JP2003199340A - Switching power supply and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption at stand-by state in a switching power supply 1 as a single body for driving a load, constituted of a drive circuit 6 as a power load and its control circuit 8. <P>SOLUTION: Continuous pulses are generated from an output PON of a control circuit 8 in a normal operation state and are integrated by C8, R9, and C7 to turn TR5 on and turn FETTR4 off. Then, a shunt regulator 9 drives D3 of PC according to the output voltage VM. In the sand-by state, the operation of control circuit 8 is stopped to turn TR5 off and turn FETTR4 on, so that D3 is always lightened and changed into an oscillation stop state. When VM is lowered by the consumption of D3, the FETTR4 is turned on to keep a minimum voltage. In this way, the VM at stand-by states requires only a voltage for keeping the D3 in a normal lightened state and in an intermittent oscillation state, and the power consumption at stand-by state can be reduced. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching power supply device and an image forming apparatus using the switching power supply device. In particular, the switching power supply device has a single power supply and drive system power for ejecting ink. For the load and the load control means for driving and controlling the power load, two systems of outputs, a main output with a relatively high voltage and a sub output with a relatively low voltage, are provided on the secondary side. Regarding things.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for low power consumption of electronic devices, and in particular, a printer which is used only occasionally when a power supply is turned on in association with a personal computer or the like,
It is effective to reduce the power consumption during standby in a device in which the ratio of standby time to the time of normal operation is very large.

Therefore, for example, Japanese Unexamined Patent Publication No. 8-286770.
Japanese Patent Laid-Open Publication No. 2004-108242 discloses a microcomputer in which two systems of outputs, a main output having a relatively high voltage and a sub output having a relatively low voltage, are respectively configured by separate power supplies, and are activated by the sub output in the standby state. It is shown that the switching operation of the main output switching power supply is stopped by the standby signal from.

[0004]

However, in such a structure, two sets of switching elements and transformers are required, which causes a problem of increased cost. On the other hand, for example, JP-A-7-213055 and JP-A-7-213055
In Japanese Patent Laid-Open No. 219687, a single power supply is used to create the outputs of the two systems.

First, Japanese Patent Laid-Open No. 7-213055 discloses that
In the basic matter of power saving during standby with a single power supply, a standby signal from the secondary side is transmitted to the primary side via a photocoupler to reduce the oscillation frequency. . Next, in Japanese Patent Laid-Open No. 7-219687, in order to stop the oscillation on the primary side in response to a power saving signal from the secondary side,
A high-sensitivity photocoupler that can be directly driven by the power saving signal from the outside is used.

However, the above-mentioned Japanese Laid-Open Patent Publication No. 7-21305.
No. 5 has a problem that the oscillation cannot be stopped completely because the control circuit on the secondary side is operating, and the effect of power saving is small. On the other hand, Japanese Patent Laid-Open No. 7-21
Since 9687 stops oscillating, the above-mentioned Japanese Patent Laid-Open No. 7-2
Although the power saving effect is greater than that of No. 13055, the external circuit that supplies the power saving signal is a device different from the on-board device of the switching power supply device such as a personal computer, and power is supplied from the switching power supply device. There is a problem that it cannot be applied to the receiving control circuit.

An object of the present invention is to provide a switching power supply device in which a load is composed of an electric power load and its load control means, and in a standby operation, the oscillation operation can be stopped in response to an output from the load control means. It is to provide an image forming apparatus using.

[0008]

The switching power supply device of the present invention comprises a main output having a relatively high voltage and a sub output having a relatively low voltage on the secondary side, and optically couples the voltage of the main output. Feedback to the switching control means on the primary side via the means to perform a constant voltage control operation, and the power load of the main output system is operation-controlled by the load control means of the sub output system.
In a switching power supply device for driving a load, wherein the load control means stops the operation of the power load,
A drive unit that is energized by the main output and that drives the optical coupling unit to light up in response to a standby output from the load control unit, is provided in association with the drive unit, and is driven by the drive unit by a user operation. And resetting means for stopping lighting of the optical coupling means.

According to the above configuration, a relatively high voltage,
For example, the operation of a drive system power load that is energized at 24V is controlled by a load control means such as a microcomputer that is energized at a relatively low voltage, for example, 1.8V, and the load is driven alone. In the switching power supply device, when the load control means stops the operation of the electric load and enters the standby state, the drive means is activated in response to the standby output from the load control means, and the voltage of the main output is changed to the primary level. The optical coupling means provided to feed back to the switching control means on the side to realize the constant voltage control operation is driven to light. Although the power load has stopped operating, if the voltage of the main output drops to a level that cannot be maintained in the oscillation stopped state due to power consumption by the driving means, the driving means does not drive the lighting of the optical coupling means. The switching control means causes the main switching element to perform switching.

As a result, while the waiting state continues,
The optical coupling means flickers with a voltage output (light load) in a pseudo intermittent oscillation state, and the switching control means can shorten the ON period of the main switching element to achieve the minimum voltage output. At this minimum voltage, the drive means is energized by the main output having a relatively high voltage, and the load control means stops operating at the sub output.
The sub output may be lower than the operation start voltage of the load control means, and may be a voltage that allows the light emitting diode of the optical coupling means to normally light up and maintain the intermittent oscillation state, thereby reducing power consumption during standby. be able to.

Further, in the switching power supply device of the present invention, the load control means sets the output in the normal operation state as a continuous pulse, the standby output as a high level or low level output, and the drive means sets the pulse. A coupling capacitor to be passed, an integrating circuit for integrating the pulse,
And a switching element for lighting and driving the optical coupling means when the integrated output of the integrating circuit is less than a predetermined level.

According to the above construction, in the normal operation state in which the load control means outputs the continuous pulse, the integrated output becomes higher than a predetermined level and the switching element is turned off.
However, the optical coupling means feeds back the output voltage for the normal constant voltage control operation. On the other hand, when the load control means stops its operation and the high-level or low-level standby output is derived, the integrated output of the integration circuit becomes less than a predetermined level and the switching element is turned on. The optical coupling means is constantly driven to be turned on.

Therefore, the drive means can be provided with a function as a watchdog timer for determining the runaway of the load control means. Further, since the pulse from the load control means is made to have both the signal for the runaway discrimination and the function as the power save signal for setting the standby state,
It is also possible to reduce the number of terminals of the load control means.

Further, in the switching power supply device of the present invention, the driving means drives the optical coupling means by lighting by changing the voltage division value of the output voltage dividing resistance for the constant voltage control operation. Is characterized by.

According to the above structure, the high voltage output state is simulated by increasing the voltage division value of the output voltage dividing resistor energized by the main output during the standby operation as compared with the normal operation. Since it is created, the shunt regulator itself, which performs the constant voltage control operation, drives the optical coupling means to light.

Therefore, as in the case of using a transistor or an FET, the influence of temperature and manufacturing variations is small, and the oscillation stop state and the oscillation state can be switched with high accuracy.

Further, in the switching power supply device of the present invention, the driving means has a hysteresis in switching between the oscillation stop state and the oscillation state.

According to the above arrangement, the intermittent oscillation operation during standby can be stabilized.

Furthermore, the image forming apparatus of the present invention is characterized by using the above switching power supply device.

According to the above arrangement, the image forming apparatus is provided with the print operation start switch serving as the user-operated resetting means, so that the present invention can be preferably implemented.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Regarding one embodiment of the present invention,
The following is a description with reference to FIGS. 1 to 4.

FIG. 1 is a block diagram showing an electrical configuration of a switching power supply device 1 according to an embodiment of the present invention.
The switching power supply device 1 is a ringing choke converter type switching power supply device. First, the commercial alternating current from the commercial power supply 2 is input from the noise filter 3 to the diode bridge 4 and further to the smoothing capacitor C1 to be rectified and smoothed.

In this way, a series circuit of the primary winding N1 of the transformer N and the main switching element Q is connected in parallel to the smoothing capacitor C1 serving as a DC power source. The main switching element Q is realized by, for example, a bipolar transistor or a field effect transistor.
In the above example, an N-type field effect transistor is shown. The smoothing capacitor C1 also has a series resistor R1,
A starting circuit 5 composed of R2 is connected in parallel, and the connection point of the series resistors R1 and R2 is connected to the gate of the main switching element Q. Therefore, the switching power supply device 1 is connected to the commercial power supply 2, the output voltage of the smoothing capacitor C1 rises, and its series resistance R
The divided voltage value by 1 and R2 is O of the main switching element Q.
When the voltage exceeds N, the main switching element Q turns on.
Then, an exciting current flows through the primary winding N1.

As a result, the relatively high voltage VM induced in the secondary winding N2 of the transformer N is smoothed by the diode D1 and the smoothing capacitor C2, and then, as a main output, the driving circuit 6 of the ink jet recording apparatus. Given to. The voltage VM is, for example, 24 V when the inkjet recording apparatus uses a thermal element, and is 40 V when the inkjet recording apparatus uses a piezoelectric element.

The secondary winding N2 of the transformer N is provided with an intermediate tap NP, and the relatively low voltage VL extracted from the intermediate tap NP is smoothed by the diode D2 and the smoothing capacitor C3. The output voltage is further stabilized and stabilized at the voltage VCC by the voltage drop type regulator 7, and then supplied as a sub output to the control circuit 8 of the inkjet recording apparatus realized by a microcomputer or the like. The voltage VCC is, for example, 3.3V or 5V.

On the other hand, the smoothing capacitor C2 on the main side
The output voltage VM of is divided by the voltage dividing resistors R3 and R4 and input to the shunt regulator 9. The shunt regulator 9 includes a reference voltage source 10, a comparator 11, and an output transistor TR1. The output voltage V of the smoothing capacitor C2 is applied to the collector of the output transistor TR1 via the photodiode D3 of the photocoupler PC and the current limiting resistor R5.
M is given and the emitter is grounded. The comparator 11 outputs the output transistor TR when the divided voltage value of the output voltage VM becomes higher than the reference voltage of the reference voltage source 10.
High level is output to the base of 1 and photodiode D
3 is driven to light.

On the other hand, on the primary side, the voltage induced in the auxiliary winding N3 of the transformer N is smoothed by the diode D4 and the smoothing capacitor C4 to become the control power supply, and its output voltage is It is given to the base of the control transistor TR3 via the phototransistor TR2 and the resistor R6 of the photocoupler PC. Control transistor TR
The collector of 3 is connected to the gate of the main switching element Q, and the emitter is grounded.

Therefore, when the main switching element Q is turned on and the divided voltage value of the output voltage VM becomes higher than the reference voltage of the reference voltage source 10, the photodiode D3 is turned on and the phototransistor TR2 to the control transistor T are turned on.
R3 is turned on to set the gate of the main switching element Q to a low level to turn off the main switching element Q.
As the output voltage VM increases, the main switching element Q
Is turned off quickly, and by thus feeding back the voltage VM of the main output to the primary side to control the switching operation, a constant voltage operation for holding the output voltage VM constant is performed.

The voltage induced in the auxiliary winding N3 generates a ringing pulse due to the parasitic capacitance and the inductance of the auxiliary winding N3, and is applied to the gate of the main switching element Q via the resistor R0. . Therefore, the main switching element Q is turned on again, and oscillation is continuously performed so that the output voltage VM corresponding to the load is obtained without using a complicated switching control circuit.

In parallel with the primary winding N1 of the transformer N,
A snubber circuit 12 including a series circuit of a diode D5 and a capacitor C5 is provided, and the counter electromotive voltage induced in the primary winding N1 when the main switching element Q is turned off is once absorbed by the capacitor C5. It circulates in the closed circuit of the primary winding N1-diode D5-capacitor C5 and is consumed and removed by the resistance component of the closed circuit.

In the switching power supply device 1 configured as described above, it should be noted that, in the present invention, an N-type FET TR4 is provided in parallel with the shunt regulator 9, and the gate of the FET TR4 has the above-mentioned configuration. A voltage obtained by charging the capacitor C6 with the voltage VM of the main output through the resistor R7 is applied.

On the other hand, the gate of the FET TR4 is also
It will be connected to the ground line via the short-circuit resistor R8 and the transistor TR5. The transistor TR5
The charging voltage of the capacitor C7 is applied to the base of the. The capacitor C7 constitutes an integrating circuit together with the resistor R9, and the output PON of the control circuit 8 is connected to the integrating circuit.
A continuous pulse from C is applied via coupling capacitor C8.

Furthermore, the gate of the FET TR4 is connected to the ground line via the short circuit resistor R10, the diode D6 and the push button switch PS1. A push button switch PS2 interlocking with the push button switch PS1 is provided. These push button switches PS1 and PS2 are switches for starting a printing operation by a user operation, and are turned on (closed) when pushed. The push button switch PS2 connects the input PSW of the control circuit 8 to a ground line, and the input PSW is also connected to the sub output voltage VCC by a pull-up resistor R11.
Has been pulled up.

In the normal operation state, the continuous pulse is output from the output PON of the control circuit 8, and the continuous pulse is given to the integrating circuit via the coupling capacitor C8.
The capacitor C7 is charged. The continuous pulse is output, and the charging voltage of the capacitor C7 changes to the transistor T.
When the voltage is equal to or higher than the ON voltage of R5, the transistor TR5 is turned on, and the terminals of the capacitor C6 are short-circuited. Therefore, the FET TR4 is turned off, and the constant voltage operation by the shunt regulator 9 is performed.

On the other hand, when the control circuit 8 finishes the predetermined operation for driving the drive circuit 6 and the control circuit 8 enters the standby state and stops its operation, the output of the pulse from the output PON is stopped. To do. As a result, the capacitor C7 is discharged, and the charged voltage is the transistor T.
When the voltage becomes lower than the ON voltage of R5, the transistor TR5 is turned off and the capacitor C6 is charged through the resistor R7. Then, when the charging voltage becomes equal to or higher than the ON voltage of the FET TR4 set to 1.8 V, which can obtain a stable ON state of the photodiode D3 of the photo coupler PC, for example, the FET TR4 is turned on and the operation of the shunt regulator 9 is performed. Regardless of this, the photodiode D3 of the photocoupler PC is constantly turned on, a pseudo high voltage output state is set, the main switching element Q remains off, and the primary side is in an oscillation stop state.

Thereafter, when the power consumption of the photodiode D3 (for example, 1.8 V and 10 mA) causes the voltage VM of the main output to drop to a voltage below 1.8 V at which the intermittent oscillation state cannot be maintained, the FET TR4 is turned off.
However, the main switching element Q is turned on by the starting circuit 5.
When the voltage VM of the main output becomes equal to or more than 1.8 V, the operation of stopping the oscillation is repeated. When the push button switches PS1 and PS2 are pushed, the FETTR4 is turned off, the constant voltage operation is performed by the shunt regulator 9, and the input PSW of the control circuit 8 is pulled down to reset the control circuit 8. Then, the normal operation starts immediately.

When the control circuit 8 goes into a runaway state and the output PON is fixed at a high level or a low level, the capacitor C7 is discharged,
Transistor TR5 turns off and FET TR4 turns on
Then, the oscillation is stopped on the primary side.

As described above, in the switching power supply device 1 of the present invention, the operation of the drive circuit 6 which is energized by the relatively high voltage VM is controlled by the control circuit which is energized by the relatively low voltage VCC. When the control circuit 8 suspends the operation of the drive circuit 6 and drives the load controlled by 8 independently, the output P of the control circuit 8 is stopped.
When the pulse from ON is stopped, FETTR4 becomes O
N, the photodiode D3 of the photocoupler PC is constantly lit, and the primary side is intermittently oscillated as a pseudo high voltage output state. Therefore, the voltage VCC of the sub output is lower than the operation start voltage of the control circuit 8. It is possible to reduce the power consumption during standby by lowering it (to a voltage at which it cannot operate).

Further, the control circuit 8 outputs a continuous pulse from the output PON during the normal operation, and when the control circuit 8 goes into a runaway state and is fixed to the high level or the low level, Since the oscillation is stopped on the primary side, the capacitors C7, C8, the resistor R8,
R9 and the transistor TR5 are provided with a function as a watchdog timer so that runaway can be determined.
Furthermore, since the pulse from the output PON also has the function of the runaway determination signal and the function of the power save signal in the standby state, the number of terminals of the control circuit 8 can be reduced.

FIG. 2 shows an ink jet recording device 21 in which the switching power supply device 1 configured as described above is used.
FIG. 3 is a perspective view showing a schematic configuration of FIG. 3, and FIG. 3 is a vertical sectional view thereof. The paper 23 stacked and stored in the paper feed tray 22 is taken out by the paper feed roller 24, and the separation pad 26 and the paper feed roller 24 are elastically abutted against the paper feed roller 24 by the spring 25. Then, the sheets are separated one by one, and are fed to the conveyance path to the printing unit 27.

Immediately before the printing section 27, a PS roller 28 is provided.
2 that has been placed and has been fed through the transport path
The sheet No. 3 is temporarily stopped in a state where the tip thereof is engaged with the PS roller 28 and the tips are aligned, and then the sheet 3 is fed to the printing unit 27 at the timing of image formation. Print part 2
A paper discharge roller 29 is provided on the downstream side of 7, and the paper 23 for which printing has been completed is discharged onto the paper discharge tray 30 by the paper discharge roller 29.

In the printing unit 27, the carriage 31 is
By the guide shaft 32 and the timing belt 33, the paper 23 is slidably displaced in the main scanning direction 35 which is orthogonal to the conveyance direction 34 of the paper 23 which is the sub-scanning direction, and at that time, the paper 23 is removed from the print head 36 mounted on the carriage 31. Printing can be performed by ejecting ink onto the.

FIG. 4 shows the ink jet recording device 21.
3 is a block diagram showing the electrical configuration of FIG. Print data and control signals from a personal computer or the like are input to an interface section 42 of the control circuit 41 realized by a microcomputer, and the print data is subjected to image processing and each pixel using a memory 44 in an image processing section 43. Data is applied to the print head 36 from the head drive circuit 45.

The control signal is given from the interface section 42 to the drive system control section 46, and is separated into a drive signal in the main scanning direction 35 and a drive signal in the sub-scanning direction (sheet conveying direction 34). It is applied to the carriage drive circuit 47 and the paper transport drive circuit 48, respectively. The carriage drive circuit 47 drives and controls a carriage motor 49, and the paper transport drive circuit 48 drives and controls a paper transport motor 50.

In the ink jet recording apparatus 21 configured as described above, the drive circuits 45, 47 and 48 for the print head 36, the carriage motor 49 and the paper transport motor 50 are driven by the voltage VM of the main output. And the control circuit 41 becomes the control circuit 8 driven by the sub output voltage VCC.

Another embodiment of the present invention will be described below with reference to FIG.

FIG. 5 is an electric circuit diagram of a switching power supply device 1a according to another embodiment of the present invention. This switching power supply device 1a is similar to the switching power supply device 1 described above, and corresponding parts are designated by the same reference numerals and description thereof is omitted. It should be noted that in the switching power supply device 1a, the output voltage VM is input to the voltage dividing resistor R3 among the voltage dividing resistors R3 and R4, although it is the same as the switching power supply device 1 in the same manner. The piezoresistor R4 is not always grounded, but is grounded via the FET TR6 or the push button switch PS1. The low level side of the shunt regulator 9 is not directly grounded, but is grounded via a parallel circuit of the resistor R12 and the diode D7, and the FET TR4 is provided in parallel with these parallel circuits.
A discharge resistor R13 is provided in parallel with the capacitor C7.

Therefore, in the normal operation state, the charging voltage of the capacitor C7 is turned on by the FETs TR4 and TR6 by the continuous pulse from the output PON of the control circuit 8.
The voltage becomes, for example, 1.8 V or more, the voltage dividing resistor R4 and the shunt regulator 9 are grounded, and the constant voltage operation is performed by the shunt regulator 9.

On the other hand, the control circuit 8 is in the standby state, the output of the pulse from the output PON is stopped, the capacitor C7 is discharged, and the FETs TR4 and TR6 are discharged.
When it becomes less than the ON voltage of, the FET TR6 is turned off. As a result, the output voltage VM is directly applied to the shunt regulator 9 via the voltage dividing resistor R3, and a pseudo high voltage output state is established, and the photo coupler P is connected.
The photodiode D3 of C is constantly turned on, and the oscillation of the primary side is stopped. At this time, FETTR4 is turned off.
However, the low level side of the shunt regulator 9 has a resistor R
12 and a diode D7 connected in parallel to ground.

Therefore, after that, the output voltage VM
Is 1.8V which is the ON voltage of the photodiode D3.
The saturation voltage Vcsat when the FETTR6 is turned on
When, for example, 0.7 V is added and the voltage becomes less than 2.5 V, the shunt regulator 9 is connected to the photo coupler PC.
The photodiode D3 of 1 is turned off, and the primary side restarts the oscillation operation.

Therefore, when the charging voltage of the capacitor C7 is 1.8 V or less, the oscillation is stopped and the output voltage VM
Since the oscillating operation is restarted at less than 2.5 V, the oscillating operation can have hysteresis to stabilize the intermittent oscillating operation during standby. Further, since the photodiode D3 is constantly switched on by changing the voltage division ratio of the output voltage VM, as in the switching power supply device 1, the FETT is turned on.
Compared with the case of switching only with R4, the influence of temperature and manufacturing variations is small, and switching can be performed with high accuracy.

When a transistor is used instead of the FETs TR4 and TR6, the ON voltage is
For example, it is 0.7V. Further, the switching power supply is not limited to the ringing choke converter system, but P
The WM method or the like may be used.

[0053]

As described above, the switching power supply device of the present invention is a microcomputer in which the operation of the drive system power load, which is energized with a relatively high voltage, is energized with a relatively low voltage. In a switching power supply device that drives a load individually controlled by load control means such as, when the load control means stops the operation of the power load and enters a standby state, the standby output from the load control means is output. In response to this, the driving means is activated, and the voltage of the main output is fed back to the switching control means on the primary side to light-drive the optical coupling means provided for realizing the constant voltage control operation.

Therefore, while the standby state continues, the optical coupling means flickers with a pseudo intermittent voltage output (light load), and the switching control means shortens the ON period of the main switching element. A minimum voltage output can be provided, and this minimum voltage is lower than the operation start voltage of the load control means, and the light emitting diode of the optical coupling means can be normally turned on to maintain the intermittent oscillation state. It is sufficient to reduce the power consumption during standby.

Further, the switching power supply device of the present invention is
As described above, the output in the normal operation state from the load control means is a continuous pulse, the standby output is a high level or low level output, the driving means, the coupling capacitor for passing the pulse, and the pulse. And an switching circuit for driving the optical coupling means to turn on when the integrated output of the integrating circuit is less than a predetermined level.

Therefore, when the load control means stops its operation and the high-level or low-level standby output is derived, the integrated output of the integration circuit becomes less than a predetermined level and the switching element is turned on. Since the optical coupling means is driven to be constantly turned on, the driving means can be provided with a function as a watchdog timer for determining the runaway of the load control means. Further, since the pulse from the load control means also has the function of the runaway determination signal and the function of the power save signal for setting the standby state, it is possible to reduce the number of terminals of the load control means.

Furthermore, in the switching power supply device of the present invention, as described above, the driving means changes the voltage division value of the output voltage dividing resistance for the constant voltage control operation to change the optical coupling means. Drives lighting.

Therefore, the shunt regulator itself that performs the constant voltage control operation drives the optical coupling means to light up, and the influence of temperature and manufacturing variations is small, as in the case of using a transistor or FET, and the oscillation stop state and the oscillation state are small. And can be switched with high accuracy.

Further, in the switching power supply device of the present invention, as described above, the driving means has hysteresis in switching between the oscillation stop state and the oscillation state.

Therefore, the intermittent oscillation operation during standby can be stabilized.

Furthermore, as described above, the image forming apparatus of the present invention uses the above switching power supply device with the start switch of the printing operation operated by the user as the reset means.

Therefore, the present invention can be preferably implemented.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a switching power supply device according to an embodiment of the present invention.

FIG. 2 is a perspective perspective view showing a schematic configuration of an inkjet recording apparatus in which the switching power supply device shown in FIG. 1 is used.

FIG. 3 is a vertical cross-sectional view of the inkjet recording apparatus of FIG.

FIG. 4 is a block diagram showing an electrical configuration of the inkjet recording apparatus shown in FIGS. 2 and 3.

FIG. 5 is a block diagram showing an electrical configuration of a switching power supply device according to another embodiment of the present invention.

[Explanation of symbols]

1, 1a Switching power supply device 2 Commercial power supply 3 Noise filter 4 Diode bridge 5 Starting circuit 6 Driving circuit (electric power load, load) 7 Regulator 8 Control circuit (load control means, load) 9 Shunt regulator 10 Reference voltage source 11 Comparator 21 Inkjet Recording device (image forming device) 22 Paper feed tray 23 Paper 24 Paper feed roller 27 Printing unit 28 PS roller 29 Paper ejection roller 30 Paper ejection tray 31 Carriage 36 Print head 41 Control circuit (load control means, load) 43 Image processing unit 45 Head Drive Circuit (Power Load, Load) 46 Drive System Control Unit 47 Carriage Drive Circuit (Power Load, Load) 48 Paper Transport Drive Circuit (Power Load, Load) 49 Carriage Motor 50 Paper Transport Motors C1 to C4 Smoothing Capacitor C5 Capacitor C6 condenser Means) C7 capacitor (driving means, integrating circuit) C8 coupling capacitor (driving means) D1, D2, D4, D5, D7 diode D3 photodiode D6 diode (reset means) N transformer PC photocoupler (optical coupling means) PS1 push Button switch (reset means) PS2 Push button switch Q Main switching element R0, R6 Resistance R1, R2 Series resistance R3, R4 Voltage dividing resistance R5 Current limiting resistance R7 resistance (driving means) R8 Short-circuit resistance (driving means) R9 resistance (driving means) Means, integrating circuit) R10 short-circuit resistance (reset means) R11 pull-up resistance TR1 output transistor TR2 phototransistor TR3 control transistor TR4 FET (driving means, switching element) TR5 transistor (driving means, switching element)

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Claims (5)

[Claims] 1. A secondary side is provided with a main output having a relatively high voltage and a sub output having a relatively low voltage, and the voltage of the main output is supplied to a switching control means on the primary side via an optical coupling means. While performing a constant voltage control operation by feeding back, the power load of the main output system is operation-controlled by the load control means of the sub output system, and during standby operation,
In a switching power supply device for driving a load in which the load control unit stops the operation of the power load, the power is energized by the main output and the optical coupling unit is responsive to a standby output from the load control unit. A switching power supply device, comprising: a driving unit that drives the lighting unit and a reset unit that is provided in association with the driving unit and that stops the lighting of the optical coupling unit by the driving unit by a user operation. 2. The load control means sets an output in a normal operation state as a continuous pulse, sets the standby output as a high level or a low level output, and the driving means includes a coupling capacitor for passing the pulse, and the pulse. 2. The switching power supply device according to claim 1, wherein the switching power supply device is configured to include an integrating circuit that integrates the light emitting element, and a switching element that drives the optical coupling unit to light up when the integrated output of the integrating circuit is less than a predetermined level. 3. The driving means drives the optical coupling means by lighting by changing a voltage division value of an output voltage dividing resistance for the constant voltage control operation. Switching power supply. 4. The switching power supply device according to claim 1, wherein the driving means has hysteresis in switching between an oscillation stop state and an oscillation state. 5. An image forming apparatus using the switching power supply device according to any one of claims 1 to 4.