Hair styling appliances and heater control circuits therefor
First Claim
1. A hair styling appliance comprising:
- a heat conductive portion for applying heat to the hair;
an electrically energizable heater element located in thermal relationship with the heat conductive portion for causing it to be heated upon application of energy;
a temperature sensor located in thermal relationship with the heat conductive portion being connected to the heater element, the temperature sensor having a positive temperature coefficient of resistance characteristic resulting in a variable resistance which changes by no more than about 240k ohm in a temperature range between 100°
C. and 165°
C.; and
pulse switching means operatively coupled to the heater and responsively coupled to the temperature sensor for controlling energization of the heater with temperature, said pulse switching means gating the heater on and off at a rate which decreases with increasing temperature in accordance with said variable resistance.
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Accused Products
Abstract
The invention is directed to a hair styling appliance having heat conductive portion for applying heat to the hair and an electrically energizable heater element located in thermal relationship with the heat conductive portion for causing it to be heated upon application of energy. A temperature sensor is located in thermal relationship with the heat conductive portion. The temperature sensor is electrically connected to the heater element and has a positive temperature coefficient of resistance. A pulse switching device is operatively coupled to the heater and responsively coupled to the temperature sensor for controlling energization of the heater with temperature. A selectable temperature setting circuit is coupled to the pulse switching device for varying energization of the heater in accordance with a selected temperature operation. In a particular embodiment, the temperature sensor has a characteristic in the form of a curve with a rate of resistance which gradually changes over the desired temperature range resulting in stable temperature control and fast recovery from thermal loads.
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Citations
22 Claims
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1. A hair styling appliance comprising:
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a heat conductive portion for applying heat to the hair; an electrically energizable heater element located in thermal relationship with the heat conductive portion for causing it to be heated upon application of energy; a temperature sensor located in thermal relationship with the heat conductive portion being connected to the heater element, the temperature sensor having a positive temperature coefficient of resistance characteristic resulting in a variable resistance which changes by no more than about 240k ohm in a temperature range between 100°
C. and 165°
C.; andpulse switching means operatively coupled to the heater and responsively coupled to the temperature sensor for controlling energization of the heater with temperature, said pulse switching means gating the heater on and off at a rate which decreases with increasing temperature in accordance with said variable resistance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A heater control for an appliance comprising:
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an electrically energizable heater element located in thermal relationship with the appliance for causing it to be heated upon application of energy; and a temperature sensor being connected to the heater element and located in thermal relationship with the appliance, said temperature sensor having a positive temperature coefficient of resistance characteristic in the form of a curve resulting in a variable resistance of said sensor which changes over a first temperature range by no more than 3.3K ohm/°
C. and which changes over a second temperature range by not less than 5K ohms/°
C. above the resistance in the first temperature range; and
pulse switching means operatively coupled for the heater element having a temperature dependent variable switching rate for periodically turning on and off the heater element and being responsively coupled to the temperature sensor for controlling electrical energization of the heater in accordance with the temperature dependent switching rate of said pulse switching means, said temperature sensor for selectively governing the rate at which said pulse switching means periodically turns on and off in the first temperature range for regulating the temperature of the heater element in accordance with the temperature of the appliance and for stabilizing the temperature of the heater element in the second temperature range.
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22. A hair styling appliance operative within a styling temperature range up to a maximum temperature suitable for styling the hair without causing damage thereto by overheating and having relatively fast recovery within said styling range comprising:
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a heat conductive portion for applying heat to the hair within said styling temperature range; an electrically energizable heater element located in thermal relationship with the heat conductive portion for causing it to be heated upon application of energy; a temperature sensor having a temperature dependent variable resistance located in thermal relationship with the heat conductive portion being connected to the heater element, said temperature sensor having a positive temperature coefficient of resistance characteristic such that the resistance thereof changes by no more than 240k ohm in the hair styling temperature range between about 100°
C. and about 165°
C.; andpulse switching means for gating energy and having a resistance dependent switching rate, said pulse switching means being operatively coupled to the heater and responsively coupled to the temperature sensor for selecting gating energization of the heater on and off at a rate dependent on the temperature of the sensor to cause said heat conductive portion to recover to said maximum temperature in about two minutes.
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Specification