housing

506

′. Heat elements

514

′,

516

′ and

518

′ are positioned so that as apparatus

500

′ moves in direction

508

, they sequentially cut a hair

522

′ at different levels in relation to skin surface

524

.

Heat element

518

′, for example, cuts hair

522

′ at two millimeters above skin surface

524

, though it could be positioned to cut hair

518

′ at one millimeter or less or 10 millimeters or more above skin

524

.

Following heat element

518

′, heat element

516

′, for example, cuts hair

522

to a lower level in relation to skin surface

524

, for example one millimeter, though it could be positioned to cut hair

528

at as little as 0.5 millimeters or less as long as 5 millimeters or more.

Following heat element

516

′, heat element

514

′ cuts hair

522

, for example, so it is flush with skin surface

524

, though heat element

514

′ could be set to cut hair

522

at 0.5 millimeters or greater. Alternatively or additionally, when heat element

516

′ is positioned flush with skin surface

524

, it is capable of cutting hair

522

below skin surface

524

due to the fact that heat from heat element

514

′ spreads along shaft of hair

522

, below skin surface

524

′.

For example, heat element

514

′ could cut hair

522

to 0.5 millimeters below skin surface

524

or even one millimeter or more below skin surface

524

, depending, for example, on the magnitude of heat generated and/or duration of contact between heat element

514

′ and skin surface

524

. Other factors affecting the depth to which hair

522

is cut below skin surface

524

include, for example, hair

522

shaft thickness and/or number of hairs

522

contacting heat element

514

′ simultaneously, thereby dissipating the peak heat from heat element

514

′ and diminishing its cutting power.

In an alternative embodiment of the present invention, heat elements

514

′,

516

′ and

518

′ (and/or elements

514

,

516

,

518

) provide pulsed heat. The pulsing of the heat can be simultaneous for heat elements

514

′

516

′ and/or

518

′. Alternatively or additionally, the pulsing of heat from heat elements

514

′,

516

′ and

518

′ may not be simultaneous, allowing lower peak power requirements for apparatus

500

′ during operation.

A bottom

512

(

FIG. 4A

) of housing

506

can be of a variety of shapes that provide, for instance, comfort to skin

524

and/or ease of use. For instance, bottom

512

could be curved with a single curve or with multiple curves.

FIGS. 6 and 7

are cross-sectional and top perspective views of an embodiment of a hair cutting device

600

, cutting a hair

602

, according to an embodiment of the present invention. A plurality of heat elements

604

(shown as round wires) are shown on a cylinder

606

. Heat elements

604

are attached to two end plates

608

, which are urged apart by a spring

610

, keeping heat elements

604

taught in spite of expansion during heating.

A motor (not shown) mechanically rotates a cylinder

606

that supports heat elements

604

in a direction

612

during the hair cutting process. Hair cutting device

600

preferably includes a housing

614

shown in cross-section in

FIG. 6. A

surface

616

of housing

614

contacts the skin. Hair

602

, for example enters housing

614

through a slot

618

, contacts heat elements

604

and are cut.

Slot

618

, for example, is between a few millimeters to 1 cm or more wide, depending on the amount of hair

602

desired to be cut on each pass. It should be noted that heat elements

604

may be in contact with the skin while cutting hair

602

. However, since heat elements

604

move along the skin surface as cylinder

608

rotates, heat elements

604

are not in any one place for a long enough time to cause damage to the skin. Pulsed or continuous heat may be generated from heat elements

602

in this embodiment.

For simplicity, in this and the other embodiments, the location of the power supply and any commutation required to transfer electricity to heat elements

604

is not shown. However, a simple commutator arrangement may be used to electrify end plates

608

and continuously electrify heat elements

604

. Alternatively, end plates

608

are non-conducting and heat elements

604

have their ends connected to a common rotating connection. Alternatively, heat elements

604

are heated only just before they reach slot

618

and the electricity is disconnected from them after they leave the vicinity of slot

618

.

While slot

618

is shown as being open, in some embodiments of the invention, a thin screen is provided over slot

618

through which hairs pass. A screen, for example that is non-heat conducting, comprises a series of slits or a mesh. Even with such a screen, heat elements

604

may be kept in effective contact with the skin surface.

Optionally, in addition to one or more heat elements

604

of one cross sectional size or thickness, an embodiment of hair cutting device

600

includes heat elements

624

of more than one cross-sectional size or thickness.

In an exemplary embodiment, heat elements

604

of different cross sectional sizes are situated on different portions of cylinder

606

so that thicker heat element

624

cuts hair

602

that, for example, is resistant to cutting by heat element

604

.

FIG. 8

shows a bottom perspective view of device

600

in

FIGS. 6 and 7

, in accordance with an exemplary embodiment of the invention.

FIGS. 9A-C

show respective cross-sectional partial side, cross-sectional end and perspective views of an alternative motorized example of a hair cutting apparatus

900

, in accordance with an exemplary embodiment of the present invention. In this embodiment, a plurality of heat elements

904

are mounted between a hub

920

and an outer ring

906

. Hub

920

is formed with a shaft

908

, which is rotated during operation by a motor

912

, which also turns an optional fan,

914

. Alternatively, two motors are provided, one that rotates hub

920

and a second motor that turn fan

914

.

As motor

912

turns, heat elements

904

pass across slots or holes in a faceplate

916

, through which hairs enter the device. The faceplate may be formed with radial or circumferential slots or with openings of round or square shape. The same variations in heating cycles, and electric power described with respect to

FIGS. 6-8

are available for this embodiment.

FIG. 9C

is a possible external view of a hair cutting apparatus embodiment, in accordance with an exemplary embodiment of the invention.

FIGS. 10A and 10B

are schematic representations of hair cutting apparati

1000

and

1002

, equipped with detectors

1070

and

1062

respectively that measure motion and/or velocity, in accordance with an exemplary embodiment of the invention. In apparatus

1000

, optical motion/velocity detector

1070

is shown while in apparatus

10

B, mechanical motion/velocity detector

1062

is shown. Both units

1000

and

1002

provide either pulsed or continuous current that is changed in relation to the motion and/or velocity.

FIG. 10A

shows hair cutting apparatus

1000

with a cross section of a wire heat element

1010

that heats with either pulsed or non-pulsed heat, in accordance with an exemplary embodiment of the invention. A base

1012

regulates the power from a power supply (not shown) to heat element

1010

according to information provided by detector

1070

.

A distance

1042

between wire heat element

1010

and base

1012

, for example, is 30 microns. Additionally or alternatively, distance

1042

is generally 10 microns or less or 40 microns to 0.1 millimeters or more, dependent, for example, upon the flexibility of wire

1010

. For example, when heat element

1010

comprises a flexible material, distance

1042

can be greater than, for example, when heat element

1010

comprises a hard material that does not bend as much.

In an exemplary embodiment, when detector

1070

is configured as a velocity detector, velocity is detected through an optical wave

1020

that reflects from skin

1018

or, for example, a hair

1024

. Velocity detector

1070

can use a variety of methods for determining velocity along a portion of skin

1018

. For instance, an optical wave

1020

can be used to register Doppler shift to determine velocity of unit

1000

. When unit

1000

ceases movement, or moves below a minimal velocity, current to wire heat element

1010

is shut off. Additionally or alternatively, unit

1000

contains a manual switch that can be operated by a user.

Alternatively, detector

1070

can be configured as a motion detector that switches on current to wire heat element

1010

so that it heats only when there is a minimal movement of hair cutting apparatus

1000

in relation to skin surface

1016

.

Optionally, heat element

1010

, for example, produces a continuous current and the level of current is varied in relationship to velocity as detected by detector

1070

. When heat element

1010

moves at a lower speed, for example 20-30 millimeters per second, current is provided to heat element

1010

, for example at 0.5 to one ampere. When the speed of heat element

1010

increases to 30-40 millimeters per second, current is provided to heat element

1010

, for example, from 1 to 1.3 amperes. Above 40 millimeters per second, the level of 1 to 1.3 amperes, for example, is maintained. These figures relating to peak current and/or duty cycle are used, for example, when heat element

1010

is made nickel chromium with a length of 20 millimeters and a diameter of 70 microns and can vary based upon changes in diameter, length and/or material.

FIG. 10B

shows a hair cutting apparatus

1002

with cross sections of heat elements

1030

and

1032

(supported by a base

1050

) that provide heat to cut hair

1024

, in accordance with an exemplary embodiment of the invention. Unit has a mechanical velocity detector

1062

that uses a mechanical wheel

1064

to determine velocity or motion in relation to skin surface

1018

.

Alternatively, a mechanical ball can be used in place of mechanical wheel

1064

, similar to those used in a computer mouse that rolls on skin surface

1018

. As in detector

1070

of unit

1000

, detector

1062

of unit

1002

functions to detect motion whereby current to heat elements

1030

and

1032

ceases below a specific amount of motion. Additionally or alternatively, detector

1062

functions to detect variations in velocity, thereby varying temperature, pulsation rate and/or width in heat elements

1030

and/or

1032

.

Optionally, both heat elements

1030

and

1032

have the same cross section and one or more of the temperature, pulse width and or pulse repetition is changed to both heat elements

1030

and

1032

in response to changes in speed of unit

1002

.

Additionally or alternatively, heat element

1030

is heated to full capacity while heat element

1032

is not heated or, optionally, heated below its maximal heat capacity. When velocity of unit

1002

is slowed, for example, velocity detector

1062

detects the change in speed and signals base

1050

. Base

1050

decreases the temperature of heat element

1030

and/or increases the temperature of heat element

1032

. As heat element

1032

is of a greater offset from skin

1018

, it cuts hair

1024

without causing damage to skin

1018

.

Additionally or alternatively, base

1050

increases the pulse width or the pulse repetition of heat element

1032

to cut hair

1024

at a lower velocity along skin

1018

.

Either motion detector and/or velocity detector

1070

can be configured with units

1000

and/or

1002

, including any of the various embodiments of either unit noted above. To understand the workings of motion detector and/or velocity detector

1070

, reference is now made to

FIGS. 14-18

.

FIG. 14

is an electrical functional block diagram of a section

1000

A of optical hair cutting apparatus

1000

including detector

1070

, power regulating base

1012

and its associated power, in accordance with an exemplary embodiment of the invention. Optical mouse sensor

1070

detects velocity of unit

1000

and signals a regulator

1052

A to regulate power from a power supply

1072

. Alternatively, a mechanical mouse sensor

1062

is utilized in place of optical sensor

1070

.

FIG. 15

is an electrical schematic diagram

1072

(not shown to scale) of pulses from power supply as a result of regulation by regulator

1052

A, in accordance with an exemplary embodiment of the invention. As the velocity of apparatus

1000

or

1002

is at a given level, pulsing from power supply

1072

appears in an area

1502

. Alternatively, as the velocity of apparatus

1000

or

1002

increases, pulsing from power supply

1072

appears in an area

1504

. More frequent pulses with the same pulse width, for example, result in a higher peak temperature.

FIG. 16

is a diagram of pulses from regulator

1052

A on hair cutting apparatus

1000

equipped with velocity detector

1070

or hair cutting apparatus equipped with velocity detector

1062

, in accordance with an embodiment of the present invention. A high repetition rate of pulses

1602

occurs when apparatus

1000

or

1002

moves rapidly in relation to a hair

1024

(FIG.

10

A). A low repetition rate of pulses

1604

occur when apparatus

1000

or

1002

moves slowly in relation to hair

1024

. Both pulses

1604

and

1602

have the same duty cycle.

Additionally or alternatively, detectors

1070

and

1062

of units

1000

and

1002

respectively, may function as motion detectors, providing heat only when a specific minimum speed is reached. Illustrations of detectors

1070

and

1062

in embodiments as motion detectors are provided in

FIGS. 17 and 18

.

FIG. 17

is an electrical schematic diagram of a DC voltage

1706

′ in response to a speed of motion

1706

, in accordance with an exemplary embodiment of the invention. Speed of motion

1706

, for example is sensed by motion detector

1070

(

FIG. 10A

) while DC voltage

1706

′ is controlled by regulator

1052

A on hair cutting apparatus

1000

.

A falling speed of motion

1702

(as sensed by sensor

1070

) that falls below a base level

1704

, causes DC voltage

1706

′ to fall shut off a voltage level

1704

′.

FIG. 11A

is a hair cutting apparatus

1100

with a heat element

1114

situated between a first line of skin depressors

1112

parallel to a second line of skin depressors

1116

that are attached to a base

1110

, in accordance with an exemplary embodiment of the invention. Base

1110

can be made of clear material, for example a clear plastic that maintains the passage of an optical sensor signal through base

1110

. Additionally or alternatively, base

1110

is made of one or more materials, including opaque materials, for example a ceramic or opaque plastic, and the path of an optical sensor signal is set to bypass the opaque areas. Additionally or alternatively, there is no optical sensor signal and heat element

1114