HK1078523B - An electric rotary shaver - Google Patents

Description

Rotary electric shaver

Technical Field

The present invention relates to a rotary electric shaver including an inner cutter which is brought into sliding contact with an inner surface of a substantially disc-shaped outer cutter having a plurality of openings on a top surface thereof while rotating.

Background

In a typical rotary electric shaver, a plurality of small hair entry openings (e.g., slits) are formed in the top surface of a substantially disc-shaped outer cutter having an annular track (groove) on the inner side thereof, and an inner cutter is provided which, when rotated, causes blades (inner blades) integrally disposed on the inner cutter to be in sliding contact with the inner surface of the outer cutter. Such a rotary electric shaver is disclosed in, for example, japanese laid-open patent publication (hei) No. 06-238070.

In particular, in the conventional inner cutter disclosed in the above prior art, an inner cutter main body made of metal is fixed to a boss made of synthetic resin.

Fig. 10 is a perspective view of the inner blade disclosed in the above prior art. Fig. 11 is a perspective view of an outer knife used with the inner knife 10. Fig. 12 is a side view of the inner blade with a portion of the inner blade removed. Fig. 13 is a partially cut-away side view of the inner knife. Figure 14 is a cut-away side view of the assembled inner and outer knives of this prior art.

As shown in fig. 11, the outer blade 12 made of metal is substantially disc-shaped. In other words, the outer cutter 12 is made into a circular plate whose periphery is bent so as to have a substantially shallow disc shape or a substantially inverted disc shape, a plurality of small hair entry ports constituting slits 14 are formed in the outer cutter 12 in the radial direction, and an annular groove 16 is formed in the outer cutter. The groove 16 extends across the slits 14 near the midpoint of each slit 14. As a result, the outer blade 12 has two annular portions (or annular rails) 12A and 12B on either side of the groove 16. This outer blade configuration with two rails 12A and 12B is referred to as a double rail configuration.

The boss 18 (see fig. 10) of the inner cutter 10 is made of POM (polyoxymethylene) resin such as "Delrin" (registered trademark) which is a product of DuPont corporation, or the like; the lower portion of the boss 18 has an inverted dish-shaped portion 20 that is open at the bottom. As shown in fig. 12, a mounting hole 22 for mounting a rotary shaft (not shown) of the shaver from below is formed in the inverted disc-shaped portion 20. A cylindrical central protrusion 24 is disposed in the center of the upper surface of the boss 18.

The inner cutter body 26 (see fig. 10) is formed by punching and bending a metal plate and is substantially in the shape of a pulley. Specifically, the inner blade body 26 has ten protrusions 30 and blade portions 32 separated from each other, the protrusions 30 protruding from the outer periphery of the circular plate portion 28, the blade portions 32 being formed by further bending the protrusions 30 in the radial direction of the boss 18. The central protrusion 24 of the boss 18 passes through the center of the circular plate portion 28 and is fixed on the upper surface of the inverted dish-shaped portion 20 of the boss 18 by thermal crimping.

An upper portion of each blade portion 32 of the inner blade main body 26 is formed in a bifurcated shape, and ends of the bifurcated blade portion are respectively formed with blades 34. Two blades 34 are formed in the two annular portions 12A and 12B of the double-rail outer cutter 12 from below (i.e., from the inside), respectively. Thus, when the inner cutter 10, which basically includes the boss 18 and the inner cutter body 26, is rotated by a rotary shaft (not shown) connected to a motor (not shown) mounted in the shaver main body, the blades 34 are operated while being in contact with the inner surfaces 12A and 12B (see fig. 14) of the annular portions 12A and 12B of the outer cutter 12. As a result, the hair (beard, etc.) entering the slit 14 of the outer blade 12 is cut by the blade 34 of the rotating inner blade 10.

The upper ends of the blades 34 of the inner cutter 10 shown here are inclined so that they are offset more in the direction of rotation of the inner cutter 10 than the lower portions of the blade portions 32, in other words, the upper ends are inclined forwardly in the direction of rotation of the inner cutter 10.

In addition, as shown in fig. 12 and 13, grooves 36 are formed on the surface of each insert 34 such that the grooves 36 face the opposite direction of the rotational direction, so that a portion of each groove 36 extends to the upper end surface of each insert 34 (i.e., the cutting surface that slidably contacts the inner surface of the outer cutter 12). These recesses 36 prevent shaving debris and dust from adhering to the blade 34 and reduce the contact area between the blade 34 and the outer knife 12, thereby reducing drive resistance (see the prior art cited above). However, in the present invention, the groove 36 may be omitted.

The inner cutter 10 and the outer cutter 12 are in pairs, for example three such pairs of cutters may be provided at the vertices of an equilateral triangle in the razor head. The three inner cutters 10 are rotationally driven by a motor installed in the shaver main body. Shavers having two pairs of inner and outer cutters as well as shavers having only one pair of inner and outer cutters are also possible.

It can be seen that in the conventional inner cutter, the entire inner cutter body 26 is made by punching a single metal plate and then bending the metal plate by about 90 ° at two positions a and B as shown in fig. 12, 13 and 14. When the number of positions where such bending is performed is large, the distance from the center of the inner cutter 10 to the insert piece 34 (particularly, the distance to the inner and outer circumferential edges of the insert piece 34) tends to be uneven, resulting in the inner and outer circumferential edges of the insert piece 34 contacting the inner and outer circumferential surfaces 12c and 12d of the inner and outer circumferential walls 12e and 12f of the respective annular portions 12A and 12B of the outer cutter 2. This brings about problems such as increased operation noise and deteriorated sharpness due to the enlarged width of the annular portion of the outer cutter 12. In addition, the inner cutter must be manufactured using a special metal material having good press working characteristics and being hardened.

In addition, in the rotary shaver, frictional resistance between the blade 34 of the inner cutter and the outer cutter 12 due to sliding and resistance generated when hairs are cut are applied to the blade 34. Therefore, the inner blade body 26 must have sufficient thickness and high rigidity so that the blade 34 does not vibrate due to these resistances. The inner blade of the rotary shaver is generally made of SUS420J2 metal plate having a thickness of 0.5 mm. When such a thick metal material is pressed (punched and bent), the machining accuracy is poor, and problems such as generation of vibration, increase of noise, deterioration of sound quality, and deterioration of sharpness occur due to the oblique wear of the blade.

In order to improve the processing accuracy, it is desirable to make the length of the bent portion (A, B) formed by pressing as small as possible. However, if the lengths of these portions are shortened, the width of the protrusion 30 is naturally reduced, which is disadvantageous from the viewpoint of preventing the blade 34 from vibrating. If the distance between the tip portion of the blade 34 exerting the resistance and the bent portion (A, B) is large, the stress exerted on the bent portion (A, B) will increase; which is also disadvantageous from a vibration point of view. However, for the inner blade having the conventional structure, there are some limitations in shortening the distance.

Therefore, due to structural problems such as poor pressing accuracy, the presence of a large number of bent portions, and the like, problems such as vibration of the blade, resonance between different parts, improvement of operating noise, and deterioration of sound quality are inevitable.

Disclosure of Invention

The present invention has been made in view of the above-mentioned facts.

An object of the present invention is to provide a rotary electric shaver in which, by adopting an inner cutter body of a novel structure, since the number of positions to be bent in pressing is reduced, the precision in manufacturing the inner cutter is improved, and each blade of the inner cutter can be prevented from deviating from a true circle when rotating, and since the vibration of the blade is reduced, the operation noise can be suppressed and the rotating sound quality of the inner cutter is excellent, and further, the deterioration of the sharpness of the blade due to the deviated wear of the blade can be prevented.

The above object is achieved by the unique structure of the rotary electric shaver of the present invention, wherein according to one aspect of the present invention, there is provided a rotary electric shaver comprising a substantially circular disk forming an outer cutter having a plurality of hair entry apertures on a top surface thereof, and an inner cutter in sliding contact with an inner surface of the outer cutter upon rotation, wherein,

at least one concentric annular track is formed inside the outer cutter; and

the inner cutter includes:

an inner cutter base including a boss engaged with a rotation shaft of the shaver and a blade holder protruding outward from the boss, the boss and the blade holder being integrated together, and

a plurality of blade segments on the blade mount; and wherein

The blade segments have blades arranged side by side in a radial direction of the inner blade and in sliding contact with the at least one concentric annular track, the blade segments being connected to each other to form at least one blade ring; and

each of the blade segments is Y-shaped in letter, the blades being formed in bifurcated portions of the Y-shaped blade segments, the blade segments being connected to one another at their junctions to form the blade ring.

Advantageously, the inner portion of the outer knife is formed with at least two concentric annular tracks, a partial circumferential edge of the at least one insert ring being cut in a circumferential direction of the at least one insert ring and bent upwardly to form the blades, the insert ring being retained on the boss at an inner circumferential edge thereof.

Advantageously, a portion of the central portion of each blade segment of the blade ring is cut in the circumferential direction of the blade ring and bent upward to form the blades.

Advantageously, a portion of the outer circumferential edge of each blade segment of the blade ring is cut in the circumferential direction of the blade ring and bent upwards to form the blades.

Advantageously, the outer cutter is formed at an inner portion thereof with a plurality of concentric annular tracks, a portion of an outer circumferential edge of one of the plurality of blade segments is cut and bent upward in a circumferential direction of the blade ring to form the blade, and a portion of an inner circumferential edge of another blade segment adjacent to the one blade segment is cut and bent upward in the circumferential direction of the blade ring to form the blade.

Advantageously, the outer cutter is formed with at least two concentric annular tracks on the inside thereof, and the blade ring is formed of an annular metal plate, wherein the blade is formed by alternately cutting a part of the annular metal plate on at least one of the inner circumference and the outer circumference to form a blade portion and bending the blade portion upward to form the blade.

Advantageously, the blade ring is formed of an annular metal plate, wherein the blades are formed by cutting a part of the annular metal plate located at least on the outer circumference to form blade portions and bending the blade portions upward to form the blades.

In the present invention, the boss and the blade holder are formed as an integral unit of an inner blade base made of synthetic resin, and the plurality of blade sections made of metal are firmly held on the blade holder. Therefore, it is not necessary to support each blade segment on a circular plate portion or a protrusion as in the conventional inner blade body, and it is also not necessary to press bent portions (A, B) as can be seen in the conventional inner blade body, and furthermore, the inner blade has high pressing or press working accuracy due to the reduced number of bent portions.

In addition, the present invention has various advantages. It is not only high in processing accuracy but also reduced in vibration of the blade, and ensures the vibration absorbing effect of the blade holder made of synthetic resin. Therefore, the operation noise is reduced and the sound quality of the rotary inner blade is high. Further, the skew abrasion of the blade caused by the blade vibration is suppressed, and the deterioration of the sharpness is prevented. Furthermore, since the blade does not vibrate, the thickness of the blade can be reduced, and therefore the amount of the special noble metal material used will be reduced.

The blade holder may be comprised of a plurality of arm members extending radially from the boss, this structure reduces the weight of the inner cutter; also, because shaving debris, etc. from the blades fall between the radial arms, the shaving debris does not adhere to the inner cutter, thereby facilitating cleaning of the inner cutter and the shaver; in this configuration, each arm holds more than one blade segment(s).

For an electric shaver having an outer cutter with a single annular track formed therein, a plurality of blade sections may be joined in an annular shape to form a blade ring, the configuration of the blade sections facilitating the machining (shaping) of the blade sections and the connection between the blade sections and the blade holder. In addition, by holding the portions of the insert ring near the blade segments on the upper surface of the blade mount, vibration of the blade segments can be more efficiently prevented. In the case of an electric shaver having an outer cutter in which a plurality of concentric annular tracks are formed, each blade section has a plurality of blades arranged side by side in a radial direction of the inner cutter, and the blade sections are connected to each other to form a blade ring, which is provided on the blade holder. Each of the blade segments may be in the shape of the letter Y, the blades being disposed in the diverging portions of the Y-shaped blade segments, and the blade segments being connected to each other at their junctions, thereby forming the blade ring.

The plurality of blade sections may be formed on each blade holder, respectively. A plurality of blade segments may be combined to form a set such that a plurality of blade sets are disposed on the blade holder. The blade holder may be in the shape of a plurality of arms, so that the same number of blade sections as the blade holder are provided on each blade holder, respectively. The plurality of blade segments may be combined to form a plurality of groups, the blade holder being formed in the same number as the number of the groups. The blade section is arranged on the blade holder by means of thermal crimping or can be insert-molded on the inner blade base when the inner blade base is injection-molded. Alternatively, the blade segment may be secured by or in combination with an adhesive material. Further, an inner blade holder for holding the blade may also be inserted into the inner blade base, thereby holding the blade on the inner blade holder.

When the plurality of blade segments are in the form of an insert ring, an inner circumferential portion of the insert ring may be retained or secured on the boss. In this structure, since the insert ring is held by the boss and the insert holder, the insert section can be more firmly fixed, so that the vibration of the insert can be further reduced.

The outer blade used together with the inner blade may form a plurality of slits extending in a radial direction thereof. It is possible to use an outer blade in which the slits are inclined with respect to the radial direction of the outer blade or an outer blade in which the slits are bent or bent into a corrugated shape extending more or less radially.

For an electric shaver having an outer cutter internally forming a single annular track, the inner cutter may be designed such that a portion of the central portion of each blade segment of an insert ring made of, for example, a metal plate, is cut (e.g., by mold punching) in the circumferential direction of the insert ring and bent upward to form the blade. In the actual manufacturing process of such an insert ring, the insert ring is formed by die-stamping a metal plate into a generally annular shape and then or simultaneously bending upward the portions constituting the insert.

For an electric shaver having an outer cutter internally forming a single annular track, the inner cutter may also be designed such that a portion of the outer circumferential edge of each blade segment of the blade ring is cut and bent upwardly in the circumferential direction of the blade ring to form blades of a slightly cantilevered configuration.

Further, for an electric shaver having an outer cutter internally formed with two annular tracks, the inner cutter may be designed such that the blade ring is composed of a plurality of blade segments connected to each other to form a blade ring, a part of an outer circumferential edge of one of the plurality of blade segments is cut and bent upward in a circumferential direction of the blade ring to form the blade, and a part of an inner circumferential edge of a next blade segment is cut and bent upward in the circumferential direction of the blade ring to form the blade. In other words, the plurality of blade segments of the blade ring are cut alternately along the inner and outer circumferential edges such that the blade ring has the outer circumferential blades and the inner circumferential blades alternately arranged.

Drawings

FIG. 1 is a partially cut-away top view of an inner blade according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is an exploded perspective view of the inner blade shown in FIG. 1;

FIG. 4 is a top view of an insert ring according to another embodiment of the present invention;

FIG. 5 is a side cross-sectional view of the entire inner knife taken along line 5-5 of FIG. 4;

FIG. 6 is a partial side cross-sectional view of an inner blade of another embodiment of the present invention;

FIG. 7 is a partial side cross-sectional view of an inner blade of another embodiment of the present invention;

FIGS. 8(a) and 8(b) are perspective views of a portion of an inner blade of another embodiment of the present invention, respectively;

FIG. 9 is a perspective view of a portion of an inner blade of yet another embodiment of the present invention;

FIG. 10 is a perspective view of a conventional inner blade;

FIG. 11 is a perspective view of a conventional outer blade;

FIG. 12 is a side view of a portion of the conventional inner knife;

FIG. 13 is a partial side cross-sectional view of a portion of the conventional inner knife; and

fig. 14 is a side cross-sectional view of a prior art inner and outer knives assembled together.

Detailed Description

In fig. 1, 2 and 3, reference numeral 100 designates an inner blade in accordance with an embodiment of the present invention, the inner blade 100 including an inner blade base 102 and a blade ring 104 attached to and forming an integral unit with the inner blade base.

The inner blade base 102 has a boss 106 and eight blade holders 108. The blade holder 108 is in the form of a plurality of arms that extend radially outward from the boss 106. The boss 106 and the arm blade holder 108 are molded integrally by synthetic resin. POM (polyoxymethylene) resin is an ideal material for manufacturing the boss and the blade holder. The top ends (distal ends) of all the arms or blade holders 108 are curved upward, and the top surfaces of the blade holders 108 lie on an imaginary plane Y perpendicular to the rotational axis X (see fig. 2) of the inner cutter 100.

Protrusions 110 and 112 extend from the top surface of each blade mount 108. Protrusions 110 secure blade ring 104 to blade holder 108 by thermal crimping, and protrusions 112 are used to position blade ring 104.

A cylindrical central protrusion 114 protrudes from the center of the top surface of the inner blade base 102. When the inner blade 10 is placed in the outer blade, the central protrusion 114 engages with a groove portion (not shown) formed in the center of the inner surface of the outer blade (shown in fig. 9), thereby preventing the inner blade 100 from being eccentric with respect to the outer blade. In other words, the central protrusion 114 prevents rotational chatter of the inner blade 100.

As best shown in fig. 3, insert ring 104 includes a substantially Y-shaped insert segment 116 connected in a ring shape; each substantially Y-shaped blade section 116 includes a connection portion 120 and a pair of blades 118, the pair of blades 118 being positioned in two concentric ring portions of the outer knife (see, e.g., fig. 14). The two bifurcated or Y-letter shaped blades 118 are inclined toward the rotation direction Y of the inner blade 110, and a recess 122 is formed on the surface of each blade 118 such that the recess 122 faces a direction opposite to the rotation direction Y. The Y-shaped blade sections 116 are connected to each other by a connection, whereby the connection extends between the bifurcating blades 118, forming a ring.

The blade ring 104 is formed by die stamping a metal plate into a generally annular shape and then or simultaneously bending the portions that make up the blades 118. In addition, a groove 122 is formed in the blade 118 and a blade securing hole 124 is formed in the blade section 116; the machining operation for forming the recess and the fixing hole may be performed at the same time as the molding and punching or may be performed through a separate process.

Further, as can be seen from FIG. 3, since the blades 118 are bent upward at a small angle, the stress applied to the metal material of the blade ring 104 is small and the characteristics of the metal material (particularly, the press working characteristics) are low.

The blade ring 104 is secured in the blade holder 108 of the inner blade base 102 by thermal crimping. In particular, the blade ring 104 of the illustrated embodiment has a total of eight inner blade fixing holes 124 formed at positions corresponding to the projections 110 of the arm members or blade holders 108, the projections 110 pass through the inner blade fixing holes 124 of the blade ring 104, and upper ends (projecting ends) of the projections 110 are curled by pressing the upper ends while applying heat. In fig. 1 and 2, reference numeral 110A denotes a thermal curling portion. As shown in fig. 1, other protrusions 112 on blade holder 108 serve to position blade ring 104 by contacting the edge of connecting portion 120.

After securing the insert ring 104 in place, the ends (tips) of all of the blades 118 are ground to form a cutting edge. Of course, insert ring 104 is heat treated at the appropriate time after press working.

The boss 106 of the inner cutter base 102 of the inner cutter 100 is formed with a mounting hole 126 (see fig. 2) which engages with a corresponding rotary shaft (not shown in the drawings) of the shaver; after being covered by the outer cutter (see fig. 9), the inner cutter is rotationally driven while the shaver is in use.

In the above embodiment, the blade mount 108 is provided in the circumferential direction of the inner cutter 100 extending or spaced in the radial direction; when blade ring 104 is provided on inner blade base 102, a pair of blades 118 are positioned between two adjacent blade supports 108. Accordingly, shaving debris generated by the blades 118 can smoothly fall through the gaps between the blade holders 108, so that the shaving debris does not adhere to the blades 118 and cleaning is easy.

Fig. 4 and 5 show another embodiment of the present invention.

As shown in fig. 4, in the insert ring 202 of this embodiment, portions corresponding to the blade segments 116 in fig. 1 and 3 are connected and integrated by a flange portion 204 located on the inner side of the ring 202.

A substantially cup-shaped small diameter portion 206 is formed at the center of the flange portion 204 by deep drawing, and an opening 208 is formed at the bottom of the small diameter portion 206. As can be seen from fig. 4, at the edge of the opening 208, two different circular arcs are alternately formed at equal intervals, each circular arc forming four. Insert 210, coupling portion 212, and insert retention aperture 214 are formed in insert ring 202 in the same manner as the components of insert ring 104 shown in fig. 1 and 3.

As can be seen in fig. 5, the inner blade base 216 has a blade holder 220 and a protrusion 222. The blade holder 220 radially protrudes from the boss 218, and a protrusion 222 protrudes from an upper surface of an end of the blade holder 220. Blade ring 202 is placed on blade holder 220 with blade retention apertures 214 aligned with protrusions 222. The ends of projections 222 protruding from blade retention apertures 214 are heat crimped to retain blade ring 202. Fig. 5 shows a state after the protrusion 222 is thermally curled. Cylindrical central projection 224 of boss 218 passes through central opening 208 of insert ring 202, and the inner periphery of central opening 208 is secured to projection 224 by thermal crimping. Reference numeral 226 in fig. 5 denotes a thermal curling portion.

In the configuration shown in fig. 4 and 5, when insert ring 202 is mounted on inner blade base 216, the portion of insert ring 202 near the outer circumference is supported from below by blade holder 220, and the portion near the inner circumference is fixed near boss 218. Accordingly, the attachment of insert ring 202 to inner cutter base 216 is greatly enhanced and insert ring 202 is highly resistant to vibration.

Fig. 6 shows a cross-sectional view of another configuration of the inner blade of the present invention.

In this structure, the blades 302 of the inner cutter 300 are in a separate form without forming a blade ring, and the individual blades 302 are inserted into a circular blade holder 306 on the inner cutter base 304. specifically, all the blades 302 are fixed in position in a mold before the inner cutter base 304 is resin-molded, and in this state, the inner cutter base 304 is injection-molded (insert-molded).

Fig. 7 shows a cross-sectional view of yet another configuration of the inner knife of the present invention.

In the configuration shown in fig. 7, the blade 352 of each inner blade 350 is secured in the blade holder 356 of the inner blade base 354 by thermal crimping. Specifically, the bottom portions 352A of the blades 352 are bent so that the bottom portions 352A are in a horizontal form and are in contact with the upper surface of the blade holder 356, the projections 358 formed on the upper surface of the blade holder 356 pass through the holes formed in the horizontal bottom portions 352A of the blades 352, and the protruding ends of the projections 358 are thermally curled. Fig. 7 shows a state after completion of the thermal curling of the projection 358.

As shown in fig. 6 and 7, when the blade sections are disposed on the inner blade base, a plurality of blade sections may be joined together to form several groups. When the blade segments form a group, the inner knife is formed with the same number of arms (or blade holders) as the group, so that each group of blade segments is disposed on each arm (blade holder). In this configuration, the top surface areas of the arms are different from each other to match the size of the blade segment being joined.

Fig. 8(a) and 8(b) each show a portion of an insert ring according to this embodiment of the invention. Each blade ring is provided for an inner cutter used in a shaver having an outer cutter with an inner portion forming a single annular portion (or a single annular track, not shown).

In the structure shown in fig. 8(a), the insert ring 400 'has a structure in which a plurality of insert segments 400 are connected to each other in an annular manner at a connecting portion 402 to form an insert ring 400'; in each blade segment 400, a blade 404 is formed by cutting in the circumferential direction of the blade ring 400' and bending upward at approximately the center of the blade segment 400, leaving an opening 406 that remains after the blade 404 is cut. Because each blade segment 400 surrounds an opening 406, blade ring 400' has increased stiffness.

In the configuration shown in fig. 8(b), a plurality of blade segments 420 are connected to one another in an annular manner at a connection 422 to form a blade ring 400 "; in each blade segment 420, a blade 424 is cut in the circumferential direction of the blade ring 400 "and bent upward along the outer periphery in a slightly cantilevered configuration. The insert ring 400 "has a narrow width and is therefore small in size and light in weight.

Fig. 9 illustrates a portion of an insert ring according to another embodiment of the present invention. Blade ring 400' ″ in fig. 9 is provided for an inner cutter for use in a shaver having an outer cutter with an inner portion forming a concentric double annular portion (or concentric double annular tracks, not shown).

The insert ring 400 "' has a structure in which a blade 426 is further formed in the blade section 420 of the insert ring as shown in fig. 8 (b). In other words, in the blade ring 400 '″, one blade 424 is formed by cutting along the circumferential direction of the blade ring 400' ″ and bending upward along the outer circumferential edge of a blade section 420 of an annular metal plate, and the other blade 426 is formed by cutting along the inner circumferential edge of a blade section 428 adjacent to the blade section 420 of the annular metal plate and bending upward, so that the outer circumferential blade 424 and the inner circumferential blade 426 are alternately arranged in the circumferential direction and the radial direction. In this configuration, a blade section of a blade (e.g., blade section 428) is a connection to the next blade section (e.g., blade section 420), and a blade section of the blade (e.g., blade section 420) is a connection to the next blade section (e.g., blade section 428). In use, blades 426 on the inner circumferential edge of blade ring 400' "contact and slide along the inner surface of the inner annular portion (rail) of a dual rail outer blade, and blades 424 on the outer circumferential edge contact and slide along the inner surface of the outer annular portion (rail) of the dual rail outer blade.

Claims (18)

1. A rotary electric shaver comprising a substantially circular disc forming an outer cutter having a plurality of hair entry apertures on a top surface thereof, and an inner cutter in sliding contact with an inner surface of the outer cutter when rotated, wherein,

at least one concentric annular track is formed inside the outer cutter; and

the inner cutter includes:

an inner cutter base including a boss engaged with a rotation shaft of the shaver and a blade holder protruding outward from the boss, the boss and the blade holder being integrated together, and

a plurality of blade segments on the blade mount; and wherein

The blade segments have blades arranged side by side in a radial direction of the inner blade and in sliding contact with the at least one concentric annular track, the blade segments being connected to each other to form at least one blade ring; and

each of the blade segments is Y-shaped in letter, the blades being formed in bifurcated portions of the Y-shaped blade segments, the blade segments being connected to one another at their junctions to form the blade ring.

2. The rotary electric shaver set forth in claim 1 wherein said blade holder is in the form of a plurality of arms extending radially from said boss.

3. The rotary electric shaver set forth in claim 1,

the outer cutter is formed with a single circular track therein.

4. The rotary electric shaver set forth in claim 1 wherein said plurality of blade segments form a plurality of groups, said groups of blade segments being located on said blade holder, wherein each of said blade segments has said blade.

5. The rotary electric shaver set forth in claim 1 wherein said blade section is disposed on said blade holder by means of thermal crimping.

6. The rotary electric shaver set forth in claim 1 wherein said blade section is insert molded onto said inner blade base.

7. The rotary electric shaver set forth in claim 1 wherein said inlet is a slit across said annular track in a radial direction of said outer cutter.

8. The rotary electric shaver set forth in claim 1,

at least two concentric annular tracks are formed inside the outer cutter;

a partial circumferential edge of the at least one blade ring is cut in a circumferential direction of the at least one blade ring and bent upward to form the blade; and

the insert ring is retained on the boss at an inner circumferential edge thereof.

9. The rotary electric shaver set forth in claim 1 wherein a portion of a central portion of each blade segment of the blade ring is cut in a circumferential direction of the blade ring and bent upward to form the blades.

10. The rotary electric shaver set forth in claim 1 wherein a portion of an outer circumferential edge of each blade segment of the blade ring is cut in a circumferential direction of the blade ring and bent upward to form the blade.

11. The rotary electric shaver set forth in claim 1,

a plurality of concentric annular tracks are formed inside the outer cutter; and

a portion of an outer circumferential edge of one of the plurality of blade segments is cut and bent upward in a circumferential direction of the blade ring to form the blade, and a portion of an inner circumferential edge of another blade segment adjacent to the one blade segment is cut and bent upward in the circumferential direction of the blade ring to form the blade.

12. The rotary electric shaver set forth in claim 1,

at least two concentric annular tracks are formed inside the outer cutter; and

the blade ring is formed of an annular metal plate, wherein the blades are formed by alternately cutting a portion of the annular metal plate on at least one of the inner circumference and the outer circumference to form a blade portion and bending the blade portion upward to form the blades.

13. The rotary electric shaver set forth in claim 12 wherein said blade ring is coupled to said blade holder by crimping projections on said blade holder extending through holes in said blade ring.

14. The rotary electric shaver set forth in claim 13 wherein at least said boss is made of synthetic resin.

15. The rotary electric shaver set forth in claim 13 wherein said boss, said blade holder and said projection on said blade holder are made of synthetic resin.

16. The rotary electric shaver set forth in claim 1 wherein said blade ring is formed of an annular metal plate, wherein said blades are formed by cutting a portion of the annular metal plate on at least an outer circumference thereof to form blade portions and bending said blade portions upward to form said blades.

17. The rotary electric shaver set forth in claim 16 wherein said blade portion is formed by die stamping said annular metal plate.

18. The rotary electric shaver set forth in claim 17 wherein said annular metal plate is further provided with an inner generally cup-shaped portion which engages said blade holder adjacent said boss.