Abstract:
A rotary hair brushing and curling appliance includes a hollow rotary barrel of a thermally conductive material mounted to rotate on a handle, and having an external hair-engaging surface. Silicone rubber bristles are mounted on the barrel, and arranged in first and second sets projecting from first and second arcuate surfaces which are axially elongated and circumferentially spaced apart. Heating elements abut respective abutment surfaces inside the barrel. A reversible motor rotates the barrel. The first and second arcuate surfaces each occupy 10% to 40% of the external surface and are subtended at the axis by respective first and second central angles. The heating elements are positioned outside first and second sectors defined by the first and second central angles, focusing the conductive heat transfer to the adjacent relatively large unobstructed external areas of the barrel.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to hair curling brushes. More particularly, although not exclusively, the invention relates to a hair curling brushes having a motor-driven rotary brush heated by internal elements. 
       BACKGROUND OF THE INVENTION 
       [0002]    Known motor-driven rotary brushes include a brush comprising a cylinder from which bristles project. A heating element in conductive contact with the inside of the cylinder is electrically coupled via slip rings to a power supply extending through a handle of the brush. For satisfactory performance of such brushes it has been considered necessary that heat should be evenly distributed throughout the cylinder, and to this end a high degree of symmetry is typically provided, with widely dispersed bristles and external hair-engaging surfaces. To distribute heat more evenly in the axial direction the elements are elongated axially, as are arrays of bristles and external hair-engaging surfaces. Even circumferential heat distribution is provided by a centrally positioned heating element, with regularly circumferentially spaced bristles interspersed with external hair-engaging surfaces. The heat distribution also influences fits and tolerances, and where the cylinder may be an assembly compromising inner and outer tubes the prior art teaches that these should of like material, thus assuring that free rotation of the cylinder assembly is not adversely affected by differential expansion during heating. 
         [0003]    However, while the brushing performance of these appliances is generally satisfactory, there remains a need for providing improved heating, curling or styling. 
         [0004]    It would be advantageous to provide a brush that provides sufficient grip for hair to be readily, evenly wound up onto the cylinder when engaged with the free end of a tress, while avoiding the typical situation where the hair is so firmly bound on the bristles that brush rotation to roll up the hair causes uneven pulling of the hair, or even jamming of the rotation. Furthermore, there is a need for more energy efficient appliances. It is an object of the present invention to address the above needs or, more generally, to provide an improved hair brushing appliance. 
       DISCLOSURE OF THE INVENTION 
       [0005]    According to one aspect of the present invention there is provided a rotary hair brushing and curling appliance comprising: 
         [0000]    a handle;
 
a hollow rotary barrel mounted to the handle to rotate about an axis, the barrel formed of thermally conductive material with an external surface;
 
at least two heating elements in the barrel, the heating elements substantially abutting respective abutment surfaces inside the barrel;
 
a reversible motor for rotating the barrel, and
 
a plurality of bristles formed of silicon rubber and mounted to the barrel, the bristles being arranged in first and second sets projecting from first and second arcuate surfaces which are axially elongated and circumferentially spaced apart.
 
         [0006]    Preferably the first and second arcuate surfaces each comprising 10 to 40% of the external surface. Preferably the first and second arcuate surfaces are subtended at the axis by respective first and second central angles, and wherein the heating elements lie outside first and second sectors having the first and second central angles. 
         [0007]    The relatively long circumferential portions between the first and second sets of bristles are heated by respective elements and, being uninterrupted, allow efficient heat transmission to the hair overlying them while, owing to their position separated from the elements the first and second sets of bristles are not excessively softened by the heat and provide sufficient grip to readily hold and wind up a tress for curling. 
         [0008]    Preferably switching means are provided on the handle proximate the barrel for controlling the direction of motor rotation. 
         [0009]    Preferably the abutment surfaces are diametrically opposing. Preferably the first and second arcuate surfaces are diametrically opposing. 
         [0010]    Preferably the bristles in each set are arrayed in rows. Preferably the bristles in each row are regularly spaced from one another. Preferably each row of bristles is mounted in a groove in the external surface. Preferably the grooves are axial. Preferably each groove has an open mouth and a closed end, the width of the mouth being greater than or equal to the width of the closed end. Preferably combined area of the open mouths comprises 10-40% of the external surface area of the barrel. Preferably the bristles of each row are joined by a strip received in the groove. Preferably the bristles are of like frusto-conical form and tapered from a broad base to a narrow tip. Preferably axes of the bristles are aligned radially. Preferably the strip is wider than the base of the bristles. Preferably the strip is recessed below the external surface. Preferably the strip comprises silicon rubber. Preferably the bristles of adjacent rows are staggered to maximise the spacing between bristles of adjacent rows. Preferably the spacing between any two bristles in adjacent rows is more than the length of the bristles projecting from the external surface. Preferably the first and second sets each comprise respective first, second and third rows of bristles, the bristles of the first and third sets being aligned in a transverse plane. 
         [0011]    Preferably 60-90 the external surface area of the barrel is exposed to the hair. 
         [0012]    Preferably the heating elements are axially elongate and received in respective axial channels, wherein the abutment surfaces comprise surfaces of the channels. Preferably the channels comprise respective axial abutment faces which are concave. Preferably the axis defines a centre of curvature of the concave axial abutment faces. 
         [0013]    Preferably the barrel is supported upon a shaft extending between axially opposing ends of the barrel, and a hollow member of thermal insulating material is spaced apart from the heating elements and substantially encloses the shaft. The thermally insulating material may comprise a polymer. Preferably the hollow member is tubular. 
         [0014]    The rotary hair appliance of the invention can not only be used for hair brushing, but also for hair curling, where it offers improved performance. Avoiding the need to manually wind the hair about the hot cylinder, or apply a clip to hold the hair in contact with the barrel, the invention provides sufficient grip for hair to be readily, evenly wound up onto the cylinder just by simple engagement with the free end of a tress, while the relatively large, continuous hair-engaging area provides for efficient curling. However, the grip provided on the hair is not enough for the hair to become so firmly bound on the bristles that rotation of the brush to roll up the hair causes uneven pulling of the hair, or even jamming of the rotation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: 
           [0016]      FIG. 1  is a top view of a first embodiment of a rotary hair brushing and curling appliance according to the invention; 
           [0017]      FIG. 2  is an end view of the appliance of  FIG. 1 ; 
           [0018]      FIG. 3  is a schematic longitudinal section through the appliance of  FIG. 1 ; 
           [0019]      FIG. 4  is a schematic section along line AA of  FIG. 1 ; 
           [0020]    Figure is an enlarged view of a bristle if  FIG. 4 ; 
           [0021]      FIG. 6  is a fragmentary side view of the barrel of the appliance of  FIG. 1 ; 
           [0022]      FIGS. 7 and 8  are fragmentary end and side views respectively of the barrel of the appliance of  FIG. 1 , and 
           [0023]      FIGS. 9 and 10  are transverse and longitudinal sections respectively of a second embodiment of a rotary hair brushing and curling appliance according to the invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    Referring to  FIGS. 1-4 , a hand-held rotary hair brushing and curling appliance according to a first embodiment of the invention comprises a handle  10  to which a rotary brush  11  is mounted. The handle  10  and brush  11  may both be elongate and coaxial, with the brush  11  mounted to one end of the handle  10  to rotate about the axis  12 . As used herein, the term “axial” refers to a direction substantially parallel to the axis  12 . The term “radial” refers to a direction substantially orthogonal to the axis  12 . The term “circumferential” refers to the direction of a circular arc having a radius substantially orthogonal to the axis  12 . 
         [0025]    The handle  13  is hollow and encloses a gearmotor  13  and a circuit board  21  to which power supply and control components (some of which are described below) may be mounted. Power may be supplied to the appliance by a cable  22  connected to a mains supply (not shown). Controls mounted to the handle  13  may include motor actuating switches  23 ,  23 , as of the push-to-make type, respective ones of which may be pressed to rotate the brush in one direction or the other as desired. The motor actuating switches  23 ,  23  may conveniently be disposed at one end of the handle  13  proximate the brush  11 . A power on/off switch  25  and a control switch  26  may be provided, along with a display  27 . The control switch  26  may be used to control settings such as brush rotation speed and temperature, in cooperation with these settings being shown on the display  27 . 
         [0026]    The brush  11  is rotated as by a gearmotor  13  mounted in the handle  13  and connected by an axially extending shaft  14  to the brush  11 . The brush  11  may generally comprise a barrel  15  of tubular form, to the axially opposing ends of which caps  16 ,  17  are fixed, and silicon rubber bristles  18 . The caps  16 ,  17  may close the distal and proximal ends of the barrel  15  respectively, and both may be fixed to turn with the shaft  14 , the cap  17  may include a hub portion or coupler  19  supported within a mouth  20  of complementary form at one end of the handle  10 , and serving to mechanically and electrically connect the brush to the handle  10 . 
         [0027]    The bristles  18  are arranged in first and second sets  30 ,  31  projecting from first and second arcuate surfaces, the angular extend of which are indicated in the drawings by  32 ,  33  respectively. The first and second arcuate surfaces  32 ,  33  may be of like angular extend and axial length, extending axially for the length of the barrel  15 , and disposed diametrically opposite one another. The first and second arcuate surfaces  32 ,  33  are circumferentially spaced apart and, in a particularly preferred embodiment each may comprise approximately 18% of the external circumferential surface of the barrel  15 . The first and second arcuate surfaces  32 ,  33  are subtended at the axis  12  by respective first and second central angles  34 ,  35 . Sectors  70 ,  71  are defined by the first and second arcuate surfaces  32 ,  33  and the first and second central angles  34 ,  35  subtending them. 
         [0028]    Two heating elements  37 ,  38  are fixed inside in the barrel  15  on the opposing side to external circumferential surface portions  39 ,  40  disposed between the first and second arcuate surfaces  32 ,  33 . The heating elements  37 ,  38  may be axially elongate, extending generally either side of a transverse plane (not shown) bisecting the barrel  15 . The heating elements  37 ,  38  lie outside first and second sectors  70 ,  71 , adjacent the larger external circumferential surface portions  39 ,  40  which engage with the hair, thus preferentially heating these unobstructed portions. 
         [0029]    The heating elements  37 ,  38  may be at least partially received in respective axial channels recessed from a cylindrical inner face  41  of the barrel  15 , and having axially elongated opposing edges  42 ,  43  joined by a face  44 . The axis  12  may define a centre of curvature of the face  44 . The concave face  44  may form the major abutment face abutting the elements  37 ,  38  through which the majority of the heat from the element is conducted, with a relatively smaller portion being transferred through the surfaces of the edges  42 ,  43 . 
         [0030]    The bristles  18  of each set  30 ,  31  are arrayed in rows. Three rows may be provided in each set  30 ,  31  with the bristles  18  in each row being regularly spaced from one another. As best seen in  FIG. 5 , each row of bristles  18  may be mounted in a groove  50  in the external surface  51  of the barrel  15 . The grooves  50  may extend axially for the length of the barrel  15 , with each groove  50  having an open mouth  52  and a dosed end  53 , the width of the mouth  52  being greater than or equal to the width of the dosed end  53 , unlike some prior art designs where a narrow mouth serves to retain the bristles  18 . In the embodiment illustrated, the edges of the grooves  50  along either side of the first and second arcuate surfaces  32 ,  33  define the boundaries of the heated, hair-engaging surface portions  39 ,  40 . Conversely, the axial edges of the circumferential hair-engaging surface portions  39 ,  40  where they intersect the grooves  50  may be considered to define the boundaries of the first and second arcuate surfaces  32 ,  33 . The bristles  18  may be of like frusto-conical form, tapered from a broad base  56  to a narrow, spheroidal tip  57 . Axes  58  of the bristles may be aligned radially. The bristles  18  of each row may joined by an integral strip  55  received in the groove  50 , and fastened to the barrel as by adhesive, welding, fasteners etc (not shown). The strip  55  may be wider than the base  56  of the bristles  18  and may be of complementary form and dimensions to the groove  50 . The strip  55  and bristles  18  may be integrally formed from a silicon rubber elastomer with a hardness between 30 Shore A and 50 Shore D, making the bristles  18  flexible and resilient. The strip  55  may be recessed below the external surface  51 , such that edges of the groove  50  do not interfere with flexure of the bristles  18 . The barrel  15  is formed of a heat conducting material, such as a heat conducting polymer or, more preferably, aluminium. 
         [0031]    Referring to  FIGS. 6 to 8 , the bristles  18  are arranged in first, second and third axial rows  60 ,  61 ,  62  and adjacent rows are staggered to maximise the spacing between bristles  18  of adjacent rows. The bristles  18  of the first and third sets  60  and  62  may be aligned in the same transverse planes  64 ,  65  etc. The spacing X between any two bristles  18  in adjacent rows  60 / 61  or  61 / 62  is more than the length Y of the bristles  18  projecting from the external surface  51 , such that when deflected in bending the bristles  18  cannot contact one another. 
         [0032]      FIGS. 9 and 10  illustrate a second embodiment of the invention comprising a brush  111  mounted to the handle  10 , in which brush  111  is of like construction to the brush  11  but further comprises a hollow member  67  extending axially between the end caps  16 ,  17  and enclosing the shaft  14 . The hollow member  67  is made of thermal insulating material, such as a polymer, and is spaced apart from the heating elements  37 ,  38 . The hollow member may be tubular, with the inside of the hollow member  67  communicating with the inside of the hollow handle  10 . The hollow member  67  thus thermally insulates the shaft  14  from heat produced by the elements. 
         [0033]    In use, the appliance may be used for brushing and simultaneously drying hair by actuating one of the switches  23 ,  24  to rotate the brush  11 ,  111 , starting at the scalp end of a tress and moving toward the free end along the tress generally tangential to the outer surface  51  and moving in the same sense as the brush is rotated. Styling and curling may be achieved in a number of ways, but advantageously curling is started by engaging the brush with the free end of the tress. While the density of bristles  18  provided in the first and second arcuate surfaces  32 ,  33  (i.e. the number of bristles per square millimetre) is within the range provided on some prior art rotary brushes, the friction between the brush  11 ,  111  and the hair has been found to be sufficient to grasp and hold the hair. With the brush preferably stationary initially while one of the sets  30 ,  31  is engaged with the hair, one of the switches  23 ,  24  is actuated to rotate the brush  11 ,  111 , whereupon the tips are wound about the barrel  15 , the appliance then being moved tangentially in the opposite sense to the brush rotation as the tress continues to be wound toward the scalp end. The relatively long uninterrupted circumferential portions  39 ,  40  provide for efficient heat transmission to the hair. Once a wave has been set the tress can be unwound without the need to rotate the brush  11 ,  111 . During the course of curling treatment a certain degree of slip may occur between the hair and the brush, thus increasing the length of hair exposed, for instance, to the convex hair-engaging surfaces  39 ,  40  and thus increasing the “effective exposed area” beyond the 60-90% of the external surface area of the barrel is exposed to the hair. 
         [0034]    Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.