Power supply apparatus and image forming apparatus

Patent metadata

Field	Value
Publication number	US-9621061-B2
Application number	US-201313953624-A
Country	US
Kind code	B2
Filing date	Jul 29, 2013
Priority date	Dec 15, 2008
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

The power supply apparatus for obtaining a direct current from an alternating voltage source includes a first DC/DC converter for outputting a first direct current and a second DC/DC converter for a second direct current lower than the first direct current from the first DC/DC converter, and the output voltage of the first DC/DC converter is changed to a lower direct current and the second DC/DC converter is driven in a continuously-conducting state.

First claim

What is claimed is:

1. A power supply apparatus comprising:
a first converter configured to convert an input direct current voltage into a first direct current voltage by switching a first switching element, and to output the first direct current voltage; and
a second converter configured to convert the first direct current voltage output from the first converter into a second direct current voltage lower than the first direct current voltage by switching a second switching element and to output the second direct current voltage,
wherein the first converter is further configured to output a third direct current voltage lower than the second direct current voltage by switching the first switching element at a second switching frequency lower than a first switching frequency of the first switching element when the first convertor outputs the first direct current voltage,
wherein the second convertor controls an operation of the second switching element so as to output the third direct current voltage input from the first convertor.

2. A power supply apparatus according to claim 1 , further comprising a feedback unit that detects a voltage according to the first direct current voltage output from the first converter and compares the detected voltage with a reference voltage,
wherein the feedback unit switches the reference voltage, the first converter decreases the first direct current voltage according to a signal from the feedback unit.

3. A power supply apparatus according to claim 1 , wherein the first converter includes start-up resistor to drive the first switching element at a start-up of the power supply apparatus, wherein the first converter decreases the first direct current voltage by switching a resistance value of the start-up resistor.

4. A power supply apparatus according to claim 1 , further comprising a load switch which outputs or stops the first direct current voltage from the first converter,
wherein after the first direct current voltage is stopped by turning the load switch off, the first converter decreases the first direct current voltage.

5. A power supply apparatus according to claim 1 , further comprising a load switch which outputs or stops the first direct current voltage from the first converter,
wherein in a case where the first direct current voltage is output by turning the load switch on, after the first converter increases the first direct current voltage, the load switch is turned on.

6. An image forming apparatus for forming an image comprising:
a power supply apparatus configured to generate a direct current voltage so as to form the image;
wherein the power supply apparatus comprises:
a first converter configured to convert an input direct current voltage into the first direct current voltage by switching a first switching element, and to output the first direct current voltage; and
a second converter configured to convert the first direct current voltage output from the first convertor into a second direct current voltage lower than the first direct current voltage by switching a second switching element, and to output the second direct current voltage,
wherein the first converter is further configured to output a third direct current voltage lower than the second direct current voltage by switching the first switching element at a second switching frequency lower than a first switching frequency of the first switching element when the first convertor outputs the first direct current voltage, and
wherein the second convertor controls an operation of the second switching element so as to output the third direct current voltage input from the first convertor.

7. An image forming apparatus according to claim 6 , further comprising a feedback unit that detects a voltage according to the first direct current voltage output from the first converter and compares the detected voltage with a reference voltage,
wherein the feedback unit switches the reference voltage, the first converter decreases the first direct current voltage by switching a reference voltage of the feedback unit.

8. An image forming apparatus according to claim 6 , wherein the first converter includes a start-up resistor to drive the first switching element at a start-up of the power supply apparatus, wherein the first converter decreases the first direct current voltage by switching a resistance value of the start-up resistor.

9. An image forming apparatus according to claim 6 , further comprising a load switch which outputs or stops the first direct current voltage from the first converter,
wherein after the first direct current voltage is stopped by turning the load switch off, the first converter decreases the first direct current voltage.

10. An image forming apparatus according to claim 6 , further comprising a load switch which outputs or stops the first direct current voltage from the first converter,
wherein in a case where the first direct current voltage is output by turning the load switch on, after the first converter increases the first direct current voltage, the load switch is turned on.

11. An image forming apparatus according to claim 6 , further comprising:
an image forming unit for forming an image; and
a drive unit for driving the image forming unit,
wherein the first direct voltage from the first converter is supplied to the drive unit.

12. An image forming apparatus according to claim 6 , further comprising:
a control unit for controlling an operation of the image forming apparatus,
wherein the second direct voltage from the second converter is supplied to the control unit.

13. A power supply apparatus according to claim 1 , further comprising a control unit configured to control a switching frequency of the first switching element of the first converter,
wherein the control unit controls the switching frequency so that the third direct current voltage output through the second converter is a constant value.

14. A power supply apparatus according to claim 1 , wherein a power consumption in a state in which the first converter outputs the third direct current voltage is less than a power consumption in a state in which the first converter outputs the first direct current voltage.

15. A power supply apparatus according to claim 1 , wherein in a state in which the first converter outputs the first current voltage, the frequency of the second switching element of the second coverter is a set so that the second converter outputs the first direct current voltage.

16. An image forming apparatus according claim 6 , wherein the first converter outputs voltage to a first load and the second coverter outputs voltage to a second load, and
wherein in a low power consumption mode of the image forming apparatus, the first converter outputs the third direct current voltage through the second coverter to the second load.

17. A power supply apparatus according to claim 1 ,
wherein in a case where the first converter outputs the third direct voltage, the second switching element is turned on.

18. An image forming apparatus according to claim 6 ,
wherein a case where the first convertor outputs the third direct voltage, the second switching element is turned on.

19. An image forming apparatus according to claim 16 , wherein in a low power consumption mode of the image forming apparatus, an output of a voltage from the first convertor to the first load is cut off.

20. A power supply apparatus according to claim 1 , further comprising a switch for providing the first direct current v

Assignees

• Canon Kk

Inventors

• Hayasaki Minoru
• Samejima Keisuke

Classifications

• H02M3/3385

  with automatic control of output voltage or current (H02M3/33561 takes precedence) · CPC title

• B41J2/435

  characterised by selective application of radiation to a printing material or impression-transfer material · CPC title

• H02M3/3381 Primary

  using a single commutation path · CPC title

• H02M7/00 Primary

  Conversion of AC power input into DC power output; Conversion of DC power input into AC power output · CPC title