US2827693A - Mechanical shaver head having cutter bars of reduced thickness - Google Patents

Description

March 25, 1958 P. KOBLER 2,827,693

MECHANICAL SHAVER HEAD HAVING CUTTER BARS OF REDUCED THICKNESS Filed Nov. 9, 1953 Has ' ]NVENTOR.. v k

into the cutting slots and the strength of the cutting niterl tates Patent strength of the cutting member as its breadth is only a fraction not more than one-tlird of the breadth of 2,s27,es3

the most efiective cutting zone. It has been found that MECHANICAL SHAVER HEAD HA I G CUTTER the wear of the cutting member due to long use of the BARS {)F REDUCED THICKNESS 5 apparatus extends to the mentioned thinned portion to a small extent onl If, for exam le, the re-shaving Paul Kgbler Lynbmsk to Victor Kobier zone is worn out trim a thickness of 0.l mm. to a thickand Kobse! bath of lunch switzefland ness of 0.07 mm. the thinned portion will practically ppli ation November 9, 1953, Serial No.391,003 keep its thickness of 0.02 mm. so that the strength of the shearhead is not im aired. The reason therefor lies Claims pnomy application Swltzefland June 1953 in the fact that the thinn ed portion, due to its small thick- 2 Cl (CL 30 ness is resilient and escapes the attack of the inner cutting member. It has further been found that apparatus, the cutting member of which has a thickness of 0.06 mm. T apPhcatlen is a Continuation-impart Of y PP or less over a larger region of its cutting zone and at Canon Serial fi y 9, 1952, r S earleast in the most effective cutting region, are rapidly head for y Shaving App ratus. now Patent No. worn out to the thickness of ca. 0.04 mm., which is abso- 39,380, dated March 27, 1956. lutely necessary to give the necessary strength to the The present invention relates to an electrical dry shavshearhead.

3 ppa of h yp having at leest one Sheafheed If, one the other hand, the thickness of the most effeccompflslng a siatlellery Outer Cuttlhg member and an tive half of the cutting portion decreases continuously inner eutthlg member fecipfoeahle Within and i i iin direction of the middle of said portion, such apparatus nally of said outer cutting member for cooperation thereha no broad pre-shaving zone as the skin enters relawith. tively deeply into the cutting slots. This drawback too, As Is known In the an, the e g 0f the l is avoided in the apparatus of the present invention. is effected, in apparatus of the mentioned closed type, The benefit of the invention are obtained more espesuccessively over the whole breadth of the shearhead, namely in apparatus of the sieve construction by the successive openings of the sieve and in apparatus of the slot construction by increasing entering of the skin into cially by providing heavier and thus, stronger parts immediately adjacent the inner portion of the shear-head used for close shaving, in the longitudinal direction as well as in the transverse direction.

the slots. i The features of novelty of the invention are of especial It 1s one Of the ohleets 0f the Pf lhvefltlento advantage when they are located toward the center of a provide an apparatus of the aforementioned type, in which curved shear-head.

the shearhead is provided with a broadest possible preshaving zone, in which the thickness of the outer cutting member is kept as small as possible to enable a closest possible shave without irritation of the skin by the inner cutting member, and without unduly reducing the resistance to wear and tear of the shearhead. Thereby the cutting region is of such arrangement that perfect close shaving is possible in spite of the relatively great thickness of the greater part of outer cutting member. According to this invention this aim is attained in that Other objects and advantages of the invention will become apparent from the description now to follow of a preferred embodiment thereof, in which reference will be had to the accompanying drawing, in which:

Fig. 1 is a longitudinal section through a shearhead of a dry shaving apparatus according to the invention;

Fig. 2 is a plan view of the most effective half of the cutting zone of the apparatus at an enlarged scale;

Fig. 3 shows in perspective part of the apparatus, with portions thereof cut away to show its transverse section; the cutting zone of the outer cutting member has an at Figs, 4 and 5 Show at an enlarggd scale partial crossleast substantially constant thickness over at least half Sections along li IV IV and V-V, respectively, of of its extent, whereby an elongated, thinned portion is Fi 2; provided, in the most efiective zone, the breadth of said Fi 6, 7 d 3 a e longitudinal sections, taken on thinned Portion being only a fraction of not more than lines VI-VI, VII-VII and VIII-VIII, respectively of one-third of the corresponding dimension of said most Fi 4 d 5; efiective zone and further being elevated with respect to Fi 9 i a l iew of the most efiective half of the the immediately adjacent portion of the cutting member. cutting Zone f an lt rnative embodiment;

Because of the aforementioned practically constant Fig 10 is a Plan View f a dry Shaving apparatus h thickness of the greater part of the most efiective part i three h h d 0f the eutfihg Portion the skill is Prevented from enter Fig. 11 is a plan view of a further embodiment of a ing too deeply into the cutting slots, whereas, in known Shearhead according to hi i i n, constructions, in which the thickness of the cutting mem- As shown i Fi 1 to 8, th elongated shearhead of her decreases progressively, such is v y Often the Case, a dry shaving apparatus comprises a base piece I mounted and causes irritation of the skin or even injuries. The by Sockets 2 on h housing 3 f the apparatus. This thinned QOIU'OII, P in widen-Shaving Zone base piece carries an outer cutting member 4 which is in Ciefs P s a Perfect close shavlllgi Whlle at the same the general form of a longitudinally arched inverted U- time it 18 so narrow that the skin cannot enter too deeply Shaped channel and h ll l flange of hi h are riveted at 5 to the base piece 1. In its top portion, the outer cutting member is provided with a series of equidistant transverse slots 6 leaving between them small bridges 7.

member is not impaired. Due to the elevation of the thinned zone over the adjacent portion of the cutting member a better support of said zone is attained so that it cannot be forced in. The mentioned elevation may be The upper side, outwardly vaulted i longitudinal 1- Obtained y Vaulting the Cutting Portion y arranging rection, of the base piece 1 has a longitudinal groove 8 the thinned Portion in the Crest of a roof-shaped vWtlihg guiding an inner cutting member 9 in the shape of a ring portion. Th PIE- ha ing Z P mi s Close shaving segment having an enlarged rim into which are cut equieven with an approximative constant thickness of 0.1 mm. distant transverse slots 11 leaving between them a series as long as the thinned portionhas a thickness of 0.02 of teeth 12. The top face of these teeth 12 conforms to mm. only. This thinned portion does not impair the the inner face of the bridges 7 left between the slots 6 and is wider, in a longitudinal direction of member 9, than the said slots 6 so that the teeth 12 cannot engage the slots 6 and the inner cutting member 9 is maintained in its guiding groove 8 by the outer cutting member but capable of longitudinal motion. along'the latters inner face. Moreover, the inner cutting member has'a recess 13 engaged by an actuating lever 14 extending through a wide opening 15 in the base piece 1. This actuating lever 14 is pivoted on a pin (not shown) in the housing 3 and in operation is oscillated by an electric motor and suitable transmission means (not shown) lodged in the said housing. 7

Thus, at operation of the apparatus, the inner cutting member 9 will be reciprocated along the inner-face of 'the outer cutting member 4 and any hair which extends into the'slots 11 through the slots 6 when these slots registerwill be cut olf between the adjacent bridge 7 and teeth 12 as the inner cuttingmember 9 moves with reaspect to the outer zone 4. ,7

Referring now particularly. to Figs. 4 and which show transverse sections on section lines IV-JV and V- V, respectively, 'of Fig. 2, of the top portion ofthe outer cutting member 4, at spaced points thereof, the said outer cutting member 4 has two inner surfaces 17 defined and represented by a pair of straight lines intersecting each other at 18, at an obtuse angle. Further, the outer cutting member 4 has two outer surfaces 19 also represented or defined by a pair of straight lines which are parallel to those representing the inner surfaces 17. In Fig. 5, which is a cross-section taken'through an end portion of member 4, the lines indicating the surfaces 19 intersect eachother at 20, which indicates an obtuse edge along which the surfaces 19 meet each other. 7

. At the central portion of outer cutter member 4, however the surfaces 19 do not meet but, in between them there is a third outer surface 21a Fig. 2, which is represented .in transverse section by a straight'line in Fig. 4.

Therebythe arrangement is such that the smallest distance between the surface 21a and the said point 18 is smaller than that between the inner and outer surfaces 17 and 19, respectively measured in the. same direction. It will be understood that all the surfaces 17, 19 and 21a are interrupted from place to place by the slots 6. Of course the transverse section of the outer surface 21 could also be an outwardly or inwardly curved line.

Figs. 6 to 8 are sections taken longitudinally through various portions ofthe outer cutting member to show the cross-section of the bridges 7. Fig. 6 represents a normal cross-section through three bridges 7 of the cutting mem-ber 4. The edges 22 of the bridges 7 at which the slots 6 meet the outer surfaces 19 are rounded, while the edges 23 at hich" the slots 6 meet the inner surfaces 17 are sharp; these sharp edges 23. are, in fact, the cutting edges of the outer cutting member Fig. 7 is'a longitudinal section of theouter cutting member, showing three bridges 7 in cross-section and applying only to the end portions, having the transverse section shown in Fig; 5. Fig. 7 differs from Fig. 6 in that its plane passes through the edges 1% and 28 (Fig. 5), i. el obliquely with respectto the surfaces 17 and 19. Therefore, the height of the bridges 7 is greater in Fig. 7 than in Fig. 6, but otherwise the two figures are identical. Fig. 8 is a longitudinal section similar to that of Fig. 7 but taken in the central portion of member 4 to which Fig. 4 applies. The height of the bridges 7 in this section, which is the distance between the surface 21a and -the edge 18, therefore is-smaller than in the section of Fig." 7. The height of thebrid ges 7 in the section according to Fig. 8 is smaller than the height of the bridges inthe section according to Fig. 6. V 7 V V t is As shown in Fig. 8, the edges 24 of the bridges 7 at which theslots 6 meet "the outer surface 21a are sharp. This will conveniently'be achieved by :first grinding the surfaces 19 and the slots 6 withtheir common rounded edges 22, throughout thelengtlr of the cutting member 4,

5 the sharp edges 24 are formed.

In an alternative embodiment shown in plan view in Fig. 9, an outer surface 21b of outer cutter 4a is provided which extends only a portionof the length of the cutting member, has a longitudinal curvature which is less pronounced than that of the remainder of the outensu'rface of the cutting member. The surface 21b could even be straight. in longitudinal profile. In both of thesecases the width of the surface 21b increases from both ends towards therniddle of said surface 21. Each of the bridges accordingly difiers in shape from the adjacent ones, so that a transverse section similar to Fig. 4 would apply only to one or two individual bridges 7 of Fig. 9, with the remaining bridgesdiifering in shape therefrom by having either a wider surface and accordingly smaller height at their apex, or a narrowerportion of surface 21b with greater height at their apex than the said one or two bridges. 1

' The surface 21c may also extend throughout portion of the length of the cutting member 4b which is provided 25 with bars and slots, only the end portion being of full thickness along the center. An especially narrow thinned 'portion is shown in Fig. 11, and the end portions longitudinally immediately adjacent thereto are of full thick 'ness. In this embodiment the surface 21c has pointed ends.

I S uch apparatus having a thinned portion within the most effective half of the cutting portion of the shearhead have the following advantage: In the shaving process, the outer surfaces of the shearhead are pressed against, or

maintained in contact with, the skin of the person to be shaved and the hair extending through the slots 6 will be cut 0E between the inner. cutting member 9 and the outer cutting member 4 atthelevel of the inner surface of the latter when the,inner cutting member is reciprocated; Thus, to obtain aclose shave, it is desirable that the distance between the outer and the inner surface of the outer cutting member l, that is, the height of the bridges 7, be as small in the cutting region as is consistent with a sufficient strength of these elements. Where the transverse section of the outer cutting member is as shown in -Fig.5, 'it will .be noted that in the region of the point 20 the heightof the bridges7-is greater and accordingly the shave le'ssclose than in other regions, although such increased height of the bridges 7 is not necessary to give 59 the bridge its'required strength. -Now, due to the obtuse angle'at which the two surfaces 19 are situated, the edge 29 in such transverse section as shown in Fig. 5 is the point. at which the skin is'best'tensioned and applied to the shearhead so that the optimum shave wiil occur at this point. if therefore the shave is not close enough at this point, it will be difficult for the user to obtain a closer shave at all. This drawback is overcome according to .the invention by providing on at least part of the length of the shearhead, an outer surface 21a, 21b or 210 which 60 is at a smaller distance from the inner surfaces 17 or their intersection 18 than the edge 20 would be. The provision of this surface 21 thus materially improves the closeness of the shave. In the embodiment represented in Fig. 4 the distance between said surface 21a and the edge 7 .18 is thesame asthe thickness of the bridges between the inner and outer surfaces 17 and 19 respectively, measured perpendicularly to said surfaces, so that the provision of surface 2 1a will not affect the strength of the bridges 7; In-fact, it may even be admissible to have atthis pointa smaller thickness of material than in the adjacent regions,.so that the. surface 21a may still be .set alittledeepier. Q .Q

Regarding Figs. 6m 8, it will be noted that the provision of rounded edges 22 in the region of the outersurfaces 19 favours the bulging of the skin into the slots 6,

whereby the shave will be substantially closer than if the skin were tensioned fiat over the surfaces 19. If, however, this desirable bulging of the skin were also favoured by rounded edges in the region of the surface 21a, that is, in the thinned portion in which the height of the bridges 7 is reduced and the tension of the skin over the apex of the shearhead is increased, the skin might bulge at this point beyond the inner surface 17 of the outer cutting member 4, become engaged with the teeth 12 of the inner cutting member 9 and be injured or irritated by them. This is avoided by the provision of the sharp edges 24 of the outer surface 21a, a feature which tends to reduce the bulging of the skin into the slots 6.

Although the intermediate outer surface 210 may be extended to the full length of barred portion of the shearhead without departing from the scope of the invention, the provision of end portions not provided with such intermediate surfaces as shown in Figs. 2 and 9 has the advantage that it ensures some additional tensioning of the skin in a longitudinal direction between such end portions, and accordingly a better shave in the region of the surface 21:: and 21b, that is, in the thinned portion.

As shown in Fig. 10, the shaving apparatus may comprise three shearheads 26, 27 and 28, the two outer shearheads 26 and 28 having no surfaces 21, that is, also no thinned portion, and the middle shearhead 27 having such a surface 21 as described with reference to Figs. 1 to 8. This arrangement ensures that the skin is tensioned in transverse direction between the shearheads 26 and 28, and in longitudinal direction between the end portions of the shearhead 27 so as to receive its optimum shaving in the central portion of the latter.

It will be observed that a feature common to all the embodiments is that in each case the shearhead has a thinned portion 21a, 21b or 210 which provides for close shaving while immediately adjacent the thinned portion, in the longitudinal direction of extent of the shearhead, the shearhead wall is thicker and stronger, thus providing strength for the outer cutter immediately adjacent the thinned portion.

Preferably the thickness of the thinned portion within the most eifective half of the cutting portion of the outer cutting member is less than 0.05 mm. While its breadth preferably does not exceed /3 of the breadth of the mentioned most efiective portion of the cutting portion.

Of course the described thinned portion could also be provided on round shearheads.

I claim:

1. In combination in a mechanical shaver, a shearhead having a longitudinally extending outer cutter member curved convexly in its longitudinal direction, an inner cutter member within said outer cutter and movable relative thereto, the outer surface of said outer cutter having a central elevated portion extending longitudinally along the curved periphery thereof and which in use presses more strongly against the surface shave than the rest of said outer surface and constitutes the most effective shaving portion, said elevated portion provided with a plurality of openings extending therethrough, providing a plurality of longitudinally spaced cutting portions, a part of said elevated portions of said outer cutter member being of less thickness than other spaced portions thereof located immediately adjacent thereto in the longitudinal direction of extent of said outer cutter member whereby said part of less thickness produces close shaving and said other longitudinally adjacent parts provide strength to the outer cutter member.

2. A shaver according to claim 1 and in which said openings are slots provided between transversely extending cutter bars, and the elevated portion of said outer cutter member is constituted by the central portions of the said bars.

References Cited in the tile of this patent UNITED STATES PATENTS 2,036,557 Viall et al. Apr. 7, 1936 2,266,884 Martin Dec. 23, 1941 2,281,841 Holsclaw May 5, 1942 2,300,140 Tepas et al. Oct. 27, 1942 2,331,274 Martin Oct. 5, 1943 2,416,094 Gray Feb. 18, 1947 2,559,772 Kobler et al. July 10, 1951 2,562,104 Kobler et al. July 24, 1951 FOREIGN PATENTS 147,119 Austria Oct. 10, 1936 469,782 Great Britain Aug. 3, 1937

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