Electric razor

Abstract: An electric razor including a plurality of external and internal cutting members (12,40) in which each external cutting member (12) has slits (23a,23b) and a plurality of concentric tracks (31,32) formed in the back and each internal cutting member (40) has a plurality of rows of cutting edges (42a,42b,52a,52b) that can rotate in the concentric tracks (31,32) of the external cutting member (12). The slits (23a,23b) are formed so that imaginary lines extending towards the center of the internal cutting member do not intersect the center of the internal cutting member (40), and the cutting edges (42a,42b,52a,52b) are at the ends of the arms (42,56,57) that extend outwardly from the internal cutting member (40).

Description: The present invention relates to an electric razor and more particularly to a multiple-track electric razor. An electric razor that has two concentric circular shaving surfaces in an external cutting member is known. Japanese Patent Application Publication No. 41-14339 is one example of this type of electric razor. In this electric razor, the external cutting member that has hair-entry apertures is provided, in its shaving surface, with a circular partition' groove for dividing the shaving surface into inner and outer concentric circular shaving surfaces. The rear of the inner and outer shaving surfaces are defined as inner and outer tracks. The internal cutting member, on the other hand, that is used together with the external cutting member, is provided with a plurality of thin-plate-form blades mounted individually on a block formed on the internal cutting member that is rotated by a power source. More specifically, in this prior art razor, eight angled-U-shape blades are installed in eight grooves formed in radial blocks of the base plate of the internal cutting member. Each one of the angled-U-shape blades has inner and outer cutting edges at the tip ends, and these inner and outer cutting edges are set in the inner and outer tracks of the external cutting member. When the internal cutting member as described above is used, a plurality of thin-plate-form blades must be mounted on the internal cutting member. Welding, pressing, and other work must be performed to obtain the internal cutting member. This, however, causes the blades to be arranged irregularly, and grinding of the blades takes further time. Thus, many parts are required, and a substantial number of steps must be taken to assemble the cutting member and therefore the razors. FR-A-895433 discloses an electric razor which includes an external cutting member having a top shaving surface provided with a plurality of slits and divided into at least two concentric shaving surfaces by at least one concentric groove, and an internal cutting member having a circular base, a plurality of arms equally spaced around the periphery of the base and a cutter provided on each of the arms. The main independent claim has been characterised over this document. IT-A-571355 discloses an electric razor which includes an external shaving member having a top shaving surface divided into two concentric shaving surfaces each provided with a plurality of holes for hair entry, and an internal cutting member comprising a circular base having a plurality of arms carrying cutters which face the concentric shaving surfaces. EP-A-0378266 discloses an electric razor which includes an external shaving member having a top shaving surface provided with a plurality of slits and one circular shaving portion, and an internal shaving member having a central body carrying a set of circumferential cutters which face the shaving portion. US-A-3119180 discloses an electric razor which includes a shear plate and cooperating cutter assembly in which the shear plate is provided with two concentric torus-like ribs, each having associated therewith an individual cutter, and wherein the cutters are pressure-balanced, each against the other. The aim of the present invention is, therefore, to eliminate problems seen in the existing electric razors and to provide an electric razor that uses an internal cutting member which is obtained from a single sheet of material and has, as an integral body, cutting edges disposed in a concentric circular arrangement. It is another aim of the present invention to provide an electric razor that uses an internal cutting member which has cutting edges that are well arranged and circularly aligned together relative to their leading edges. Accordingly, the present invention provides an electric razor, comprising: an external cutting member having a circular shaving top surface, said top surface being provided with a plurality of radial slits for hair entry and divided into at least two concentric shaving surfaces by at least one concentric groove; and an internal cutting member comprising a circular base which in use is rotated by a rotary power source, a plurality of arms equally spaced around a periphery of said circular base, said arms extending upwardly and outwardly from said circular base, and a cutter provided on each of said plurality of arms, each cutter having a cutting edge; wherein said circular base, plurality of arms and cutters are integrally formed; characterised in that said plurality of arms are provided at a fixed radius from a centre of said circular base, in that each cutter is formed in a U-shape with a bottom of said U-shape being connected to a distal end of a respective arm, in that a cutting edge is formed on each of two upwardly extending arms of said said U-shaped cutter, wherein said cutting edges formed on said two upwardly extending arms of said U-shaped cutter engage respectively with a rear of said at least two concentric shaving surfaces. With the structure above, when the internal cutting member is rotated, the concentric cutting edges of the internal cutting member are rotated within the circular tracks of the external cutting member, thus cutting the hair which has entered through the slits into the external cutting member. Preferably, said slits are formed such that an imaginary line inwardly extending from each one of said slits does not intersect a centre of said external cutting member. Preferably, said electric razor is provided with three pairs of said internal and external cutting members. More preferably, said three pairs of internal and external cutting members are arranged in a triangular configuration. In a preferred embodiment half of said radial slits only extend through an outer of said at least two concentric shaving surfaces. A preferred embodiment of the invention will now be described, by way of example only, with reference to the following drawings, in which: Figure 1 shows, partially and in cross section, an internal cutting member and an external cutting member fitted together in an electric razor according to the present invention; Figure 2 is a top view of one of the external cutting members, showing some of the slits formed thereon; Figure 3 is a front view of the electric razor according to the present invention; Figure 4 is a front view of the internal cutting member used in the electric razor of the present invention; Figure 5 is a top view thereof; Figure 6 illustrates how the slits are made in two shaving surfaces of the external cutting member; and Figure 7 illustrates how the slits are made in a shaving surface of the external cutting member. As shown in Figure 3, the housing 10 of the electric razor has a shaving frame 11 on the upper front portion. The shaving frame 11 has substantially an inverted triangular shape and has a substantially flat surface. In this shaving frame 11, three external cutting members 12 are installed with equal distance therebetween, forming an inverted triangle. Figure 1 shows one of the three external cutting members installed in the shaving frame 11. The external cutting member 12 has a shallow cap-shape as a whole with a circular top. The cylindrical periphery of the external cutting member 12 has a flange 13 at the lower edge which is bent outwardly over the entire circumference. The flange 13 is for preventing the cutting member 12 from coming out of the shaving frame 11. The external cutting member 12 has a hole at the center, and a center cover 18 is installed fixedly in this hole. The center cover 18 has a recess 18a to the rear. The external cutting members 12 thus structured are installed in the shaving frame 11 from the rear by pressing them into apertures 11a opened in the shaving frame 11. Each external cutting member 12 is located in an aperture 11a so as to be movable slightly in the axial direction (or slightly depressable) but not rotatable. With the flange 13, the external cutting member 12 does not come out of the shaving frame 11. A more detailed description of the external cutting member will be described below. The area around the center cover 18 of the outer surface of the external cutting member 12 is defined as a shaving surface 20 that comes into contact with skin when shaving is performed. The shaving surface 20 has two circular shaving surfaces, an inner shaving surface 21 and an outer shaving surface 22. Between these shaving surfaces 21 and 22, there is a circular groove 25 that protrudes downwardly (in the drawing). The rear of the inner shaving surface 21 is an inner circular track 31, and the rear of the outer shaving surface 22 is an outer circular track 32. The external cutting member 12 is formed with a plurality of slits that allow hairs to enter the circular tracks 31 and 32 from outside. As seen from Figures 1 and 2, two different types of slits are formed on the shaving surfaces, these being first slits 23a and second slits 23b. The first slits 23a are formed radially and across both the inner and outer circular shaving surfaces 21 and 22. The second slits 23b, in contrast, are formed radially and across only the outer circular shaving surface 22. The slits 23a and 23b have a predetermined depth. Figure 2 only shows three first and second slits 23a and 23b, though in practice, these slits are formed alternately over the entire shaving surface 20. As described above, in the outer circular shaving surface 22 both the first and second slits 23a and 23b are formed alternately over its entire surface; thus, the number of slits defined in the outer circular shaving surface 22 is twice the number defined in the inner circular shaving surface 21. The outer circular shaving surface 22 is wider in the radial direction than the inner circular shaving surface 21. Accordingly, the distance between adjacent slits in the outer circular shaving surface 22 is substantially the same as the distance between adjacent slits formed in the inner circular shaving surface 21. Figure 3 shows a different arrangement of the slits in the shaving surface 20. In the arrangement of Figure 3, only one type of the slits, the first slits 23a, are formed, and these slits 23a are formed across both the inner and outer circular shaving surfaces 21 and 22. The external cutting member 12 of this embodiment does not have slits that extend across only the outer circular shaving surface 22. As described above, the external cutting member 12 in Figure 3 has the same number of slits on both the inner and outer circular shaving surfaces 21 and 22. Furthermore, the slits in the arrangement of Figure 3 are formed with a predetermined angle as compared to the slits which are formed radially in the arrangement of Figure 2. More specifically, the slits in the arrangement of Figure 3 are formed at a predetermined angle (about 5°, for instance) relative to the radius of the cutting member; in other words, imaginary lines extended inwardly from the slits do not intersect the center of the external cutting member 12. It, of course, is possible to apply the angled-slit-arrangement as described above in an external cutting member that has both first and second slits 23a and 23b that are formed in the inner and outer shaving surfaces 21 and 22, respectively. A description of the internal cutting member 40 will be given below with reference to Figures 1, 4 and 5. As particularly seen from Figure 5, the internal cutting member 40 has a row of inner cutting edges 42a and a row of outer cutting edges 42b which are, as seen in Figure 1, brought into the inner circular track 31 and the outer circular track 32, respectively. The internal cutting member 40 has a central circular base 44 and ten arms 46 which extend outwardly from the circumferential edge of the circular base 44. These arms 46 are integral with the circular base 44 and equally spaced with respect to one another in the circumferential direction. More specifically, each one of the arms 46 extends in the radial direction for some distance and is bent upright at approximately 90° (upward in Figure 4). The arm 46 has a first, upright portion of predetermined width which extends vertically (in Figure 4) at a right angle relative to the radius of the circular base 44, and a second, slanting portion which is of gradually reducing width and extends slantingly (in Figure 4) in a direction between a counter-rotational direction (counter-clock wise in Figure 5) and a perpendicular direction of the internal ,cutting member 40. That is, the top of the upright portion of the arm 46 is bent. The arm 46 further extends in the direction of the radius of the circular base 44 and has a cutter 42 which is integral with the arm 46. The cutter 42 is branched into a U-shape so that it has at the top an inner cutting edge 42a and an outer cutting edge 42b. The cutter 42 is a flat plate shape and is disposed at an angle, relative to the circular base 44, SO that it extends slantingly in a direction between the rotational direction (clockwise in Figure 5) and the perpendicular direction (upward in Figure 4). In other words, the cutter 42 is slanted in the direction of rotation when viewed from the side as shown in Figure 4. In addition, the inner cutting edge 42a and the outer cutting edge 42b have flat top surfaces (as seen in Figure 4). The leading edges of the inner and outer cutting edges 42a and 42b are arranged so that an inwardly extended imaginary straight line from the two leading edges of the cutting edges 42a and 43b crosses the center of the circular base 44 or the center of the internal cutting member 40 (as viewed in Figure 5). Furthermore, all the cutting edges 42a and 42b of the internal cutting member 40 are formed so that when the external cutting member 40 and the internal cutting member 12 are assembled together as shown in Figure 1, the inner and outer cutting edges 42a and 42b come into close contact with the inner and outer circular tracks 31 and 32, respectively, of the external cutting member 12. In the above embodiment, the circular base 44, the arms 46, the cutters 42 and the inner and outer cutting edges 42a and 42b are made from a single metallic plate. As seen in Figure 1, into the hole at the center of the circular base 44 of the internal cutting member 40 is brought a transmission block 16 from the rear (from below in Figure 1) so that the intermediate diameter portion of the block 16 is securely fitted in the center hole of the circular base 44. The transmission block 16 transmits the driving force of the electric razor to the internal cutting member 40. The transmission block 16 has a small diameter portion (the upper most portion in Figure 1), which is at the top of the transmission block 16 and defined as a guide part 16A. The transmission block 16 also has a large diameter portion, which is at the base (the lower most portion in Figure 1) of the transmission block 16 and is defined as a driving force transmission part 16B. The driving force transmission part 16B has a cone-shaped entrance 16c; and above this entrance 16 and inside the intermediate diameter portion is a connection hole 16d which has a substantially rectangular cross section. Thus, when the tip end 15a of a drive shaft 15 is fitted in the connection hole 16d, the drive force from a driving source (not shown) is transmitted to and rotates the internal cutting member 40. Figure 1 shows the internal and external cutting members 12 and 40 as assembled. The guide part 16A of the block 16 which is secured to the internal cutting member 40 is brought into the rear recess 18a of the center cover 18 of the external cutting member 12. As a result, any movement of the internal cutting member 40 in the radial direction is prevented. In addition, when the internal and external cutting members 40 and 12 are assembled as in Figure 1, the inner cutting edges 42a and the outer cutting edges 42b of the internal cutting member 40 come into close contact with the inner and outer circular tracks 31 and 32, respectively. As a result, when the internal cutting member 40 is rotated by the driving force transmitted to it, the cutting edges 42a, and 42b of the internal cutting member 40 are rotated, maintaining contact with the inner and outer circular tracks 31 and 32 of the external cutting member 12, cutting the hair. A method for making the external cutting member 12 will now be described. The slits of the shaving surface 20 of the external cutting member 12 are formed on the shaving surfaces 21 and 22 by use of a rotary cutter 70. For opening the first slits 23a into the shaving surfaces 21 and 22, the rotary cutter 70 is positioned to come into contact with the shaving surfaces 21 and 22 and then moved toward the rear of the external cutting member 12 (see Figure 6). For opening the first slits 23b in the outer side shaving surface 22, the rotary cutter 70 is moved to a position where it comes into contact with only the outer circular shaving surface 22. Then, the rotary cutter 70 is moved toward the rear of the external blade 12 while being kept in contact with the outer shaving surface 22 (see Figure 7). In either case, after making one slit, the external cutting member is rotated by a predetermined distance, and the slit forming is repeated for the entire shaving surface 20. The slits 23a and 23b are deepest at the outer circumference of the outer circular shaving surface 22. In the embodiment described above, the shaving surface 20 is divided into two concentric circular surfaces to form the two concentric circular tracks 31 and 32 (a "dual-track" formation), and the inner and outer cutting edges are rotated inside the two circular tracks, respectively. However, the shaving surface and therefore the tracks of the external cutting member may be formed of three, four or five in number, i.e. in triple, quadruple, or quintuple formation. If these plural (more than two) shaving surfaces and plural (more than two) tracks are employed, then the internal cutting member is provided with a plurality of rows of concentric cutting edges that correspond to the number of circular tracks. The internal cutting members described above may be obtained by cutting, pressing, bending, etc. strips of steel or other suitable metal by any prior art technique. In addition, each of the internal cutting members of the present invention is formed so that a plurality of integral arms extend from the circumferential edge of the circular base of the cutting member, and the cutting edges at the ends of the arms are arranged concentrically. Thus, the internal cutting members are obtained from a single sheet of material by cutting and bending. Thus, the internal cutting members obtained according to the present invention can have cutting edges that are regularly and uniformly arranged (in height, direction, length, etc.) compared to the prior art cutting members that are made out of several parts that are welded, pressed, etc. Furthermore, the number of parts that make up the internal cutting member of the present invention is less than those of the prior art cutting members; as a result, the steps needed to obtain the cutting member are less, the time required to obtain the cutting member is short, and the cost of manufacturing is low. Furthermore, the cutting member of the present invention can have more cutting edges than the cutting members of the prior art; accordingly, the speed of rotation of the cutting member of the present invention can be lowered giving rise to less vibration and noise.

Claims: An electric razor, comprising: an external cutting member (12) having a circular shaving top surface (20), said top surface (20) being provided with & plurality of radial slits (23a,23b) for hair entry and divided into at least two concentric shaving surfaces (21,22) by at least one concentric groove (25); and an internal cutting member (40) comprising a circular base (44) which in use is rotated by a rotary power source, a plurality of arms (46) equally spaced around a periphery of said circular base (44), said arms (40) extending upwardly and outwardly from said circular base (44), and a cutter (42) provided on each of said plurality of arms (46), each cutter (42) having a cutting edge (42a,42b); wherein said circular base (44), plurality of arms (46) and cutters (42) are integrally formed; characterised in that said plurality of arms (46) are provided at a fixed radius from a centre of said circular base (44), in that each cutter (42) is formed in a U-shape with a bottom of laid U-shape being connected to a distal end of a respective arm (46), in that a cutting edge (42a,42b) is formed on each of two upwardly extending arms of said U-shaped cutter (42), wherein said cutting edges (42a,42b) formed on said two upwardly extending arms of said U-shaped cutter (42) engage respectively with a rear of said at least two concentric shaving surfaces (21,22). An electric razor according to claim 1, wherein said slits (23a,23b) are formed such that an imaginary line inwardly extending from each one of said slits (23a,23b) does not intersect a centre of said external cutting member. An electric razor according to claim 1 or claim 2, wherein said electric razor is provided with three pairs of said internal and external cutting members (12,40). An electric razor according to claim 3, wherein said three pairs of internal and external cutting members (12,40) are arranged in a triangular configuration. An electric razor according to any one of claims 1 to 4, wherein half of said radial slits (23b) only extend through an outer (22) of said at least two concentric shaving surfaces.

Inventors: OKABE MASAKI, UCHIYAMA HIROMI, OKABE, MASAKI, UCHIYAMA, HIROMI
Applicants: IZUMI PROD CO, IZUMI PRODUCTS COMPANY
Application year: 1993
Main classification: B26B19
IPC codes: B26B19