Hair styling apparatus, temperature control systems, and methods for controlling hair styling apparatus

Abstract

A hair styling apparatus includes a heating assembly that is configured to deliver heat to hair. The hair styling apparatus is configured to energize a heating element of the heating assembly to deliver heat to the hair during a first styling operation. In one embodiment, the hair styling apparatus is configured to determine an estimated hair temperature, compare the estimated hair temperature to a desired hair temperature profile, and energize the heating assembly during a second styling operation based on the comparison. In another embodiment, the hair styling apparatus determines a curl profile of the hair based on a temperature of the heating assembly or the hair. The hair styling apparatus is configured to compare the curl profile to a desired curl profile, and energize the heating assembly during a second styling operation based on the comparison.

1 . A hair straightener comprising:
 a first arm and a second arm, the first arm and the second arm being pivotably coupled to each other for selective, pivotal movement relative to each other to selectively configure the hair straightener between an opened position and a closed position, wherein the hair straightener is arranged so that hair can be disposed between the first arm and the second arm in the closed position;   a heating assembly attached to at least one of the first arm and the second arm and configured to deliver heat to the hair disposed between the first arm and the second arm, the heating assembly including a heating element;   at least one sensor configured to detect at least one temperature of the heating assembly; and   a controller in communication with the sensor, the controller configured to:
 energize the heating element of the heating assembly in accordance with a first temperature set point to deliver heat to hair during a first hair styling operation; 
 determine an estimated hair temperature of the hair disposed between the first arm and the second arm based on the at least one temperature of the heating assembly; 
 compare the estimated hair temperature and a desired hair temperature profile; 
 determine a second temperature set point of the heating assembly based on the comparison of the estimated hair temperature and the desired hair temperature profile; and 
 energize the heating element of the heating assembly in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation. 
   
     
     
         2 . The hair straightener of  claim 1 , wherein the heating assembly includes a surface, the at least one temperature of the heating assembly includes a surface temperature of the surface of the heating assembly, wherein the controller is configured to determine the estimated hair temperature based on the surface temperature and a rate of change of the surface temperature. 
     
     
         3 . The hair straightener of  claim 1 , wherein the desired hair temperature profile includes an upper threshold value and a lower threshold value. 
     
     
         4 . The hair straightener of  claim 3 , wherein the controller is configured to increase the second temperature set point of the heating assembly if the estimated hair temperature is less than the lower threshold value, and decrease the second temperature set point of the heating assembly if the estimated hair temperature is greater than the upper threshold value. 
     
     
         5 . The hair straightener of  claim 1 , wherein the heating assembly includes a hair contact plate having a surface that is heated by the heating element, wherein the at least one sensor comprises a temperature sensor configured to detect a temperature at the surface of the hair contact plate, and wherein the at least one temperature received from the at least one sensor includes a plurality of surface temperatures of the surface of the hair contact plate received from the temperature sensor. 
     
     
         6 . The hair straightener of  claim 5 , wherein the controller is configured to determine a rate of change of the surface temperatures, and wherein the estimated hair temperature is determined based on the surface temperatures and the rate of change of the surface temperatures. 
     
     
         7 . The hair straightener of  claim 6 , wherein the controller is configured to determine the rate of change of the surface temperatures by calculating a derivative of the surface temperatures received from the temperature sensor. 
     
     
         8 . The hair straightener of  claim 1 , wherein the controller is configured to:
 determine a second estimated hair temperature of the hair during the second hair styling operation;   compare the second estimated hair temperature and the desired hair temperature profile; and   determine a third temperature set point of the heating assembly based on the comparison of the second estimated hair temperature and the desired hair temperature profile.   
     
     
         9 . The hair straightener of  claim 8 , wherein the desired hair temperature profile includes an upper threshold value and a lower threshold value, and wherein the controller is configured to increase the second temperature set point of the heating assembly if the second estimated hair temperature is less than the lower threshold value, and decrease the second temperature set point of the heating assembly if the second estimated hair temperature is greater than the upper threshold value. 
     
     
         10 . The hair straightener of  claim 8 , wherein the controller is configured to operate the heating assembly in accordance with the determined third temperature set point for a third hair styling operation. 
     
     
         11 . The hair straightener of  claim 1  wherein the at least one sensor comprises a positive temperature coefficient thermistor. 
     
     
         12 . The hair straightener of  claim 1  wherein the at least one sensor comprises a negative temperature coefficient thermistor. 
     
     
         13 . The hair straightener of  claim 1 , further comprising a monitoring device coupled to the controller and operable to monitor movement of the first arm and the second arm between the opened position and the closed position of the hair straightener. 
     
     
         14 . A temperature control system for a hair styling apparatus having a heating assembly configured to deliver heat to hair, the control system comprising:
 a memory configured to store a first temperature set point and temperatures of the heating assembly received from a sensor; and   a processor communicatively coupled to the memory and configured to:
 retrieve from the memory the first temperature set point and at least one temperature received from the sensor; 
 energize a heating element of the heating assembly in accordance with the first temperature set point to deliver heat to hair during a first hair styling operation; 
 determine an estimated hair temperature of the hair based on the at least one temperature received from the sensor; 
 compare the estimated hair temperature and a desired hair temperature profile; 
 determine a second temperature set point of the heating assembly based on the comparison of the estimated hair temperature and the desired hair temperature profile; and 
 energize the heating element in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation. 
   
     
     
         15 . The temperature control system of  claim 14 , wherein the processor is configured to determine the estimated hair temperature based on a surface temperature of a surface of the heating assembly and a rate of change of the surface temperature. 
     
     
         16 - 24 . (canceled) 
     
     
         25 . A method for controlling a hair styling apparatus, the hair styling apparatus including a heating assembly, the method comprising:
 energizing a heating element of the heating assembly in accordance with a first temperature set point to deliver heat to hair during a first hair styling operation;   receiving, at a controller, a signal relating to a temperature of the heating assembly during the first hair styling operation;   determining, at the controller, an estimated hair temperature during the first hair styling operation based on the temperature of the heating assembly;   comparing the estimated hair temperature and a desired hair temperature profile;   determining, at the controller, a second temperature set point of the heating assembly based on the comparison of the estimated hair temperature and the desired hair temperature profile; and   energizing the heating element in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation.   
     
     
         26 . The method of  claim 25 , wherein determining the estimated hair temperature during the first hair styling operation comprises determining the estimated hair temperature based on a surface temperature of a surface of the heating assembly and a rate of change of the surface temperature. 
     
     
         27 . The method of  claim 25  further comprising:
 increasing the second temperature set point of the heating assembly if the estimated hair temperature is less than a lower threshold value; and 
 decreasing the temperature set point of the heating assembly if the estimated hair temperature is greater than an upper threshold value. 
 
     
     
         28 . The method of  claim 25  further comprising
 determining a second estimated hair temperature; 
 comparing the second estimated hair temperature and the desired hair temperature profile; and 
 determining a third temperature set point of the heating assembly based on the comparison of the second estimated hair temperature and the desired hair temperature profile. 
 
     
     
         29 . The method of  claim 28  further comprising energizing the heating element in accordance with the third temperature set point to deliver heat to hair during a third hair styling operation 
     
     
         30 - 59 . (canceled)