Cutter head assembly for an electric dry shaver
This is a continuation of application Ser. No. 759,933 filed Jan. 17, 1977, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention is directed to new and useful improvements in electric dry shavers and in particular to means for mounting a movable inner cutter on motor operated drive means. 
     Electric dry shavers usually include a cutter head assembly comprising an outer cutter and a motor driven inner cutter operable to shear hair bristles combed through slots or apertures in the outer cutter into the path of the moving inner cutter. In certain type eletric dry shavers the outer cutter comprises a thin flexible metallic foil provided with a plurality of hair receiving apertures. The inner cutter is comprised of a plurality of arcuate shaped cutter blades urged into contact with the undersurface of the foil to conform the foil to the arcuate shape of the edges of the cutter blades. Certain of these foil type cutter heads include a plurality of parallel arcuate surfaces in conformance to a like number of rows of arcuate inner cutter blades. 
     It is known in these foil type shavers to mount the inner cutter on a support member which is interconnected to the motor operated drive means. The outer cutter foil is usually secured to a removable hairpocket section of the shaver casing with spaced longitudinally extending marginal portions connected to the spaced sidewalls of the hairpocket. When the hairpocket section is connected to the main shaver casing the flexible foil engages the resiliently mounted inner cutter to conform to the configuration thereof. In use of the shaver the inner cutter will reciprocate relative to the stationary foil. When the foil outer cutter is pressed against the skin surface it will deflect downwardly against the moving inner cutter. It is desirable that during this movement that the inner cutter be maintained in shearing engagement with the undersurface of the foil for proper cutting action. In order to accommodate the movement of the foil and the downward and sideways movement of the inner cutter in response thereto as it reciprocates, the inner cutter must therefore be permitted to move about the axis of the drive member. 
     In the past problems have been encountered in providing efficient interconnecting means for mounting the inner cutter to the drive means to allow for efficient drive of the inner cutter. Further means must be provided to both mount the inner cutter for ready detachment when necessary and for securely mounting the same against accidental disconnection during operation. Various means, such as interlocking pins, lock washers and bifurcated detenting drive arms have been used in the past to interconnect the inner cutter to the drive means. Typical of these prior art devices are disclosed in U.S. Pat. Nos. 2,900,719; 2,908,970; 3,290,781; 3,783,508; and 3,838,314. Although these known devices have proven generally satisfactory they present relatively complex assembly procedures leading to increased manufacturing costs both in time and parts. 
     It is an object of the present invention to provide novel means for mounting an inner cutter assembly in an electric dry shaver. 
     Another object is to provide novel means for maintaining an inner cutter in driving relationship with the undersurface of a foil type outer cutter. 
     Another object is to provide novel inner cutter drive means which allows for universal swiveling movement of the inner cutter about the axis of the drive member upon downward or sideways flexing of the foil outer cutter during use of the shaver. 
     Another object is to provide novel drive means for an inner cutter assembly which may be utilized with drive means which is movable in either a linear or an arcuate path. 
     A still further object is to provide a novel mounting means for an inner cutter which includes means for securely attaching the inner cutter to the motor operated drive means and which means is when desired operable to readily release the inner cutter assembly from the drive means. 
     SUMMARY OF THE INVENTION 
     The present invention contemplates a novel cutter head assembly for an electric dry shaver wherein the outer cutter member comprises a foil member in engagement with a movable inner cutter which is mounted on a support member. Motor operated drive means are interconnected to the central portion of the support member whereby when the foil outer cutter is flexed downwardly or sideways during use of the shaver in the direction of the inner cutter during operation of the shaver the inner cutter will move in the same direction without losing contact with the foil. The motor operated drive means for the support member includes a drive arm disposed in driving relationship with the central portion of the support member and is maintained in contact with the support by an arcuate shaped drive head which provides a universal connection between the drive arm and the inner cutter support member to permit swiveling movement of the inner cutter. 
     The above and other objects and advantages of the present invention will appear more fully hereinafter from a consideration of the detailed description which follows taken together with the accompanying drawings where one embodiment of the invention is illustrated. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a fragmentary perspective view of the upper portion of an electric dry shaver incorporating the present invention; 
     FIG. 2 is a fragmentary front elevational view of the electric dry shaver of FIG. 1 with parts of the casing broken away to show portions of the interior thereof; 
     FIG. 3 is a fragmentary side elevational view of the shaver taken on the line 3--3 of FIG. 2; 
     FIG. 4 is an exploded perspective view of the inner cutter assembly and drive means therefor; 
     FIG. 5 is a fragmentary plan view of the drive connection in the inner cutter support member; 
     FIG. 6 is a diagrammatic front view of the inner cutter showing the directions of movement of the cutter support member; and 
     FIG. 7 is a diagrammatic plan view of FIG. 6. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings for a more detailed description of the present invention, an electric dry shaver is generally indicated by the reference numeral 10 in FIGS. 1 to 3. Shaver 10 includes a casing made of a hard plastic material and comprises a main body section 11 and a hairpocket section 12. Hairpocket 12 is detachably mounted on main casing section in a well-known manner such as by spring biased releasable detent (not shown). 
     A motor (not shown) is provided within main body portion 11 for operating an auxiliary trimmer device 14 and a main cutter head assembly generally indicated by the reference numeral 15. 
     Cutter head assembly 15 includes an outer cutter comprising a generally rectangular flexible foil member 16 having spaced marginal portions 17 and 18 (FIG. 3) secured to spaced sidewall portions 19 and 20 of hairpocket 12 in any well-known manner (not shown). The foil 16 is made of nickel by an electroforming process and is provided with a plurality of apertures 22 for combing hair bristles into the cutter head 15. Foil 16 in mounted position on casing section 11 includes spaced arcuate shaped bowed cutting rows 23 and 24. Rows 23 and 24 are spaced one from the other by a bar member 26 which extends longitudinally accross hairpocket 12. Rows 23 and 24 are maintained in arcuate shape by the engagement of movable inner cutter assembly 28 with the undersurface of the foil 16. Inner cutter assembly 28 is operably by a motor drive arm 13 in a manner to be hereinafter explained in further detail. 
     Inner cutter assembly 28 comprises a plurality of spaced metal blades 29 each having a pair of arcuate shaped cutting edges 30 and 32. Rods 33 interconnect blades 29 in aligned relationship and which blades 29 are mounted on a support member 34. Support member 34 comprises a rectangular shaped frame having detent fingers 35 in locking engagement with lower rods 33 of inner cutter assembly 28 to maintain inner cutter blades 29 securely thereon. A spring 36 located around drive arm 13 engages the undersurface of support 34 and urges inner cutter assembly 28 and aligned arcuate cutting edges 30 and 32 into engagement with the undersurface of foil cutting rows 23 and 24 respectively. 
     As mentioned it is a feature of the present invention to provide novel means for mounting inner cutter assembly 28 on motor drive arm 13 (FIGS. 2 and 3). To this end support member 34 is provided with a rectangular shaped drive slot 37 at the central portion thereof. Drive arm 13 includes an arcuate shaped rounded drive head 38 mounted in drive slot 37 with the forward and rear surfaces 39 and 40 thereof (FIG. 2) in contact with endwalls 41 and 42 of slot 37. The side surfaces of drive head 38 are spaced from sidewalls 43-44 of slot 37 to allow for either sideways or rotative movement of support 34 about head 38 without the latter losing contact with the endwalls of 41 and 42 of slot 37. Spaced detent tabs 45 are provided on the lower portions of endwalls 41-42 to prevent upward release of support member 34 from drive arm 13 in the direction of arrow A in FIG. 2. In order to remove support 34 from drive head 38 hairpocket 12 must be removed from casing section 11. Support 34 is then rotated from the position shown in FIG. 7 to a position where at the tabs 45 are rotated free of the rounded ends of head 38 by support 34 may be lifted from drive arm 13. 
     In operation of shaver 10 as support member 34 is reciprocated by drive arm 13 in a linear direction as foil 16 is pressed against the user&#39;s skin support member 34 will bend to move downardly in the direction designed by the arrow B in FIG. 2. Inner cutter 28 will follow in the direction of the pressure exerted against the foil 16 and against the resilient restraining action of spring 36. Support 34 may also tend to rotate or move sideways about drive head 38 in the downward movement as lateral pressure is exerted against the foil 16. As diagrammatically illustrated in FIGS. 6 and 7 the novel interconnection of drive head 38 to drive slot 37 will allow for constant contact of drive head 38 with endwalls 41-42 of drive slot 37 in any direction of movement of inner cutter 28 as indicated by the arrows c, d, e, f, g, h, i and k as inner cutter 28 is reciprocated. 
     It will be apparent from the foregoing description that the novel inner cutter mounting means has many advantages in use. One advantage is that inner cutter assembly 28 is securely connected to the drive means 13 without the provision of additional parts or complicated forming of interconnection means. In addition the novel configuration of drive slot 37 and drive head 38 provides for universal movement of inner cutter 28 on drive arm 13 without the latter losing contact therewith or inner cutter 28 with the undersurface of the foil 16 thereby providing for a more efficient shaving action. Another advantage is that the disclosed novel drive connection may be used with a drive arm movable either in a linear or arcuate path in the same manner without loss of efficiency. 
     Although one embodiment of the present invention is illustrated and described in detail it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.