Electric safety razor

[57] ABSTRACT

The rotary cutters cooperating with the two opposed cutting edges of the safety razor blade are enclosed by tubular guards in which longitudinal slots are provided leaving only a predetermined gap parallel to each of the cutting edges, the width of which can be varied to suit the closeness of shave a person desires, while also insuring safety of operation by positively limiting the extent of bulge of the skin between the adjacent rounded edge of the clamp that serves as a guard and the far edge of the slot in the tubular guard, the latter taking over completely the function heretofore served by the guard on the head of the conventional interchangeable blade safety razor. The split head of the razor permits easy assembling of the rotary cutters and their cooperating tubular metal or plastic guards and the guards can be clamped at their extreme ends in the two sections of the guard or can be secured by set screws in adjusted position, the screws being loosenable and tightenable from behind the guard portion of the razor head where they are out of the way completely.

Claims, 7 Drawing Figures

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PATENTED APR 91974

3.802.072

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3,802,072

ELECTRIC SAFETY RAZOR

This invention relates to electric safety razors designed for “wet” and “dry” shaving.

The principal object is to improve the construction disclosed in the earlier Wintercom et al. U.S. Pat. No. 2,229,159, to make it not only safer, but also improve it from the stand-point that the user can by proper adjustment vary the closeness of shaving to suit the needs of his beard, while still retaining the important advantages of the earlier patented razor construction, namely, its rotary operation and its unique drive, utilizing a pair of parallel helically grooved rollers as cutters on the head meshing with a central helical gear rotatable in a recess provided in the center of the head substantially concentric with the handle and disposed in the plane of the head in direct meshing engagement with the helically grooved rollers to transmit drive thereto in opposite directions toward the opposed straight cutting edges on the opposite sides of an interchangeable safety razor blade. Thus, tubular metal or plastic guards surround these cutters and have longitudinal slots provided therein in spaced parallel relationship to the cutting edges of the blade, these guards being easily adjustable rotatably relative to the cutting edges to vary the width of gap in which the cutters cooperating with the cutting edges of the blade to do the shaving operation for as close a shave as the operator may desire or as the characteristics of the beard may require.

A square or rectangular plug type space gauge insertable between the blade edge and the guard slot determines the width of cutting gap and the closeness of shave.

The invention is illustrated in the accompanying drawing, in which:

FIG. 1 is a top view of an electric safety razor made in accordance with my invention;

FIG. 2 is a vertical section on the line 2—2 of FIG. 1;

FIG. 3 is an enlarged sectional detail on the line 3—3 of FIG. 1;

FIG. 4 is a top view of the two-piece head by itself;

FIG. 5 is a greatly enlarged segmentary sectional view illustrating the operation of the razor;

FIG. 6 illustrates a razor like that of FIGS. 1 to 5, but having a motor for driving the same forming the handle thereof, and

FIG. 7 is a perspective view of one of the longitudinally slotted tubular guards.

The same reference numerals are applied to corresponding parts in the above mentioned views.

Referring to the drawing, the blade 13 is of the conventional interchangeable blade safety razor type, having two parallel cutting edges 14 and 15 adapted to cooperate with the rotary roller type cutters 16 and 17, respectively, the latter being located so that when the blade 13 is clamped down and is thereby arched slightly, its edge portions will come directly over the centers of the cutters and be substantially tangent to the periphery thereof, as indicated by the fact that the radius lines a-b and c-d, drawn from the center of the arc of the blade in FIG. 5, pass through the centers of the cutters 16 and 17 adjacent the cutting edges 14 and 15.

The edges 14 and 15 are double bevel edges and the bottom bevel of each edge will permit adjusting the blade so that the edges have the requisite small working clearances with respect to the peripheries of the cutters for good shearing action. At the same time, since the cap 18 has its arcuate top surface 19 on the same arc 5 with the top surfaces 20 and 21, providing for the same, or substantially the same, clearance with respect to the cutting edges 14 and 15 as in the conventional interchangeable blade safety razor, it follows that the present razor, although power operated, will be capable of 10 shaving just as closely as the conventional handoperated Gillette safety razor when operated the old way and with the same degree of safety, as well as the same degree of handiness and facility of operation, that being due mainly to the tubular metallic or plastic 15 guards 22 that closely enclose the cutters 16 and 17 but have longitudinal gap determining slots 23 which, when the guards are properly adjusted rotatably, leave only a predetermined cutting gap between one edge of the slots parallel to each of the cutting edges 14 and 15, 20 the width of which can be varied with the help of a plug type gauge inserted between the cutting edge and the adjacent edge of the slot, to suit the closeness of shave a person desires, while also insuring safety of operation by positively limiting the extent of bulge of skin be25 tween the adjacent round ege 24 of the clamp 18 that serves as a guard and the far edge of the slot 23 in the tubular guard. The latter, therefore, takes over completely the function heretofore served by the guard portions 20 and 21 on the head of the conventional inter³⁰ changeable blade safety razor. If plastic guards are used at 22 I prefer they be of polyethylene because of its lubricity, helping to reduce drag on the rollers 16 and 17 in the event of a close fit and also to reduce friction on the person’s face. It is also believed that with plastic ³⁵ guards there is less likelihood of uncomfortable heating due to friction, while a better appearance is also obtainable and at lower cost, as the chances are the plastic guards could be molded to final form, requiring little or no machining. It should be obvious that the two tubular ⁴⁰ guards 22 could be set differently, one with the slot 23 opened up slightly wider than the other to give a closer shave with the wider gap than the one with the narrower gap, although both tubular guards are preferably 45 set at the factory so these slots are well within the range ⁰ of good safety for all around operation regardless of how careless the operator might be in shaving on any given occasion due to being in more of a hurry than usual. I have, in other words, retained all of the advantages inherent in the electric safety razor of the earlier Wintercorn et al. Pat. No. 2,229,159, while adding improved safety of operation and a simple means of varying the closeness of shave obtainable. Once a tubular guard 22 has been set for the desired width of cutting 55 gap at 23, the set screw 24 can be tightened to maintain the adjustment.

In operation, with this razor a “once over lightly” should usually be enough for a clean shave, because all of the hairs coming into the path of the blade should be ₆₀ shaved off in one pass. There will usually be no necessity for going over a given area more than once, any more so than with the ordinary interchangeable blade safety razor. The fact, that the entire cutting edge of the blade is used instead of having to work the hair ₆₅ through fine slots to get them into the path of the cutter makes the shaving action with this razor so much quicker and more positive than with the razors with the reciprocating type cutters and is the thing which makes

3,802,072 the razor good for wet or dry shaving. Obviously, with the shearing action obtained there will be no “pulling” with this razor, even when the blade may be a trifle dull. The only thing that determines the closeness of shaving is the adjustment of the tubular guards 22 for a wider or narrower cutting gap between the cutting edge of the blade and the adjacent edge of the the slot in the guard. The manufacturer will set these guards for a recommended medium close shave but leave it up to the user to adjust for a closer shave, furnishing a properly marked plug type space gauge for that purpose, and another properly marked space gauge for the opposite extreme setting. With a rectangular plug both extremes could, of course, be taken care of in one plug type space gauge.

In passing, it should be obvious that since the helically grooved roller-type cutters 16 and 17 are driven by meshing engagement with diametrically opposite sides of an intermediate helical drive pinion 25, each of the tubular guards 22 requires, in addition to the longitudinal slot 23 previously described, a wider but shorter slot 26, as shown in FIG. 7, through which the pinion 25 projects enough to transmit drive to the roller 16 and 17 operating inside the guard, enough clearance being left above and below the pinion 25 for ample operating clearance in both extreme settings of the tubular guard. The required length of the slot is easily determinable from a study of FIG. 1, while the required width of the slot is easily determinable from a study of FIG. 2, keeping in mind the fact that there is only a fairly small range of rotary adjustment from one extreme position to the other.

The razor shown in FIGS. 1 to 6, except for the two features herein disclosed is otherwise the same in construction as disclosed in Wintercorn et al., U.S. Pat. No. 2,229,159. Both have a pinion drive shaft 34 extending through a slender handle 35 adapted for a flexible shaft drive similar to those employed in connection with dental drills, but the invention is not to be construed as limited to such a drive, inasmuch as the handle may be provided by the motor for driving the razor, as illustrated at 36 in FIG. 6, and in that case the razor can be turned on and off by turning a switch knob 37 on the far end of the motor housing from which the flexible extension cord 38 extends.

The head 39 shown in FIGS. 1 to 7, is are made of two die-cast parts that interfit across the middle of the head, as shown at 40, and have half-round shanks 41, which, when the two halves are placed together, form a bearing 42 for the drive shaft 34. Half-round recesses 43 formed in the abutting ends of the two halves provide a circular chamber in the head for the drive pinion 25 connected to the enlarged fluted end 44 of the shaft 34. The two halves of the head may, if desired, have the shank portions 41 thereof left blank in the die-casting of these parts so that the two halves can be identical and then later when the two halves are suitably held in assembled relation the shank portions can be threaded, as shown, to thread in the internally threaded enlarged upper end 45 of the handle 35, or the corresponding parts 35a on the end of the housing of the motor 36, whereby to secure the two halves of the head together. At the same time that the shank portions are threaded, the bearing 42 can, if desired, be reamed to insure good fit for the shaft 34 therein. The latter, it will be noted, extends through the hollow handle 35 and in the case of a flexible shaft drive will be suitably coupled at the outer end of the handle to the flexible shaft, the casing of which will be attached to the handle. However, in the case of a direct motor drive, the shaft 35 can be regarded as the armature shaft of the motor or the shaft coupled directly to the armature shaft.

The head 39, as seen in FIG. 4, has guards 46 on opposite sides thereof provided by a series of laterally spaced prongs similar to what are provided on the conventional interchangeable blade safety razor. It will be noticed that each half of the head 39 has five of these prongs on one side and six on the other and that the sixth prong necessitates the small shoulder 47 on the end of each half, which, however, is not objectionable, but is really an advantage from the standpoint of interlocking the two halves of the head more firmly in assembled relation and securing better alignment between the halves. As shown in FIG. 4, the recessing for the cutters 16 and 17 at 48' is deep enough radially to provide the additional space required for the tubular guards 22, and there is in addition annular recesses 49 as seen in FIG. 3 provided in the opposite ends of the head 39 to receive the ends of the tubular guard 22. A screw 50, threaded in a radial hole in the head at each end, serves, when tightened, to clamp the tubular guard 22 in its adjusted position. The recesses 49 are, of course, in concentric relationship to the bearings 51 in which the reduced journal portions 52 on the ends of the rotary cutters 16 and 17 are received for support of the cutters in accurately spaced relationship to the opposite sides of the drive pinion 25, and, of course, in true parallel relationship to the cutting edges 14 and 15 of the razor blade 13.

The fact that the drive is a helical gear drive manifestly makes for smooth, quiet operation, even though the pinion cannot operate with lubricant for obvious reasons. Also, the fact that there is balanced drive with rotary cutters operating on opposite sides of the handle axis, this arrangement insures reduced vibration. It is obvious that in the assembling of the razor in either form, the cutters 16 and 17 can be assembled in the one half of the head in meshing engagement with the pinion 25 also assembled in that half, and then the other half of the head can be brought into position, thus encasing the working parts in the head in proper assembled relation, whereupon the handle 35 or motor 36, as the case may be, can be attached to the head, securing the two halves thereof together. The tubular guards 22 will be assembled in the recesses 49 on the one half before the other half of the razor is assembled in place.

The cap 18 is generally similar to the blade clamping cap on the ordinary interchangeable blade safety razor and has a longitudinal rib 53 extending along the middle of the bottom thereof, which fits in a longitudinal slot 54 in the middle of the blade and a registering groove 55 in the head so as to accurately locate the blade with respect to the head at the same time that it is clamped in place. There are two studs 56 projecting downwardly from the cap 18 near its opposite ends and these pass through holes in the blade at opposite ends of the slot 54 and then through holes 57 in the head to receive knurled nuts 58 arranged to be tightened by hand up against the flat bottom of the head in the manner clearly shown in FIG. 2. Realizing the importance of correct clearance between the edges 14 and 15 of the blade 13 and the cutters 16 and 17 and also the importance of avoiding having the tightly clamped blade bearing too heavily on the cutters, or either of them,

3,802,072 and acting as a brake, four adjusting screws 59 are provided in vertical holes 60 in the head in the vicinity of the four corners of the blade 13 arranged to be adjusted Up or down in these holes to provide adjustable seats for the blade at the four comers, so that, regardless of 5 minor variations in the manufacture of the head or in the cutters 16 and 17, it will be possible to align both ends of each cutting edge in the proper relation to the associated cutter and thereby obtain good shaving action. 10

It is believed the foregoing description conveys a good understanding of the objects and advantages of my invention. While a preferred embodiment of the invention has been illustrated and described, this is only for the purpose of illustration, and it is to be under- 15 stood that various modifications in structure will occur to a person skilled in this art.