Patent ID: 7936131

Claim:
An AC power feedback control device, comprising: a controller generating a control signal; a first driver receiving the control signal to generate a first high-frequency driving signal; a first filter filtering the first high-frequency driving signal to generate a first sine wave signal with a maximum peak and a minimum peak; a filament driven by the first sine wave signal; a second driver receiving the control signal to generate a second high-frequency driving signal; a second filter filtering the second high-frequency driving signal to generate a second sine wave signal with a maximum peak and a minimum peak; a first peak detector detecting a value of the maximum peak of each the sine wave signals; a first and a second comparators comparing the values of the maximum peaks with a first and a second predetermined voltage values respectively so as to modulate the control signal; a second peak detector detecting a value of the minimum peak of each the sine wave signals; and a third and a fourth comparators comparing the values of the minimum peaks with a third and a fourth predetermined voltage values respectively so as to modulate the control signal.