US3890709A

US3890709A - Rotatable cutter head for an electric dry shaver

Info

Publication number: US3890709A
Application number: US421069A
Authority: US
Inventors: Eduard Willem Tietjens
Original assignee: US Philips Corp
Current assignee: US Philips Corp
Priority date: 1973-01-12
Filing date: 1973-12-03
Publication date: 1975-06-24
Anticipated expiration: 1992-06-24
Also published as: AU6431774A; GB1453944A; CA1003627A; FR2213839A1; JPS49121792U; ES422171A1; DE2364646B2; FR2213839B1; BR7400113D0; AR199940A1; ATA13674A; IT1006832B; DE2364646A1; DE2364646C3; AT329405B; NL7300454A

Abstract

A rotatable cutter head for an electric dry-shaving apparatus having a perforated shear foil, the cutter head including a supporting member provided with slots, and in each slot a plateshaped cutter, which extends through the supporting member and is pressed against the lower surface of the shear foil by a spring, which extends through an opening in the lower part of the cutter.

Description

United States Patent [191 Tietjens 1 [451 June 24, 1975 ROTATABLE CUTTER HEAD FOR AN ELECTRIC DRY SHAVER [75] Inventor: Eduard Willem Tietjens, Drachten,

Netherlands [73] Assignee: U.S. Philips Corporation, New

York, NY.

[22] Filed: Dec. 3, 1973 [21] Appl. No.: 421,069

[30] Foreign Application Priority Data Jan. 12, 1973 Netherlands 7300454 [52] US. Cl. 30/43.6 [51] Int. Cl B26b 19/14 [58] Field of Search 300/43.343.6, 300/346.5l

[56] References Cited UNITED STATES PATENTS Meyer 30/436 FOREIGN PATENTS OR APPLICATIONS 1,033,090 6/1958 Germany ..30/43.6 1,188,529 3/1959 France ..30/43.6

Primary ExaminerAl Lawrence Smith Assistant Examiner-Gary L. Smith Attorney, Agent, or Firm-Fr"ank R. Trifari 57 ABSTRACT A rotatable cutter head for an electric dry-shaving apparatus having a perforated shear foil, the cutter head including a supporting member provided with slots, and in each slot a plate-shaped cutter, which extends through the supporting member and is pressed against the lower surface of the shear foil by a spring, which extends through an opening in the lower part of the cutter. Y

9 Claims, 2 Drawing Figures ROTATABLE CUTTER HEAD FOR AN ELECTRIC DRY SHAVER BACKGROUND OF THE INVENTION The invention relates to a rotatable cutter head for an electric dry-shaving apparatus provided with a thin round perforated shear plate or foil. The cutter head comprises a number of substantially plate-shaped cut ters each of which is separately guided in an associated guide slot in a supporting member, projects from the supporting member at either side, and has a cutting edge at one side; the other side is connected to a spring which is attached to the supporting member for resiliently loading the cutter in the direction of the cutting edge.

A rotatable cutter head of this type is described in German Pat. No. 1,033,090, the cutters being secured in leaf springs in slots near the ends thereof. These slots are formed in the springs by bending tabs which are stamped out of the springs at three sides. In the slots the cutters are secured so that free ends of the stampedout, bent tabs engage with a correspondingly bent portion of the cutters, the cutter with the porjecting portions resting at the top of the leaf spring.

The leaf springs are combined to a spring element, which has the shape of a ring, and whichis located near the hub of the cutter head. From the ring part the leaf springs extend radially, with the ends near the cutter head bent tangentially, and the free ends carrying the cutters.

It is considered to be a drawback of this known cutter head that the ends of the cutters which are situated opposite their cutting edges are secured in the springs. This substantially effects the freedom of movement of the cutters relative to the shear foil, and also relative to the cutter support. It is particularly disadvantageous in shaving apparatus having cutters which are manufactured in accordance with the Applicants Pat. application Ser. No. 841,237, filed July 14, 1969 and which are used in a shaving head with separately springmounted cutters in accordance with the Applicants Netherlands Pat. application Ser. No. 117,502, filed Feb. 22, 1971. In a shaving head, which is constructed in accordance with the principles as laid-down in these two Applications, the individual cutters should have a comparatively high degree of freedom in their guide slots. In the direction of the shear plate the cutters are loaded very moderately by a small spring force only, with frictional locking of the cutter in the associated guide slot to prevent the cutter from being pressed away from the shear foil under the influence of the forces exerted on it during shaving, while the hairs are being out. In view of this frictional locking action, it is essential that the cutter can press against the cutter support at the top and the bottom edge of the slot, because it is the locally occurring frictional forces which should prevent the deflection of the cutters relative to the shear foil. Furthermore, the cutters are disposed in the cutter support in such a way that, if they should assume an oblique position relative to the shear plate under the influence of forces exerted on them during shaving, automatically a torque is produced owing to the centrifugal force acting on the cutter and a centripetal reaction force, which restores the cutter to its original position. In such an embodiment of a rotating cutter head the cutters should be capable of performing a tilting movement in the guide slot, in a plane which extends through the axis of rotation of the cutter head, irrespective of the previously discussed tilting movement in a plane perpendicular to said plane.

Another drawback of the known cutter head is that the spring element, which is known from this, cannot suitably be used when more than four cutters per cutter head are required. It is comparatively difficult to adapt the previously discussed embodiment of the spring element to a greater number of cutters for lack of room for the resilient arms. Another drawback is, moreover, that when only small spring forces are required, the springs required for this must also be small and of relatively small width, so that it becomes difficult to stamp tabs out of the springs in which the cutters can be fitted.

An advantage of the fixation of the cutters in the leaf springs is, however, that the cutters are thus retained in the cutter head when the shaving head is removed.

SUMMARY OF THE INVENTION It isan object of the invention to provide a rotatable cutter head of the type mentioned in the preamble, which mitigates the above-described drawbacks of the known cutter head, while maintaining the stated advantage, and in addition offers further advantages. Therefore the invention is characterized in that the part of each cutter near the end thereof which cooperates with the spring and which projects from the supporting member has an opening, through which the free end of the associated spring extends.

Since the springs extend through an opening in the cutters, the freedom of movement of each cutter is not substantially affected by the spring, the dimensions of the springs can be very small, and the cutters are moreover locked against dropping out.

Of special importance for mounting, in particular when the number of cutters to be used in the cutter head is great, is an embodiment of the invention which is characterized in that (a) the length of the part of the spring between its free end and the opening in the cutter through which the spring extends, (b) the distance between the opening in the cutter and the nearest end thereof, (0) the slidability of the cutter in its associated guide slot in the supporting member, and (d) the dimensions of the spring and the opening in the cutter are such that, when the springis mounted and the cutter is not mounted, a cutter which is inserted through a guide slot with its end containing the opening, (i) first bends the spring to a maximum, (ii) subsequently pushes the end of the spring along the lateral edge facing the spring, (iii) and finally engages with and passes through the opening towards the other side under the influence of its own elasticity. 1

Mounting is still further facilitated and inadvertent damaging of the springs owing to excessive deformation is prevented by another embodiment of the invention; this is characterized (a) in that the cutter head comprises a stop for the associated cutter, which stop is rigidly connected to the supporting member, (b) and that the spring extends through the opening in the cutter when the cutter is pressed against the stop.

A preferred embodiment of the invention is characterized in that the stop is located at the side opposite the guide slot, and the cutter cooperates with the stop with its end which cooperates with the spring.

In a cutter head, provided with leaf springs for resiliently loading the cutters, where the springs are interconnected to form one spring member consisting of a resilient sheet material, a further embodiment is of importance for exactly matching the force to be provided by the leaf springs and for providing a method of manufacturing the resilient member which is simple and suited for mass production. The embodiment is characterized in that the spring member is entirely flat, and that the leaf springs are connected to parts of the spring member which are clamped between the supporting member and one or more compression members connected thereto. Apart from being stamped from sheets, as is known from the previously mentioned publication, the entirely flat spring member according to this embodiment of the invention may for example also be manufactured by an etching process or by electrodepositing.

A favorable construction of a cutter head according to the invention, which is eminently suited for mass production, can be obtained by means of a further embodiment of the invention, which is characterized in that the spring member comprises a number of substantially radially extending arms, that the leaf springs extend substantially tangentially, that the supporting member has a hub on which a single compression member is disposed, which is provided with raised clamping parts corresponding to the arms of the spring member and which also serves as a stop for the cutters.

The invention will be described in more detail with reference to the drawing, where:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows a side elevation, partly in crosssection, of a cutter head, in which the separately springmounted cutters press against a flat shear plate, only one cutter being situated in the part shown in crosssection, and

FIG. 2 is a top plan view of. the cutter head of FIG. 1, in which part of the supporting member is cut away, so that the Figure partly showsthe compression member which is disposed underneath the supporting member and the spring member which bears thereon, part of the spring member being also cut away.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a dry-shaving apparatus, from which all parts which are irrelevant for the invention have been omitted. A perforated shear foil 1, provided with hair entrance apertures 2, is shown in cross-section. Underneath the foil a cutter head 3 is located, which is dis posed on a rotatable spindle 4 of the shaving apparatus. The cutter head comprises a number of substantially plate-shaped cutters 5, which are each separately guided in an associated guide slot 6 in a supporting member 7 and which project from either side of the supporting member. Each of the cutters has a cutting edge 8 at one side, and at its other end 9 is connected to a leaf spring 10 which is attached to the supporting member 7. The leaf spring resiliently loads the cutter 5 in the direction of the cutting edge 8. The leaf springs 10 are interconnected to form a spring member 11 formed of a resilient sheet material. The part of each of the cutters 5 near the ends 9 thereof, which projects from the supporting member 7 and cooperates with the leaf spring 10, is provided with an opening 12 through which the free end 13 of the associated leaf spring 10 extends. The leaf springs 10 are entirely flat.

The length of the part of the leaf spring 10 between its free end 13 and the opening 12 in the cutter 5, the distance between the opening 12 and the nearest end 9 of the cutter, the slidability of the cutter 5 in its associated guide slot 6 and the supp rting member 7, and the dimensions of the leaf spring 10 and the opening 12 have been selected so that, with a leaf spring 10 mounted and a cutter 5 not mounted, a cutter which is inserted through a guide slot 6; with its end 9 which contains the opening 12, first bends a leaf spring 10 to a maximum, then pushes the end 13 of the leaf spring 10 along the lateral edge 14 of the cutter which faces the spring, and finally engages with and passes through the opening 12 towards the other side under the influence of the spring action.

At the side of each leaf spring 10 which faces the guide slot 6, a stop 15 for the associated cutter 5 is located, rigidly connected to the supporting member 7, and at such a distance that when the cutter 5 is pressed against the stop 15, the leaf spring 10 extends through the opening 12 in the cutter.

The spring member 11 is entirely flat. The leaf springs 10 are connected to parts 16 of the spring member 11 which are clamped between the supporting member 7 and one or more compression members 17 connected thereto. The spring member 11 comprises a number of arms 18 which extend substantially radially. The leaf springs 10 extend substantially tangentially. The supporting member 7 has a hub 19 on which the one-piece compression member in the form of a pressure cup 17 is secured with the aid of speed nut 20. The pressure cup 17 comprises a number of clamping members 21, which correspond to the radially extending arms 18 of the spring member 11. The bottom surface 22 serves as a stop for each of the cutters 5.

In order to locate the spring member 11 relative to the other parts of the cutter head 3, two earns 23 are provided on the supporting member. In FIG. 2 the projection of the cams 23 is shown and it can be seen that the distance of the cams has been selected so that this is just slightly greater than the local width of the arm 18 of the spring member. The cams 23 also serve to locate the pressure cup 17 relative to the supporting member 7. I

The scope of the invention is not limited to the embodiment shown in the drawing. In particular, it is possible to use wire springs instead of leaf springs, whose ends extend through the openings 12 in the cutters. These springs may be rod-shaped and connected with one end to the supporting member 7 and/or the pressure cup 17, for example, by clamping them in openings in the supporting member 7 or the pressure cup 17 provided for this purpose, or by clamping them between the supporting member and the pressure cup. The springs may then be connected to each other in pairs to form one unit. The springs may also be spiral or helical springs manufactured from a filamentary material. However, the embodiment shown has the advantage over such other embodiments in that the spring can readily be adapted to produce very small compression forces of the order of magnitude of 5 to 10 grams per cutter, and can be manufactured, handled and assembled simply and inexpensively in mass production.

I claim:

I. In an electric dry shaver including a perforated shear plate, the improvement comprising a rotatable cutter head including a support member having top and bottom surfaces, being rotatable about a central axis, and including a plurality of slots extending therethrough with corresponding top and bottom parts, a plurality of cutters each being situated in one of said slots, means for rotating said support member, each cutter having a central part in said slot, a top part extending above the top of said slot and terminating in a cutting edge for engaging said shear plate, and a bottom part extending below the bottom of said slot with an aperture in said bottom part of said cutter transverse of said slot, and spring means secured to the said support member and having a resilient finger extending at least partially across the bottom of each slot and having diameter smaller than said aperture in the cutter, said finger when a cutter is inserted downward through each slot, initially blocking the cutters bottom part from extending through the bottom of the slot, said spring being deflectable when the cutter is urged further downward until said finger springs through said aperture, said finger then positioned while traversing said aperture and being deflected, to alone resiliently urge the cutter upward.

2. Apparatus according to claim 1 further comprising stop means carried by said cutter head and situated below each slot for preventing movement of said cutter through said slot beyond a predetermined lower limit, after said fingers have traversed said apertures.

3. Apparatus according to claim 2 wherein said stop means is fixedly secured to said support member at the bottom surface thereof.

4. Apparatus according to claim 3 wherein said spring means comprises a plurality of said fingers all extending from and contiguous with a central member.

5. Apparatus according to claim 4 wherein said spring means comprises flat sheet material.

6. Apparatus according to claim 5 wherein said spring means comprises an inner ring as said central member, an outer ring of larger diameter concentric with said inner ring, a plurality of arms extending generally radially between said rings, and a plurality of said fingers extending generally tangentially angled from said arms.

7. Apparatus according to claim 1 wherein said spring means comprises a plurality of said fingers all extending from and contiguous with a central member.

8. In an electric dry shaver including a perforated shear plate, the improvement comprising a rotatable cutter head including a support member having top and bottom surfaces, being rotatable about a central axis, and including a plurality of slots extending therethrough with corresponding top and bottom parts, a plurality of cutters each being situated in one of said slots, means for rotating said support member, each cutter having a central part in said slot, at top part extending above the top of said slot and terminating in a cutting edge for engaging said shear plate, and a bottorn part extending below the bottom of said slot with an aperture in said bottom part of said cutter transverse of said slot, and spring means secured to the said support member and having a resilient finger extending at least partially across the bottom of each slot and having diameter smaller than said aperture in the cutter, said finger when a cutter is inserted downward through each slot, initially blocking the cutters bottom part from extending through the bottom of the slot, said spring being deflectable when the cutter is urged further downward until said finger springs through said aperture, said finger then positioned while traversing said aperture and being deflected to alone resiliently urge the cutter upward, said cutter head further comprising stop means fixedly secured to said support member at the bottom surface thereof adjacent each slot for preventing movement of each cutter through its corresponding slot beyond a predetermined lower limit, after said fingers have traversed said apertures.

9. Apparatus according to claim 8 wherein said spring means comprises an inner ring, an outer ring of larger diameter concentric with said inner ring, a plurality of arms extending generally radially between said rings, af d a plurality of said fingers extending'generally tangentially angled from said arms.

Claims

1. In an electric dry shaver including a perforated shear plate, the improvement comprising a rotatable cutter head including a support member having top and bottom surfaces, being rotatable about a central axis, and including a plurality of slots extending therethrough with corresponding top and bottom parts, a plurality of cutters each being situated in one of said slots, means for rotating said support member, each cutter having a central part in said slot, a top part extending above the top of said slot and terminating in a cutting edge for engaging said shear plate, and a bottom part extending below the bottom of said slot with an aperture in said bottom part of said cutter transverse of said slot, and spring means secured to the said support member and having a resilient finger extending at least partially across the bottom of each slot and having diameter smaller than said aperture in the cutter, said finger when a cutter is inserted downward through each slot, initially blocking the cutter''s bottom part from extending through the bottom of the slot, said spring being deflectable when the cutter is urged further downward until said finger springs through said aperture, said finger then positioned while traversing said aperture and being deflected, to alone resiliently urge the cutter upward.

8. In an electric dry shaver including a perforated shear plate, the improvement comprising a rotatable cutter head including a support member having top and bottom surfaces, being rotatable about a central axis, and including a plurality of slots extending therethrough with corresponding top and bottom parts, a plurality of cutters each being situated in one of said slots, means for rotating said support member, each cutter having a central part in said slot, a top part extending above the top of said slot and terminating in a cutting edge for engaging said shear plate, and a bottom part extending below the bottom of said slot with an aperture in said bottom part of said cutter transverse of said slot, and spring means secured to the said support member and having a resilient finger extending at least partially across the bottom of each slot and having diameter smaller than said aperture in the cutter, said finger when a cutter is inserted downward through each slot, initially blocking the cutter''s bottom part from extending through the bottom of the slot, said spring being deflectable when the cutter is urged further downward until said finger springs through said aperture, said finger then positioned while traversing said aperture and being deflected to alone resiliently urge the cutter upward, said cutter head further comprising stop means fixedly secured to said support member at the bottom surface thereof adjacent each slot for preventing movement of each cutter through its corresponding slot beyond a predetermined lower limit, after said fingers have traversed said apertures.

9. Apparatus according to claim 8 wherein said spring means comprises an inner ring, an outer ring of larger diameter concentric with said inner ring, a plurality of arms extending generally radially between said rings, and a plurality of said fingers extending generally tangentially angled from said arms.