POWER SUPPLY UNIT AND IMAGE FORMING APPARATUS

• US 20160378052A1
• Filed: 04/18/2016
• Published: 12/29/2016
• Est. Priority Date: 06/23/2015
• Status: Active Grant

• Current Assignee: Oki Data Corporation (OKI Electric Industry Company Limited)
• Original Assignee: Oki Data Corporation (OKI Electric Industry Company Limited)
• Inventors: KOSAKA, Toru
• Granted Patent: US 9,740,158 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G03G 15/2039 with means for controlling the fixing temperature
• CPC Class Codes: G03G 15/80 Details relating to power supplies, circuits boards, electrical connections

Abstract

Provided is a power supply unit that includes a switching section and a controller. The switching section is configured to perform a switching operation and thereby generate, based on an input signal, a first alternating-current signal. The controller is configured to control the switching operation and thereby perform an amplitude control that involves increasing, based on an input current in the switching section, a signal amplitude of the first alternating-current signal.

Claims

1. A power supply unit, comprising:

a switching section configured to perform a switching operation and thereby generate, based on an input signal, a first alternating-current signal; and

a controller configured to control the switching operation and thereby perform an amplitude control that involves increasing, based on an input current in the switching section, a signal amplitude of the first alternating-current signal.

2. The power supply unit according to claim 1, wherein the controller increases the signal amplitude by a predetermined amount, not to allow the input current to exceed a predetermined current value.

3. The power supply unit according to claim 1, wherein the controller determines, based on the input current, a timing of increasing the signal amplitude.

4. The power supply unit according to claim 1, wherein the controller controls the switching operation, based on the first alternating-current signal.

5. The power supply unit according to claim 1, further comprising a plurality of switches that turn on and off supply of the first alternating-current signal to different loads from one another,

wherein the controller performs the amplitude control when one or more of the plurality of switches are changed from an off state to an on state.

6. The power supply unit according to claim 1, further comprising a switch that turns on and off supply of the first alternating-current signal to a load,

wherein the controller performs the amplitude control when the switch is changed from an on state to an off state, and is changed again to the on state after a lapse of predetermined time.

7. The power supply unit according to claim 1, further comprising a power factor correction circuit,

wherein the input signal is a direct-current signal, and

the power factor correction circuit generates the direct-current signal, based on a second alternating-current signal.

8. The power supply unit according to claim 7, further comprising a synchronizing signal generator that generates a synchronizing signal in synchronization with the second alternating-current signal,

wherein the controller controls, based on the synchronizing signal, the switching operation to allow a frequency of the first alternating-current signal to coincide with a frequency of the second alternating-current signal.

9. The power supply unit according to claim 8, wherein the controller selectively generates, based on the synchronizing signal, one of a first pulse signal and a second pulse signal, the first pulse signal including a plurality of pulses and having a first time length, and the second pulse signal including a plurality of pulses and having a second time length, and

the switching section performs the switching operation, based on a pulse signal selected from the first pulse signal and the second pulse signal.

10. The power supply unit according to claim 1, wherein the switching section includes

a first switching circuit including a first terminal to which the input signal is supplied, and a second terminal, the first switching circuit turning on and off between the first terminal and the second terminal, and

a second switching circuit, including a third terminal coupled to the second terminal of the first switching circuit, and a fourth terminal, the second switching circuit turning on and off between the third terminal and the fourth terminal, and

the controller

has a first mode and a second mode that involve controlling the switching section not to generate the first alternating-current signal,

controls, in the first mode, the switching operation to turn off one or both of the first switching circuit and the second switching circuit, and

fixes, in the second mode, one or both of the first switching circuit and the second switching circuit to an off state.

11. The power supply unit according to claim 1, wherein the switching section supplies the first alternating-current signal to a heater.

12. An image forming apparatus, comprising:

a developing unit;

a fixing unit including a heater, and configured to fix a developer onto a recording medium; and

a power supply unit configured to supply the heater with electric power, and including;

a switching section configured to perform a switching operation and thereby generate, based on an input signal, a first alternating-current signal; and

a controller configured to control the switching operation and thereby perform an amplitude control that involves increasing, based on an input current in the switching section, a signal amplitude of the first alternating-current signal.