Abstract:
A hair-plucking assembly includes a helical springs motor-driven to rotate about a straight axis. Cam devices displace opposing ends of the spring periodically as the spring rotates, opening spaces between adjacent loops of the spring to receive hair. The loops are then closed to pinch and pluck the hair. A combing device includes a quasi-continous longitudinal channel in the imaginary outer surface of the spring.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to motorised epilating devices for removing unwanted body hair by uprooting the hair. 
       BACKGROUND OF THE INVENTION 
       [0002]    A known epilating device, such as that described in U.S. Pat. No. 4,935,024, includes a motor-driven rotating helical spring bent into an arcuate configuration to produce spaces between adjacent loops of the spring on a convex side. Hair received in these spaces is pinched between adjacent loops and plucked when these loops close together as the spring rotates toward the concave side. 
         [0003]    While these prior art epilating devices perform satisfactorily, it will be understood that in developing epilating devices of this type, care must be taken to ensure that the pulling of hair occurs sufficiently quickly that the user does not sense an unacceptable amount of discomfort. To achieve this it is also preferable that there be a relatively large number of hair-plucking movements—opening and closing the hair-receiving space—with each rotation of the spring. To grasp the hair and uproot it, and avoid cutting of the hair, it is desirable to increase the area of contact between which hairs are grasped. Of course, in addressing these requirements it is important that the product can be produced cost-effectively, having components which are not unnecessarily complicated or otherwise costly to manufacture, while also allowing for ready assembly and maintenance of the unit. It is an object of the present invention to meet the above needs or more generally to provide an improved epilating device. 
       DISCLOSURE OF THE INVENTION 
       [0004]    According to one aspect of the present invention there is provided an epilating device, comprising: 
         [0005]    a housing; 
         [0006]    a spring supported in the housing for rotation about a straight axis, the spring being helical, adjacent loops of the spring defining spaces for receiving and pinching hair therebetween; 
         [0007]    a rotary motor disposed in the housing and drivingly connected to the helical spring, and 
         [0008]    at least one cam and cam-follower pair, relative rotation between the cam and cam-follower displacing an end of the spring axially and closing the spaces periodically as the spring rotates to pluck the hair. 
         [0009]    Preferably one of the cam and cam-follower of the at least one pair is fixed to the housing, the other of the cam and cam-follower of the at least one pair is fixed to an end of the spring, and the spring urges the cam and cam-follower into engagement. Preferably the spring is maintained in compression. Optionally, the spring may be maintained in tension. 
         [0010]    Preferably the device comprises first and second cam and cam-follower pairs, each pair engaging an opposing end of the spring and both pairs cooperating to substantially simultaneously displace both ends of the spring axially and close the spaces periodically as the spring rotates. 
         [0011]    Preferably the cam has a cam surface extending circumferentially relative to the axis and the cam-follower has at least one contacting face making sliding contact with the cam surface. 
         [0012]    Preferably the cam surface includes diametrically opposing concave portions and the cam-follower has a two contacting faces disposed diametrically opposite one another. Preferably the contacting faces are spheroidal. 
         [0013]    Preferably the cam and cam-follower pair displace the spring to open and close the spaces at least twice per revolution of the spring. 
         [0014]    Preferably the spring is formed from a thread and includes a combing device to align the hair to be pinched in the spaces and plucked out, the combing device comprising at least one groove extending substantially transversely to the thread and lying in the area of an imaginary outer surface of the spring in at least one loop of the spring. 
         [0015]    Preferably adjacent loops of the spring are each provided with at least one groove, the grooves forming a quasi-continuous channel in the area of the imaginary outer surface of the spring. 
         [0016]    Preferably the channel extends parallel to the axis of the spring. Preferably the channels have substantially identical cross-sections. 
         [0017]    Preferably the groove has a cross-section with a first flat thereon, the first flat defining a radially outermost surface of the spring. Preferably the thread comprises awire. 
         [0018]    Preferably the imaginary outer surface of the spring is substantially cylindrical. Optionally imaginary outer surface may be convex or barrel-shaped. Alternatively the imaginary outer surface may be concave or waisted in shape. 
         [0019]    This invention provides an epilating device which is effective and efficient in operational use, providing reliable clamping action over a large area between the adjacent loops of the spring. In particular, the device may be economically constructed and has an overall simple design which minimizes manufacturing costs and increases the number of common parts that are used. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: 
           [0021]      FIG. 1   a  is side view of an epilating device according to the present invention; 
           [0022]      FIG. 1   b  is side view of the epilating device of  FIG. 1   a  showing part of the housing removed; 
           [0023]      FIG. 2  is an exploded perspective view of the hair plucking assembly of the device of  FIG. 1   a;    
           [0024]      FIG. 3  is a fragmentary side view of the spring of the hair plucking assembly of  FIG. 2 ; 
           [0025]      FIG. 4  is a fragmentary end view of spring of  FIG. 1   a;    
           [0026]      FIG. 5  is a fragmentary sectional view along line AA of  FIG. 3 ; 
           [0027]      FIG. 6  is a central longitudinal section through the hair plucking assembly of the device of  FIG. 1   a  in a first position, and 
           [0028]      FIG. 7  is a view corresponding to  FIG. 6  showing the cam follower rotated 90 degrees. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    Referring to the drawings,  FIGS. 1 and 2  illustrate a preferred embodiment of an epilating device having a housing  10 , or handle, which is manually grippable by the user; and a hair-plucking assembly  11 . The housing  10  holds a motor  12  powered by mains power through a plug connector  13 , although in alternative embodiments it may be powered by batteries. 
         [0030]    A reduction gear train serves to transmit torque from the motor output to the hair-plucking assembly  11  which is rotated at a reduced speed. In the system illustrated in  FIG. 1 , a pinion  15  is mounted on the motor shaft  14  and meshes with a gear  16  mounted rotationally fast with gear  17  to provide a first reduction. Gear  17  engages with a gear  18  to provide a second reduction. An idler gear  19  transfers torque from the gear  18  to a journal block  22 , engaging a toothed gear portion  31  thereof. 
         [0031]    Hair-plucking assembly  11  includes a cam device mounted at each end of the spring  24  and further includes a cam  20 , a cam-follower  21  and a journal block  22  each with apertures therethrough for receiving an axle  23 . As used herein, the term “axial” refers to a direction substantially parallel to the longitudinal axis of the assembly and the term “radial” refers to a direction substantially orthogonal to this axes. The term “circumferential” refers to the direction of a circular arc having a radius substantially orthogonal to the axis  25 . 
         [0032]    Each cam  20  includes a circumferentially-extending cam surface  27  which is generally symmetrical and includes two diametrically opposing lobes  28 . The cam surface  27  is partly surrounded by a larger diameter abutment face  30  which lies in a transverse plane. The cam  20  further includes coaxial cylindrical tabs  29  integral therewith. 
         [0033]    Each journal block  22  includes a gear portion  31  having a plurality of external teeth. Opening outwardly is a recess  32  in which the lobes  28  of cam  20  are received and which is surrounded with a rim  33  that generally abuts the abutment face  30 . Extending axiallty inwardly of the gear portion  31  is a cylindrical face  34 . An inner transverse face  35  includes a pair of axially-extending openings  36  in diametrically opposite positions. 
         [0034]    Each cam-follower  21  includes a spigot portion  37  with a cylindrical face and a concavity  38  with inner walls complementary to the cylindrical face  34  received therein. The spigot portion  37  is bounded by a radially-outwardly-projecting shoulder  46 . Projecting axially from the concavity  38  are two parallel arms  39  located diametrically opposite one another and sized for a sliding fit in respective ones of the openings  36  such that the cam follower  22  is thereby rotated together with the journal block  22 . The arms  39  are curved in cross-section, with coaxial concave and convex faces on their radially inner and outer sides respectively. 
         [0035]    The spring  24  is helically wound from wire thread and has a shape defining imaginary inner and outer cylindrical boundary surfaces, the axially opposing ends of the spring  24  being received and supported by the spigot portions  37  and abutting the shoulders  46 . Opposing ends  41  of the wire from which the spring is wound project inwardly through the imaginary inner boundary surface of the spring and are received in apertures in the cam-followers  21 , so that the spring  24  is rotated together with the cam-followers  21 . The axle is received in a tubular spacer  40 , the opposing ends of which abut the two cam-followers  21 . 
         [0036]    A bracket  26  includes a pairs of recesses  42  at its opposing ends for receiving the tabs  29 , to mount the cams  20 . A resilient metal clip  43  has an elongate portion  45  which abuts the bracket  26  and hooks  44  at its ends which engage the opposite ends of the axle  23 . When assembled the spring  24  urges the convex ends  49  of the arms  39  against the cam surface  37 . 
         [0037]      FIGS. 2-5  illustrate in detail one of four quasi-continuous channels  50  which are formed in the outer surface of the spring  24 . The channels  50  are elongate axially and substantially equally angularly spaced. The channels  50  form a combing device to align the hair to be pinched in the spaces  51  between adjacent loops  52  of the spring. 
         [0038]    Each channel  50  is quasi-continuous in as much as it is defined by a groove  54  in each of the loops  52 . Each groove  54  extends substantially transversely to the wire and lies recessed below an imaginary cylindrical outer surface  55  of the spring. The spring  24  is wound from wire having a circular cross-section and the grooves  54  are formed as by grinding. Each groove  54  has a shape which is asymmetrical in a transverse direction, having a surface  53  with a leading edge  56  and trailing edge  57  which intersect at a relatively small angle, and a relatively large angle respectively, to the convex face of the wire. 
         [0039]    The operation of the hair-plucking assembly  11  is best seen with respect to  FIGS. 6 and 7 , where the spring is shown expanded and compressed respectively. With the spring expanded to open the hair-receiving spaces  51  between loops  52  the arms  39  are positioned  900  out of phase with the lobes  28  ( FIG. 6 ). Relative rotation between the cam and cam-follower thereafter impels both of the cam-followers  21  axially, moving them together until the arms  39  abut the crests of respective lobes  28  whereupon the spring is fully compressed to generally close the spaces between the loops ( FIG. 7 ). 
         [0040]    It will be understood that throughout the operation the axis of the spring  24  remains straight and the outermost ends of loops of the spring are displaced axially without rotation. The spring  7  is compressed twice and relaxed twice per revolution, thereby providing a relatively large number of hair-plucking movements per rotation.