Switching power supply device and image forming apparatus including switching power supply device

• US 8,655,216 B2
• Filed: 11/16/2011
• Issued: 02/18/2014
• Est. Priority Date: 11/30/2010
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Mori, Atsunobu
• Primary Examiner(s): LaBalle, Clayton E
• Assistant Examiner(s): BUTLER, KEVIN C
• Application Number:
  US13/298,113
• Publication Number:
  US 20120134706A1
• Time in Patent Office: 825 Days
• Field of Search: 399/88, 363/21.15
• US Class Current: 399/88
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence

Abstract

A switching power supply device including: a transformer configured to include a primary winding, a secondary winding, and an auxiliary winding; a switching unit configured to switch a current that flows through the primary winding of the transformer; a control unit configured to control a switching operation of the switching unit; a starting resistor connected between a voltage input side of the primary winding and a power supply terminal of the control unit; a voltage supply unit configured to rectify and smooth a voltage output from the auxiliary winding and supply the resultant to the power supply terminal; and an activation control unit configured to control activation timing of the control unit by inputting a voltage to an ON/OFF terminal of the control unit, the activation control unit being connected between the voltage input side of the primary winding and a ground side of the auxiliary winding.

Claims

1. A switching power supply device comprising:

a transformer configured to include a primary winding, a secondary winding, and an auxiliary winding;

a switching unit configured to switch a current that flows through the primary winding of the transformer;

a control unit configured to control a switching operation of the switching unit, the control unit including a power supply terminal to which a power-supply voltage is supplied and an ON/OFF terminal for activating the control unit;

a starting resistor connected between a voltage input side of the primary winding and the power supply terminal of the control unit;

a voltage supply unit configured to rectify and smooth a voltage output from the auxiliary winding and supply the rectified and smoothed voltage to the power supply terminal; and

a timing control unit configured supply a value according to a voltage to be input to the primary winding to the ON/OFF terminal of the control unit so as to control startup timing of the control unit.

2. The switching power supply device according to claim 1, further comprising a restriction unit configured to restrict a voltage that is input to the control unit through the starting resistor.

3. The switching power supply device according to claim 1, further comprising a discharge unit configured to discharge the voltage on the ON/OFF terminal of the control unit upon activation of the switching power supply device.

4. The switching power supply device according to claim 3, wherein the discharge unit discharges the voltage on the ON/OFF terminal of the control unit depending on a control signal from outside.

5. An image forming apparatus including an image forming unit configured to form an image on an image bearing member, the image forming apparatus comprising:

a control unit configured to control an image forming operation of the image forming unit; and

a switching power supply device configured to supply power to the control unit,

wherein the switching power supply device comprises;

a transformer configured to include a primary winding;

a secondary winding, and an auxiliary winding,

a switching unit configured to switch a current that flows through the primary winding of the transformer;

a switching control unit configured to control a switching operation of the switching unit the control unit including a power supply terminal to which a power-supply voltage is supplied and an ON/OFF terminal for activating the control unit;

a starting resistor connected between a voltage input side of the primary winding and the power supply terminal of the control unit;

a voltage supply unit configured to rectify and smooth a voltage output from the auxiliary winding and supply the rectified and smoothed voltage to the power supply terminal; and

a timing control unit configured to supply a value according to a voltage to be input to the primary winding to the ON/OFF terminal of the control unit so as to control startup timing of the control unit.

6. The image forming apparatus according to claim 5, further comprising a restriction unit configured to restrict a voltage that is input to the switching control unit through the starting resistor.

7. The image forming apparatus according to claim 5, further comprising a discharge unit configured to discharge the voltage on the ON/OFF terminal of the switching control unit upon activation of the switching power supply device.

8. The image forming according to claim 7, wherein the discharge unit discharges the voltage on the ON/OFF terminal of the switching control unit depending on a control signal from outside.