JP2002287575A - Power unit and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power unit to enhance reliability by preventing increase of down time of equipment when a load becomes a short-circuit state or an open state. SOLUTION: Power output is surely stopped when the power output comes to an abnormal state, etc., by providing a switch means Q2 in series with a resistor R4 to constitute a pull-up means to be connected with the outside of a CPU 1, and further by providing an abnormality judging means 3 to detect output voltage (1) by an output level detecting means 2 and to judge the abnormal state by comparing the voltage with a prescribed value and controlling the switch means Q2 according to an output signal of the abnormality judging means.

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 used for an image forming apparatus and the like and a control method therefor.

[0002]

2. Description of the Related Art Hitherto, a power supply control IC including a CPU for controlling an image forming apparatus has been proposed as a power supply for an image forming apparatus such as a copying machine or a printer. For example, Patent No. 2984616 and Patent No. 2662976
Pulse width modulation circuit (hereinafter referred to as PW
The contents of operating a variety of power supplies of an image forming apparatus in a configuration of a CPU including an M circuit) are disclosed, and are mainly used in power supply apparatuses of the image forming apparatus.

[0003]

SUMMARY OF THE INVENTION However, CPU
When a power supply device such as an image forming apparatus is driven, the output is converted in order to supply power to various circuits and process elements such as a charger inside the power supply device. In addition, there is a problem that not only an image failure occurs when the open state is obtained, but also a failure of a circuit component used may be caused and a downtime of the device may be increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to prevent an increase in downtime of a device when a load is short-circuited or open, and to improve reliability. It is an object of the present invention to provide a power supply device with improved performance and a control method thereof.

[0005]

A power supply device and a control method thereof according to the present invention are configured as follows.

(1) A power supply device used in an image forming apparatus, which includes a transformer for performing voltage conversion, a switching element that is turned on / off to drive the transformer, and rectifying an output of the transformer. Rectifying means, a CPU for controlling the switching element to perform switching control and supplying power to the electrophotographic process means, and controlling the rectified output to an arbitrary value, and for turning on and off power supply of a driving power supply to the switching element. Switch means, and the CP
A pull-up means connected to an output terminal different from the output terminal for switching control of U and connected in series with the switch means, and connected to the drive power supply via the switch means; Current detection means for detecting a current supplied to the processing means; and when the current value detected by the current detection means exceeds a preset reference value, the power supply to the electrophotographic processing means is in an abnormal state. Abnormality determination means for outputting an abnormality signal to the CPU, and when the abnormality signal is input, the CPU turns off the switch means to cut off power supply to the electrophotographic process means. I heard

(2) A power supply device used in an image forming apparatus, which is a transformer for performing voltage conversion, a switching element that is turned on / off to drive the transformer, and rectifies an output of the transformer. Rectifying means, a CPU for controlling the switching element to perform switching control and supplying power to the electrophotographic process means, and controlling the rectified output to an arbitrary value, and for turning on and off power supply of a driving power supply to the switching element. Switch means, and the CP
A pull-up means connected to an output terminal different from the output terminal for switching control of U and connected in series with the switch means, and connected to the drive power supply via the switch means; Voltage detecting means for detecting a voltage supplied to the processing means, and when the voltage value detected by the voltage detecting means exceeds a preset reference value, the power supply to the electrophotographic processing means is in an abnormal state. Abnormality determination means for outputting an abnormality signal to the CPU, and when the abnormality signal is input, the CPU turns off the switch means to cut off power supply to the electrophotographic process means. I did it.

(3) A power supply device used in an image forming apparatus, which is a transformer for performing voltage conversion, a switching element that is turned on / off to drive the transformer, and rectifies an output of the transformer. Rectifying means, a CPU for controlling the switching element to perform switching control and supplying power to the electrophotographic process means, and controlling the rectified output to an arbitrary value, and for turning on and off power supply of a driving power supply to the switching element. Switch means, and the CP
A pull-up means connected to an output terminal different from the output terminal for switching control of U and connected in series with the switch means, and connected to the drive power supply via the switch means; Current detection means for detecting a current supplied to the processing means; and when the current value detected by the current detection means exceeds a preset reference value, the power supply to the electrophotographic processing means is in an abnormal state. Abnormality determination means for outputting an abnormality signal to the CPU, and a switch drive means for receiving the output signal from the abnormality determination means and a drive signal from the CPU to drive the switch means, A switch driving unit that, when receiving the abnormal signal, turns off the switch unit regardless of the driving signal from the CPU; And so as to cut off the power supply to the stage.

(4) A power supply device used in an image forming apparatus, which is a transformer for performing voltage conversion, a switching element that is turned on / off to drive the transformer, and rectifies an output of the transformer. Rectifying means, a CPU for controlling the switching element to perform switching control and supplying power to the electrophotographic process means, and controlling the rectified output to an arbitrary value, and for turning on and off power supply of a driving power supply to the switching element. Switch means, and the CP
A pull-up means connected to an output terminal different from the output terminal for switching control of U and connected in series with the switch means, and connected to the drive power supply via the switch means; Voltage detecting means for detecting a voltage supplied to the processing means, and when the voltage value detected by the voltage detecting means exceeds a preset reference value, the power supply to the electrophotographic processing means is in an abnormal state. Abnormality determination means for outputting an abnormality signal to the CPU, and a switch drive means for receiving the output signal from the abnormality determination means and a drive signal from the CPU to drive the switch means, A switch driving unit that, when receiving the abnormal signal, turns off the switch unit regardless of the driving signal from the CPU; And so as to cut off the power supply to the stage.

(5) In any of the above power supplies (1) to (4), the output terminal for switching control of the CPU has an open drain configuration.

(6) In the power supply device according to any one of the above (1) to (5), the pull-up means is a resistor, and is connected between the output terminal of the CPU to which the pull-up means is connected and the pull-up means. A resistor was provided.

(7) A method of controlling a power supply device used in an image forming apparatus, comprising: a transformer for performing voltage conversion, a switching element that is turned on / off to drive the transformer, and an output of the transformer. Rectifying means, a CPU for controlling the switching element to perform switching control and supplying power to the electrophotographic process means and controlling the rectified output to an arbitrary value, and turning on power supply of a driving power supply to the switching element. A switch means for turning off, and an output terminal for switching control of the CPU, which is connected to a different output terminal, is connected in series with the switch means, and is connected to the driving power supply via the switch means. A pull-up unit, a current detecting unit for detecting a current supplied to the electrophotographic process unit, and a current detecting unit. Abnormality determining means for determining that the power supply to the electrophotographic process means is in an abnormal state when the detected current value exceeds a preset reference value and outputting an abnormal signal to the CPU; , The CP
When the abnormal signal is input by U, the switch means is turned off to cut off the power supply to the electrophotographic process means.

(8) A method for controlling a power supply device used in an image forming apparatus, comprising a transformer for performing voltage conversion, a switching element that is turned on / off to drive the transformer, and an output of the transformer. Rectifying means, a CPU for controlling the switching element to perform switching control and supplying power to the electrophotographic process means, controlling the rectified output to an arbitrary value, and turning on power supply of a driving power supply to the switching element. A switch means for turning off, and an output terminal for switching control of the CPU, which is connected to a different output terminal, is connected in series with the switch means, and is connected to the driving power supply via the switch means. Pull-up means, voltage detecting means for detecting a voltage supplied to the electrophotographic process means, and voltage detecting means. Abnormality determining means for determining that power supply to the electrophotographic process means is in an abnormal state when the detected voltage value exceeds a preset reference value and outputting an abnormal signal to the CPU; , The CP
When the abnormal signal is input by U, the switch means is turned off to cut off the power supply to the electrophotographic process means.

(9) A method of controlling a power supply device used in an image forming apparatus, comprising: a transformer for performing voltage conversion, a switching element that is turned on / off to drive the transformer, and an output of the transformer. Rectifying means, a CPU for controlling the switching element to perform switching control and supplying power to the electrophotographic process means and controlling the rectified output to an arbitrary value, and turning on power supply of a driving power supply to the switching element. A switch means for turning off, and an output terminal for switching control of the CPU, which is connected to a different output terminal, is connected in series with the switch means, and is connected to the driving power supply via the switch means. A pull-up unit, a current detecting unit for detecting a current supplied to the electrophotographic process unit, and a current detecting unit. Abnormality determining means for determining that power supply to the electrophotographic process means is in an abnormal state when the detected current value exceeds a preset reference value and outputting an abnormal signal to the CPU; A switch driving means for driving the switch means in response to an output signal from the means and a driving signal from the CPU, wherein the driving signal from the CPU is received when the switch driving means receives the abnormal signal. Regardless of the above, the switch means is turned off to shut off the power supply to the electrophotographic process means.

(10) A method of controlling a power supply device used in an image forming apparatus, comprising: a transformer for performing voltage conversion, a switching element that is turned on / off to drive the transformer, and an output of the transformer. Rectifying means, a CPU for controlling the switching element to perform switching control and supplying power to the electrophotographic process means and controlling the rectified output to an arbitrary value, and turning on power supply of a driving power supply to the switching element. A switch means for turning off, and an output terminal for switching control of the CPU, which is connected to a different output terminal, is connected in series with the switch means, and is connected to the driving power supply via the switch means. A pull-up unit, a voltage detection unit for detecting a voltage supplied to the electrophotographic process unit, and a voltage detection unit. Abnormality determining means for determining that power supply to the electrophotographic process means is in an abnormal state when the detected voltage value exceeds a preset reference value and outputting an abnormal signal to the CPU; A switch driving means for driving the switch means in response to an output signal from the determination means and a driving signal from the CPU; and providing the drive signal from the CPU when the switch driving means receives the abnormal signal. The switch means is turned off irrespective of the signal to cut off the power supply to the electrophotographic process means.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a circuit block diagram showing a configuration of a high-voltage power supply according to a first embodiment. In FIG. 1, reference numeral 1 denotes a CPU including a control circuit for controlling the power supply device. The internal configuration of the CPU 1 includes a VDD terminal and a GND terminal as terminals for supplying power, an output terminal (1) and an output terminal (2) as output terminals, and an input terminal (1) as an input terminal. .

The output terminal (1) of the CPU 1 has an open-drain configuration and is connected to a resistor R2. The other end of the resistor R2 is connected to an FET connected to a switch means Q1 for driving a transformer T1 for performing voltage conversion. It is connected to the gate input and the resistors R1 and R3.

The other end of the resistor R3 is connected to GND, and the resistor R3
The other end of 1 is connected in series to the terminal to the collector of the transistor indicated by switch means Q2.

The base terminal of the switch means Q2 is connected to a resistor R
5 is connected to the output terminal (2) of the CPU 1, a resistor R4 is connected between the base terminal and the emitter terminal, and the emitter terminal of the switch means Q2 is connected to the power supply VDD. The other end of the primary side of the transformer T1 which is connected to the source terminal of the switch means Q1 is a resistor R
6 and a power supply Vcc.

A diode D1, a capacitor C1, a resistor R7, and a resistor R8 for rectifying the secondary output are connected to the secondary side of the transformer T1 as shown in FIG. 1, and the other end of R8 is connected to the output ( 1).

Reference numeral 2 denotes output amount detecting means for detecting the output amount of the output (1). In FIG. 1, the output amount detecting means constitutes voltage detecting means for detecting a voltage. Reference numeral 3 denotes an abnormality determination unit that compares the value of the output amount detection unit 2 with a predetermined value inside, and outputs an abnormality signal when it is determined that an abnormality has occurred. The abnormality determination means 3 is connected to the input terminal (1) of the CPU 1.

As described above, the high-voltage power supply according to the present embodiment includes the transformer T1 for performing voltage conversion and the transformer T1.
, A switch D1 that constitutes a rectifier that rectifies the output of the transformer T1, and a switch C1 that constitutes a rectifier that rectifies the output of the transformer T1. CPU1 for controlling the rectified output for supplying power to the electrophotographic process means to an arbitrary value, switch means Q2 for turning on and off the power supply for driving from the power supply VDD to switch means Q1, A pull-up means connected to an output terminal (2) different from the switching control output terminal (1), connected in series with the switch means Q2, and connected to the driving power supply via the switch means Q2. A resistor R4 which constitutes a current detecting means for detecting a current supplied to the electrophotographic process means. The power supply to the electrophotographic process means is determined to be in an abnormal state when the current value detected by the power amount detection means 2 and the current value detected by the output amount detection means 2 exceeds a preset reference value. The CPU 1 switches off the switch Q2 when the abnormal signal is input to cut off the power supply to the electrophotographic process.

The operation in the above configuration will be described in detail.

In FIG. 1, the control of the power supply unit is performed by a CPU 1
Can be operated by the CPU 1 while appropriately changing the output voltage in accordance with various image forming conditions and sequences.

At this time, a transformer T is connected to the output terminal 1 of the CPU 1.
1 is output and the CPU is driven according to various conditions.
1, a pulse width corresponding to the target output determined inside is output, and the output pulse drives a transformer T1 via a resistor R2 and a switch means Q1, and a diode D1 on the secondary side of the transformer T1. Capacitor C1, resistor R
Power is supplied to a process element for electrophotography such as a charger and a developing device as a power supply output (1) through a rectification and output circuit composed of R7 and R8.

Next, an example of control of the switch means Q1 and Q2 from the CPU 1 at the time of power activation and operation will be described.

The output terminals (1) and (2) of the CPU 1 become high impedance until the state is set via software after the power is turned on and the software inside the CPU 1 is started. The cage switch means Q2 is turned off.

When the power supply is started, the switching means Q
At the same time as turning on 2, a pulse is output from the output terminal (1) of the CPU 1 and the power supply device can be operated by driving the switch means Q1.

Next, the operation when an abnormality of the power supply is detected will be described.

In FIG. 1, when a process element such as a charger fails during power supply operation, the output value of the output amount detecting means 2 which detects the state of the output (1) is input to the abnormality determining means 3. When it is determined that there is an abnormality by comparing with a reference value set inside the abnormality determination means 3,
An abnormal signal is output to the input terminal (1) of the CPU 1,
The CPU 1 monitors the state of the input terminal 1 at a predetermined cycle. When an abnormal signal is detected from the abnormality determining means 3 at the input terminal (1), the CPU 1 is connected to the output terminal (2) of the CPU 1. The output terminal (2) is set to a high level in order to turn off the switching means Q2.

Thereafter, the pulse output from the output terminal (1) is stopped, and the operation of the power supply device is stopped.

As described above, the CPU (1) monitors the input terminal 1 at a predetermined cycle, and when the power supply unit is stopped and the abnormality signal output from the abnormality determination means 3 is released, a predetermined time elapses. In this case, the power supply start operation is started again. At this time, when an abnormal signal is generated again and this state is continuously output for a predetermined time, the operation is stopped without performing the power supply start operation.

Further, by transmitting power supply abnormality information to the controller of the electrophotographic apparatus via the CPU 1, it is possible to display the status on the apparatus main body and prompt for service (not shown).

Further, in FIG. 1, since the power supply device is operated via the CPU 1, the number of abnormal signals can be measured. Therefore, the number of abnormal signals is measured within a predetermined time or within a predetermined sequence. And the predetermined number of times CP
When an abnormal signal is measured at the input terminal (1) of U1, the state can be set so that the power supply is not restarted. Furthermore, by transmitting the number and state of the abnormal signal to the controller of the electrophotographic apparatus, the state can be easily displayed on the apparatus main body (not shown).

In FIG. 1, the output voltage is detected as the output amount of the output terminal 1, but as shown in FIG. 2, the output current is detected by the output amount detecting means (current detecting means) 2 as the output amount. It is also possible.

(Second Embodiment) A second embodiment will be described.

In the first embodiment, the signal output from the abnormality judging means 3 is turned off by using the CPU 1 and the switch means of Q2 is turned off via software inside the CPU 1. In some cases, the operation may not be stable.

In the second embodiment, the structure will be described with reference to FIG. 3 as a more effective means.

FIG. 3 is a circuit block diagram showing the configuration of the high-voltage power supply according to the second embodiment. In FIG. 3, FIG.
Similarly, 1 is a C including a control circuit for controlling the power supply device.
It is a PU and has a VDD terminal and a GND terminal as terminals for supplying power as an internal configuration of the CPU 1, an output terminal (1) and an output terminal (2) as output terminals, and an input terminal (1) as an input terminal. are doing.

The output terminal (1) of the CPU 1 has an open-drain configuration and is connected to a resistor R2. The other end of the resistor R2 is connected to an FET connected to a switch means Q1 for driving a transformer T1 for performing voltage conversion. It is connected to the gate input and the resistors R1 and R3.

The other end of the resistor R3 is connected to GND, and the resistor R
The other end of 1 is connected in series to the collector terminal of a transistor indicated by switch means Q2.

A resistor R4 is connected between the base terminal and the emitter terminal of the transistor represented by the switch means Q2, and the emitter terminal is connected to the power supply VDD.

The base terminal is connected to the collector terminal of the transistor represented by the switch means Q3 via a resistor R11, a resistor R5 is arranged between the base and the emitter, and the base terminal of the switch means Q3 is connected to the CPU via a resistor R9.
1 output terminal (2).

One end of the primary side of the transformer T1 is connected to the source terminal of the switch means Q1, and the other end of the primary side of the transformer T1 is connected to the power supply voltage Vcc via the resistor R6.

A diode D1, a capacitor C1 and a resistor R7 for rectifying the secondary output of T1 are connected to the transformer secondary side as shown in FIG. 3, and the other end of R8 is connected to the output (1). ).

Reference numeral 2 denotes output amount detecting means for detecting the output amount of the output 1. In FIG. 1, the output amount detecting means constitutes a voltage detecting means for detecting a voltage.

Numeral 3 denotes an abnormality judging means for comparing the value of the output amount detecting means 2 with a predetermined value internally and outputting an abnormal signal when it is judged to be abnormal.

The abnormality judging means 3 has a time constant means in addition to the above-mentioned operation, and when the abnormality is judged and an abnormal signal is outputted, a predetermined time width is constituted by the time constant means. When output, an output signal is output for a predetermined time.

The abnormality determining means 3 is a switching means (switch driving means) via the transistor of the switching means Q4.
It is connected to the base terminal of Q3.

The input terminal (1) of the CPU 1 is connected to the base terminal of the switch means Q2 via a resistor R10, and monitors the on / off state of the switch means Q2.

As described above, in addition to the configuration of the first embodiment, the switching means constituting the switch driving means for driving the switching means Q2 in response to the output signal from the abnormality determining means 3 and the driving signal from the CPU 1 Q3 is provided, and when the switch means Q3 receives the abnormal signal, the switch means Q2 is turned off irrespective of the drive signal from the CPU 1 to cut off the power supply to the electrophotographic process means.

The operation in the above configuration will be described in detail.

In FIG. 3, the control of the power supply unit is performed by the CPU 1.
It is done in. The output of the power supply device can be operated by the CPU 1 while appropriately changing the voltage according to various image forming conditions and sequences.

At this time, a pulse for driving the transformer T1 is output to the output terminal (1) of the CPU 1, and C is output according to various conditions.
A pulse width corresponding to the target output determined inside the PU1 is output, and the output pulse drives the transformer T1 via the resistor R2 and the switching means Q1, and
The secondary side of 1 constitutes a rectification and output circuit composed of a diode D1, a capacitor C1, and resistors R7 and R8.
Power is supplied to a process element of electrophotography such as a charger and a developing device as a power supply output (1).

Next, an example of control of the switch means Q1 and Q2 from the CPU 1 at the time of power activation and operation will be described.

The output terminal (1) and the output terminal (2) of the CPU 1 are in a high impedance state after power is turned on and the software is started until the state is set via the software. Q2 is turned off.

When the power supply is started, the switching means Q
At the same time as turning on 2, a pulse is output from the output terminal (1) of the CPU 1 to drive the switch means Q1 to operate the power supply device.

Next, the operation when the abnormality of the power supply is detected will be described.

In FIG. 3, the output value of the output amount detecting means 2 which detects the state of the output (1) when a process element such as a charger fails during the power supply operation is input to the abnormality determining means 3. When it is determined that an abnormality has occurred in comparison with a reference value set in the abnormality determination means 3, an abnormality signal is output and the switch means Q4 is turned on, so that the switch means Q
3, the switching means Q2 is turned off at the same time as turning off the power supply to the gate of the switching means Q1 of the transformer T1 via the resistor R1, and the switching means Q1 is turned off.

As described above, the abnormality judging means 3 has the time constant means at the same time, so that when the abnormality is judged and an abnormal signal is output, a predetermined time width is constituted by the time constant means. Is output, the output signal continues for a predetermined time, whereby the switch means Q2 can be turned off for a predetermined time.

The CPU 1 monitors the input terminal (1) at a predetermined cycle, and monitors the state of the switch means Q2 based on the input level of the terminal of the input terminal (1).

In this embodiment, it is monitored that the collector voltage level of the switch Q3 changes depending on the ON and OFF states of the switch Q2.

When the abnormality judging means 3 outputs an abnormal signal, the switching means Q3 is turned off so that the input terminal (1)
Changes from low to high.

As described above, when the abnormality detection level is detected at the input terminal of the CPU 1 and is detected a plurality of times or a plurality of times within a predetermined time and within a predetermined sequence, the switch connected to the output terminal (2) of the CPU 1 The output terminal (2) is set to a high level to turn off the means Q2.

Thereafter, the output of the pulse output from the output terminal (1) is stopped, and the operation of the power supply device is stopped.

The CPU 1 monitors the input terminal (1) at a predetermined cycle as described above. When the power supply unit stops and the abnormality signal output from the abnormality determination means 3 is released, a predetermined time elapses. In this case, the power supply starting operation is started again. However, when the abnormal signal is generated again and this state is continuously output for a predetermined time, the operation is stopped without performing the power supply starting operation.

Further, by transmitting power supply abnormality information to the controller of the electrophotographic apparatus via the CPU 1, it is also possible to display the status on the apparatus main body and prompt for service (not shown).

As described above, according to the first and second embodiments, the switch means Q2 is provided in series with the pull-up means connected to the outside of the CPU. Abnormality judging means 3 for judging an abnormal state by comparing the value with the value is provided, and by controlling switch means Q2 according to the state, the power output is reliably stopped when the power output becomes abnormal output or the like. And at the same time improve reliability.

[0069]

As described above, according to the present invention,
Prevents equipment downtime from increasing when the load is shorted or opened,
There is an effect that reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a configuration according to a first embodiment.

FIG. 2 is a circuit block diagram showing a configuration according to a first embodiment.

FIG. 3 is a circuit block diagram showing a configuration according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU 2 Output amount detection means (voltage detection means, current detection means) 3 Abnormality determination means R1-R11 Resistance Q1 Switch means (FET) (switching element) Q2 Switch means (transistor) Q3 Switch means (transistor) T1 transformer

Claims (10)

[Claims] 1. A power supply device for use in an image forming apparatus, comprising: a transformer for performing voltage conversion; a switching element that is turned on / off to drive the transformer; and a rectifier for rectifying an output of the transformer. Means for controlling the switching of the switching element and supplying power to the electrophotographic process means for controlling the rectified output to an arbitrary value;
PU, switch means for turning on and off the power supply of the drive power supply to the switching element, and connected to an output terminal different from the switching control output terminal of the CPU and connected in series with the switch means A pull-up means connected to the driving power supply via the switch means, a current detection means for detecting a current supplied to the electrophotographic process means, and a current value detected by the current detection means Abnormality determination means for determining that the power supply to the electrophotographic process means is in an abnormal state when the reference value exceeds a preset reference value and outputting an abnormality signal to the CPU; A power supply unit, wherein when a signal is input, the switch unit is turned off to cut off power supply to the electrophotographic process unit. 2. A power supply device for use in an image forming apparatus, comprising: a transformer for performing voltage conversion; a switching element that is turned on / off to drive the transformer; and a rectifier for rectifying an output of the transformer. Means for controlling the switching of the switching element and supplying power to the electrophotographic process means for controlling the rectified output to an arbitrary value;
PU, switch means for turning on and off the power supply of the drive power supply to the switching element, and connected to an output terminal different from the switching control output terminal of the CPU and connected in series with the switch means A pull-up unit connected to the driving power supply via the switch unit; a voltage detection unit for detecting a voltage supplied to the electrophotographic process unit; and a voltage value detected by the voltage detection unit. Abnormality determination means for determining that the power supply to the electrophotographic process means is in an abnormal state when the reference value exceeds a preset reference value and outputting an abnormality signal to the CPU; A power supply unit, wherein when a signal is input, the switch unit is turned off to cut off power supply to the electrophotographic process unit. 3. A power supply device for use in an image forming apparatus, comprising: a transformer for performing voltage conversion; a switching element that is turned on / off to drive the transformer; and a rectifier for rectifying an output of the transformer. Means for controlling the switching of the switching element and supplying power to the electrophotographic process means for controlling the rectified output to an arbitrary value;
PU, switch means for turning on and off the power supply of the drive power supply to the switching element, and connected to an output terminal different from the switching control output terminal of the CPU and connected in series with the switch means A pull-up means connected to the driving power supply via the switch means, a current detection means for detecting a current supplied to the electrophotographic process means, and a current value detected by the current detection means An abnormality determining unit that determines that power supply to the electrophotographic process unit is in an abnormal state when the value exceeds a preset reference value and outputs an abnormal signal to the CPU; and an output signal from the abnormality determining unit. And the CP
A switch driving means for driving the switch means in response to a drive signal from U, and the switch drive means, when receiving the abnormal signal, switches the switch means irrespective of the drive signal from the CPU. A power supply device for turning off the power supply to the electrophotographic process means by turning off the power supply; 4. A power supply device for use in an image forming apparatus, comprising: a transformer for performing voltage conversion; a switching element that is turned on / off to drive the transformer; and a rectifier for rectifying an output of the transformer. Means for controlling the switching of the switching element and supplying power to the electrophotographic process means for controlling the rectified output to an arbitrary value;
PU, switch means for turning on and off the power supply of the drive power supply to the switching element, and connected to an output terminal different from the switching control output terminal of the CPU and connected in series with the switch means A pull-up unit connected to the driving power supply via the switch unit; a voltage detection unit for detecting a voltage supplied to the electrophotographic process unit; and a voltage value detected by the voltage detection unit. An abnormality determining unit that determines that power supply to the electrophotographic process unit is in an abnormal state when the value exceeds a preset reference value and outputs an abnormal signal to the CPU; and an output signal from the abnormality determining unit. And the CP
A switch driving means for driving the switch means in response to a drive signal from U, and the switch drive means, when receiving the abnormal signal, switches the switch means irrespective of the drive signal from the CPU. A power supply device for turning off the power supply to the electrophotographic process means by turning off the power supply; 5. The power supply device according to claim 1, wherein an output terminal for switching control of the CPU has an open drain configuration. 6. The pull-up means is a resistor, and a resistor is provided between the pull-up means and an output terminal of the CPU to which the pull-up means is connected.
6. The power supply device according to any one of claims 5 to 5. 7. A method for controlling a power supply device used in an image forming apparatus, comprising: a transformer for performing voltage conversion, a switching element that is turned on / off to drive the transformer, and an output of the transformer. Rectifying means for rectifying; a CPU for controlling the switching element to perform switching control and supplying power to the electrophotographic process means; and a CPU for controlling the rectified output to an arbitrary value; and turning on / off power supply of a driving power supply to the switching element. And a switching control output terminal of the CPU connected to a different output terminal and connected in series with the switching means, and connected to the driving power supply via the switching means. Pull-up means, current detection means for detecting a current supplied to the electrophotographic process means, and detection by the current detection means Abnormality determining means for determining that power supply to the electrophotographic process means is in an abnormal state when the current value exceeds a preset reference value and outputting an abnormal signal to the CPU, A method for controlling a power supply device, comprising: turning off the switch means when the abnormal signal is input by the CPU to cut off power supply to the electrophotographic process means. 8. A method for controlling a power supply device used in an image forming apparatus, comprising: a transformer for performing voltage conversion, a switching element that is turned on / off to drive the transformer, and an output of the transformer. Rectifying means for rectifying; a CPU for controlling the switching element to perform switching control and supplying power to the electrophotographic process means; and a CPU for controlling the rectified output to an arbitrary value; and turning on / off power supply of a driving power supply to the switching element. And a switching control output terminal of the CPU connected to a different output terminal and connected in series with the switching means, and connected to the driving power supply via the switching means. Pull-up means, voltage detecting means for detecting a voltage supplied to the electrophotographic process means, and detection by the voltage detecting means Abnormality determining means for determining that power supply to the electrophotographic process means is in an abnormal state when the voltage value exceeds a preset reference value and outputting an abnormal signal to the CPU, A method for controlling a power supply device, comprising: turning off the switch means when the abnormal signal is input by the CPU to cut off power supply to the electrophotographic process means. 9. A method for controlling a power supply device used in an image forming apparatus, comprising: a transformer for performing voltage conversion, a switching element that is turned on / off to drive the transformer, and an output of the transformer. Rectifying means for rectifying; a CPU for controlling the switching element to perform switching control and supplying power to the electrophotographic process means; and a CPU for controlling the rectified output to an arbitrary value; and turning on / off power supply of a driving power supply to the switching element. And a switching control output terminal of the CPU connected to a different output terminal and connected in series with the switching means, and connected to the driving power supply via the switching means. Pull-up means, current detection means for detecting a current supplied to the electrophotographic process means, and detection by the current detection means Abnormality determining means for determining that power supply to the electrophotographic process means is in an abnormal state when the set current value exceeds a preset reference value and outputting an abnormality signal to the CPU; And a switch driving means for driving the switch means in response to an output signal from the CPU and a driving signal from the CPU, wherein the CPU is adapted to receive the abnormal signal by the switch driving means.
A power supply control method comprising: turning off the switch means irrespective of the drive signal from the controller to cut off power supply to the electrophotographic process means. 10. A method for controlling a power supply device used in an image forming apparatus, comprising: a transformer for performing voltage conversion, a switching element that is turned on / off to drive the transformer, and an output of the transformer. Rectifying means for rectifying,
A CPU for controlling the switching element to perform switching control and supplying power to the electrophotographic process means to control the rectified output to an arbitrary value; and A pull-up unit connected to an output terminal different from an output terminal for switching control of the CPU and connected in series with the switch unit, and connected to the driving power supply via the switch unit; Voltage detecting means for detecting a voltage supplied to the electrophotographic process means; and an abnormal state of power supply to the electrophotographic process means when a voltage value detected by the voltage detecting means exceeds a preset reference value. Abnormality determination means for outputting an abnormality signal to the CPU by determining that Receiving a drive signal may be provided a switch drive means for driving the switch means, the CP when receiving the abnormal signal by the switch driving means
A control method for a power supply device, wherein the switch means is turned off irrespective of the drive signal from U to cut off power supply to the electrophotographic process means.