INDUCTION HEATING FUSER UNIT AND IMAGE FORMING APPARATUS INCLUDING THE SAME
First Claim
1. An induction heating fuser unit comprising a series resonance circuit that comprises an induction coil and a condenser, the induction heating fuser unit comprising:
- a phase comparing unit that compares a phase of a pulse for driving the series resonance circuit with a phase of a current flowing through the induction coil to obtain a phase difference;
a resonant frequency following oscillation unit that changes an oscillation frequency such that a driving frequency of the series resonance circuit follows a resonant frequency of the series resonance circuit by using the phase difference obtained by the phase comparing unit; and
a pulse-width modulation (PWM) signal generating unit that generates a pulse for driving the series resonance circuit based on the oscillation frequency,wherein the phase comparing unit, the resonant frequency following oscillation unit, and the PWM signal generating unit are controlled digitally.
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Accused Products
Abstract
An induction heating fuser unit including a series resonance circuit that includes an induction coil and condenser includes a phase comparing unit that compares a phase of a pulse for driving the series resonance circuit with a phase of a current flowing through the induction coil to obtain a phase difference; a resonant frequency following oscillation unit that changes an oscillation frequency such that a driving frequency of the series resonance circuit follows a resonant frequency of the series resonance circuit by using the phase difference obtained by the phase comparing unit; and a PWM signal generating unit that generates a pulse for driving the series resonance circuit based on the oscillation frequency. The phase comparing unit, the resonant frequency following oscillation unit, and the PWM signal generating unit are controlled digitally. Accordingly, PWM control is accomplished without considering a temperature change or a change of numerical value of component.
21 Citations
13 Claims
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1. An induction heating fuser unit comprising a series resonance circuit that comprises an induction coil and a condenser, the induction heating fuser unit comprising:
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a phase comparing unit that compares a phase of a pulse for driving the series resonance circuit with a phase of a current flowing through the induction coil to obtain a phase difference; a resonant frequency following oscillation unit that changes an oscillation frequency such that a driving frequency of the series resonance circuit follows a resonant frequency of the series resonance circuit by using the phase difference obtained by the phase comparing unit; and a pulse-width modulation (PWM) signal generating unit that generates a pulse for driving the series resonance circuit based on the oscillation frequency, wherein the phase comparing unit, the resonant frequency following oscillation unit, and the PWM signal generating unit are controlled digitally. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An image forming apparatus comprising an induction heating fuser unit comprising a series resonance circuit that comprises an induction coil and a condenser, the induction heating fuser unit comprising:
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a phase comparing unit that compares a phase of a pulse for driving the series resonance circuit with a phase of a current flowing through the induction coil to obtain a phase difference; a resonant frequency following oscillation unit that changes an oscillation frequency such that a driving frequency of the series resonance circuit follows a resonant frequency of the series resonance circuit by using the phase difference obtained by the phase comparing unit; and a pulse-width modulation (PWM) signal generating unit that generates a pulse for driving the series resonance circuit based on the oscillation frequency, wherein the phase comparing unit, the resonant frequency following oscillation unit, and the PWM signal generating unit are controlled digitally.
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13. A method of following a resonant frequency of an induction heating fuser unit comprising a series resonance circuit that comprises an induction coil and a condenser, the method comprising:
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comparing a phase of a pulse for driving the series resonance circuit with a phase of a current flowing through the induction coil to obtain a phase difference; changing an oscillation frequency such that a driving frequency of the series resonance circuit follows a resonant frequency of the series resonance circuit by using the phase difference; and generating a PWM signal for generating a pulse for driving the series resonance circuit based on the oscillation frequency, wherein the comparing of the phases, the changing of the oscillation frequency, and the generating of the PWM signal are controlled digitally.
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Specification