Patent ID: 7138611
Filing Date: 2006-11-21
Classification: H05B

Abstract:
1. A temperature control method for a heating structure comprising: a. setting a heating temperature, and making electric conduction; b. heating a PTC (positive temperature coefficient) element to render a part of current to be input into an AC phase shaping circuit to shape alternative string wave signals into direct current square wave signals waves the PTC element including a core member, a PTC element, an insulating fusible layer and a short circuit line, one end of said PTC element is connected with one end of said short circuit line, and generates heat after being electrically conducted, said AC phase shaping circuit includes an NPN-bipolar transistor, a diode and a resistor; c. entering a part of current into an AC phase delay shaping circuit to delay string wave signals, and then to convert alternative string wave signals into square wave signals, said AC phase delay shaping circuit includes a resistor-capacitor (RC) circuit, an NPN-bipolar transistor, a diode and a resistor; d. during the heating step b) said PTC element, measuring by a microprocessor at a given time a phase shift between said direct current square wave signals respectively converted by said AC phase shaping circuit and said AC phase delay shaping circuit; and e. controlling a switch of a trigger circuit to form a turning on or off state, in order to heat or reduce temperature of said PTC element to keep a heat generating line at a predetermined working temperature.