Power supply control apparatus and image formation apparatus

• US 20020131788A1
• Filed: 03/13/2002
• Published: 09/19/2002
• Est. Priority Date: 03/14/2001
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Nakaya, Masahide
• Granted Patent: US 6,701,103 B2
• Time in Patent Office: Days
• US Class Current: 399/88
• CPC Class Codes: G03G 15/80 Details relating to power supplies, circuits boards, electrical connections
• CPC Class Codes: H02J 1/14 Balancing the load in a network
• CPC Class Codes: H02J 9/061 for DC powered loads
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/008 Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

In the image formation apparatus, an active filter converts an AC power supply supplied from an AC power supply to a DC voltage, and first and second DC-DC converters convert the DC voltage converted by the active filter to voltages at predetermined levels and respectively supplies the voltages to an image forming engine and an engine control unit. A power supply control unit stops the operation of the first DC-DC converter in order to allow the second DC-DC converter to continue supply of the voltage to the engine control unit when disconnection of the AC power supply is detected.

Claims

1. A power supply control apparatus comprising:

an active filter which converts an AC voltage supplied from an AC power supply to a DC voltage;

a DC-DC converter which converts the DC voltage converted by said active filter to voltages at predetermined levels, and respectively supplies the voltages to a load and a load control unit that controls said load;

a power supply control unit which controls operation of said DC-DC converter; and

a detection unit which detects disconnection of the AC power supply,

wherein said power supply control unit controls said DC-DC converter in order to allow said DC-DC converter to continue supply of the voltage to said load control unit for a predetermined time when said detection unit detects disconnection of the AC power supply.

2. The power supply control apparatus according to claim 1, wherein said DC-DC converter includes:

a first DC-DC converter which converts the DC voltage converted by said active filter to a voltage at a first level and supplies the voltage to said load; and

a second DC-DC converter which converts the DC voltage converted by said active filter to a voltage at a second level that is lower than the first level, and supplies the voltage to said load control unit,

wherein said power supply control unit stops operation of said first DC-DC converter in order to allow said second DC-DC converter to continue supply of the voltage to said load control unit for a predetermined time when said detection unit detects disconnection of the AC power supply.

3. The power supply control apparatus according to claim 1, wherein said load control unit saves job information in processing on a nonvolatile memory when said detection unit detects disconnection of the AC power supply.

4. The power supply control apparatus according to claim 1,

wherein said active filter is a unit that rectifies the AC voltage supplied from the AC power supply to a full-wave rectified waveform and then generates the DC voltage, and

said detection unit is a unit that detects disconnection of the AC power supply through detection of the full-wave rectified waveform of the AC power supply.

5. The power supply control apparatus according to claim 1, further comprising an active filter control unit which controls said active filter so that a waveform of an input current to said active filter is formed to a waveform similar to a waveform of an input voltage.

6. An image formation apparatus comprising:

an image forming engine which emits laser beams corresponding to image information onto a photoreceptor to form an electrostatic latent image on the photoreceptor, forms a toner image on the electrostatic latent image, and transfers a formed toner image to a transfer sheet;

an image forming engine control unit which controls said image forming engine;

an active filter which converts an AC voltage supplied from an AC power supply to a DC voltage;

a DC-DC converter which converts the DC voltage converted by said active filter to voltages at predetermined levels, and respectively supplies the voltages to said image forming engine and said image forming engine control unit;

a power supply control unit which controls operation of said DC-DC converter; and

a detection unit which detects disconnection of the AC power supply,

wherein said power supply control unit controls said DC-DC converter in order to allow said DC-DC converter to continue the supply of the voltage to said image forming engine control unit for a predetermined time when said detection unit detects disconnection of the AC power supply.

7. The image formation apparatus according to claim 6, wherein said DC-DC converter includes:

a first DC-DC converter which converts the DC voltage converted by said active filter to a voltage at a first level and supplies the voltage to said image forming engine; and

a second DC-DC converter which converts the DC voltage converted by said active filter to a voltage at a second level that is lower than the first level, and supplies the voltage to said image forming engine control unit,

wherein said power supply control unit stops operation of said first DC-DC converter in order to allow said second DC-DC converter to continue supply of the voltage to said image forming engine control unit for a predetermined time when said detection unit detects disconnection of the AC power supply.

8. The image formation apparatus according to claim 6, wherein said image forming engine control unit saves image information and job information in processing on a nonvolatile memory when said detection unit detects disconnection of the AC power supply.

9. The image formation apparatus according to claim 6,

wherein said active filter is a unit that rectifies the AC voltage supplied from the AC power supply to a full-wave rectified waveform and then generates the DC voltage, and

said detection unit is a unit that detects disconnection of the AC power supply through detection of the full-wave rectified waveform of the AC power supply.

10. The image formation apparatus according to claim 6, further comprising an active filter control unit which controls said active filter so that a waveform of an input current to said active filter is formed to a waveform similar to a waveform of an input voltage.