Patent ID: 8742302

Claim:
A temperature control method for a heating device which comprises a heat emitting line, a capacitor, a switch, and a microprocessor, where the heat emitting line includes a core member, a negative temperature coefficient (NTC) element and a sensing wire, the NTC element the NTC element wraps the core member, the sensing wire is wound around an outside periphery of the NTC element; the capacitor is serially connected with the sensing wire to form a resistance-capacitor (RC) circuit, one end of the RC circuit is connected with a direct-current electric power source; the switch is connected to the direct-current electric power source and the RC circuit; the microprocessor is connected with the switch and the RC circuit; the temperature control method comprising: a. using the microprocessor to output a control signal containing at least a duty cycle square wave in a predetermined time for controlling the switch to make the direct-current electric power source electrically charge/discharge for the RC circuit with the NTC element; b. heating the NTC element with the core member connected with the direct-current electric power source to decrease the resistance of the NTC element, so as to change an RC time constant of the RC circuit; and c. during processing of heating, using the microprocessor to detect changing of the RC time constant of the RC circuit at set times and to output a control signal by the microprocessor when the RC time constant reaches a value predetermined by the microprocessor, so that the core member and the direct-current electric power source are in a state of circuit turning on or off.