Patent Publication Number: US-2007114219-A1

Title: Hair dryers containing high-watt density ceramic heaters

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      None.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to hair appliances and, more particularly, to a heated hairdryer, especially of the type employing a fired ceramic heater.  
      2. Description of Related Art  
      It is known in the art to employ positive temperature coefficient ceramic heaters and high-fired ceramic supports for wire heaters in hand-held, pistol-style hairdryers. These heater designs are robust and avoid problems with the overheating and rupturing of resistance wire heaters that can spit coils and cause burns. These prior art ceramic hairdryer heaters, however, because of their relatively large mass and relatively small surface areas, are slow to heat up and are not efficient at heating the moving air.  
      While various known hair-drying devices exist generally, there is a need for a hairdryer that offers the robust structure of a ceramic heater, but that also improves on the surface area to mass ratio.  
     OBJECTS AND SUMMARY OF THE INVENTION  
      It is an object of the present invention to provide a hair-drying device that overcomes the above-mentioned shortcomings.  
      It is a further object of the present invention to provide a hair-drying device that heats up quickly and is efficient at heating moving air. These and other objects are described below or inherent with respect to the present invention.  
      In the preferred embodiment of the invention, a heated hairdryer employs flat, thick film ceramic heaters. The ceramic heaters are high Watt density, low mass, resistance heaters that operate at a high temperature. A conductor is applied to one or both sides of either a fired or green ceramic plate. The conductor is then applied in circuit tracks upon the ceramic surface or surfaces. The conductive material is then covered by a second plate or by glass or other high temperature enamel to prevent the conductive circuit from oxidizing. The plate is then fired at high temperatures. These ceramic heaters can be formed into a variety of configurations for use as hairdrying heating elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention is more fully understood by reference to the following detailed description of an illustrative embodiment with the drawings identified below.  
       FIG. 1  is a schematic illustration of an electric hairdryer with a spiral wound ceramic heater.  
       FIG. 2  is a schematic illustration of the components of a heater plate.  
       FIG. 3  is a schematic illustration of an electric hairdryer with a square tube array of ceramic heater plates.  
       FIG. 4  is an illustration of various alternative configurations of ceramic heater plates.  
       FIG. 5  is an illustration of a ceramic heater formed into a spiral wound tube and a spiral wound cone.  
       FIG. 6  is an illustration of a ceramic heater assembled of increasing diameter tubes and a stack of increasing diameter cones.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention is directed to a hair-drying device that employs a fired ceramic heater in the form of an array of flat, thick ceramic heaters or of a spiral cone formed of printed and fired ceramic plates. As shown in  FIG. 1 , the preferred embodiment of the device is a hairdryer  12  that employs a ceramic heater  14  as the primary heat source.  
      The ceramic heaters applied in this device are high Watt density, low mass, resistance heaters. The ceramic heater technology is developed out of IC thick film technologies and is distinguished by a relatively thin and light substrate of high fired ceramic, Alumina or aluminum nitride, for example.  
      Referring to  FIG. 2 , the conductor  16  is applied to one or both sides of either a fired or green ceramic plate  18 . The resistive conductor  16  is generally applied as conductive ink and often contains tungsten or precious metals. There are also systems using carbon conductors. The conductor  16  is applied in circuit tracks upon the ceramic surface or surfaces  18 . The conductive material  16  is then covered by a second plate  20  or alternatively, by glass or other high temperature enamel to prevent the conductive circuit from oxidizing. The plate is then fired at high temperatures. Contact areas  22  are plated or vacuum metallized to make solder pads  22  for the applied circuits. The result is a relatively low mass, but high temperature, heater.  
      The most common heater form is a simple flat rectangular plate, approximately 3 mm thick or less. The plates can be grouped together in various configurations to be used in the heating of moving air, such as in a hairdryer.  FIG. 3  illustrates an array of flat plates  24  in a hairdryer  12 .  FIG. 4  illustrates alternative arrays  26 ,  28  and  30  of heater plates that could alternatively be assembled for use as hairdryer heating elements. Ceramic heater technologies that apply the conductor onto green clays before firing have the flexibility to wrap the green clay into three-dimensional structures and to fire the heaters into three-dimensional forms.  FIG. 1  illustrates a spiral tube  14  inside a hairdryer  12 . Such an open three-dimensional form offers increased surface area and a simple heater assembly. The number of electrical connections is considerably reduced.  FIG. 5  illustrates an assembled heater in the form of a wound spiral tube  32  and a wound spiral cone  34 .  FIG. 6  illustrates an assembled heater using a stack of fired tubes  36  or fired cones  38  of increasing diameters.  
      While the preferred embodiments of the present invention have been described herein, various modifications can be made without departing from the scope of the invention.