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US 9,071,156 B2Granted
Switching power supply device and image forming apparatus with switching power supply device
AssigneeCanon Kabushiki Kaisha
InventorTakayuki Fukutani
Life of this patent
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Abstract
A current resonance type switching power supply device controls an ON/OFF operation of two switching elements according to an amount of change in voltage of a current resonance capacitor.
Claims14
A switching power supply device comprising:
- a transformer;
- a first switching element and a second switching element connected to a primary winding of the transformer, the first switching element and the second switching element being connected in series;
- a capacitance element connected to the primary winding in series;
- a control unit configured to drive the first switching element and the second switching element alternately;
- a detection unit configured to detect a voltage of the capacitance element;
- a first generation unit configured to generate a first pulse signal according to the voltage of the capacitance element detected by the detection unit;
- and
- a second generation unit configured to generate a second pulse signal according to a driving state of the first switching element and the second switching element,
- wherein the control unit is configured to control the first switching element and the second switching element so as to provide a period in which the first switching element and the second switching element are turned off, when a state where a first timing for switching a level of the first pulse signal from high to low is earlier than a second timing for switching a level of the second pulse signal from high to low is changed to a state where the first timing is later than the second timing.
6 more elements
An image forming apparatus with an image forming unit configured to form an image on an image bearing member, comprising:
- a control unit configured to control an image forming operation by the image forming unit;
- a driving unit configured to drive the image forming unit;
- and
- a switching power supply device configured to supply electric power to the control unit or the driving unit,
- wherein the switching power supply device includes:
- a transformer;
- a first switching element and a second switching element connected to a primary winding of the transformer, the first switching element and the second switching element being connected in series;
- a capacitance element connected to the primary winding in series;
- a switching control unit of the supply device configured to drive the first switching element and the second switching element alternately;
- a detection unit configured to detect a signal according to a voltage of the capacitance element;
- a first generation unit configured to generate a first pulse signal according to the voltage of the capacitance element detected by the detection unit;
- and
- a second generation unit configured to generate a second pulse signal according to a driving state of the first switching element and the second switching element,
- wherein the switching control unit of the supply device is configured to control the first switching element and the second switching element so as to provide a period in which the first switching element and the second switching element are turned off, when a state where a first timing for switching a level of the first pulse signal from high to low is earlier than a second timing for switching a level of the second pulse signal from high to low is changed to a state where the first timing is later than the second timing.
11 more elements
Dependencies are inferred from the claim text.