Single-Sided Ceramic Heater Two-Phase Heating
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Solution Overview
Problem
Conventional hair styling appliances with ceramic heaters face issues such as cracking due to differential thermal expansion and poor thermal mass distribution, which reduces their longevity and accuracy in temperature measurement.
Innovation Solution
A hair styling appliance with a single-sided ceramic heater that employs a two-phase heating method, controlling the temperature rise with different slew rates to minimize cracking, using a ceramic layer with an electrical conducting element on one face and a heating layer on the opposite face, allowing for controlled thermal expansion and reducing thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single-sided ceramic heater is used for rapid heating, then heating speed is improved, but thermal stress and cracking increase
Solution Approach 1:
The heating process is divided into multiple phases with periodic pauses. The controller applies power in cycles: heating phase, pause phase, another heating phase, and a longer pause phase. This periodic action allows thermal stress to relax during pauses, preventing cumulative stress that leads to cracking, while still achieving rapid overall heating.
Solution Approach 2:
The controller dynamically changes heating parameters (power level, duration, pause intervals) based on the heating phase. During heating phases, high power is applied for rapid temperature rise. During pause phases, power is reduced or interrupted to allow stress relaxation. This parameter modulation optimizes both heating speed and ceramic durability.
2Reliability
If an embedded heater structure is used to balance thermal expansion, then ceramic cracking is reduced, but thermal mass increases and manufacturing complexity increases
Solution Approach 1:
The invention extracts the heating function from a traditional embedded heater structure and places it on a single face of the ceramic heater. This eliminates the need for a sandwich structure with ceramic layers on both sides of the heater element, reducing overall thermal mass while maintaining the ability to control thermal stress through phased heating.
Solution Approach 2:
The phased heating approach with periodic pauses compensates for the reduced thermal mass by controlling the rate of temperature change. This prevents thermal shock and cracking that would otherwise occur with rapid heating of the lighter, single-sided structure.
3Stability of the object's composition
If an embedded heater is used to balance thermal expansion, then ceramic bending is minimized, but temperature measurement accuracy deteriorates
Solution Approach 1:
The heating function is extracted from an embedded configuration and placed on a single face, creating a single-sided heater structure. This allows unobstructed thermal contact between the ceramic surface and the temperature sensor (thermistor), enabling accurate temperature measurement while maintaining ceramic stability through controlled heating phases.
Solution Approach 2:
The periodic heating with pause phases allows the ceramic to remain relatively stable during measurement intervals, improving temperature sensor accuracy. The pauses reduce thermal gradients and stress, creating more stable conditions for accurate temperature feedback.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly increases the lifetime of the ceramic heater from thousands to tens of thousands of cycles, maintaining effective thermal control and preventing cracking, while allowing rapid heating without compromising the appliance's performance.
Implementation Method 1
a ceramic layer 320 with an electrically conductive pattern 330 forming a heating element
Implementation Method 2
heating ceramic used in such heaters is that they can bend as they heat due to differential thermal expansion
Data Source
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AI summary
We describe a hair styling apparatus and method of heating a ceramic heater in a hair styling apparatus, the ceramic heater comprising a ceramic layer and a heating element thermally coupled to said ceramic layer, the method comprising: heating the ceramic layer in at least two successive phases, wherein in a first phase the ceramic layer is heated at a first rate of heating to a first temperature; pausing the heating of said ceramic layer at the first temperature; and wherein in a second phase the ceramic layer is heated at a second rate of heating from the first temperature to a second temperature.