INDUCTION HEATING FUSING DEVICE AND IMAGE FORMING APPARATUS
First Claim
1. An image forming apparatus comprising:
- an image developing device configured to develop an image on a print medium; and
an induction heating fusing device configured to fuse the image developed on the print medium by applying heat,wherein the induction heating fusing device comprising;
a serial resonance circuit having an induction coil and a condenser;
a phase comparator, a phase controller, a resonance frequency tracking oscillator, and a PWM (pulse width modulation) signal generator,wherein the phase comparator compares a phase of a pulse outputted by the PWM signal generator with a phase of current flowing through the induction coil, outputs a comparison result obtained by the comparing to the phase controller when controlling the phase, and outputs the comparison result to the resonance frequency tracking oscillator when performing PWM control,the phase controller outputs a frequency control signal which has a predetermined phase value based on an output of the phase comparator and a predetermined coil current phase amount,the resonance frequency tracking oscillator changes an oscillation frequency by using an output of the phase controller such that a driving frequency of the serial resonance circuit tracks the resonance frequency,the PWM signal generator generating a pulse to drive the serial resonance circuit based on the resonance frequency by the resonance frequency tracking oscillator, andthe phase comparator, the phase controller, the resonance frequency tracking oscillator, and the PWM signal generator are digitally controlled.
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Accused Products
Abstract
An induction heating fusing device and an image forming apparatuses that may control even a very small current region by tracking a resonance frequency to perform PWM control and phase control without considering a deviation of a part constant or a temperature change are provided. The induction heating fusing device includes: a serial resonance circuit having an induction coil and a condenser; a phase comparator, a phase controller, a resonance frequency tracking oscillator, and a PWM (pulse width modulation) signal generator. The phase comparator compares a phase of a pulse outputted by the PWM signal generator with a phase of current flowing through the induction coil, outputs a comparison result obtained by the comparing to the phase controller when controlling the phase, and outputs the comparison result to the resonance frequency tracking oscillator when performing PWM control.
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Citations
9 Claims
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1. An image forming apparatus comprising:
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an image developing device configured to develop an image on a print medium; and an induction heating fusing device configured to fuse the image developed on the print medium by applying heat, wherein the induction heating fusing device comprising; a serial resonance circuit having an induction coil and a condenser; a phase comparator, a phase controller, a resonance frequency tracking oscillator, and a PWM (pulse width modulation) signal generator, wherein the phase comparator compares a phase of a pulse outputted by the PWM signal generator with a phase of current flowing through the induction coil, outputs a comparison result obtained by the comparing to the phase controller when controlling the phase, and outputs the comparison result to the resonance frequency tracking oscillator when performing PWM control, the phase controller outputs a frequency control signal which has a predetermined phase value based on an output of the phase comparator and a predetermined coil current phase amount, the resonance frequency tracking oscillator changes an oscillation frequency by using an output of the phase controller such that a driving frequency of the serial resonance circuit tracks the resonance frequency, the PWM signal generator generating a pulse to drive the serial resonance circuit based on the resonance frequency by the resonance frequency tracking oscillator, and the phase comparator, the phase controller, the resonance frequency tracking oscillator, and the PWM signal generator are digitally controlled. - View Dependent Claims (2, 3)
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4. An image forming apparatus comprising:
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an image developing device configured to develop an image on a print medium; and an induction heating fusing device configured to fuse the image developed on the print medium by applying heat, wherein the induction heating fusing device for an image forming apparatus having a fusing roller or a fusing belt, comprising; an alternating current (AC) power supply; a diode bridge; a noise filter; a half bridge output circuit, an AC current from the AC power supply being full-wave rectified, passing through the noise filter, and being supplied to the half bridge output circuit, the half bridge output circuit including IBGTs, an induction heating low loss coil and condensers, the induction heating low loss coil and the condensers constituting an LC resonance circuit; a central processing unit (CPU) to measure a temperature of the fusing roller or fusing belt; a current transformer; a limiter circuit to limit the output voltage of the current transformer to within a predetermined range; and a rectifying circuit to rectify an output of the current transformer; and an application specific integrated circuit (ASIC) including a phase comparator to detect a phase difference, a resonance frequency tracking oscillator and a PWM signal generator, wherein the CPU controls a duty of a PWM signal generated by the PWM signal generator based on the temperature of the fusing roller or the fusing belt. - View Dependent Claims (5, 6, 7, 8)
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9. An image forming apparatus comprising:
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an image developing device configured to develop an image on a print medium; and an induction heating fusing device configured to fuse the image developed on the print medium by applying heat, wherein the induction heating fusing device, comprising; a serial resonance circuit including an induction coil and a condenser; and an application specific integrated circuit (ASIC) comprising a phase comparator, a phase controller, a resonance frequency tracking oscillator, and a PWM signal generator, wherein the phase comparator is configured to compare a phase of a pulse outputted by the PWM signal generator with a phase of current flowing through the induction coil, such that the phase comparator outputs a comparison result of the comparing to the phase controller when controlling the phase, and outputs the comparison result to the resonance frequency tracking oscillator when performing PWM control.
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Specification