Abstract:
A heater for a hand held appliance, the heater comprising a first layer, a second layer and a separator for separating the first and second layers of the heater wherein the separator is a tube. The first layer and/or second layer may be a wire element. The first layer may extend at least partially around and/or partially along the tube. The tube may comprise spacers extending along the tube and radially away from the tube for supporting the first layer. An outer tube may be provided wherein the outer tube extends at least around and along the first layer. The outer tube may extend around and along the tube. An inner support structure for supporting the second layer may be provided. The inner support structure may comprise an inner tube or support wings and the second layer may extend at least partially around the inner tube or support wings.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of United Kingdom Application No. 1312680.0, filed Jul. 16, 2013, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     This invention relates to a heater for a hand held appliance such as a hairdryer or other hair grooming appliance such as a hot styling brush. 
     SUMMARY OF THE INVENTION 
     According to a first aspect, the invention provides a heater for a hand held appliance, the heater comprising a first layer, a second layer and a separator for separating the first and second layers of the heater wherein the separator is a tube. 
     Preferably, the first layer is a wire element. Preferably, the second layer is a wire element. 
     It is preferred that the first layer extends at least partially around the tube. Preferably, the first layer extends at least partially along the tube. 
     It is preferred that the tube comprises spacers extending along the tube and radially away from the tube for supporting the first layer. Preferably, the spacers extend orthogonally away from the tube. It is preferred that the spacers include insertion recesses. Preferably, the insertion recesses are substantially uniformly spaced along the length of the spacers. It is preferred that a wire element is located in the insertion recesses. 
     Preferably, the heater comprises an outer tube wherein the outer tube extends at least around and along the first layer. It is preferred that the outer tube extends around and along the tube. 
     Also provided is a heater for a hand held appliance, the heater comprising a first layer, a second layer and a separator for separating the first and second layers of the heater wherein the separator is a tube and the first layer extends at least partially around the tube. 
     Also provided is a heater for a hand held appliance, the heater comprising a first layer, a second layer and a separator for separating the first and second layers of the heater wherein the separator is a tube and the first layer extends at least partially along the tube. 
     The heater is preferably a double stacked heater having a first layer and a second layer. 
     Also provided is a heater for a hand held appliance, the heater comprising a first layer, a second layer and a separator for separating the first and second layers of the heater wherein the separator is a tube and the heater is a double stacked heater. 
     Preferably, the heater comprises an inner support structure for supporting the second layer. It is preferred that the inner support structure comprises an inner tube. 
     Also provided is a heater for a hand held appliance, the heater comprising a first layer, a second layer, a separator for separating the first and second layers of the heater and an inner support structure for supporting the second layer, wherein the separator is a tube and the inner support structure comprises an inner tube. 
     Preferably, the tube extends around and at least partially long the inner tube. It is preferred that the tube extends around and along the inner tube. Preferably, the second layer extends at least partially around the inner tube. It is preferred that the second layer extends at least partially along the inner tube. 
     Preferably, the inner tube comprises inner spacers extending along and radially away from the tube for supporting the second layer. 
     Preferably, when the inner tube is inserted within the tube, the inner spacers maintain the position of the inner tube within the tube. 
     Preferably, the inner spacers extend orthogonally away from the inner tube. It is preferred that the inner spacers include insertion recesses. Preferably, the insertion recesses are substantially uniformly spaced along the length of the inner spacers. It is preferred that a wire element is located in the insertion recesses. 
     Preferably, when the inner tube is inserted in the tube, the wire element is fixed in location in the insertion recesses. 
     Alternatively, the inner support structure comprises support wings. Preferably, when the inner support structure is inserted within the tube, the support wings maintain the position of the inner support structure within the tube. It is preferred that the support wings extend at least partially along the length of the tube. 
     Preferably, the support wings include extensions which extend radially towards the tube. 
     Preferably, the support wings form a generally triangular shape. 
     Preferably, the support wings include extensions which extend radially from apexes of the generally triangular shape. Preferably, the extensions form a Y shape. Preferably, the second layer is supported by the extensions. 
     It is preferred that the extensions include insertion recesses for supporting the second layer. Preferably, the insertion recesses are substantially uniformly spaced along the length of the extensions. 
     It is preferred that the second layer is a wire element and the wire element is located in the insertion recesses. 
     Preferably, when the inner support structure is inserted in the tube, the wire element is fixed in location in the insertion recesses. 
     It is preferred that the generally triangular shape is formed from three shaped parts wherein each apex is formed from two of the three shaped parts. 
     Preferably, the separator is made from an insulating material. It is preferred that the separator is formed from Mica. 
     Preferably, the first layer and the second layer are formed from different wire elements. 
     Also provided is a hair care appliance such as a hairdryer or a hot styling brush comprising a heater according to the invention 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of example, with reference to the accompanying drawings, of which: 
         FIG. 1  shows an exploded view of a heater according to the invention; 
         FIG. 2  shows a cross section through a heater of  FIG. 1 ; 
         FIG. 3  shows another cross section through the heater of  FIG. 1 ; 
         FIG. 4  shows a perspective view of a first layer of a heater; 
         FIG. 5  shows a portion of the second layer of the heater of  FIG. 1  in more detail; 
         FIG. 6  shows a perspective view of a second layer of a heater; 
         FIG. 7  shows an appliance in which the heater of  FIGS. 1 to 6  is used; 
         FIG. 8  shows a cross section through an alternative heater according to the invention; 
         FIG. 9  shows a perspective view of the alternative heater; 
         FIG. 10  shows an exploded view of the alternative heater; 
         FIG. 11  shows another exploded view of the alternative heater; and 
         FIG. 12  shows an appliance in which the heater of  FIGS. 8 to 11  is used. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 to 5 , the heater  10  has a first layer  100  and a second layer  200 . The first layer  100  includes a tube  110  having a number of spacers  112  which extend radially out from the tube  110 . The spacers  112  include insertion recesses  114  into which a heater element  120  is located. 
     The heater element  120  is a wire made from a suitable material such as Nichrome which is shaped into zig zags or undulations and then wound around the tube  110 . The spacers  112  provide support for the heater element  120  as it is wound around the tube  110  and the insertion recesses  114  keep individual coils  122  of the heater element  120  separate from each other. The insertion recesses  114  maintain the spacing between different coils  122  of the heater element reducing the chance of hot spots and restrictions to air or fluid flow through the heater. 
     The tube  110  and the spacers  112  are formed from an insulating material such as Mica. 
     Internal of the first layer  100  and tube  110 , is a second layer  200 . The second layer  200  includes a second heater element  220  which is a wire shaped into zig zags or undulations and wound onto a support structure  250 . In this embodiment, the support structure  250  is a tri-support and is geometrically similar to a triangular prism. However other shapes can be used such as a quad or cross shaped support. 
     The support structure  250  is formed from three rectangular pieces  260  of an insulating material, such as Mica and a pair of end clamps  270 . The end clamps  270  hold the three rectangular pieces  260  together so that one long edge  260   a  of each of the rectangular pieces is upstanding  260  and forms an apex of a triangle. This triangle forms the frame around which a wire element  220  is wound. 
     The end clamps  270  are formed from a shaped piece of metal which has end tabs  272  which are folded one on each side of a rectangular piece  260  to hold it in position. 
     The rectangular piece  260  has insertion slots  262  extending along the length of the protruding part with the apertures  264  for each slot being disposed along the length of the upstanding long end  260   a  of each of the rectangular pieces  260 . The wire element  220  is wound around the rectangular piece  260  and located within the insertion recesses  262 . Thus, the rectangular piece  260  provides supports for the wire element  220  along and around the length of the heater element  200 . 
       FIG. 6  shows an alternative second heater layer  300  having a different support structure  350 . In this example, the support structure  350  is formed from three insulating sheets  352  formed in a Y shape. A tri support clip  360  is provided at each end of the insulating sheets  352  to retain the angular separation of the insulating sheets. Insertion recesses  354  are disposed along the length of each of the insulating sheets  352  for receiving the wire element  320 . The insulating sheets are preferably formed from Mica. 
     In conventional heaters, the use of a tri-support can be problematic. Although a tri-support provides a more compact heater element than for example a cross shaped support, the relatively larger distance between supporting locations on the wire element produces less tension on the wire element  220 ,  320  leading to an increased risk that the wire element  220 ,  320  will move out of an insertion recess to an adjacent recess. This is undesirable as it results in hot spots and premature failure of the heater element can occur. In the embodiments having a tri-support  250 ,  350  the advantages resultant from using a tri-support are maintained due to the structure of the first layer  100  which surrounds the second layer. As the tri-supported element  220 ,  320  is housed within the first layer  100 , the tube  110  surrounds the second heater element  200 ,  300  and prevents longitudinal movement of the second wire element  220 ,  320 . 
     Around the outside of the first layer  100 , an outer tube  150  is provided. This outer tube  150  is optional and provides an insulating layer for the heater  10  and whatever houses the heater  10 . In addition to insulating the outer surface of the heater  10 , the outer tube  150  and prevents longitudinal movement of the individual coils  122  of the first wire element  120  with respect to their insertion recesses  114 . 
       FIG. 7  shows a hot styling brush  20  which incorporates a heater  10 . The hot styling brush  20  has a body  22  and a styling head  24 . The body  22  has an inlet  30  at one end where fluid is drawn into the appliance through the action of a fan unit  26 . The fluid is subsequently heated by a heater  10  before entering the head  24 . 
     The head  24  includes a plurality of radially spaced slots  32  which extend longitudinally along the head  24 . Between adjacent pairs of slots  32  are a line of bristles  34  so during a styling procedure, the hair is brushed whilst hot fluid passes through the hair, drying and styling the hair. 
     Power is supplied by a cable  28  which in this example enters the hot styling brush  20  at the inlet  30 . Internal wiring (not shown) provides power to the heater  10  and to the fan unit  26  to run a motor that drives the impeller of the fan unit  26 . 
     The body  22  includes a handle portion  36  which extends generally from the inlet  30 . The body  22  includes a generally circular fluid flow path  38  from the inlet  30  along the body  22  through the heater  10  and into the head  24 . The heater  10  is a double stacked heater having a first layer  100  and a second layer  200 ,  300 . This is advantageous for a number of reasons. Firstly, the fluid that flows through the fluid flow path  38  is heated evenly as the heater elements  120 ,  220 ,  320  cover a large proportion of the cross section through the body  22  (See  FIG. 2 , for example). Second, the heater elements  100 ,  200 ,  300  can be powered and controlled separately enabling a variety of temperature of fluid emitted from the head  24 . Also, by having a double stacked heater  10 , the length of the heater can be reduced compared with a single stack heater providing a more compact component. 
     In order to enable a variety of temperature and flow rates through the appliance, a PCB  40  is provided. The PCB is electrically connected to both the heater  10  and the fan unit  26  and can vary the power supplied to both. As an example, a user can chose different power and heater settings. The PCB  40  controls the power to each heater layer  100 ,  200 ,  300  independently so for low temperature settings, only one heater layer needs to be used. In addition, the speed at which the fan unit  26  is operated can be varied to enable wet hair to be dried quickly initially and then the one or more of the heat and power can be reduced or increased to enable styling. 
     Each of the first layer  100  and second layer  200 , 300  can be assembled or constructed separately i.e. the wire element is wound around each layer in a separate process and then the second or inner layer is inserted within the first or outer layer. Each of the first layer  100  and second layer  200 , 300  are self supporting which assists in this form of assembly. 
     Alternatively, the first or inner layer is constructed and the same wire element is subsequently wound around the second layer. This results in less internal connections within the appliance but means that the two heater layers will function as a single heater element which could reduce flexibility and control of the temperature range the appliance can output fluid at. 
     The heater  10  is suitable for use in other heated blowers such as conventional hairdryers and in particular travel appliances where space is at a premium. 
       FIGS. 8 to 11  show various views of an alternate heater  400 . In this embodiment, components illustrated and already described in relation to  FIGS. 1 to 6  have like reference numerals. The first heater layer  100  is similar to the one described in reference to  FIGS. 1 to 6  but has a larger diameter. The second heater layer  402  is also annular with a cylindrical or tubular support  410 . A plurality of spacers  412  extend around and radially away from the cylindrical support  410 . The spacers  412  include insertion recesses  414  into which the heater element  420  is located. 
     The heater element  420  is a wire which is shaped into zig zags or undulations and then wound around the tube  410 . The spacers  412  provide support for the heater element  420  as it is wound around the tube  410  and the insertion recesses  414  keep individual coils  422  of the heater element  420  separate from each other. 
     The tube  410  and the spacers  412  are formed from an insulating material such as Mica. 
       FIG. 12  shows a hairdryer  450  which incorporates heater  400 . The hairdryer  450  is an amplifying hairdryer where processed flow  452  or that which is drawn into the appliance by the action of a fan unit  454  and optionally heated is augmented or increased by an entrained flow. 
     The hairdryer  450  has a handle  460  and a body  470 . An inlet  462  is provided in the handle  460  at the distal end from the body  470 . Fluid is drawn into the inlet  462  by the action of a fan unit  454  and flows within a fluid flow path  452  along the handle  460  from the inlet  462  towards the body  470 . The fluid flow path  452  within the handle is generally circular but, within the body it becomes annular. 
     The body  470  is tubular and has an internal duct  472  which extends along the length of the body  470  from an inlet end  470   a  to an outlet end  470   b . This duct  472  defines the entrained fluid flow path  490  which flows within the duct  472  from a second inlet  492  to a second outlet  494 . The duct  472  and an outer wall  474  of the body  470  define the fluid flow path  452  through the body from the handle  460  towards a fluid outlet  456  of the fluid flow path  452 . Within the body  470 , a heater  400  is disposed and the heater extends along and around the duct  472  and directly heats fluid flowing in the fluid flow path  452 . Fluid flowing through the entrained flow path  490  may be indirectly heated by the heater  400 . 
     In operation, the fan unit  454  draws fluid in through the inlet  462  along the fluid flow path  452  to the body, through the heater  400  and to the fluid outlet  456 . The action of this fluid flowing through the hairdryer and out of the fluid outlet  456  causes fluid to be entrained or pulled into the duct  472  at the second inlet  492  and along the entrained fluid flow path  490  towards the second outlet  494 . 
     In this example the processed flow exits from the hairdryer as an annular ring that extends around the entrained flow. Thus the output from the hairdryer is a heated ring of fluid surrounded on both sides by cooler air. As an alternative, the fluid outlet  456  is located within the body  470  and the heated fluid mixes with the entrained flow before the fluid exits from the appliance. 
     Power is supplied to the hairdryer via a cable  464  which enters the hairdryer  450  at the inlet  462 . Internal wiring (not shown) provides power to the heater  400  and the fan unit  454  to run a motor that drives the impeller of the fan unit  454 . 
     In order to provide a variety of temperature and flow rates through the appliance, a PCB  476  is provided. The PCB  476  is electrically connected to both the heater  400  and the fan unit  454  and enables a user to vary power to both. As an example, the user can chose different power and heat settings. The PCB  476  controls the power to each heater layer  100 ,  400  independently so for low temperature settings, only one heater needs to be used. In addition, the speed of the fan unit  454  can be varied to change the flow through the appliance. 
     In all of the embodiments shown, the first layer  100  and second layer  200 ,  300 ,  402  can be made from a single continuous wire or, as is preferred two separate wires. Each layer can be designed to have the same power output or different power outputs for example, one layer can have twice the power output of the other. The different power outputs can be achieved by various methods that will be apparent to the skilled person and include using wires of different gauge or different length, the same gauge and different length or different gauge and the same length. Layers having the same power output do not need to use the same gauge and length of wire in fact this may be impractical due to the volume constraints of each layer.