HAIR CUTTING APPARATUS

Abstract: This invention discloses a hair cutting apparatus comprising a housing (10), a source (40) of non-coherent light disposed in the housing (10), a hair entry opening (14) defining in the housing (10) for permitting hair to be cut to enter the housing (10), and optics (42, 44, 46) directing said non-coherent light from said source (40) of non-coherent light along a hair cutting pathway (48) adjacent said hair entry opening (14) for cutting said hair.

Description: HAIR CUTTING APPARATUS FIELD OF THE INVENTION The present invention relates to shavers gener¬ ally and more particularly to radiation operative shav¬ ers. BACKGROUND OF THE INVENTION Laser operative shavers have been proposed in the patent literature. The following references are believed to represent the state of the art in the patent literature. U.S. Patents 1,378,137; 1,720,775 3,093,724; 3, 197,612 3,538,919; 3,659,613; 3,-693,623 3,83 ,391; 3,934,115 4,051,760; 4,089,110; 4,388,924 4,578,558; 4,608,978 4,617,926; 4,819,669; 4,819,669 5,037, 183; 5,038,015 5,043,553; 5,065,515; 5,059,192 5,079,402; 5,093,549 5,182,857; 5,226,907; Published PCT patent applications WO 91/06406; WO 92/16338; WO 93/05920; British Patent 2,123,287; Canadian Patent 1,041,610; French Patent 2,590,791; German Patent 3,220,962. SUBSTITUTESHEET(RULE261 SUMMARY OF THE INVENTION The present invention seeks to provide improved hair cutting apparatus. There is thus provided in accordance with a preferred embodiment of the invention, hair cutting apparatus including: a housing; a source of non-coherent light disposed in the housing; a hair entry opening defining in the housing for permitting hair to be cut to enter the hous¬ ing; and optics directing the non-coherent light from the source of non-coherent light along a hair cutting pathway adjacent the hair entry opening for cutting the hair. There is also provided in accordance with a preferred embodiment of the invention hair cutting appa¬ ratus including: a housing; a source of coherent light disposed in the housing; a hair entry opening defining in the housing for permitting hair to be cut to enter the housing; and optics directing the coherent light from the source of coherent light along a hair cutting pathway adjacent the hair entry opening for cutting the hair into plural pieces, such that a portion of the hair remains attached to skin of a user and another part remains intact and separated therefrom. Preferably, the hair cutting apparatus includes a moustache trimmer disposed in the housing. In accordance with a preferred embodiment of the present invention the hair cutting apparatus also includes a cut hair receptacle removably disposed within the housing. Preferably, the hair cutting apparatus also includes a fluid pump disposed within the housing for providing a fluid flow which draws cut hairs into the receptacle. The fluid pump also preferably provides a fluid flow directed at the optics for maintaining at least a portion of the optics clear of spurious matter. Additionally, the fluid pump also preferably provides a fluid flow directed at either or both the light source and the optics for cooling thereof. The fluid pump is preferably powered by an electric motor which preferably also powers the mous¬ tache trimmer. The hair cutting apparatus preferably also includes electronic control circuitry governing the operation of the source. Preferably, the electronic control circuitry includes at least one detector for determining correct orientation of the light and wherein the electronic control circuitry is operative in the absence thereof, for modifying or terminating operation of the source. In accordance with a preferred embodiment of the present invention, the electronic control circuitry includes at least one detector for determining the exist¬ ence of operative contact between the housing and a user's skin and wherein the electronic control circuitry is operative in the absence thereof, for modifying or terminating operation of the source. Preferably, the hair entry opening defines a plurality of hair entry apertures. In accordance with one embodiment of the invention, the hair entry apertures are formed with tapered side walls arranged such that light from the source impinging thereon is not reflected thereby outside of the housing. In one embodiment of the invention, the hair entry opening is located at a location along the housing having a radius of curvature in at least one plane which is smaller than that the radii of curvature of at least most of the remainder of the housing. Preferably, the hair entry opening includes at least one portion having a thickness which is less than the thickness of at least most of the remainder of the housing. Preferably, the hair cutting apparatus com¬ prises optics which is operative to provide a beam of light impinging on hair to be cut for cutting thereof, the beam having a width which exceeds its height along the hair cutting pathway. In accordance with a preferred embodiment of the present invention, the beam and the hairs are ori¬ ented such that the beam may simultaneously impinge upon multiple hairs along its width and that the extent of its impingement on each hair is approximately equal to the height of the beam. Preferably, the hair cutting apparatus also includes light source operating circuitry for causing the source to emit light in a plurality of relatively short high energy pulses. Preferably, each of the relatively short high energy pulses is configured to produce an at least partially rounded hair stump. In accordance with a preferred embodiment of the present invention, the hair cutting apparatus in¬ cludes a receptacle includes an air permeable filter having odor absorbing capability. Preferably, the recep¬ tacle includes an entry passage which is configured to prevent cut hairs from readily exiting the receptacle therethrough. In accordance with a preferred embodiment of the present invention, the entry apertures are formed with tapered side walls arranged to assist in lifting hairs into cutting engagement with the pathway. There is also provided in accordance with a preferred embodiment of the present invention a hair cutting method comprising: providing a source of non-coherent light dis¬ posed in a housing having a hair entry opening for per¬ mitting hair to be cut to enter the housing; and directing non-coherent light from the source of non-coherent light along a hair cutting pathway adjacent the hair entry opening for cutting the hair. There is additionally provided in accordance with a preferred embodiment of the present invention a hair cutting method comprising: providing a source of light disposed in a housing having a hair entry opening for permitting hair to be cut to enter the housing; and directing non-coherent light from the source of non-coherent light along a hair cutting pathway adjacent the hair entry opening for cutting the hair into plural pieces, such that a portion of the hair remains attached to skin of a user and another part remains intact and separated therefrom. Preferably, the above-describes methods also include providing a fluid flow which carries out at least one of the following functions: draws cut hairs into the receptacle, maintains at least a portion of the optics clear of spurious matter, and cools at least one of the light source and the optics for cooling thereof. Preferably, the method also includes determin¬ ing correct orientation of the light and in response to the absence of correct orientation, modifying or termi¬ nating operation of the source. Preferably, the method also includes determin¬ ing the existence of operative contact between the hous¬ ing and a user's skin and in the absence thereof, modify¬ ing or terminating operation of the source. Preferably, the method also includes causing the source to emit light in a plurality of relatively short high energy pulses. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood and appreciated more fully from the following detailed de¬ scription, taken in conjunction with the drawings in which: Figs. 1A, IB and IC are pictorial illustrations of shaving apparatus constructed and operative in accord¬ ance with a preferred embodiment of the present inven¬ tion; Fig. 2 is a generalized illustration of the optical, electronic and mechanical elements employed in the shaving apparatus of Figs. 1A - IC; Figs. 3A, 3B and 3C are generalized illustra¬ tions of the optical apparatus employed in the shaving apparatus of Figs. 1A - IC in accordance with three alternative embodiments of the present invention; Figs. 4A and 4B simplified illustrations of part of the shaving apparatus of Figs. 1A - 3C; Figs. 5A and 5B are partially cut away illus¬ trations of the shaving apparatus of Figs. 1A - IC in respective shaving and non-shaving orientations; Fig. 6 is a partial illustration of a hair engagement portion of the shaving apparatus of Figs. 1A - IC in hair engagement; Figs. 7A and 7B are sectional illustrations taken along lines A - A and B - B respectively in Fig. 6; Fig. 8A is an illustration of an undesired theoretical construction, such as could be taken along line VIII-VIII of Fig. 6, showing limits of angular regions for beams impinging thereon; Figs. 8B, 8C and 8D illustrate beam paths for various beams for the undesirable construction shown in Fig. 8A; Fig. 9A is a sectional illustration typically taken along line A - A of Fig. 6, showing limits of angular regions for beams impinging thereon for a desired construction; Figs. 9B and 9C illustrate beam paths for various beams for the embodiment of Fig. 9A; Fig. 10 is a simplified illustration of a laser beam used for cutting hair in accordance with a preferred embodiment of the present invention; Fig. 11 is a simplified illustration of a Gaussian distribution of energy of the laser beam of Fig. 10; Figs. 12A and 12B are illustrations of relative portions of the energy of a laser light beam in the embodiment of Fig. 10 which are permitted to escape the enclosure via the hair entry apertures 152 for different disposition angles of walls of the hair entry apertures; Figs. 13A and 13B are illustrations of relative portions of the energy of a non-coherent light beam in the embodiment of Fig. 10 which are permitted to escape the enclosure via the hair entry apertures 152 for dif¬ ferent disposition angles of walls of the hair entry apertures; Fig. 14 illustrates a rounded top edge of a hair entry aperture in accordance with a preferred embod¬ iment of the present invention; Fig. 15 is an illustration of a preferred construction of a hair engagement portion including a hair entry aperture in accordance with a preferred embod¬ iment of the present invention; Figs. 16A and 16B are illustrations of a possi¬ ble shaver construction arrangement; Figs. 17A and 17B are illustrations of a pre¬ ferred shaver construction arrangement; Figs. 18A and 18B are illustrations of another preferred shaver construction arrangement; Fig. 19A is an illustration of a preferred cutting beam ar¬ rangement which also includes plural beam detectors; Fig. 19B is an illustration of a preferred cutting beam arrangement which also includes plural beam detectors sensing an auxiliary test beam; Fig. 20 is an illustration of the provision of a skin contact detector in a shaver in accordance with a preferred embodiment of the present invention; Fig. 21A and Fig. 21B together provide a flow chart illustration of the operation of a shaver employing the sensors of Figs. 19A, 19B and 20; Fig. 22 is a sectional illustration of part of a shaver housing constructed and operative in accordance with a preferred embodiment of the present invention; Fig. 23 is a simplified illustration indicating typical cross sectional dimensions of a hair cutting beam used in the present invention in relation to hairs to be cut; Figs. 24A, 24B and 24C illustrate various stages in hair cutting in accordance with one embodiment of the present invention; Figs. 25A and 25B illustrate various stages in hair cutting in accordance with another embodiment of the present invention; Figs. 26A and 26B are timing diagrams which illustrate two alternative embodiments of pulsed laser operation particularly useful in the present invention; and Figs. 27A and 27B are simplified electrical schematic illustrations of two alternative embodiments of electronic circuitry useful in the embodiment of Fig. 20. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Reference is now made to Figs. 1A, IB and IC which illustrate a radiation operative shaver constructed and operative in accordance with a preferred embodiment of the present invention. The shaver comprises a housing 10 which defines adjacent a first end 12 thereof a hair entry opening 14 and adjacent a second end 15 thereof an air outlet opening 16. The shaver preferably includes a mechanical moustache trimmer 18, as well as an operator controlled three position switch 20, which enables the user to select OFF status (0), radiation shaving only (1) or moustache trimming only (2) . A whisker collection receptacle is indicated at reference numeral 22. Malfunction warning indicators 24 and 26 may also be provided. Reference is now made to Fig. 2, which illus¬ trates in general the optical and mechanical elements employed in the shaving apparatus of Figs. 1A - IC. A light source 40, which may be a coherent light source, such as a diode laser, or a non-coherent light source, such as a Zirconium arc lamp, a Xenon arc lamp or a halogen lamp, directs a beam of light via a collimator lens 42 and a plurality of lenses 44 to a folding prism 46 which directs the beam along a hair cutting path 48 adjacent and generally parallel to hair entry opening 14. When a non-coherent light source is employed, the energy efficiency thereof may be maximized by design¬ ing it such that it either emits a parallel beam which is collected by the optical assembly downstream thereof. Alternatively the light source may provide a converging beam which may be focussed by the optical assembly into a suitable beam shape for hair cutting. Either possibility may be achieved by suitable positioning of reflecting mirrors and/or lenses having positive power as integral parts of the light source, taking into account the posi¬ tion and design of the lamp filament. In accordance with one embodiment of the inven¬ tion, the path 48 may terminate at a termination element 50. Termination element 50 may be a beam absorber and may include a detector. Alternatively, the beam absorber may be replaced by a reflecting element which is opera¬ tive to reflect the beam and thus provide a multiple- traversal hair cutting path. Under certain circum¬ stances, it may be necessarily to provide a flow of pressurized air to termination element 50 in order to keep it free of debris. This may be accomplished in a manner similar to that shown in Fig. 2 for prism 46. The region traversed by hair cutting path 48.is partially enclosed by a removable enclosure 52 which forms part of receptacle 22 (Fig. IB). Coupled to the interior of enclosure 52 is an inlet 53 to a vacuum pump 54 which is controlled by control electronics 56 and which causes cut hairs and other debris to be drawn into engagement with a filter 58 disposed within enclosure 52 and preferably away from hair cutting path 48. The vacuum pump 54 provides two air outputs. One such output is supplied via an air cleaning filter 60 to the region adjacent prism 46 for blowing away cut hairs or other debris therefrom and for maintaining positive air pressure along the optical path between the light source 40 and the prism 46, thereby to reduce ingress of contaminants thereto. A second air output is supplied to the region adjacent light source 40 and collimating lens 42, for cooling thereof. The second air output is vented through air outlet opening 16 (Figs. IB and IC) . Control electronics 56 will be described here- inbelow in greater detail and is at least partially responsive to inputs from various detectors along path 48 for governing the proper operation of the light source 40 and the vacuum pump 54. Reference is now made to Fig. 3A which illus¬ trates the optical elements employed in the shaving apparatus of Figs. 1A - IC when a coherent light source 80, such as a gallium arsenide diode laser, is employed. The coherent light source 80 directs a beam of light via a collimator lens 82 and a plurality of cylindrical lenses 84 to a folding prism 86 which directs the beam along a hair cutting path 88 adjacent and generally parallel to hair entry opening 14. In accordance with one embodiment of the inven¬ tion, the path 88 may terminate at a beam absorber 90, which may include a detector. Alternatively, beam absorb¬ er 90 may be replaced by a reflecting element which is operative to reflect the beam and thus provide a multi¬ ple-traversal hair cutting path. Reference is now made to Fig. 3B, which illus¬ trates the optical elements employed in the shaving apparatus of Figs. 1A - IC when a non-coherent light source 100, such as a Zirconium, Xenon or halogen light source, is employed. In this embodiment the light source 100 directs a beam of light via a plurality of lenses, indicated for example by reference numerals 102, 103, 104 and 105. These lenses are preferably either coated or colored so as to provide filtering to a plurality of narrow bands, such as, for example, the bands in the near InfraRed (IR) region between 750 nm and 980 nm, in the visible region between 480 nm and 680 nm, and in the Ultra Violet (UV) region between 330 nm and 480 nm. The actual filtered bands may have a Full Width At Half Maximum (FWHM) band width typically less than lOnm. For example lenses 102, 104 and 105 may be either coated or colored so as to absorb light of given wavelengths and lens 103 may be coated so as to reflect light of another given wavelength. Any other suitable combination of lenses having absorption and/or reflection properties may alternatively be employed. The filtered light output from light source 100 is reflected by a folding prism 106 which directs the beam along a hair cutting path 108 adjacent and generally parallel to hair entry opening 14. Alternatively filter¬ ing may be achieved by employing a discrete filter in addition to the lenses 102 - 105. It is noted that the filter coatings on the lenses 103 are operative to reflect light away from the lenses and into the interior of housing 10. This provides a relatively efficient heat dispersion result and pre¬ vents localized overheating of individual optical ele¬ ments or particular regions of the housing 10. Reference is now made to Fig. 3C, which illus¬ trates another embodiment of the optical elements em¬ ployed in the shaving apparatus of Figs. 1A - IC when a non-coherent light source 120, such as a Zirconium, Xenon or halogen light source, is employed. In this embodiment the light source 120 directs a beam of light via a collimator lens 122 and a plurality of lenses 124 which are not coated to provide filtering as in the embodiment of Fig. 3B. Substantially the total light output from light source 120 is reflected by a folding prism 126 which directs the beam along a hair cutting path 128 adjacent and generally parallel to hair entry opening 14. Reference is now made to Figs. 4A and 4B, which are simplified illustrations of part of the shaving apparatus of Figs. 1A - 3C. Fig. 4A illustrates a remova¬ ble cut hair receptacle assembly employed in accordance with a preferred embodiment of the present invention. The assembly of Fig. 4A includes a removable receptacle 130 including an end wall 132 having formed thereon a protrusion or recess 134 for enabling it to be grasped by a user and pulled out of the shaver housing 10. Aside from the end wall 132, the receptacle 130 may be formed of an air porous mesh 135, which is reinforced by ribs 136. The end wall 132 may be separable from the mesh 135 to enable easy emptying of the receptacle. Alternatively, any other suitable emptying arrangement may be made. A microswitch 133 is preferably provided to sense removal of the receptacle 130 and to disable shaver operation when the receptacle is removed. Air porous mesh 135 may also be operable to absorb unpleasant odors from the hair cutting operation and is preferably operative to absorb, rather than reflect, light beams which may inad¬ vertently impinge thereon. Mesh 135 typically functions as the filter 58 described generally with reference to Fig. 2. A pair of walls 137 and 138 define an entry passage 139 communicating with the hair entry opening 14 of shaver housing 10 for receiving cut hairs. The walls 137 and 138 are inclined so as to prevent, insofar as possible, most of the cut hairs from exiting the recepta¬ cle 130 via the entry passage 139, as will be described herein in connection with Figs. 5A and 5B. Receptacle 130 is slidably engageable within enclosure 52 (Fig. 2) and mesh 135 preferably defines filter 58 mentioned above in connection therewith. Fig. 4B illustrates mechanical apparatus for operating the moustache trimmer 18 (Fig. IB). The appara¬ tus includes a clutch 140 which includes a first clutch plate 141 which is fixed to an output shaft 142 of motor 55 and a second clutch plate 143 which is coupled via a shaft 144 to an eccentric drive element 145, which en¬ gages a cam 146 in a moustache cutting blade 147. Blade 147 is thus driven in vibratory motion indicated by arrows 148 relative to a static blade 149. Second clutch plate 143 is coupled to three position switch 20 by a connecting element 151, for selectable operation of the moustache trimmer 18. Reference is now made to Figs. 5A and 5B, which are partially cut away illustrations of the shaving apparatus of Figs. 1A - IC in respective shaving and non- shaving orientations. It is seen that during shaving, shown in Fig. 5A, cut hairs enter the receptacle 130 via entry passage 139. When the shaver is oriented in a non- shaving orientation, as shown in Fig. 5B, the inclined orientation of walls 137 and 138 prevents most of the hairs from exiting the receptacle 130 via the entry passage 139. Fig. 5A also illustrates how the vacuum gener¬ ated by the pump 54 (Fig. 2) draws the hair bearing skin surface into the hair entry opening 14. Reference is now made to Figs. 6, 7A and 7B which are illustrations of a preferred embodiment of a hair engagement portion 150 of the shaving apparatus of Figs. 1A - IC, defining hair entry opening 14 (Fig. 1A) . The hair engagement portion 150 defines a multiplicity of hair entry apertures 152, one of which is shown in hair engagement. A typical principal direction of movement of the shaving apparatus relative to the skin of a user, is indicated by an arrow 153. It may be appreciated that the configurations illustrated in Figs. 7A and 7B are intended to assist in lifting hairs into cutting engagement with the beam and straightening the hairs such that they are cut as close to the skin as possible. It is seen that the angles B and C along which the sides 154 of the hair entry apertures 152 are disposed, may differ from each other along the periphery of the aperture, as indicated by Figs. 7A and 7B. Alternatively, the apertures may be formed with conical walls. Reference is now made to Figs. 8A - 8D which show a undesirable structure for the hair engagement portion shown in Fig. 6. Fig. 8A is a sectional illustra¬ tion taken along line VIII-VIII of Fig. 6, showing limits of angular regions for beams impinging thereon. Angle Al is given by the following expression: Al = arctan 0.5h/L Angle A2 is given by the following expression: A2 = arctan h/L where L is the longitudinal opening parallel to the beam axis; and h is the thickness of the hair engagement portion, as shown in Figs. 8A - 8D. It is seen that in the undesirable structure illustrated in Figs. 8A - 8D, the side walls of hair entry apertures 150 are perpendicular to the plane of the hair engagement portion. In the illustrated structure, all light which travels towards an aperture side wall 154 in a direction which is at more than 90 degrees with respect to the side wall 154 eventually passes outside of the enclosure defined in part by the hair engagement portion. Figs. 8A and 8C show that a light beam imping¬ ing on side wall 154 at an angle A4 between angles Al and A2 with respect to the perpendicular to side wall 154 is reflected off side wall 154 and exits the enclosure. Fig. 8B shows that a light beam whose direction lies at an angle A3, which is greater than angle A2, exits the enclosure without impinging on side wall 154. Fig. 8D shows that a light beam whose direction lies at an angle A5, which is less than Al but greater than 90 degrees with respect to side wall 154 undergoes multiple reflections from the side walls but eventually exists the enclosure. Reference is now made to Figs. 9A - 9C which show a desirable structure for the hair engagement por¬ tion shown in Fig. 6. Fig. 9A is a sectional illustration taken along line VIII-VIII of Fig. 6, showing limits of angular regions for beams impinging thereon. Angle B2 is given by the following expres- sion: B2 = arctan k/D where W is the longitudinal opening parallel to the beam axis at the outside surface of the hair engagement por¬ tion; k is the thickness of the hair engagement portion, as shown in Figs. 9A - 9C; T is inclination angle after each individual open¬ ing; and D is the distance indicated in Fig. 9A. It is seen that in the desirable structure illustrated in Figs. 9A - 9C, the side walls 162 and 164 of hair entry apertures 150 are tapered towards each other from the interior of the housing to the exterior thereof. Figs. 9A and 9B show that a light beam directed towards side wall 162 at an angle B3 greater than B2 exits the enclosure without impinging on side wall 162. Fig. 9C shows that a light beam whose direction lies at an angle B4, which is less than angle B2 is reflected off side wall 162 back towards the inside of the enclosure. In accordance with a preferred embodiment of the present invention the opposite side wall 164 of each hair entry aperture may be angled at an opposite but equal angle to that of side wall 162, but one which tapers towards the opposite side wall from the interior of the housing to the exterior thereof. Thus, if a beam impinges upon side wall 164 in directions opposite to those described hereinabove in connection with side wall 162, equivalent results will be achieved. Further in accordance with an embodiment of the present invention, the hair entry apertures may be con¬ figured to have conical side walls, such that their angular configuration is identical along any section taken perpendicular to the plane thereof. Reference is now made to Figs. 10 - 12B which illustrate, not necessarily to scale, the laser beam used for cutting hair and the Gaussian distribution of energy thereof. Fig. 10 shows in a generalized form the cutting beam 270 which is typically reflected from prism 46 (Fig. 2) . P is shown as the distance between the reflected optical axis of the beam at its intersection with prism 46 and the internal surface of the hair engagement portion and J is shown as the distance from the. above point of inter¬ section to the furthest opening in the hair engagement portion. Fig. 11 illustrates the Gaussian energy distri¬ bution of beam 270 at a given location along beam 270. It may be seen from a consideration of Fig. 12A that for a laser beam when T is less than or equal to 0 in the context of Figs. 9A - 9C, (e.g. the example of Figs. 8A - 8D) a substantial portion of the energy is allowed to exit the enclosure. If T is selected to be greater than 0, however, as indicated in the example of Figs. 9A - 9C, only approximately 10~ 6 of the energy is permitted to exit the enclosure, as indicated in Fig. 12B. By a consideration of Figs. 12A and 12B, it is seen that the energy indicated in the Gaussian between angles G and B2 is prevented from exiting the enclosure by virtue of the inclined orientation of the walls of the hair entry aperture 152, as shown in Figs. 9A - 9C. Referring now to Figs. 13A and 13B, it may be seen that for a Zirconium, Xenon or halogen light beam even when T is less than or equal to 0 in the context of Figs. 9A - 9C, (e.g. the example of Figs. 8A - 8D) a substantial portion of the energy is not allowed to exit the enclosure. If T is selected to be greater than 0, however, as indicated in the example of Figs. 9A - 9C, substantially no energy is permitted to exit the enclo¬ sure, as indicated in Fig. 13B. Reference is now made to Fig. 14 which illus¬ trates a preferred embodiment of the top edge 280 of the hair entry aperture 152. As illustrated in Fig. 14, it is preferred that the portion of the top edge 280 along which a beam 282 may impinge tangentially be rounded, so as to minimize diffraction which would occur were the edge to be sharp. Fig. 15 illustrates a preferred configuration of a hair engagement portion 300 which is characterized in that the regions defining hair entry apertures 302 are raised inwardly away from the skin of the user, designat¬ ed by reference numeral 304. This configuration enables a relatively smooth shaving surface to be presented to the user's skin while maintaining the desired angle T of the side walls 306 of the hair entry apertures 302. Alterna¬ tively, a hair engagement portion may be provided defin¬ ing hair entry apertures which are raised outwardly towards the skin of the user. Reference is now made to Figs. 16A and 16B, which are illustrations of a possible shaver construc¬ tion arrangement. The configuration of Figs. 16A and 16B, which is not preferred, locates a hair engagement portion 320 at a portion of the housing 322 having a relatively large radius r 1 which is identical to the general radius R l wh i ch extends over a relatively large area of the housing. Using this configuration, it is relatively easy for a user to position the housing incorrectly with respect to his skin, indicated by reference numeral 324, such that the hair engagement portion 320 is not optimal¬ ly located with respect thereto, as exemplified in Fig. 16B. An ideal orientation of the hair engagement portion 320 is shown in Fig. 16A, where the plane of the hair engagement portion lies perpendicular to the skin surface 324. Reference is now made to Figs. 17A and 17B which are illustrations of a preferred shaver construc¬ tion arrangement. Here the area surrounding a hair en¬ gagement portion 340 has a smaller radius r2, as compared with the radius R2 of the lower portion of the corre¬ sponding housing 342. Using this configuration, improper positioning of the housing with respect to the skin surface 344, does not space the hair engagement portion significantly away from the skin surface as in the embod¬ iment of Fig. 17B. Furthermore, the relatively small radius of the housing adjacent the hair engagement por¬ tion 340 enables the hair engagement portion to be pressed against and into the skin surface 344 so as to maintain reasonably good shaving engagement therewith. Reference is now made to Figs. 18A and 18B, which are illustrations of another preferred shaver construction arrangement. Here the area surrounding a hair engagement portion 360 has an even smaller radius r3, as compared with the radius R3 of the lower portion of the corresponding housing 362. Using this configura¬ tion, improper positioning of the housing with respect to the skin surface 364, does not space the hair engagement portion significantly away from the skin surface as in the embodiment of Fig. 18B. Here, the very small radius of the housing adjacent the hair engagement portion 360 enables the hair engagement portion to be readily pressed against and into the skin surface 364 so as to maintain reasonably good shaving engagement therewith. Reference is now made to Fig. 19A, which is an illustration of a preferred cutting beam arrangement of the type shown in Fig. 2, which also includes plural beam detectors. An input radiation beam 380 is principally reflected by a prism 382 to define a cutting beam 384 which travels generally parallel to a hair engagement portion 386 and impinges onto a radiation beam detector 388. A relatively small part of the energy of radiation beam 380 is not reflected by prism 382 but is reflected by a downstream prism 390 and is focussed by lenses 392 onto a second detector 394. The purpose of providing plural detectors is to verify proper beam delivery from the light source to the prism independently of verification of proper orientation of the cutting beam 384. Thus, if proper beam delivery is indicated but proper orientation of the cutting beam 384 is not, an indication may be given to the user that cleaning of the vicinity of the hair engagement portion 386 is required. Furthermore, and perhaps more impor¬ tantly, if proper beam delivery is not indicated, the shaver may be disabled until it is serviced by an author¬ ized person. Reference is now made to Fig. 19B, which is.an illustration of a preferred cutting beam arrangement which also includes plural beam detectors sensing an auxiliary test beam. The auxiliary test beam is provided by means of an auxiliary light source 400 such as a GaAlAs or InGaAsP LED, for example a Model SDL-2380, manufactured by Spectra-Diode Labs (SDL) of San Jose, California, U.S.A., and associated optics 402 and a beam splitter 404 and enables the integrity of the imaging optics of the device to be confirmed before a high energy beam is directed therealong. In this case the detectors and detector optics are chosen to correspond to the test beam and are indicated respectively by reference numerals 389, 395 and 393. In this case, sensor 389 is preferably operative to absorb only the light from auxiliary light source 400 and is operative to reflect high intensity light from the cutting beam, so as not to be damaged thereby. Fig. 20 illustrates the use of a skin contact sensor 410 in a shaver. The sensor 410 operates in con¬ junction with sensor electronics 412, which forms part of electronics 56 (Fig. 2) Two alternative embodiments of electrical circuitry forming part of the sensor electron- ics 412 are illustrated in Figs. 27A and 27B. Referring now to Fig. 27A, there is shown electronic circuitry comprising a resistance bridge 414 which is coupled to a pair of skin contact electrodes 416 and 418 forming part of sensor 410. The resistance bridge 414 comprises three resistors, 420, 422 and 424, each preferably of identical resistance, such as 15 Kohm. A DC voltage source 417 is coupled across the junction between resistor 420 and electrode 416 and the junction between resistors 422 and 424. A voltage amplifier 426 is coupled across the junction between resistor 424 and electrode 418 and the junction between resistors 420 and 422. The output of the voltage amplifier is supplied to a comparator 428, which provides a digital output. Referring now to Fig. 27B, there is shown electronic circuitry comprising a capacitance bridge 434 which is coupled to a pair of skin capacitance electrodes 436 and 438, one of which may comprise the hair engage¬ ment portion, and another of which may form part of sensor 410. The capacitance bridge 434 comprises three capacitors 440, 442 and 444, each preferably of identical capacitance. An oscillator 447 is coupled across the junction between capacitor 440 and electrode 436 and the junction between capacitors 442 and 444. A voltage amplifier 446 is coupled across the junction between capacitor 444 and electrode 438 and the junction between capacitors 440 and 442. The output of the voltage amplifier is supplied to a comparator 448, which provides a digital output. Reference is now made to Figs. 21A and 21B which together provide a flow chart illustration of the operation of control electronics 56 (Fig. 2) in a shaver employing the sensors of Figs. 19A, 19B and 20. Two modes of operation are available and controllable by the three position switch 20 (Fig. IB). If a moustache trimmer mode is selected, the cutting beam is not enabled and the moustache trimmer 18 is operated. If a shaver mode of operation is selected, the input radiation beam 380 is operated initially at low intensity. The output of sensor 394 (Fig. 19A) indicates initially whether the beam 380 is properly directed. If not, the light source 40 (Fig. 2) is turned off, thus turning off beam 380. A malfunction warning indicator 24 (Fig. 1A) is illuminated. The operation of the entire shaver is then disabled until it is reset by service personnel. If sensor 394 indicates that the beam 380 is properly directed, sensor 388 (Fig. 19A) indicates wheth¬ er the cutting region between prism 382 and sensor 388 is clear. If the cutting region is clear, a skin contact sensor 410 (Fig. 20) indicates whether the hair engage¬ ment portion is in hair cutting engagement with the skin of the user. If so, shaving operation begins, and beam 380 is provided at high intensity. If the cutting region is not clear, a malfunc¬ tion warning indicator 26 (Fig. 1A) is illuminated. The user may then clean the cutting area, using a brush or other suitable implement. If the malfunction warning indicator is extinguished following cleaning and the skin contact sensor 410 indication is received, shaving opera¬ tion begins, and beam 380 is provided at high intensity. If the malfunction warning indicator 26 remains illuminated after cleaning, another attempt may be made to clean the cutting area. If it is successful, and the indicator 26 is extinguished, and the skin contact sensor 410 indication is received, shaving operation begins, as described above. If the malfunction warning indicator 26 remains illuminated after further cleaning, the receptacle 22 may be cleaned or replaced. Upon removal of the receptacle 22, the action of microswitch 133 (Fig. 4A) should cause the shaver to be turned off. If the shaver is not turned off due to some malfunction, the cutting beam 380 is nevertheless immediately turned off. In either event, following cleaning of the receptacle, the user may turn the shaver on again and begin the operation anew. Shaving operation takes place so long as sensor 410 indicates that the hair engagement portion is in hair cutting engagement with the skin of the user. Upon inter¬ ruption of hair cutting engagement with the skin for at least a predetermined time, such as 100 msec, the cutting beam is turned off. Following turning off of the cutting beam, and a suitable delay, the beam is operated at low intensity. Thereafter, the beam is only turned on at high intensity if positive indications are received from sensors 388 and 410. . The operation of the shaver has been described hereinabove for an embodiment according to Fig. 19A. The operation is similar for the embodiment of Fig. 19B, wherein the low energy level operation of the light source is replaced by operation of the auxiliary light source 400 for determining whether the cutting region is clear. According to an alternative embodiment of the present invention, which is not preferred, the various sensors may be eliminated. In such a case, the function¬ ality described hereinabove with reference to Figs. 21A and 21B is reduced to a degenerate case. Reference is now made to Fig. 22, which is a sectional illustration of part of a shaver housing con¬ structed and operative in accordance with a preferred embodiment of the present invention. Here it is seen that the hair engagement portion 420 is formed as a relatively thin insert in a housing 422 and has a non-uniform thick¬ ness. In this way, the mechanical strength of hair en¬ gagement portion 420 may be maximized, while permitting the thickness of the hair engagement portion adjacent the cutting beam 384 to be relatively small. Alternatively, the hair engagement portion 420 may be integrally formed with all or part of the housing 422. Reference is now made to Fig. 23 which is a simplified illustration indicating typical cross section¬ al dimensions of a hair cutting beam 384 (Fig. 19A) used in the present invention in relation to hairs to be cut for a laser source. Both for laser and Zirconium, Xenon or halogen light sources, the width of the beam is great¬ er, preferably by a factor of at least 2, than its depth along the axis of hair to be cut. In Fig. 23 it is seen that preferably, when a laser is employed, the width of the beam may be approxi¬ mately 0.5 mm and its thickness (along the axis of hair to be cut) may be typically 0.2 mm. The cutting beam cross section is generally rectangular or elliptic and indicated by reference numeral 430. One or more hairs, indicated by reference numeral 432 may lie in the cutting beam at any time. Any other suitable cutting beam cross sectional configurations may alternatively be provided. It is to be appreciated that although the cutting beam is shown in Fig. 23 as a perfectly collimated beam, in fact, it is a focused beam and exhibits divergence which is not illustrated. Reference is now made to Figs. 24A, 24B and 24C, which illustrate various stages in hair cutting in accordance with one embodiment of the present invention. A consideration of Figs. 24A, 24B and 24C shows that cutting the hair using a laser beam in accordance with the present invention preferably causes a part 440 of the hair to be blown away, leaving a part 442 of the hair attached to the skin and another part 444 of the hair loose, to be collected in receptacle 22 (Fig. IB). Reference is also made to Figs. 25A and 25B, which illustrate various stages in hair cutting in ac¬ cordance with another embodiment of the present inven- tion. Here, the hair is cut into only two pieces. This result may replace that illustrated in Figs. 24A - 24C depending on the power of the laser or other light source employed and depending on the color or other characteris¬ tics of the hair to be cut. It is a particular feature of the present invention that cutting according to the present inven¬ tion, as shown in either Figs. 24A - 24C or Figs. 25A and 25B provides a somewhat rounded and less sharp cut of the hair attached to the skin, and thus provides a smoother feel to the user. The smoothness of the shave, to the extent that it depends on the configuration of the cut end of the hair remaining on the user's skin, may be affected by the nature and the timing of the cutting beam employed. Figs. 26A and 26B are timing diagrams which illustrate two alternative embodiments of pulsed laser operation partic¬ ularly useful in the present invention, which have been found experimentally to provide satisfactory results in terms of rounded cutting of hair. In the embodiment of Fig. 26A, a series of discrete multi-level pulses are employed, each having a typical duration of 10 msec. In the embodiment of Fig. 26B, a continuous varying level pulse is provided, with a periodicity of approximately 13 msecs. In both cases, the high power portion of the pulse has a preferred duration of about 2 msec, the low power portion of the pulse has a preferred duration of about 8 msecs and the pulses are preferably separated by about 3 msecs. The preferred ration of power between the high power portion and the low power portion is approximately 2 - 3: 1. It is to be appreciated that any suitably shaped waveform and pulse timing may be employed in accordance with a preferred embodiment of the invention. It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. The scope of the present invention, as defined by the claims, is intended to also include equivalents of the embodiments described hereinabove.

Claims: C L A I M S 1. Hair cutting apparatus comprising: a housing; a source of non-coherent light disposed in the housing; a hair entry opening defining in the housing for permitting hair to be cut to enter the hous¬ ing; and optics directing said non-coherent light from said source of non-coherent light along a hair cutting pathway adjacent said hair entry opening for cutting said hair. 2. Hair cutting apparatus comprising: a housing; a source of coherent light disposed in the housing; a hair entry opening defining in the housing for permitting hair to be cut to enter the housing; and optics directing said coherent light from said source of coherent light along a hair cutting pathway adjacent said hair entry opening for cutting said hair into plural pieces, such that a portion of said hair remains attached to skin of a user and another part remains intact and separated therefrom. 3. Hair cutting apparatus according to either of claims 1 and 2 and also comprising a moustache trimmer disposed in said housing. 4. Hair cutting apparatus according to any of the preceding claims and also comprising a cut hair recepta¬ cle removably disposed within said housing. 5. Hair cutting apparatus according to claim 4 and also comprising a fluid pump disposed within said housing for providing a fluid flow which draws cut hairs into said receptacle. 6. Hair cutting apparatus according to claim 5 and wherein said fluid pump also provides a fluid flow di¬ rected at said optics for maintaining at least a portion of said optics clear of spurious matter. 7. Hair cutting apparatus according to either of claims 5 and 6 and wherein said fluid pump also provides a fluid flow directed at at least one of said light source and said optics for cooling thereof. 8. Hair cutting apparatus according to any of claims 5 - 7 and also comprising an electric motor power¬ ing said fluid pump. 9. Hair cutting apparatus according to claim 3 and claim 8 and wherein said electric motor also powers said moustache trimmer. 10. Hair cutting apparatus according to any of the preceding claims and also comprising electronic control circuitry governing the operation of said source. 11. Hair cutting apparatus according to claim 10 and wherein said electronic control circuitry comprises at least one detector for determining correct orientation of said light and wherein said electronic control cir¬ cuitry is operative in the absence thereof, for modifying or terminating operation of said source. 12. Hair cutting apparatus according to either of claims 10 and 11 and wherein said electronic control circuitry comprises at least one detector for determining the existence of operative contact between the housing and a user's skin and wherein said electronic control circuitry is operative in the absence thereof, for modifying or terminating operation of said source. 13. Hair cutting apparatus according to any of the preceding claims and wherein said hair entry opening defines a plurality of hair entry apertures. 14. Hair cutting apparatus according to claim 13 and wherein said hair entry apertures are formed with tapered side walls arranged such that light from said source impinging thereon is not reflected thereby outside of the housing. 15. Hair cutting apparatus according to any of the preceding claims and wherein said hair entry opening is located at a location along the housing having a radius of curvature in at least one plane which is smaller than that the radii of curvature of at least most of the remainder of the housing. 16. Hair cutting apparatus according to any of the preceding claims and wherein said hair entry opening includes at least one portion having a thickness which is less than the thickness of at least most of the remainder of the housing. 17. Hair cutting apparatus according to any of the preceding claims and wherein said optics is operative to provide a beam of light impinging on hair to be cut for cutting thereof, said beam having a width which exceeds its height along said hair cutting pathway. 18. Hair cutting apparatus according to claim 17 and wherein the beam and the hairs are oriented such that the beam may simultaneously impinge upon multiple hairs along its width and that the extent of its impingement on each hair is approximately equal to the height of the beam. 19. Hair cutting apparatus according to any of the preceding claims and also comprising light source operat- ' ing circuitry for causing said source to emit light in a plurality of relatively short high energy pulses. 20. Hair cutting apparatus according to claim 19 and wherein each of the relatively short high energy pulses is configured to produce an at least partially rounded hair stump. 21. Hair cutting apparatus according to claim 4 and wherein said receptacle comprises an air permeable filter having odor absorbing capability. 22. Hair cutting apparatus according to claim 4 and wherein said receptacle comprises an entry passage which is configured to prevent cut hairs from readily exiting said receptacle therethrough. 23. Hair cutting apparatus according to claim 13 and wherein said hair entry apertures are formed with tapered side walls arranged to assist in lifting hairs into cutting engagement with said pathway. 24. A hair cutting method comprising: providing a source of non-coherent light dis¬ posed in a housing having a hair entry opening for per¬ mitting hair to be cut to enter the housing; and directing non-coherent light from said source of non-coherent light along a hair cutting pathway adja- cent said hair entry opening for cutting said hair. 25. A hair cutting method comprising: providing a source of light disposed in a housing having a hair entry opening for permitting hair to be cut to enter the housing; and directing non-coherent light from said source of non-coherent light along a hair cutting pathway adja¬ cent said hair entry opening for cutting said hair into plural pieces, such that a portion of said hair remains attached to skin of a user and another part remains intact and separated therefrom. 26. A method according to claim 24 or claim 25 and also comprising providing a fluid flow which draws cut hairs into said receptacle. 27. A method according to any of claims 24 - 26 and also comprising providing a fluid flow directed at said optics for maintaining at least a portion of said optics clear of spurious matter. 28. A method according to any of claims 24 - 26 and also comprising providing a fluid flow directed at at least one of said light source and said optics for cool¬ ing thereof. 29. A method according to any of claims 24 - 28 and also comprising determining correct orientation of said light and in response to the absence of correct orienta¬ tion, modifying or terminating operation of said source. 30. A method according to any of claims 24 - 29 and also comprising determining the existence of operative contact between the housing and a user's skin and in the absence thereof, modifying or terminating operation of said source. 31. A method according to any of claims 24 - 30 and wherein the beam and the hairs are oriented such that the beam may simultaneously impinge upon multiple hairs along its width and that the extent of its impingement on each hair is approximately equal to the height of the beam. 32. A method according to any of claims 24 - 31 and also comprising causing said source to emit light in a plurality of relatively short high energy pulses.

Inventors: KELMAN ELLIOT, KELMAN, ELLIOT
Applicants: KELMAN ELLIOT, KELMAN, ELLIOT
Application year: 1995
Main classification: B26B21
IPC codes: A61B18, B23K26, B26B19