JPH09168243A - Power supply device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the functional stop of the entire device where a power supply device is mounted even if the output of the power supply device partially fails. SOLUTION: In a power supply device 27 which has a plurality of output parts 27-1-27-3 for outputting an output power at the same level and supplies output power from the output parts 27-1-27-3 to a plurality of loads, priorities are given in advance to a plurality of loads which are connected to a plurality of output parts 27-1-27-3, the output is stopped when the output parts 27-1-27-3 of the power supply device 27 being connected to a load with a higher priority order out of the above loads fail, and at the same time power is supplied to a load with a higher priority order from the output part of the power supply device 27 which is connected to a load with a lower priority order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device and an image forming apparatus which have a plurality of output units that output the same level of output power and supply the output power from the output units to a plurality of loads. In particular, the present invention relates to a power supply device and an image forming apparatus suitable for a so-called multi-function peripheral having a plurality of functions such as a copying function, a facsimile function, and a printer function.

[0002]

2. Description of the Related Art Heretofore, as a power supply device of this type, a switching power supply which is small and lightweight, has a low cost, has a high conversion efficiency, has an excellent constant voltage characteristic, and includes a DC-DC converter in its circuit configuration ( A power supply device called "switching regulator" is also known. The output capacity and the number of output systems of such a power supply device tend to increase as the function of the image forming apparatus and the like in which the power supply device is adopted increases and the processing speed increases. In particular, an image forming apparatus in recent years is often formed as a multifunction machine in which a plurality of functions such as a copying function, a facsimile function, and a printer function are installed in one machine. In order to control various functions, a so-called image forming apparatus has a plurality of control boards equipped with a control circuit including a large number of processing devices (CPUs) in one device. In order to supply a predetermined electric power to the above circuit elements, the power supply device has a large capacity and multi-output, and a power supply device having a plurality of output sections for outputting the same level of electric power has been adopted. On the other hand, in order to protect various loads such as control circuit parts connected to the output of the power supply device, an output abnormality of the power supply device is detected, and if an abnormality occurs, the output of the power supply device is stopped. It is known (for example, JP-A-2-68570).

[0003]

However, according to the conventional technique as described in Japanese Patent Laid-Open No. 2-68570, there is a case where some of the outputs of the power supply device are abnormal. However, since the output of the entire power supply device is stopped, for example, when a conventional power supply device for an image forming apparatus formed as a multi-function peripheral is adopted, an output that does not cause an abnormality is output. Although the connected specific function can be maintained, the entire image forming apparatus becomes unusable.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an entire device including the power supply device even if an abnormality occurs in a part of the output of the power supply device. It is an object of the present invention to provide a power supply device and an image forming apparatus that reduce the number of function interruptions.

[0005]

In order to solve the above-mentioned problems, the power supply device according to claim 1 has a plurality of output sections for outputting the same level of output power, and a plurality of output powers from the output sections, respectively. In the power supply device that supplies the load, the plurality of loads connected to the plurality of output units have priorities set in advance, and the output unit of the power supply device connected to a load having a higher priority among the loads has an abnormality. When this occurs, the output is stopped, and power is supplied to the high-priority load from the output unit of the power supply device connected to the lower-priority load. . In this, among the plurality of output parts of the power supply device,
Even if an output unit that supplies power to a load with a higher priority than another load fails, power is preferentially supplied from an output unit that supplies power to another load with a lower priority. Can be supplied.

According to a second aspect of the present invention, there is provided the power source apparatus according to the first aspect, wherein the output of the power source apparatus connected to the low-priority load is supplied to the high-priority load. It is characterized in that the supply of electric power to a load having a low priority is cut off. In this case, by supplying power from the output section of the power supply device connected to the low priority load to the high priority load, the output section of the power supply unit connected to the low priority load is connected. It is possible to prevent an overcurrent from flowing.

Further, in particular, in the power supply device according to claim 3, in the power supply device according to claim 1, the output of the power supply device connected to the load with the low priority is supplied to the load with the high priority. The power supply to the low-priority load is interrupted only when the rated output of the output unit connected to the low-priority load is exceeded. In this case, when power is supplied from an output unit connected to a low priority load to a high priority load, the output unit of the power supply unit supplying power to the low priority load is rated. It is possible to prevent an overcurrent that exceeds the current from flowing, and even if an overcurrent that exceeds the rated current flows to the output section connected to a load with a low priority, power is supplied to the load with a low priority. Can be supplied.

According to another aspect of the power supply device of the present invention, a plurality of sub-control units provided corresponding to a plurality of functions and a main control unit for sending a predetermined signal to the plurality of sub-control units have the same level. In a power supply device that supplies output power, when an abnormality occurs in the output part of the power supply device that is connected to the main control part, the output is stopped, and power is supplied to the plurality of sub control parts. Power is supplied to the main control unit from the output unit of the power supply device. In this case, even if an abnormality occurs in the output unit of the power supply device that supplies power to the main control unit, from the output unit of the power supply device connected to the sub control unit to the main control unit Can be powered.

According to a fifth aspect of the present invention, there is provided the power supply apparatus according to the fourth aspect, wherein the sub-control unit supplies power to the main control unit from an output unit of the power supply unit connected to the sub-control unit. The power supply to the control unit is cut off. In this case, when power is also supplied to the main control unit from the output unit of the power supply device connected to the sub control unit, the output unit of the power supply device that supplies power to the sub control unit. It is possible to prevent an overcurrent from flowing through.

Further, in particular, in the power supply device according to claim 6, in the power supply device according to claim 4, when power is supplied from the output part of the power supply device connected to the sub control part to the main control part, It is characterized in that the power supply to the sub control unit is cut off only when the rated output of the output unit connected to the sub control unit is exceeded. In this case, when power is also supplied from the output unit connected to the sub-control unit to the main control unit, an overcurrent exceeding the rated current is output to the output unit of the power supply device that supplies power to the sub-control unit. It is possible to prevent the electric current from flowing and also to supply electric power to the sub control unit until an overcurrent exceeding the rated current flows to the output unit connected to the sub control unit.

Further, in particular, the image forming apparatus of claim 7 is
The power supply device according to claim 1, 2, 3, 4, 5, or 6 is used. In this case, even if an abnormality occurs in a part of the output section of the power supply device, the power can be preferentially supplied to the load having a high priority in the image forming apparatus. Alternatively, power can be preferentially supplied to the main control unit in the image forming apparatus.

[0012]

DETAILED DESCRIPTION OF THE INVENTION A power supply device and an image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to this embodiment. The image forming apparatus 26 includes an image reading unit 20 for reading a document image, and the image reading unit 20.
A control unit 21 for electrically performing image processing on a digital signal output from the device and for other internal control of the image forming apparatus.
And an image forming section 22 that forms an image on a transfer sheet based on a digital signal output from the control section.

In the image reading section 20, the image of the original placed on the original placing table is read by an image reading device (not shown) through an irradiation lamp, a mirror, and a lens (not shown), and the data is read. It is sent to the control unit 21. In the control unit 21, this data is subjected to necessary processing, converted into an image signal, and then the image forming unit 22.
Sent to

In the image forming section 22, the surface of the photosensitive drum 1 as an image carrier, which is rotationally driven in the direction of arrow A in the figure, is uniformly charged by the charger 2. And
A latent image corresponding to the image of the original is formed on the surface of the photoconductor drum 1 by the exposure device 3 including a semiconductor laser, a polygon mirror, a reflection mirror, and the like, based on an image signal from the control unit 21. The latent image on the photoconductor drum 1 is developed with a developer supplied from a developing roller 41 as a developer carrying member of the developing device 4 at a portion facing the developing device 4 to form a visible image. The visible image is, for example, recording paper (not shown) that is placed on the belt-shaped transport device 7 from the paper feed tray 5 at a timing by the registration rollers 6 and is transported to the portion facing the photoconductor drum 1. ) Is transferred by the transfer device 8.
The recording paper on which the visible image is transferred is conveyed by the conveying device 7,
When the image passes through the fixing device 9, the visible image is fixed, and the paper discharge tray 10
Is discharged. Here, the untransferred toner remaining on the photoconductor drum 1 after the image transfer is cleaned from the photoconductor drum 1 by the cleaning device 11 and collected by the cleaning device 11. Then, the surface of the photosensitive drum 1 after cleaning is subjected to elimination of residual electric charges by an elimination lamp (not shown).

Through such a series of processes, the copying function in the image forming apparatus 26, that is, the function of copying the original image on the recording paper is realized.

On the other hand, the image forming apparatus 2 in this embodiment
6 can be connected to the host computer 23 and can execute a printer function and a scanner function.
Further, it is possible to connect to the facsimile device 25 via the telephone line 24, and the facsimile function can be executed. The printer function, the scanner function, and the facsimile function are positioned as additional functions, and can be realized by newly mounting a control board corresponding to each function in the control unit 21. Therefore, the user who uses the image forming apparatus can freely add the printer function, the facsimile function, and the scanner function to the copy function which is the original function of the image forming apparatus 26, and an image having a desired composite function can be obtained. A forming device can be obtained.

The scanner function among the above functions is a function for sending data read by the image reading unit of the image forming apparatus to a host computer or another image forming apparatus connected to the image forming apparatus. Yes, this is different from the copying function of simply reading an original image with the image reading unit of the image forming apparatus and copying the original image onto recording paper in the image forming apparatus.

FIG. 2 is a block diagram showing an outline of the relationship between the power supply device according to the present embodiment and each part of the image forming apparatus.
The power supply device 27 has three output units, a first output unit 27-1, a second output unit 27-2, and a third output unit 27-3. The first output section 27-1 is a section that supplies electric power to a so-called drive system such as a motor and a solenoid in the image forming apparatus, and outputs DC 24V.

The second output section 27-2 is a section for supplying electric power to the main control section 29 in the image forming apparatus, and outputs 5V of direct current. Here, the main control unit is based on a signal from a sensor or the like in the image forming apparatus, and controls the conveyance of recording paper performed in the image forming apparatus and the entire image forming apparatus such as an image forming process. When the main controller stops its function, the function of the entire image forming apparatus is stopped. Therefore, the main control unit has a higher priority in power supply than the sub-control unit described later.

The third output unit 27-3 supplies power to the sub-control units 31, 32 and 33 in the image forming apparatus when the output of the power supply unit is not abnormal. Its output is DC 5V. Here, the sub-control unit means three control units, that is, a facsimile control unit 31, a scanner control unit 32, and a printer control unit 33 corresponding to the respective functions of the facsimile function, the scanner function, and the printer function. Each sub-control unit controls execution of each function by exchanging various signals with the main control.

The output from the first output section 27-1 is
It is connected to a drive system such as a motor and a solenoid, and the output from the second output section 27-2 is connected to the main control section 29. On the other hand, the output from the third output unit 27-3 is connected to the main control unit 29 and the three sub control units 31, 32 and 33 via the switch circuit 34.

The switch circuit 34 includes the first switch 3
4a, second switch 34b, third switch 34c, fourth
The switch 34d is composed of four switch elements, and the on / off state of the switch adjusts the state of power supply to each control unit. The first switch 34a of the switch circuit 34 is
It is normally in the off state, while the second switch 34
b, the third switch 34c, and the fourth switch 34d are normally on. Therefore, the third output unit 27
-3 normally does not supply power to the main control unit, but supplies power to only the three sub-control units.

When an abnormality occurs in the second output section 27-2 which supplies electric power to the main control and the output is stopped,
First switch element 34a in the switch circuit 34
Is turned on, and power is supplied from the third output unit 27-3 to the main control. As a result, power is supplied from the third output unit 27-3 to the main control unit and the sub control unit, but if all of these power supply amounts are the third output unit 27-3. When it exceeds the output capacity of No. 3, an overcurrent flows in the third output unit 27-3, which causes a failure of the power supply device. Therefore, when the output power from the third output unit 27-3 when the first switch element 34a is turned on exceeds the rated output capacity of the third output unit 27-3, the main control unit A signal from 29 turns off any or all of the second switch element, the third switch element, and the fourth switch element so that the output capacitance of the third output unit is not exceeded.

As a result, even if an abnormality occurs in the second output section 27-2 that supplies power to the main control section, normally, the second control section that supplies power to the sub control section It is possible to preferentially supply power from the output unit 27-3 of No. 3 to the main control unit having a higher priority than the sub control unit. As described above, when the rated output capacity of the third output unit 27-3 is exceeded, the second switch element, the third switch element and the fourth switch are instructed by the signal from the main control unit 29. If any or all of the elements are turned off, the third
Although some or all of the additional functions of the facsimile, scanner and printer functions achieved by the sub-control unit connected to the output unit 27-3 of the above can not be used, the copying function achieved by the main control unit, and Since some of the additional functions that are still connected to the third output section can be used,
It is possible to prevent all the functions of the image forming apparatus from being stopped because the power supply to the main control unit is stopped.

FIG. 3 is a circuit diagram of the power supply device according to the embodiment. The AC power input from the AC power supply 41, which is a commercial power supply, is input to the diode bridge circuit DB1 via the input fuse F1, the noise filter circuit 35, and the choke coil L2 when the power switch (not shown) is turned on. Full-wave rectification is performed by the circuit DB1. This rectified diode bridge circuit D
The output of B1 charges the primary rectifying / smoothing capacitor C0. (Hereinafter, margin)

The primary DC power charged in the capacitor C0 is intermittent by the operation of the switching element Q1 which is turned on / off by the drive pulse output from the output terminal OUT of the first PWM (pulse width modulation) control circuit 2. It becomes the primary current. This primary current is the primary winding N of the transformer T1.
1, switching element Q1, and primary current detection resistor R7
2 for the external output of the transformer T1
Electric power is induced in the secondary winding N2, the first internal output secondary winding N3, and the second internal output secondary winding N4.

The first internal output secondary winding N3 supplies power to the power supply input terminal Vcc of the first PWM control circuit 36 via a rectifying / smoothing circuit composed of a diode D3 and a capacitor C6, and power is supplied outside the power supply device. Do not supply. still,
A series circuit including a resistor R4 and a diode D1 connected to the positive end of the capacitor C0 is also connected to the power supply input terminal Vcc, which supplies power to the first PWM control circuit 36 when the power supply device is started. When the power supply from the first internal output secondary winding N3 is started, it becomes irrelevant to the first PWM control circuit 36.

The second internal output secondary winding N4 supplies power to the gate terminal of the triac TRI. When power is induced in the second internal output secondary winding N4, a current flows through the resistor R3 to the gate terminal of the triac TRI, and the triac TRI becomes conductive. As a result, the current flowing in the inrush current suppressing resistor R2 is
Bypassed by TRIAC TRI.

A resistor R connected in parallel with the primary winding N1.
The series circuit including the capacitor 8, the capacitor C5 and the diode D2 is a snubber circuit, and is a transient voltage generated when the primary current flowing through the primary winding N1 is turned on / off, particularly a fly voltage generated when turned off. The back voltage is absorbed to protect the switching element Q1.

The electric power induced in the secondary winding N2 for external output by turning on / off the primary current flows through the diode D4 and the choke coil L3 when the primary current is turned on, and charges the capacitor C11. The electric power stored as magnetic energy in the core of the choke coil L3 while the capacitor C11 is being charged is reconverted to a current when the primary current is off, and further passes through the commutation diode D5 to further charge the capacitor C11.

A series circuit composed of a resistor R10, a capacitor C7, a resistor R11 and a capacitor C8 respectively connected in parallel to the diode D4 and the diode D5 is also a snubber which suppresses a spike voltage due to a reverse recovery current of the diode D4 and the diode D5. ) Circuit.

In this way, the power rectified and smoothed and charged in C11 is supplied from the first output section 27-1 to the load 1 through the fuse F2. Here, the first output unit 27
The first output voltage output from -1 is a DC output of 24 V, which is mainly used as driving power. The load 1 includes a motor, a solenoid, etc., and the first output voltage V1 is used to drive these.

First output from the first output section 27-1
The output voltage V1 is divided by the resistors R22 and R23, and forms a series circuit with the resistor R21 and the first light emitting device PC1-a of the first photocoupler PC1 to form the first output unit 2
It is output to the shunt regulator ZD1 connected between the output terminals of 7-1. The shunt regulator ZD1 causes the first light emitting element PC1-a to emit light in accordance with the difference between the input signal obtained by dividing the first output voltage V1 and the reference voltage inside the shunt regulator ZD1. This light emitting device PC
The optical signal from 1-a is the first light receiving element PC1-b in the circuit.
Is fed back to the F / B terminal of the first PWM control circuit 2 via.

The first PWM control circuit 36 controls the pulse width of the drive pulse given to the switching element Q1 according to the signal fed back, and the first output section 27-1.
Output voltage V1 output from the predetermined value (24
V). As a result, the first output voltage V1 output from the first output unit 27-1 is stabilized against AC input fluctuations and load fluctuations from the commercial power supply 7.

When the output voltage from the first output section 27-1 exceeds a predetermined value, the Zener diode ZD2 becomes conductive, causing the second light emitting element PC2-a to emit light, and the second light receiving element P.
By setting the OVP terminal of the first PWM control circuit 36 to a high level (ON) via C2-b, the output from the OUT terminal of the first PWM control circuit 36 is turned off, and the entire output of the power supply device is stopped.

This is because the output from the first output unit 27-1 is used to realize any function such as a copying function, a facsimile function and a printer function of the image forming apparatus equipped with the power supply device. This is because it is used for driving required motors, solenoids, etc., and when an abnormality occurs in the output section that supplies power to these, any of the above functions can no longer be operated. This is also because, as will be described later, the outputs of the other output units are also formed based on the output from the first output unit 27-1.

A part of the output voltage from the first output section 27-1 charges the switching noise blocking capacitor C12 via the backflow prevention diode D8 and the first chopper circuit 37 which is a step-down type stabilizing circuit. Entered in. The first chopper circuit 37 includes a switching noise blocking capacitor C12, a first transistor Q2 for turning on / off an input current, a smoothing circuit including a commutation diode D7, a choke coil L5, and a capacitor C13, and an output current detecting device. And a second resistor R19 for controlling the on / off of the first transistor Q2 by outputting a driving pulse.
And a PWM control circuit 38.

When the second transistor Q3 provided in the next stage of the first chopper circuit 37 is turned on, the current from the switching noise blocking capacitor C12 passes through the choke coil L5 and charges the capacitor C13. Meanwhile, the electric power stored as magnetic energy in the core of the choke coil L5 is reconverted into a current when the current from the switching noise blocking capacitor C12 is turned off, and further charges the capacitor C13 through the commutation diode D7. The voltage across the terminals of the capacitor C13 is smoothed,
A second output voltage V2 is supplied to the load 2 from the second output section 27-2 via the output current detection resistor R19.
Here, the second output voltage is a DC output and is 5V. The load 2 is the main control unit of the image forming apparatus.

The output side terminal voltage of the output current detection resistor R19 is the second PWM as the output voltage signal of the second output voltage V2.
It is fed back to the F / B (feedback) terminal of the control circuit 38. The current flowing between the terminals of the output current detection resistor R19 is fed back to the C / L terminal of the second PWM control circuit 4 as an output current signal. here,
The C / L terminal is an abbreviation for current limit terminal, which is a terminal for monitoring current and the like. The second PWM control circuit 38 responds to the fed back output voltage signal by
The on / off of the second transistor Q2 is controlled by controlling the pulse width of the drive pulse applied to the base terminal of the first transistor Q2. This second transistor Q
The second output voltage V2 output from the second output unit 27-2 by the ON / OFF control of No. 2 is maintained at a predetermined voltage (5V). In this way, the second output voltage from the second output section 27-2 is stabilized against input fluctuations and load fluctuations.

Further, a part of the output from the first output section 27-1 charges the switching noise blocking capacitor C18 via the backflow prevention diode D10 and the second chopper circuit 39 which is a high voltage stabilizing circuit. Entered in. The second chopper circuit 39 includes a switching noise blocking capacitor C18, a third transistor Q4 for turning on / off an input current, a smoothing circuit including a commutation diode D13, a choke coil L6, and a capacitor C19, and an output current detecting device. And the third resistor R28 for controlling the on / off of the third transistor Q4 by outputting a driving pulse.
It is configured by the PWM control circuit 40.

When the fourth transistor Q5 provided in the next stage of the second chopper circuit 39 is turned on, the current from the switching noise blocking capacitor C18 passes through the choke coil L6 and charges the capacitor C19. Meanwhile, the electric power stored as magnetic energy in the core of the choke coil L6 is reconverted into a current when the current from the switching noise blocking capacitor C18 is turned off, and further charges the capacitor C19 through the commutation diode D13. The voltage across the terminals of the capacitor C19 is smoothed and supplied to the load 3 as the third output voltage V3 from the third output section 27-3 via the output output current detection resistor R28. Here, the third output voltage is a DC output and
V.

Further, the load 3 further includes the load 3a and the load 3
The load 3a is a facsimile control unit for realizing a facsimile function, the load 3b is a scanner control unit for realizing a scanner function, and the load 3c is a printer function. It is a printer control unit for performing. These three control units are positioned as sub-control units with respect to the main control unit which is the load 2.

The output side terminal voltage of the output current detecting resistor R28 is the third PWM as the output voltage signal of the third output voltage V3.
It is fed back to the F / B terminal of the control circuit 6. The current flowing between the terminals of the output current detection resistor R28 is fed back to the C / L terminal of the third PWM control circuit 40 as an output current signal. The third PWM control circuit 6
The ON / OFF of the third transistor Q4 is controlled by controlling the pulse width of the drive pulse applied to the base terminal of the first transistor Q2 according to the fed back output voltage signal. By the on / off control of the third transistor Q4, the third output voltage V2 output from the third output section 27-3 is maintained at a predetermined voltage (5V). In this way, the third output voltage from the third output section 27-3 is stabilized against input fluctuations and load fluctuations.

When an overcurrent flows due to a short circuit between the output terminals of the second output section 27-2 or the like, the voltage across the resistor R19 increases, and the second transistor Q3 changes from the off state to the on state and a current flows. This current is input to the C / L terminal of the second PWM control circuit 4 via the resistor 18 and the diode D9. When the input to the C / L terminal exceeds a predetermined value, the output from the OUT terminal of the second PWM control circuit 4 is turned off and the output of the second PWM control circuit 4 stops. As a result, the output from the second output unit 27-2 is stopped and the power supply to the load 2 is cut off.

When it is detected that the input of the power supply voltage monitoring IC (not shown) provided on the control board of the main control unit exceeds a predetermined value, the fifth transistor Q6 is turned on and the third output unit 27 is turned on. -3 supplies power to the main control unit, which is the load 2. The fifth transistor Q6 corresponds to the switch element 34a in FIG.

When the cause of the overcurrent in the second output section 27-2 is the abnormality of the load 2, the voltage across the resistor 28 increases, and this voltage is C / C of the third PWM control circuit 40.
By being input to the L terminal and stopping the output of the third PWM control circuit 40, the output from the third output unit 27-3 is also stopped. Therefore, due to the abnormality of the load 2, the second
When an overcurrent flows to the output unit 27-2 of the above, not only the output of the second output unit but also the output of the third output unit is stopped.

The second output section 27-2 and the third output section 2
When any output from 7-3 is stopped and the voltage supplied to the load 2 becomes a predetermined value or less, the second photo coupler PC2
The light emitting element PC2-a of No. 3 is made to emit light. This light emitting device PC
The light receiving element PC2-b of the second photocoupler PC2 receives the optical signal from 2-a and inputs the output to the OVP terminal of the first PWM control circuit, thereby stopping the output of the first PWM control circuit. This shuts down all power supply output.

As described above, when an overcurrent flows through the second output unit 27-2 due to a short circuit between the output terminals of the second output unit 27-2, the output from the second output unit 27-2 is output. The output is supplied from the third output unit 27-3 to the load 2, but in this case, depending on the load capacity of the load 3, even if there is no abnormality in the load 2, the resistance 28 The voltage across both ends of the third output section 27-3 increases as described above.
All outputs from may stop.

In order to prevent this, when power is being supplied from the third output section 27-3 to the load 2, the switches 34b, 34c, 34d are appropriately opened so that
The power supply from the third output unit to the front part or a part of the load 3 may be cut off. In this way, the load 2, which is the main control unit, replaces the second output unit 27-2 and has the same level as the second output unit (even if an abnormality occurs in the second output unit 27-2). Power can be supplied from the third output unit having an output voltage of DC 5V. In addition, when an overcurrent occurs in the third output unit 27-3 due to an abnormality of the load 3 or the like,
Only the output from the third output unit 27-3 is stopped.

[0051]

According to the power supply device of the first aspect, it is possible to preferentially supply power to a load having a high priority, so that the load having a high priority can be set in the device in which the power supply device is mounted. It has an excellent effect that it is possible to prevent the stoppage of the high-priority function to be achieved.

In particular, according to the power supply apparatus of claim 2, a low-priority load generated by supplying power to the high-priority load from the output section of the power-supply apparatus connected to the low-priority load. Since it is possible to prevent the occurrence of overcurrent in the output section of the power supply device connected to the
It has an excellent effect that it is possible to reduce the subsequent failure of the power supply device.

Further, in particular, according to the power supply device of the third aspect, it is possible to prevent an overcurrent exceeding the rated current from flowing in the output portion of the power supply device which supplies power to the load having a low priority. At the same time, power can be supplied to a load with a lower priority until an overcurrent exceeding the rated current flows in the output unit connected to the load with a lower priority. This has an excellent effect that it is possible to reduce the stoppage of the function of the function mounted by the low-priority load in the device in which the power supply device is mounted, while preventing the breakdown.

According to another aspect of the power supply device of the present invention, the power supply device connected to the sub-control unit even when an abnormality occurs in the output unit of the power supply device that supplies power to the main control unit. Since electric power can be supplied to the main control unit from the output unit of the device, it is possible to reduce the stoppage of the function of the entire device in which the power supply device is mounted.

According to the power supply device of claim 5,
When power is also supplied to the main control unit from the output unit of the power supply device that is connected to the sub control unit, an overcurrent occurs in the output unit of the power supply device that supplies power to the sub control unit. Since it can be prevented from flowing, there is an excellent effect that it is possible to reduce the secondary failure of the power supply device caused by the overcurrent.

According to the power supply device of claim 6,
It is possible to prevent an overcurrent exceeding the rated current from flowing in the output section of the power supply device that supplies power to the sub-control section, and to prevent the overcurrent exceeding the rated current in the output section connected to the sub-control section. Since electric power can be supplied to the sub-control unit until the current flows, it has an excellent effect that it is possible to reduce the suspension of the function achieved by the sub-control unit. .

Further, particularly in the image forming apparatus of claim 7, even when an abnormality occurs in a part of the output portion of the power supply device, power is preferentially supplied to a load having a high priority in the image forming apparatus. Alternatively, the power can be preferentially supplied to the main control unit in the image forming apparatus, so that it is possible to reduce a plurality of functions of the image forming apparatus from being completely stopped. It has an excellent effect.

[0058]

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment.

FIG. 2 is a block diagram schematically showing the relationship between the power supply device according to the embodiment and each unit of the image forming apparatus.

FIG. 3 is a circuit diagram of the power supply device according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Charging device 3 Exposure device 4 Developing device 5 Paper feed tray 6 Registration roller 7 Conveying device 8 Transfer device 9 Fixing device 10 Paper ejection tray 11 Cleaning device 20 Image reading unit 21 Control unit 22 Image forming unit 23 Host Device 24 Telephone line 25 Facsimile 26 Image forming device 27 Power supply device 27-1 First output unit 27-2 Second output unit 27-3 Third output unit 28 Drive system 29 Main control unit 30 Sensor 31 Facsimile control unit 32 scanner control section 33 printer control section 34 switch circuit 34a first switch element 34b second switch element 34c third switch element 34d fourth switch element 35 noise filter circuit 36 first PWM control circuit 37 first chopper circuit 38 second PWM control circuit 39 2nd chopper circuit 40th PWM control circuit 41 commercial power supply

Claims (7)

[Claims] 1. A power supply device that has a plurality of output units that output the same level of output power and that supplies the output power from the output units to a plurality of loads, respectively, and a plurality of output units connected to the plurality of output units. If a load is assigned a priority in advance and an abnormality occurs in the output section of the power supply device that is connected to a load having a higher priority among the loads, this output is stopped and the load having a lower priority is selected. A power supply device, characterized in that power is supplied from an output unit of the connected power supply device to the load having a high priority. 2. When supplying the output of the power supply device connected to the low priority load to the high priority load, the power supply to the low priority load is cut off. The power supply device according to claim 1. 3. When supplying the output of the power supply device connected to the load of low priority to the load of high priority, the rated output of the output unit connected to the load of low priority is changed. The power supply to the load with the lower priority is shut off only when the load is exceeded.
Power supply. 4. A power supply for supplying the same level of output power to a plurality of sub-control units provided respectively corresponding to a plurality of functions, and a main control unit that sends a predetermined signal to the plurality of sub-control units. In the device, when an abnormality occurs in the output unit of the power supply device connected to the main control unit, while stopping this output, from the output unit of the power supply device that supplies power to the plurality of sub-control unit A power supply device for supplying power to the main control unit. 5. The power supply to the sub control unit is cut off when power is supplied from the output unit of the power supply device connected to the sub control unit to the main control unit. The power supply device according to item 4. 6. The rated output of the output unit connected to the sub control unit is exceeded when power is supplied from the output unit of the power supply device connected to the sub control unit to the main control unit. The power supply device according to claim 4, wherein the power supply to the sub-control unit is shut off only in such a case. 7. An image forming apparatus using the power supply device according to claim 1, 2, 3, 4, 5, or 6.