POWER SUPPLY SYSTEM, IMAGE FORMING APPARATUS HAVING THE SAME, AND LOW-CAPACITY POWER SUPPLY CIRCUIT
First Claim
1. A power supply system comprising:
- a switching power supply comprising a controller, the switching power supply being configured to generate a predetermined DC voltage by rectifying and smoothing an AC voltage of an AC power supply;
a control device configured to switch the switching power supply betweena normal mode in which the controller oscillates and the switching power supply generates the predetermined DC voltage, anda power saving mode in which the controller stops oscillating and the switching power supply stops generating the predetermined DC voltage; and
a low-capacity power supply circuit configured to supply electric power to the control device in the power saving mode, the low-capacity power supply circuit including;
a first capacitor including a first electrode connected to one end of the AC power supply, and a second electrode;
a second capacitor including a first electrode connected to the other end of the AC power supply, and a second electrode;
a rectifier circuit that is electrically connected between the second electrode of the first capacitor and the second electrode of the second capacitor, and is configured to rectify the AC voltage applied between the first electrode of the first capacitor and the first electrode of the second capacitor; and
a zero-crossing detecting circuit that is connected to a current path at a rear stage of the rectifier circuit, and is configured to detect zero-crossing points of the AC power supply on the basis of a rectified current flowing in the current path.
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Accused Products
Abstract
A power supply system comprises: a switching power supply for generating a DC voltage by rectifying and smoothing an AC voltage of an AC power supply; a control device switching the switching power supply between the normal mode and a power saving mode; and a low-capacity power supply circuit supplying electric power to the control device in the power saving mode. The low-capacity power supply circuit includes: two capacitors, each including one end connected to the AC power supply; a rectifier circuit that is electrically connected between the other ends of the capacitors, and rectifies the AC voltage applied between the first and second capacitors; and a zero-crossing detecting circuit that is connected to a current path at the rear stage of the rectifier circuit, and detects zero-crossing points of the AC power supply.
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Citations
9 Claims
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1. A power supply system comprising:
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a switching power supply comprising a controller, the switching power supply being configured to generate a predetermined DC voltage by rectifying and smoothing an AC voltage of an AC power supply; a control device configured to switch the switching power supply between a normal mode in which the controller oscillates and the switching power supply generates the predetermined DC voltage, and a power saving mode in which the controller stops oscillating and the switching power supply stops generating the predetermined DC voltage; and a low-capacity power supply circuit configured to supply electric power to the control device in the power saving mode, the low-capacity power supply circuit including; a first capacitor including a first electrode connected to one end of the AC power supply, and a second electrode; a second capacitor including a first electrode connected to the other end of the AC power supply, and a second electrode; a rectifier circuit that is electrically connected between the second electrode of the first capacitor and the second electrode of the second capacitor, and is configured to rectify the AC voltage applied between the first electrode of the first capacitor and the first electrode of the second capacitor; and a zero-crossing detecting circuit that is connected to a current path at a rear stage of the rectifier circuit, and is configured to detect zero-crossing points of the AC power supply on the basis of a rectified current flowing in the current path. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An image forming apparatus comprising:
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a power supply system comprising; a switching power supply comprising a controller, the switching power supply being configured to generate a predetermined DC voltage by rectifying and smoothing an AC voltage of an AC power supply; a control device configured to switch the switching power supply between a normal mode in which the controller oscillates and the switching power supply generates the predetermined DC voltage, and a power saving mode in which the controller stops oscillating and the switching power supply stops generating the predetermined DC voltage; and a low-capacity power supply circuit configured to supply electric power to the control device in the power saving mode, the low-capacity power supply circuit including; a first capacitor including a first electrode connected to one end of the AC power supply, and a second electrode; a second capacitor including a first electrode connected to the other end of the AC power supply, and a second electrode; a rectifier circuit that is electrically connected between the second electrode of the first capacitor and the second electrode of the second capacitor, and is configured to rectify the AC voltage applied between the first electrode of the first capacitor and the first electrode of the second capacitor; and a zero-crossing detecting circuit that is connected to a current path at a rear stage of the rectifier circuit, and is configured to detect zero-crossing points of the AC power supply on the basis of a rectified current flowing in the current path; and an image forming unit driven by the power supply system.
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9. A low-capacity power supply circuit comprising:
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a first capacitor including a first electrode connected to one end of the AC power supply, and a second electrode; a second capacitor including a first electrode connected to the other end of the AC power supply, and a second electrode; a rectifier circuit that is electrically connected between the second electrode of the first capacitor and the second electrode of the second capacitor, and is configured to rectify an AC voltage applied between the first electrode of the first capacitor and the first electrode of the second capacitor; and a zero-crossing detecting circuit that is connected to a current path at a rear stage of the rectifier circuit, and is configured to detect zero-crossing points of the AC power supply on the basis of a rectified current flowing in the current path.
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Specification