Patent ID: 8164035
Filing Date: 2012-04-24
Classification: H05B

Abstract:
1. A heating device, comprising a heating cable and a controller circuit; wherein said heating cable has a core and said core is wound spirally by a heating wire; said core and said heating wire are clad in a NTC (negative-temperature-coefficient) layer which is wound spirally by a PTC (positive-temperature-coefficient) heating wire; said NTC layer and said PTC heating wire are clad in an insulating layer; a first end of said PTC heating wire is connected to an AC power source ( a DC voltage circuit has a first terminal connected to said AC power source via said fuse and produces a DC voltage Vcc at a second terminal of said DC voltage circuit; said controller circuit comprises a microcontroller having terminals ( a first comparator and a second comparator have their power terminals connected to said Vcc, their ground terminals connected to ground, and their output terminals to said terminals ( a synchronous signal input circuit has a first terminal and a second terminal connected to said AC power source via said fuse and said terminal ( a reference voltage circuit has a first terminal connected to said AC power source via said fuse, a second terminal connected to a positive terminal of said first comparator, a third terminal connected to a negative terminal of said second comparator, a fourth terminal connected to said terminal ( an adjustment circuit has a first terminal connected to said terminal ( a NTC detection circuit has a first terminal connected to at least an end of said heating wire to receive said leakage current, a second terminal connected to a negative terminal of said first comparator; a PTC detection circuit has a second terminal connected to a positive terminal of said second comparator; a switch circuit has a second terminal connected to a first terminal of said PTC detection circuit, and a third terminal connected to said terminal ( a load detection circuit has a first terminal connected to the other end of said PTC heating wire, and a second terminal connected to said terminal ( a protection circuit has a power terminal connected to said Vcc, a first terminal connected to the other end of said PTC heating wire, a second terminal connected to said AC power source via said fuse, and a third terminal connected to a first terminal of said switch circuit; and a function selection circuit has a first terminal connected to said terminal (