JP5453987B2 - Switching power supply device and image forming apparatus using the same - Google Patents

Description

  The present invention relates to a switching power supply apparatus and an image forming apparatus such as an electrophotographic printer, a copying machine, and a facsimile machine using the switching power supply apparatus.

In recent years, in an image forming apparatus, the proportion of waiting time is much larger than the printing time when the power is turned on. Therefore, an energy saving mode is provided during standby to reduce power consumption and save energy. Improving time efficiency is a proposition.
Various proposals have been made for image forming apparatuses having energy saving means.
The invention described in Patent Document 1 is one of them.
The invention described in Patent Document 1 is an invention related to a power supply device for an image forming apparatus. Specifically, during image formation, based on the output of the active filter AF, different DC voltages are generated from the converters to generate power supply voltages. obtain. During non-image formation in the standby mode, the power supply voltage is obtained only from the converter based on the output of the active filter. During non-image formation in the sleep mode, the power supply voltage is obtained only from the converter based on the AC voltage without passing through the active filter.
According to the invention described in Patent Document 1, the power factor is improved at the time of image formation, the power supply voltage with reduced harmonic current is output, and the operation circuit is changed based on the magnitude of the output power at the time of non-image formation. Thus, it is possible to suppress the deterioration of efficiency.

By the way, the invention described in Patent Document 1 determines whether or not to bypass the active filter that suppresses harmonics of the input current based on the magnitude of the output power, and improves the efficiency in the energy saving mode. Yes.
However, in the invention described in Patent Document 1 in which the bypass is performed only when the output power is large or small, it is difficult to simply bypass the noise filter because the noise generation state cannot be determined only from the output power information. is there.

  In addition, for example, the conventional self-excited switching power supply circuit has a significantly increased switching frequency at a light load such as in a standby state, and is rather noise compared with a normal load or a heavy load such as an operating state of the main unit. There is a problem that the noise level cannot be suppressed.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a switching power supply apparatus that suppresses the noise level and improves the efficiency in the energy saving mode, and an image forming apparatus using the switching power supply apparatus.

  In order to solve the above problem, the invention according to claim 1 is a diode bridge that rectifies an AC input voltage input from a commercial power supply via a noise filter, rectified by the diode bridge, and smoothed by a smoothing capacitor. An insulating transformer in which a voltage is input to the primary side, a switching element provided between the primary side of the insulating transformer and the smoothing capacitor and switching the primary side of the insulating transformer, and a secondary of the insulating transformer A control circuit for controlling the switching element according to the output voltage on the side, and a switching power supply device that inputs an energy saving mode signal and shifts to the energy saving mode from the noise filter via the bypass. AC input switching means for directly inputting commercial power to the diode bridge is provided. It is characterized by performing the soft switching control by transition to the power saving mode.

  According to a second aspect of the present invention, in the first aspect of the present invention, the noise filter includes an X capacitor, a Y capacitor, and a common mode choke coil, and the AC input switching unit is connected to the input side of the noise filter. And a mechanical relay to which a coil current is supplied when the output side is connected to the contact a and shifts to the energy saving mode.

  According to a third aspect of the present invention, in the first aspect of the present invention, the noise filter includes an X capacitor, a Y capacitor, and a common mode choke coil, and the AC input switching unit is connected to the input side of the noise filter. And an output side is connected to the semiconductor output element, and a solid state relay is provided in which the semiconductor element is turned on by shifting to the energy saving mode.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the control is performed when the AC input is performed by shifting to the energy saving mode after performing the control during standby. The switching means is operated to switch from the noise filter to the bypass path.

Invention according to claim 5, in the invention described in any one of claims 1 to 3, when the energy saving mode is canceled by using the energy-saving mode signal, the commercial and controls the AC input switching means A power supply is connected to the diode bridge via the noise filter .

  According to a sixth aspect of the present invention, a diode bridge that rectifies an AC input voltage input from a commercial power supply through a two-stage noise filter, and a voltage rectified by the diode bridge and smoothed by a smoothing capacitor is a primary side. An isolation transformer that is input to the isolation transformer, a switching element that is provided between the primary side of the isolation transformer and the smoothing capacitor, and that switches the primary side of the isolation transformer, and an output voltage on the secondary side of the isolation transformer Accordingly, a control circuit for controlling the switching element, a fixing device for stabilizing the developed image, and a fixing control unit for controlling the fixing device with the input side connected to the output side of the noise filter in the preceding stage. An image forming apparatus having an energy-saving mode signal is input to switch to the energy-saving mode, thereby shutting off the energization of the fixing device. And an AC input switching means for bypassing the preceding noise filter by shifting to the energy saving mode, and the control circuit performs soft switching control by shifting to the energy saving mode. Features.

  The invention according to claim 7 is the invention according to claim 6, wherein the noise filter includes an X capacitor, a Y capacitor, and a common mode choke coil, and the AC input switching means is connected to an input side of the noise filter. And the output side is connected to a contact, and it has a mechanical relay to which a coil current is supplied by shifting to the energy saving mode.

  The invention according to claim 8 is the invention according to claim 6, wherein the noise filter includes an X capacitor, a Y capacitor, and a common mode choke coil, and the AC input switching means is connected to an input side of the noise filter. And an output side is connected to the semiconductor output element, and a solid state relay is provided in which the semiconductor element is turned on by shifting to the energy saving mode.

  According to a ninth aspect of the present invention, in the invention according to any one of the sixth to eighth aspects, the control circuit performs energization of the fixing device by the energization cut-off means after performing control during standby. The AC input switching means for bypassing the noise filter in the previous stage is controlled after the power is cut off.

The invention according to claim 10, in the invention described in any one of claims 6 9, when the energy saving mode is canceled by using the energy-saving mode signal during the energy-saving mode, controls said AC input switching means and via the noise filter to the commercial power supply connected to said diode bridge, and said to Rukoto heater energized by the energizing interrupting means.

  The invention according to claim 11 is the invention according to any one of claims 6 to 10, wherein the control circuit for controlling the switching circuit and the AC input switching control means include at least one energy saving mode signal. It is controlled by.

  According to the present invention, it is possible to improve the efficiency at low load and reduce noise by performing soft switching control in the control circuit of the switching circuit by inputting the energy saving mode signal. In addition, by bypassing the noise filter with the AC input switching means, it is possible to improve the power loss in the noise filter in the energy saving mode, and to further improve the efficiency and the power factor. It is possible to provide a switching power supply apparatus that suppresses the efficiency and improves the efficiency in the energy saving mode, and an image forming apparatus using the switching power supply apparatus.

It is an example of the circuit diagram of the switching power supply device which concerns on this invention. 1 is an example of a circuit diagram of a switching power supply device of an image forming apparatus according to the present invention.

Embodiments of the present invention will be described with reference to the drawings.
The power supply circuits of the following first and second embodiments will be described as being applicable to image forming apparatuses such as printers, copiers, and facsimiles.

<Embodiment 1>
[Constitution]
FIG. 1 is an example of a circuit diagram of a switching power supply device according to the present invention.
In this switching power supply device, 11 is a commercial power supply.
Reference numeral 12 denotes a current fuse that prevents an excessive current from flowing into the power supply unit from the commercial power supply.
Reference numeral 13 denotes a noise filter that removes noise of the AC input voltage input from the commercial power supply 11 and suppresses leakage of noise generated from the inside of the power supply circuit to the outside. A typical configuration of the noise filter 13 includes an X capacitor 23, a common mode choke coil 24, and Y capacitors 25 and 26.
The X capacitor 23 is called an across-the-line capacitor and removes normal mode noise.
The Y capacitors 25 and 26 are called line bypass capacitors, and together with the common mode choke coil 24, remove common mode noise.

Reference numeral 18 denotes AC input switching means for bypassing the AC input from the noise filter 13 to the bypass path by the energy saving mode signal 21. For example, a double-pole single-throw mechanical relay can be mentioned. The AC input switching means 18 may be a solid state relay in which the input side and the output side of the noise filter are connected to the semiconductor output element, and the semiconductor element becomes conductive by shifting to the energy saving mode.
Here, the energy saving mode signal 21 is responsible for shifting to and releasing from the energy saving mode. For this reason, the energy saving mode signal 21 is input both when shifting to the energy saving mode and when canceling the energy saving mode. That is, when the energy saving mode signal 21 is input and the mode is shifted to the energy saving mode, the energy saving mode is canceled when the energy saving mode signal 21 is next input, and the energy saving mode is again shifted when the energy saving mode signal 21 is further input. .

Reference numeral 14 denotes a diode bridge that rectifies the AC input voltage after noise removal, and reference numeral 15 denotes a smoothing capacitor that smoothes the voltage rectified by the diode bridge 14. An example of the smoothing capacitor is an electrolytic capacitor.
Reference numeral 17 denotes an insulating transformer having a primary winding (upper left side in the figure) and two secondary windings (lower left side and right side in the figure), and a primary side (left side in the figure) and a smoothing capacitor. 15, a control unit 16 that performs switching control of the primary side of the insulating transformer 17 is provided.
The control unit 16 includes a control circuit 28 and an N-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) 29 as a switching element. A noise absorbing capacitor 37 is connected between the drain and source of the MOSFET 29.
The control circuit 28 is configured to perform soft switching control on the MOSFET 29 and is connected to the collector of the phototransistor portion 30a of the photorelay. The power source of the control circuit 28 uses a DC voltage obtained by rectifying the switching output of one secondary side (lower left side in the figure) of the insulating transformer 17 with the diode 32 and smoothing it with the smoothing capacitor 31.

Further, the output on the other secondary side (right side in the figure) of the insulating transformer 17 is rectified by a diode 33 and smoothed by a smoothing capacitor 34 to obtain a DC voltage. This DC voltage is input to the voltage feedback circuit 35 and the DC-DC converter 22.
The voltage feedback circuit 35 is a circuit for monitoring the switching output voltage, and the monitoring result is represented by the light emission amount of the light emitting diode portion 30b of the photorelay. That is, the monitoring result of the voltage feedback circuit 35 is reflected in the control circuit 28.
The DC-DC converter 22 converts the switching output voltage into a desired DC voltage.
Reference numeral 19 is a terminal for outputting a driving output (24V system) voltage, 20 is a terminal for outputting a control output 20 stepped down by DC-DC conversion, and 21 is an energy saving mode signal (energy saving mode transition). This is a terminal to input (cancel energy saving mode).

[Operation]
In the configuration as described above, the control unit 16 that controls the switching circuit of the insulation transformer 17 by the input of the energy saving mode signal 21 performs soft switching control that reduces switching loss and noise during low load (standby). . This soft switching control can improve efficiency at low load and reduce noise.

  By having such a switching power supply device, the image forming apparatus enters an energy saving mode state. After entering the energy saving mode, the AC input switching means 18 bypasses the noise filter 13 installed for the purpose of optimally removing noise during operation and standby of the image forming apparatus. By this bypass, it is possible to improve the power loss in the noise filter 13 during the energy saving mode, and to further improve the efficiency and the power factor.

  Further, when the energy saving mode is canceled, the energy saving mode signal 21 is input to control in the reverse sequence at the time of shifting to the energy saving mode. With this sequence, it is possible to provide an efficient switching power supply device that does not always impair the noise suppression effect.

  In the circuit configuration of the present embodiment, the quasi-resonant circuit is described as an example of the circuit for controlling the switching of the isolation transformer 17. However, the control unit 16 reduces the switching loss and noise during low load (standby). The method is not limited as long as the method is reduced. For example, methods disclosed in Japanese Patent Application Laid-Open Nos. 2006-287429 and 2004-112913 may be used.

  Further, by bypassing at least one of the X capacitor 23, the common mode choke coil 24, and the Y capacitor 25 constituting the noise filter 13, the noise suppression effect emitted to the commercial power supply 11 and the power factor and efficiency of the switching power supply can be reduced. It is also possible to have an optimal configuration.

<Embodiment 2>
[Constitution]
FIG. 2 is an example of a circuit diagram of the switching power supply device of the image forming apparatus according to the present invention.
The switching power supply device shown in FIG. 2 is a circuit diagram in the case where two noise filters 13 in the switching power supply device shown in FIG. 1 are configured. Since the circuits after the diode bridge 14 are the same as those in the first embodiment, they are omitted in FIG.

A fixing control unit 31 and a heater 28 for controlling the fixing device are provided between the noise filter 13a at the front stage and the noise filter 13b at the rear stage. Reference numeral 38 denotes an energization cut-off means that cuts off the energization of the heater 28 and the fixing control unit 31 that controls the voltage of the heater 28 of the fixing device by the input of the energy saving mode signal 21.
As the power cut-off means 38, a mechanical relay or a solid state relay is used as in the AC input switching means 18.

In the above configuration, the noise filter 13a is connected mainly for the purpose of suppressing noise from the heater 28 during printing and standby.
In the energy saving mode, the control unit 16 that controls the switching circuit of the insulation transformer 17 by the input of the energy saving mode signal 21 performs soft switching control to reduce switching loss and noise at low load, and the power cut-off means 38 The fixing controller 31 that controls the fixing device and the energization of the heater 28 are cut off. After the energization is cut off, the noise filter 13 a is bypassed by the AC input switching means 18. By this bypass, noise in the heater 28 can be cut off during printing and standby, and in the energy saving mode, power loss in the noise filter 13a can be improved, and further improvement in efficiency and improvement in power factor can be achieved. .

  Further, when the energy saving mode is canceled, the energy saving mode signal 21 is input to control in the reverse sequence at the time of shifting to the energy saving mode. With this sequence, an efficient switching power supply device can be provided without impairing the noise suppression effect in each mode.

  Further, by bypassing at least one of the X capacitor 23a, the common mode choke coil 24a, and the Y capacitor 25a constituting the noise filter 13a, a noise suppressing effect released to the commercial power supply 11 as in the first embodiment. It is also possible to optimize the power factor and efficiency of the switching power supply.

In the first embodiment and the second embodiment, the control signal for the control unit 16 that controls the switching circuit, the AC input switching means 18 and the energization cutoff means 38 is described as one energy saving mode signal. However, the present invention is not limited to this, and the same effect can be obtained by controlling each control signal. The AC input switching means 18 is not limited to a switching means such as a relay or a switch as long as ON / OFF switching is possible.

<Effect>
According to the present invention, the soft switching control for reducing the switching loss and noise at the time of low load is performed in the control unit that controls the switching circuit of the insulation transformer by the input of the energy saving mode signal. By this soft switching control, it is possible to improve the efficiency at low load (standby time) and reduce noise. After the soft switching control, a noise filter installed for the purpose of optimally removing noise during operation and standby of the image forming apparatus is bypassed by the AC input switching means. By this bypass, power loss in the noise filter in the energy saving mode can be improved, and further improvement in efficiency and power factor can be achieved.

  Further, when the energy saving mode is released, control is performed in the reverse sequence at the time of shifting to the energy saving mode by inputting the energy saving mode signal. With this sequence, it is possible to provide an efficient switching power supply device that does not always impair the noise suppression effect.

  The present invention uses a switching system that controls a steady state and an energy saving mode state as an image forming apparatus power supply circuit that can operate in an energy saving mode, and that improves efficiency and reduces power consumption in each state. It can be used for an image forming apparatus such as a facsimile machine, a copier, a scanner, a scanner printer, a multifunction machine, and the power supply apparatus.

DESCRIPTION OF SYMBOLS 11 Commercial power supply 12 Current fuse 13 Noise filter 14 Diode bridge 15, 31, 34 Smoothing capacitor 16 Control part 17 Isolation transformer 18 AC input switching means 19, 20, 21 Terminal 22 DC-DC converter 23 X capacitor 24 Common mode choke coil 25 , 26 Y capacitor 27 Varistor 28 Control circuit 29 MOSFET
30a Phototransistor part of photorelay 30b Light emitting diode part of photorelay 32, 33 Diode 35 Voltage feedback circuit 37 Capacitor 38 Current cut-off means

JP 2006-276341 A

Claims (11)

A diode bridge that rectifies an AC input voltage input from a commercial power supply via a noise filter;
An insulating transformer in which a voltage rectified by the diode bridge and smoothed by a smoothing capacitor is input to the primary side;
A switching element provided between the primary side of the isolation transformer and the smoothing capacitor and switching the primary side of the isolation transformer;
A control circuit that controls the switching element in accordance with the output voltage on the secondary side of the isolation transformer;
AC input switching means for inputting the commercial power source directly to the diode bridge from the noise filter via a bypass when the energy saving mode signal is input to shift to the energy saving mode,
The switching power supply device, wherein the control circuit performs soft switching control by shifting to the energy saving mode. The noise filter has an X capacitor, a Y capacitor, and a common mode choke coil,
2. The AC input switching means includes a mechanical relay in which an input side and an output side of the noise filter are connected to a contact, and a coil current is supplied by shifting to the energy saving mode. Switching power supply. The noise filter has an X capacitor, a Y capacitor, and a common mode choke coil,
2. The AC input switching means includes a solid state relay in which an input side and an output side of the noise filter are connected to a semiconductor output element, and the semiconductor element is turned on by shifting to the energy saving mode. The switching power supply device described in 1.   4. The control according to claim 1, wherein after performing the control during standby, the AC input switching unit is operated to switch from the noise filter to the bypass path by shifting to the energy saving mode. The switching power supply device according to any one of the above. If the energy saving mode is canceled by using the energy-saving mode signal, said commercial power source by controlling the AC input switching means, claims 1 via the noise filter, characterized in that connected to the diode bridge 4. The switching power supply device according to any one of 3. A diode bridge for rectifying an AC input voltage input from a commercial power supply through a two-stage noise filter;
An insulating transformer in which a voltage rectified by the diode bridge and smoothed by a smoothing capacitor is input to the primary side;
A switching element provided between the primary side of the isolation transformer and the smoothing capacitor and switching the primary side of the isolation transformer;
A control circuit for controlling the switching element according to the output voltage on the secondary side of the isolation transformer;
A fixing device for stabilizing the developed image;
A fixing control unit for controlling the fixing device, the input side being connected to the output side of the noise filter in the previous stage;
An image forming apparatus having
An energization shut-off means for shutting off energization of the fixing device by inputting an energy-saving mode signal and shifting to the energy-saving mode;
AC input switching means for bypassing the previous stage noise filter by shifting to the energy saving mode,
The image forming apparatus, wherein the control circuit performs soft switching control by shifting to the energy saving mode. The noise filter has an X capacitor, a Y capacitor, and a common mode choke coil,
The AC input switching unit includes a mechanical relay in which an input side and an output side of the noise filter are connected to a contact, and a coil current is supplied by shifting to the energy saving mode. Image forming apparatus. The noise filter has an X capacitor, a Y capacitor, and a common mode choke coil,
7. The AC input switching means includes a solid state relay in which an input side and an output side of the noise filter are connected to a semiconductor output element, and the semiconductor element is turned on by shifting to the energy saving mode. The image forming apparatus described in 1.   The control circuit controls the AC input switching unit that bypasses the preceding noise filter after the energization of the fixing unit is interrupted by the energization interrupting unit after performing the control during standby. The image forming apparatus according to any one of claims 6 to 8. If the energy saving mode is canceled by using the energy-saving mode signal during the energy-saving mode, the control to the commercial power source AC input switching means via said noise filter connected to said diode bridge, by the energizing interrupting means the image forming apparatus according to any one of claims 6, wherein to Rukoto heater energized 9.   11. The image forming apparatus according to claim 6, wherein the control circuit that controls the switching circuit and the AC input switching control unit are controlled by at least one energy saving mode signal. .

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