US2245795A - Electric shaver - Google Patents

Description

June 17, 1941. M. J. LANDGRAF ELECTRIC SHAVER Filed Sept. 25, 1957 i l ldizjyraf Jiaufzn/iav" Patented June 17, 1941 UNITED STATES PATENT OFFICE EIECIRIO-SHAVEB am *1. management. 111., assignmto p I Hentylfialdblathfihieagmlll. Y

' Application September 25, 1931, Serial'No. 185,655

Myinvention relates. to improvements in 8 called electric shavers;

In recent years, there has been somecommercialization of special types othair clippers so designed as to clip the hair very close to the skinso as to produce substantially the same eiiect as that obtained by the use oirsoap and the conventional razor. Such specially. designed ha r clippers have gone by various names, the commonest designation being-electric shaver;

Electric shavers heretofore produced have not been entirely satisfactory under all circumstances. Since. the teeth arein-general of the same width as the hair receiving slots between them, there is substantially as sleatipossibility oi the hair engaging the teeth as entering the slots between them,-so that not appreciably more than hall or thehair can be. expected tovbe sheared close to. the skin when the shaver. is passed over the face once.- Asaconsequence,- the shaver must be passed over the .skin an unreasonable number of times in order to-shear all 01 the hairs of they beard adequately closeto the skin. ,Ihave found, moreover. that the surface of the shaver in contact with the skin-andwhich carries hair receiving slots or openings has not been properly shaped, to cause the hair 1 to enter the hair receiving slots readily, parmaximum engagement of the hair of the beard and adequately large area of contact, coupled at the same time with a design which permits the user to err somewhat in the angle at which he applies the shaver to the face without at the same time decreasing markedly the cutting emciency of the instrument.

The principal object of my invention is the provision of an improved shaver adapted for operation with electrical or other suitable power.

A further object is the provision of an electrical shaver which overcomes thedisadvantases oi shavers heretofore designed. 1 I

A still further object is-to overcome the disadvantages and objections outlined hereinabove.

Other specific objects and features of the invention will be apparent from the following detailed description, taken with the accompanying drawing, wherein I s Fig. 1 is a front elevational view showing one embodiment of my invention;

Fig. 2 is a side view of the shaver shown in taken on the line 4-4 of Fig. 3;

Fig. 5 is an enlarged perspective view, showing a portion of the head which carries the shear Fig. 6 is an enlarged perspective view oi the shearing cutter which reciprocates within the head toshear the hair entering the slots in the shear plate; and

' mg. 'l is an enlarged fragmentary perspective view showing a modification oi the member illusutilization of several novel features which will be described in detail by reference to the various figures. In general, I utilize a cutting head with a shear plate having a plurality of longitudinally extending rowsoi' teeth with hair-receiving slots between them, and extending transversely of the head, the several rows of teeth being so placed'that the teeth of one row coincide transversely with the slots of the next adjacent row, so that hairs which do not enter one series of slots will readily-enter the adjacent set of slots. Preferably, I use two rows or teeth, the teeth of one row terminating short of the teeth or the other row, leaving a narrow longitudinally extending opening between the teeth. I also shape the shear plate (and the shearing cutter disposed in contact with the underside thereof) to present a cross section in the form of a transverse curve having a relatively large radius of curvature at every point thereof. Preferably the cross section comprises 'an arc of a relatively large. circle,generated about a point lying out- .side the area of the shear plate member of which the shear plate forms a part. The gentle curve thus given the shear plate provides for ready entrance of the hairs into the slots, allows the angle at whichthe shaver is applied to the face to be modified extensively without impairing the efliciency oi the instrument, and provides alwaystor a relatively large area of the shear plate to be in contact with the face, whereby therezis ample slot surface for the reception of hairs, all 01'. which will be sheared oil? substantially at the skin line. Preferably, my shaver utilizes a small portable electric motor housed in the handle, but it may be adapted for operation by means of a flexible shaft driven by a suitable prime mover.

Reference may now be made to Figs. 1 to 7, inclusive, showing in detail a preferred embodiment of my invention. The shaver uses a suitable handle I having a channel at the top thereof in which a cutting head is supported, generally indicated by the reference character H. A suitable screw i2 is provided for securing the head H in place. The handle preferably is hollow and houses a small electric motor, not here shown in detail since the invention is not primarily concerned therewith. A starting wheel i3 has a portion of its periphery extending through the wall of the handle, and the motor has a rotatable shaft l4 utilized to actuate the shear cutter as will be pointed out.

The head ll comprises two main parts, carrying respectively a shear plate l6 and a shearing cutter II. The shear plate comprises part of a shear plate member of generally channel shape,

as shown in Fig. 5, having sides l8 and IS. A

block 2! is recessed near its top as shown to receive the sides of the shear plate member, and screws 22 extending through both sides l8 and I9 and the block 2| mount the shear plate member firmly in place on the block and provide a generally rectangular space bounded by the two sides [8 and 19, the top of block 2|, and the bottom surface of the shear plate l6. It is the block 2| which extends into the channel at the-top of the handle 10, and against which the screw l2 engages.

The shear plate is provided with two rows of teeth, all the teeth in one row being numbered 23, and all the teeth of the other row being numbered 24. Hair receiving slots 26 are provided between the teeth 23, and hair receiving slots 21 are provided between the teeth 24. The two rows of teeth terminate short of the longitudinal center line of the shear plate so as to leave a narrow longitudinal slot 28. The provision of this slot facilitates formation ofthe teeth, and also seems to improve the cutting action of the instrument somewhat. Two narrow transverse bands 3| join the two sides It! and .19 together, and serve to strengthen and reinforce the head as a whole.

It will be noted that the sides'lB and I9 are flat and parallel to each other, and that the shear plate 1 6 is transversely arcuate. The shape and disposition of the sides l8 and I 9 are of no prime moment so far as the functioning of the shaver is concerned, but the arcuate shape of the shear plate is of great advantage. Notwithstanding the shape, the member of which it forms a part is rather inexpensively made. The channel is first formed with the web of the channel solid and running at right angles tothe sides. The slots are first cut and the teeth formed. The web is then ground to an arcuate shape at both sides thereof, leaving a sharp edge, particularly on the inside surface against which the hair is cut. The teeth are finished relatively very thin, but not thin enough to lose their requisite strength. The top face of the teeth where they come into contact with the skin may be slightly rounded, and the ends of the teeth may be slightly rounded if desired to produce a more pleasing appearance. It will be noted that the slots are cut down relatively low at the sides of the shear plate to further facilitate the entrance of the hairs of the beard. The teeth may also be ground thinner, if desired, near their ends, but so far as their width is concerned, it should be substantially uniform. I have determined that if there are about 32 teeth to the inch, with slots between them, very good results are obtained, although the number of teeth and/or width of slots may be modified to meet unusual hair beard conditions. The transverse curvature of the shear plate should be on a relatively large radius, but not too great to provide a cross section presenting a very definite and easily defined curve. Said cross section should at least comprise (if a true arc) an arc of a circle generated about a point lying below the center of the shear plate member, that is, the radius is greater than half the total height of the shearplate member. The actual radius of curvature may be as great as about six inches, but preferably should be somewhat shorter. A inch radius, for example, may be employed. In general, .about a /2 inch radius of curvature is very suitable, which is generally close to that shown in the drawing.

The shearing cutter is part of a shearing cutter member of generally channel shape, including a web 32, and a side piece 33, the shear cutter proper comprising the remaining side of the channel. The shear cutter has a plurality of shearing blades 34, with slots 36 between them. I may, if found advisable, provide a reinforcing rib 35 which engages the ends of the blades,

but I have found that good results are also obtained without using this rib. The blades may be modified in shape, butI have found that very good shearing action is obtained if the blades extend transversely straight across the shearing cutter and parallel to each other, having, at least on their top, however, .the same curvature as the shear plate. The shearing blades may-be somewhat thicker than the teeth of the shear plate, but in width they should preferably correspond therewith. The shearing cutter and the side 33 are wide enough to prevent side play, but still permit free sliding movement. While the parts I! and 33 comprise structurally the sides of a channel, when the entire member is assembled into position, they comprise top and bottom members respectively as the drawing clearly shows. The shearing cutter member is formed readily and inexpensively in the same general manner as described in connection with the shear plate member. The top edges of the blades 34, however, are left sharp, that is, they are truly right angular, in order to produce the most advantageous shearing action when operating in combination with the lower corresponding edges of the teeth on the shear plate.

The part 3-3 is provided with a slot 31 at its center, into which a crank pin 33 carried off center on the shaft ll extends. The slot 3 is wide enough to accommodate the full throw of the crank pin without causing any binding of the shearing cutter against the Walls of the sides It and I! of the shear plate member. Longitudinally, however, the slot 31 is only slightly wider than the diameter of the crank pin, so as to form a sliding fit, whereby the shearing cutter is caused to reciprocate longitudinally a distance substantially equal to the full throw of the crank pin. The crank pin is so disposed with respect to the center of shaft N that the blades on the shearing cutter pass at least two teeth on the shear plate, or, stated in another way, a given blade will pass. one opening enrtlon as those acquainted with the operation of hair clippers and similar instruments will unrsta r In order to compensate for whatever slight wear may occur between the shear plate and shearing cutter, and to maintain firm engagement between these members at all times, I provide spring pressed means in the form of balls 39. urged by compression springs 4! into contact with the lower face of the part 33. These' balls and springs are disposed in recesses provided in the block II, and screws 42 are utilizedtohold the assemblyinplace.

I have reierred to the teeth and slots in the shear plate, and the shearing teeth and slots in the shearing cutter, and stated that these teeth. slots andblades are preferably oi! substantially the same width. It should be understood th'at these members should not be so dimensioned that there can be any tendency for the blades on the shearing cutter to fall into the slots of the shear plate. I may make the blades slightly wider than the slots, or, if desired, I may form the blades at a slight angle erally U-shaped member having hair receiving slots in one leg thereof, said leg bearing said hair receiving slots being in contact with said shear plate.

2. In an electric shaver, a head having a shear plate provided with two rows of teeth with slots between them, the teeth of one of said rows being substantially in line with the slots of the other of said rows, and a shearing cutter having hair receiving slots disposed in contact with said shear plate, said shearing cutter comprising a generally U-shaped member having hair receiving slots in one leg thereof, said leg bearing said hair receiving slots being in contact with said shear plate.

3. In an electric shaver, a head having a shear plate provided with two 'rows of teeth with slots between them, the teeth of one of said rows being substantially in line with the slots of the other of said rows, said rows of teeth being separated from each other to provide an open space between them running longitudinally of said shear plate, and a shearing cutter having hair receiving slots disposed in contact with said shear plate, said shearing cutter comprising a generally U-shaped memor even a relatively large angle, so that the blades will tend to engage more than one tooth at any one time, and also to produce a sharper shearing action. In general, however, ample shearing action may be obta ed by running the blades at true right angles to r direction of movement, and the hairs seem to presented to the blades for cutting somewhat more readily, ii this construction be employed.

In the modification of Fig. 7, the construction is substantially identical with thatoi i the preferred embodiment, except that the teeth on the shear plate meet in the center and thereis no central open space corresponding to the longitudinal slot 28 shown in Fig. 5. In order to shorten the description, I identify the parts in Fig. '7 by the same references employed in Fig. 5. except that the numeral i is used as a prefix in each instance.

It will be understood that my invention is capable of further modification while still securing the same advantages and novel functions outlined hereinabove. My invention is limited, therefore, only by the scope of the appended claims.

What I claim as new and desire to protect by, Letters Patent of the United States is:

1. In an electric shaver, a head having a shear plate provided with a plurality of rows of teeth having hair receiving slots between them, slots of successive rows being staggered with respect to each other, and a shearing cutter having hair replate, said shearing cutter comprising a genher having hair receiving slots in one leg thereof, said leg bearing said hair receiving slots being in contact with said shear plate.

4. In an electric shaver, a head provided with a shear plate having teeth therein and hair receiving slots between the teeth, said head provided with a longitudinal opening of generally rectangular cross section, and a shearing cutter slidably supported in said opening, said shearing cutter comprising a generally U-shaped member, one leg of the U being finished to provide'blades with hair receiving slots between them, and the other leg of the U provided with means whereby to connect said shearing, cutter with a source of power for reciprocating the shearing cutter in contact with the said shear plate.

5. In an electric shaver, a head comprising a block, -a shear plate member of generally U' shape having its sides secured to the sides of the :ter of generally channel shape,'one.side of said ceiving slots disposed in contact with said shear channel being provided with cutting blades with hair receiving slots between them, and shaped to engage snugly against the under side of I said shear'plate, said shearing cutter being reciprocably supportedwithin the said generally rectangular opening in .the head, the ends of the blades of the shearing cutter not in contact with the web'of the U being provided with a reinforcing rib substantially parallel with said web whereby to strengthen said blades and prevent them from being forced out'of parallelismwith each other. i

MYRON J. LANDGRAF.

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