JP2002010642A - Power unit and output-control method for the unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power unit that generates a plurality of high voltages corresponding to each process with a few parts of a circuit. SOLUTION: A pulse-width control circuit 4 controls a high-voltage output 1 and an output pulse from the pulse-width control circuit 4 is output to a drive circuit 2 that drives a transformer 1 in order to control the high-voltage output 1 to a predetermined value. And, the output pulse from the pulse-width control circuit 4 is used as a drive pulse of a drive circuit 6 that drives a transformer 5 that generates a high-voltage output 2. A series-control circuit 8 is connected to a primary winding of the transformer 5, and a voltage VS2, which is an output amount fed by an output-amount detection circuit 7, is deemed as an input. And then, the input voltage VS2 is compared with a predetermined amount in the series-control circuit 8, and an input voltage applied to the primary winding of the transformer 5 is series-controlled with the comparison-error amount as an output signal. Then, the high-voltage output 2 is so controlled as to get to the predetermined value.

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 such as a high-voltage power supply device used in an electrophotographic image forming apparatus and the like, and to an output control method thereof.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine or a printer, an image forming process is performed using a plurality of high-voltage power supply devices provided independently for each process.

[0003]

However, when a plurality of independent high-voltage power supplies are provided for various processes as in the prior art, it has been difficult to reduce the size of the image forming apparatus.

Therefore, the present invention can generate a plurality of high voltages corresponding to various processes with a small number of circuit components.
It is an object of the present invention to provide a power supply device which can be reduced in size and cost when mounted on an image forming apparatus, and an output control method thereof.

[0005]

In order to achieve the above object, a power supply device according to a first aspect of the present invention comprises a first voltage output means for outputting a first voltage and a second voltage output means for outputting a second voltage. A first voltage output means for boosting an input voltage; rectifying an output of the first transformer;
First rectifying means for outputting the first voltage, first output amount detecting means for detecting the output amount of the first voltage, and controlling the pulse width of the output pulse signal based on the detected output amount. Pulse width control means, and first drive means for driving the first transformer according to the pulse width of the output pulse signal, wherein the second voltage output means increases a second voltage for increasing an input voltage. According to the pulse width of the output pulse signal supplied from the pulse width control means,
A second driving unit for driving the second transformer, a second rectifying unit for rectifying an output of the second transformer and outputting the rectified output as the second voltage, and an output amount of the second voltage. It is characterized by comprising a second output amount detecting means for detecting, and a voltage control means for controlling the second voltage based on the detected output amount.

[0006] In the power supply device according to the second aspect, the first aspect is provided.
The voltage control means is connected to an input side winding of the second transformer and comprises a series control circuit for controlling a voltage applied to the input side winding.

[0007] In the power supply device according to the third aspect, the first aspect.
Alternatively, in the power supply device according to claim 2, the first and second output amount detecting means output the voltage divided by a resistor connected to an output side of the first and second rectifying means, respectively. It is characterized in that it is detected as a competence.

[0008] In the power supply device according to the fourth aspect, the first aspect is provided.
Alternatively, in the power supply device according to claim 2, the first and second output amount detection means detects a current flowing through a resistor connected to an output side of each of the first and second rectification means as the output amount. It is characterized by doing.

[0009] In the power supply device according to the fifth aspect, the first aspect is provided.
The voltage control means is connected to an output side winding of the second transformer and comprises a series control circuit for controlling a voltage of the output side winding.

In the power supply device according to the sixth aspect, the power supply device according to the fifth aspect is provided.
Wherein the first and second output amount detection means detect, as the output amount, a voltage divided by a resistor connected to the output side of the first and second rectification means, respectively. It is characterized by the following.

[0011] In the power supply device according to claim 7, the power supply device according to claim 5 is provided.
Wherein the second output amount detection means detects a current flowing through a resistor connected to an output side of the second rectification means as the output amount.

In the power supply device according to claim 8, the voltage control means is connected to an output side winding of the second transformer in the power supply device according to claim 1, and the second output amount detection means. Comparing means for comparing the output amount of the second voltage detected by the above with a reference value, and according to the comparison result,
Switch means for performing an on / off operation of the second drive means, wherein the on / off operation of the second drive means is performed in a cycle longer than a cycle of the output pulse signal supplied from the pulse width control means. It is characterized by.

In the power supply device according to the ninth aspect, the power supply apparatus according to the eighth aspect is provided.
Wherein the second output amount detecting means detects a voltage divided by a resistor connected to an output side of the second rectifying means as the output amount.

According to a tenth aspect of the present invention, in the power supply unit according to the eighth aspect, the first and second output amount detecting means are respectively connected to output sides of the first and second rectifying means. A current flowing through the detected resistor is detected as the output amount.

[0015] The power supply device according to claim 11 is the power supply device according to claim 1.
The power supply device according to any one of claims 10 to 11, wherein the power supply device is applied to a high-voltage power supply device used in an image forming process of an image forming apparatus.

According to a twelfth aspect of the present invention, there is provided an output control method for a power supply device, wherein the first voltage output circuit and the second voltage output circuit output a first voltage and a second voltage, respectively. In the first voltage output circuit, a step of rectifying an output of a first transformer for boosting an input voltage and outputting the rectified output as a first voltage; and a step of detecting an output amount of the first voltage; Controlling the pulse width of the output pulse signal based on the detected output amount; and driving the first transformer in accordance with the pulse width of the output pulse signal; In the output circuit,
A step of driving a second transformer that boosts an input voltage according to a pulse width of the output pulse signal; a step of rectifying an output of the second transformer and outputting the rectified output as the second voltage; A step of detecting the output amount of the second voltage, and a step of controlling the second voltage based on the detected output amount.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power supply device and an output control method thereof according to the present invention will be described. The power supply according to the present embodiment is applied to a high-voltage power supply mounted on an electrophotographic image forming apparatus.

[First Embodiment] FIG. 1 is a circuit diagram showing a configuration of a high-voltage power supply device according to a first embodiment. In the figure, reference numeral 1 denotes a transformer for generating a high voltage. A rectifier circuit including a diode D1 for rectifying the high voltage generated in the transformer 1 and a capacitor C2 is connected to the secondary winding of the transformer 1, and the output of the rectifier circuit is a resistor R.
4 to the output terminal of the high voltage output 1. The output terminal of the high voltage output 1 is connected to a process element (for example, a charger) in the image forming apparatus.

A power supply + B is connected to one end of the primary winding of the transformer 1 via a resistor R1 and a capacitor C1. A drive circuit 2 for driving the transformer 1 is connected to the other end of the primary winding. The drive circuit 2 has a transistor Q1.

The above-mentioned rectifier circuit connected to the secondary winding of the transformer 1 is connected to an output amount detection circuit 3 including resistors R2 and R3 and detecting an output amount of a high voltage output. In the present embodiment, the output amount detection circuit 3 outputs the voltage V
s1 is detected. This output amount detection circuit 3 is connected to a pulse width control circuit 4.

The pulse width control circuit 4 has a built-in pulse oscillator and compares a voltage Vs1 as an output amount from the output amount detection circuit 3 with a predetermined value. Is smaller than the predetermined value, the output is increased by increasing the pulse width of the output pulse signal of the predetermined drive frequency from the pulse oscillator,
When the voltage Vs1 as the output amount is larger than the predetermined value, pulse width control is performed to reduce the output by reducing the pulse width of the output pulse signal of the predetermined drive frequency from the pulse oscillator to make the output amount constant. The output pulse signal of the pulse width control circuit 4 is output to the drive circuit 2.

A drive circuit 6 having a transistor Q2 is connected to one end of the primary winding of the transformer 5, and an output pulse signal of the pulse width control circuit 4 is output to the drive circuit 2 described above. At the same time, it is also output to the drive circuit 6. A series control circuit 8 is connected to the other end of the primary winding of the transformer 5, and an input terminal of the series control circuit 8 is connected to a power supply + B via a resistor R5 and a capacitor C3. The series control circuit 8 controls the voltage applied to the primary winding of the transformer 5 according to the voltage Vs2 as the output amount from the output amount detection circuit 7 described later so that the output amount becomes constant.

The secondary winding of the transformer 5 includes a transformer 5
A rectifier circuit composed of a diode D2 and a capacitor C4 for rectifying the high voltage generated by the rectifier circuit is connected, and the output of this rectifier circuit is led to the output terminal of the high voltage output 2 via a resistor R8. The output terminal of the high voltage output 2 is connected to a process element (for example, a charger) in the image forming apparatus.

The above-mentioned rectifier circuit connected to the secondary winding of the transformer 5 is connected to an output amount detection circuit 7 including resistors R7 and R6 and detecting an output amount of high voltage. In the present embodiment, the output amount detection circuit 7 outputs the voltage Vs2 as the output amount.
Is detected. Voltage V as output amount of output amount detection circuit 7
s2 is input to the series control circuit 8 and is used to control the input voltage applied to the primary winding of the transformer 5.

The operation of the high voltage power supply having the above configuration will be described. The pulse width control circuit 4 controls the output of the high voltage output 1, and the output pulse from the pulse width control circuit 4 is output to the drive circuit 2 that drives the transformer 1 to control the high voltage output 1 to a predetermined value. . The output pulse from the pulse width control circuit 4 is also used as a drive pulse of a drive circuit 6 that drives a transformer 5 that generates the high voltage output 2.

Here, since it is necessary to control the output of the high voltage output 2, the series control circuit 8 is connected to the primary winding of the transformer 5 as described above. The series control circuit 8 receives a voltage Vs2 as an output amount from the output amount detection circuit 7 as an input, compares the input voltage Vs2 with a predetermined value inside the series control circuit 8,
Using the error amount as an output signal, series control of the input voltage applied to the primary winding of the transformer 5 is performed to control the high voltage output 2 to a predetermined value. As a result, the output of both the high voltage output 1 and the high voltage output 2 can be stably controlled by one pulse width control circuit 4.

[Second Embodiment] FIG. 2 is a circuit diagram showing a configuration of a high-voltage power supply according to a second embodiment. The same components as those in the first embodiment are denoted by the same reference numerals.

In FIG. 1, reference numeral 1 denotes a transformer for generating a high voltage. A rectifier circuit including a diode D1 for rectifying the high voltage generated in the transformer 1 and a capacitor C2 is connected to the secondary winding of the transformer 1, and the output of the rectifier circuit is a high voltage output 1 via a resistor R4. Output terminal. The output terminal of the high voltage output 1 is connected to a process element (for example, a charger) in the image forming apparatus.

A power supply + B is connected to one end of the primary winding of the transformer 1 via a resistor R1 and a capacitor C1. A drive circuit 2 for driving the transformer 1 is connected to the other end of the primary winding of the transformer 1. Drive circuit 2
Has a transistor Q1.

The rectifier circuit connected to the secondary winding of the transformer 1 is connected to an output amount detection circuit 13 including a resistor R3 and detecting a high-voltage output amount. In the present embodiment, the output amount detection circuit 13 detects the current Is1 as the output amount. The output amount detection circuit 13 is connected to the pulse width control circuit 4.

The pulse width control circuit 4 has a built-in pulse oscillator, and outputs a current I as an output amount of the output amount detection circuit 13.
s1 is compared with a predetermined value. In the present embodiment, when the current Is1 as the output amount is smaller than the predetermined value, the pulse width of the output pulse signal of the predetermined drive frequency from the pulse oscillator is increased. While increasing the output,
When the current Is1 as the output amount is larger than the predetermined value, pulse width control is performed to reduce the output by reducing the pulse width of the output pulse signal of the predetermined drive frequency from the pulse oscillator to make the output amount constant. The output pulse from the pulse width control circuit 4 is output to the drive circuit 2.

On the other hand, a drive circuit 6 having a transistor Q2 is connected to one end of the primary winding of the transformer 5, and an output pulse signal from the pulse width control circuit 4 is output to the drive circuit 2. At the same time, it is also output to the drive circuit 6. The other end of the primary winding is connected to a series control circuit 8, and an input terminal of the series control circuit 8 is connected to a power supply + B via a resistor R5 and a capacitor C3. The series control circuit 8 calculates a current Is2 as an output amount from an output amount detection circuit 17 described later.
The voltage applied to the primary winding of the transformer 5 is controlled so that the output amount becomes constant.

The secondary winding of the transformer 5 includes a transformer 5
A rectifier circuit composed of a diode D2 and a capacitor C4 for rectifying the high voltage generated in the above is configured, and the output of the rectifier circuit is guided to the output terminal of the high voltage output 2 via the resistor R8. The output terminal of the high voltage output 2 is connected to a process element (eg, a charger).

The rectifier circuit connected to the secondary winding of the transformer 5 is connected to an output amount detection circuit 17 including a resistor R7 and detecting a high voltage output amount. In the present embodiment, the output amount detection circuit 17 detects the current Is2 as the output amount. The current Is2 as the output amount from the output amount detection circuit 17 is input to the series control circuit 8 and is used for controlling the input voltage of the primary winding of the transformer 5.

As described above, in the second embodiment, the output amount detection circuit 13 for detecting the output amount of the high-voltage output 1 includes the resistor R
An output amount detection circuit 17 for detecting the output amount of the high voltage output 2 is a resistor R7.
Is a current detection circuit.

In the second embodiment, similarly to the first embodiment, the series control circuit 8 receives the signal of the current Is2 from the output amount detection circuit 17 as an input, and receives the input signal and the internal signal of the series control circuit 8. Compare with the value determined in advance,
By performing series control of the input voltage of the primary winding of the transformer 5 using the error amount as an output signal, the high voltage output 2
Control. As a result, both the high voltage output 1 and the high voltage output 2 can be stably controlled by one pulse width control circuit 4.

[Third Embodiment] FIG. 3 is a circuit diagram showing a configuration of a high-voltage power supply device according to a third embodiment. The same components as those in the first embodiment are denoted by the same reference numerals. In the figure, reference numeral 1 denotes a transformer for generating a high voltage. A rectifier circuit including a diode D1 for rectifying the high voltage generated in the transformer 1 and a capacitor C2 is connected to the secondary winding of the transformer 1, and the output of the rectifier circuit is the output of the high voltage output 1 via a resistor R4. It is led to the terminal. The output terminal of the high voltage output 1 is connected to a process element (for example, a charger) in the image forming apparatus.

The power supply + B is connected to one end of the primary winding of the transformer 1 via a resistor R1 and a capacitor C1. A drive circuit 2 for driving the transformer 1 is connected to the other end of the primary winding of the transformer 1. Drive circuit 2
Has a transistor Q1.

The above-mentioned rectifier circuit connected to the secondary winding of the transformer 1 is connected to an output amount detection circuit 3 including resistors R2 and R3 and detecting a high-voltage output amount. In the present embodiment, the output amount detection circuit 3 outputs the voltage Vs1 as the output amount.
Is detected. The output amount detection circuit 3 is connected to the pulse width control circuit 4.

The pulse width control circuit 4 has a built-in pulse oscillator, and compares a voltage Vs1 as an output amount from the output amount detection circuit 3 with a predetermined value. Is smaller than the predetermined value, the output is increased by increasing the pulse width of the output pulse signal of the predetermined drive frequency from the pulse oscillator,
When the voltage Vs1 as the output amount is larger than the predetermined value, pulse width control is performed to reduce the output by reducing the pulse width of the output pulse signal of the predetermined drive frequency from the pulse oscillator to make the output amount constant. The output pulse signal from the pulse width control circuit 4 is output to the drive circuit 2.

A drive circuit 6 having a transistor Q2 is connected to one end of the primary winding of the transformer 5,
The other end of the secondary winding is connected to a power supply + B via a resistor R5 and a capacitor C3. Pulse width control circuit 4
Is output from the driving circuit 2 as described above.
Is output to the drive circuit 6 at the same time.

The secondary winding of the transformer 5 includes a transformer 5
A rectifier circuit composed of a diode D2 and a capacitor C4 for rectifying the high voltage generated by the rectifier circuit is connected, and the output of the rectifier circuit is led to the output terminal of the high voltage output 2 via the resistor R8. The output terminal of the high voltage output 2 is connected to a process element (for example, a charger) in the image forming apparatus.

The rectifier circuit connected to the secondary winding of the transformer 5 is connected to an output amount detection circuit 27 that includes resistors R7, R6, and R9 and detects a high-voltage output amount. In the present embodiment, the output amount detection circuit 27 detects the voltage Vs2 as the output amount.

The voltage Vs2 as the output amount from the output amount detection circuit 7 is input to the series control circuit 18. The series control circuit 18 compares the voltage Vs2 as an output amount from the output amount detection circuit 27 with a predetermined value Vref by an error amplifier IC1, outputs the comparison result as an error amount, outputs a transistor Q3, R10, R1
1. The output voltage of the secondary winding is controlled in series to a predetermined value by the capacitor C5 and the like. Thus, the transformer 5
, The high-voltage output 2 is controlled to a predetermined value.

The operation of the high voltage power supply having the above configuration will be described. The pulse width control circuit 4 controls the output of the high voltage output 1, and the output pulse from the pulse width control circuit 4 is output to the drive circuit 2 that drives the transformer 1 to control the high voltage output 1 to a predetermined value. . The output pulse from the pulse width control circuit 4 is also used as a drive pulse of a drive circuit 6 that drives a transformer 5 that generates the high voltage output 2.

When controlling the output of the high voltage output 2, the series control circuit 18 connected to one end of the secondary winding of the transformer 5 controls the voltage generated in the secondary winding. As a result, the output of both the high voltage output 1 and the high voltage output 2 can be stably controlled by one pulse width control circuit 4.

In the third embodiment, the case where the output voltage of the secondary winding of the transformer 5 is controlled using the series control circuit 18 has been described, but a switching control circuit is used instead of the series control circuit. You may. The switching control circuit is realized by deleting the capacitor C5 and the like in the series control circuit 18 shown in FIG. 3 and turning on / off the transistor Q3 using the error amplifier IC1 as a comparator. It can be performed.

In the third embodiment, the case where the series control circuit 18 is inserted at one end of the secondary winding of the transformer 5 has been described. However, the connection method of the series control circuit is not limited to this. The connection method as shown in FIG. 4 may be used.
FIG. 4 is a circuit diagram showing a configuration of a series control circuit portion connected to the secondary winding of the transformer 5 by another connection method. FIG. 4 shows a configuration of the secondary winding portion of the transformer 5 different from that of FIG. 3, and the other configuration is the same as that of FIG.

In FIG. 4, the secondary winding of the transformer 5 has:
A rectifier circuit including a diode D2 for rectifying the high voltage generated in the transformer 5 and a capacitor C4 is connected. On the output side of the rectifier circuit, a resistor R13, a capacitor C
6. The output terminal of the high voltage output 2 is connected via the resistor R8, and the output terminal of the high voltage output 2 is connected to a process element (for example, a charger) in the image forming apparatus.

The rectifier circuit connected to the secondary winding of the transformer 5 is connected to an output amount detection circuit 27 including resistors R7, R6 and R9 and detecting a high-voltage output amount. . In the present embodiment, the output amount detection circuit 27 detects the voltage Vs1 as the output amount.

Further, a series control circuit 28 is connected in parallel with the output amount detection circuit 27. The series control circuit 28 compares the voltage Vs1 as the output amount of the output amount detection circuit 27 with a predetermined value by the error amplifier IC1, outputs the comparison result as an error amount, and outputs the transistor Q3 and the resistor R10, The output voltage of the secondary winding is controlled in series by R11 and the like.

[Fourth Embodiment] FIG. 5 is a circuit diagram showing a configuration of a high-voltage power supply device according to a fourth embodiment. The same components as those in the first embodiment are denoted by the same reference numerals. In the figure, reference numeral 1 denotes a transformer for generating a high voltage. A rectifier circuit is connected to a secondary winding of the transformer 1 from a diode D1 for rectifying the high voltage generated in the transformer 1 and a capacitor C2, and the output of the rectifier circuit is an output terminal of the high voltage output 1 via a resistor R4. It is led to. The output terminal of the high voltage output 1 is connected to a process element (for example, a charger) in the image forming apparatus.

A power supply + B is connected to one end of the primary winding of the transformer 1 via a resistor R1 and a capacitor C1. A drive circuit 2 for driving the transformer 1 is connected to the other end of the primary winding. The drive circuit 2 has a transistor Q1.

The above-mentioned rectifier circuit connected to the secondary winding of the transformer 1 is connected to an output amount detection circuit 3 including resistors R2 and R3 and detecting a high-voltage output amount. In the present embodiment, the output amount detection circuit 3 outputs the current Is1 as the output amount.
Is detected. The output amount detection circuit 3 is connected to the pulse width control circuit 4.

The pulse width control circuit 4 has a built-in pulse oscillator, compares a current Is1 as an output amount from the output amount detection circuit 3 with a predetermined value, and in this embodiment, determines the output amount as an output amount. When the current Is1 is smaller than the predetermined value, the output is increased by increasing the pulse width of the output pulse signal of the predetermined drive frequency from the pulse oscillator,
When the current Is1 as the output amount is larger than the predetermined value, pulse width control is performed to reduce the output by reducing the pulse width of the output pulse signal of the predetermined drive frequency from the pulse oscillator to make the output amount constant. The output pulse signal of the pulse width control circuit 4 is output to the drive circuit 2.

A drive circuit 6 having a transistor Q2 is connected to one end of the primary winding of the transformer 5,
The other end of the secondary winding is connected to a power supply + B via a resistor R5 and a capacitor C3. The output pulse signal of the pulse width control circuit 4 is output to the drive circuit 2 at the same time as being output to the drive circuit 2.

The secondary winding of the transformer 5 includes a transformer 5
A rectifier circuit composed of a diode D2 and a capacitor C4 for rectifying the high voltage generated in the above is configured, and the output of the rectifier circuit is guided to the output terminal of the high voltage output 2 via the resistor R8. The output terminal of the high voltage output 2 is connected to a process element (for example, a charger) in the image forming apparatus.

A series control circuit 38 is connected to the low voltage side of the rectifier circuit connected to the secondary winding of the transformer 5. The output side of the series control circuit 38 is connected to an output amount detection circuit 37 including a current detection resistor R7, a capacitor C6, a resistor R9, and the like. The output amount detection circuit 37 detects the current Is2 as an output amount. .

The output amount detection circuit 37 is a series control circuit 3
The series control circuit 38 controls the output voltage of the transformer 5 to a predetermined value according to the current Is2 as the output amount from the output amount detection circuit 37.

As described above, in the fourth embodiment, the output amount detection circuit 3 is a voltage detection circuit including the resistors R2 and R3, and the output amount detection circuit 37 is a current detection circuit including the resistor R7. Circuit. In addition, 2 of transformer 5
A rectifier circuit is connected to the secondary winding, a series control circuit 38 is connected, and an output amount detection circuit 37 for detecting a current as an output amount is connected.

The series control circuit 38 includes an error amplifier IC
1, the current Is2 as the output amount of the output amount detection circuit 37
And a predetermined value, and outputs the result of the comparison as an error amount.
The output voltage of the secondary winding is controlled in series by 0, R11 and the like.

[Fifth Embodiment] FIG. 6 is a circuit diagram showing a configuration of a high-voltage power supply according to a fifth embodiment. The same components as those in the first embodiment are denoted by the same reference numerals. In the figure, reference numeral 1 denotes a transformer for generating a high voltage. A rectifier circuit including a diode D1 for rectifying the high voltage generated in the transformer 1 and a capacitor C2 is connected to the secondary winding of the transformer 1, and the output of the rectifier circuit is the output of the high voltage output 1 via a resistor R4. It is led to the terminal. The output terminal of the high voltage output 1 is connected to a process element (for example, a charger) of the image forming apparatus.

A power supply + B is connected to one end of the primary winding of the transformer 1 via a resistor R1 and a capacitor C1. A drive circuit 2 for driving the transformer 1 is connected to the other end of the primary winding of the transformer 1.

The above-mentioned rectifier circuit connected to the secondary winding of the transformer 1 is connected to an output amount detection circuit 3 including resistors R2 and R3 and detecting a high-voltage output amount. In the present embodiment, the output amount detection circuit 3 outputs the voltage Vs1 as the output amount.
Is detected. The output amount detection circuit 3 is connected to the pulse width control circuit 4.

The pulse width control circuit 4 has a built-in pulse oscillator, compares the voltage Vs1 as the output amount from the output amount detection circuit 3 with a predetermined value, and in this embodiment, determines the output amount as the output amount. When the voltage Vs1 is smaller than a predetermined value, the output is increased by widening the pulse width of the predetermined driving frequency from the pulse oscillator, while when the output amount is larger than the predetermined value, the output pulse of the predetermined driving frequency from the pulse oscillator is Pulse width control is performed to reduce the output by reducing the pulse width of the signal and to keep the output amount constant.

The output pulse signal from the pulse width control circuit 4 is output to the drive circuit 2 and at the same time
Is also output. A drive circuit 6 is connected to one end of the primary winding of the transformer 5, and a power supply + B is connected to the other end of the primary winding via a resistor R5 and a capacitor C3.

The secondary winding of the transformer 5 includes a transformer 5
A rectifier circuit composed of a diode D2 and a capacitor C4 for rectifying the high voltage generated by the rectifier circuit is connected, and the output of the rectifier circuit is led to the output terminal of the high voltage output 2 via the resistor R8. The output terminal of the high voltage output 2 is connected to a process element (for example, a charger) in the image forming apparatus.

The above-mentioned rectifier circuit connected to the secondary winding of the transformer 5 is connected to an output amount detection circuit 7 including resistors R7 and R6 and detecting a high-voltage output amount. In the present embodiment, the output amount detection circuit 7 outputs the voltage Vs2 as the output amount.
Is detected.

Voltage V as output amount of output amount detection circuit 7
s2 is input to the comparison circuit 9 and used to control the input voltage of the transformer 5, and is controlled to a predetermined value.

The comparison circuit 9 compares the voltage Vs2 from the output amount detection circuit 7 with a predetermined value inside the comparison circuit 9, and outputs the comparison result to the gate switch circuit 10. When the voltage Vs2 of the output amount detection circuit 7 is larger than a predetermined value inside the comparison circuit 9, the gate switch circuit 10 operates to stop the output of the drive circuit 6,
If the voltage Vs2 of the output amount detection circuit 7 is smaller than a predetermined value inside the comparison circuit 9, the gate switch circuit 1
0 operates so as to continue the output of the drive circuit 6, and is controlled so that the output amount of the high voltage output 2 becomes constant.

The operation of the high voltage power supply having the above configuration will be described. The pulse width control circuit 4 controls the output of the high voltage output 1, and an output pulse signal from the pulse width control circuit 4 is output to control the high voltage output 1 to a predetermined value. Also,
The output pulse signal from the pulse width control circuit 4 is a high voltage output 2
Is also used as a driving pulse of a driving circuit 6 for driving the transformer 5 to control the driving of the transformer 5.

When the output of the high voltage output 2 is controlled, the voltage Vs2 as the output amount from the output amount detection circuit 7 and the comparison circuit 9
The gate switch circuit 10 is operated based on the comparison result, and the output and stop of the drive circuit 6 are repeated, so that the output amount of the high voltage output 2 becomes constant. Is controlled as follows.

Here, the repetition cycle of outputting / stopping the drive circuit 6 by the comparison circuit 9 is determined by the capacitor C4 of the rectifier circuit connected to the secondary winding of the transformer 5, the resistor R6,
It is determined by the time constant of the control loop including R7 and the internal circuit (not shown) of the comparison circuit 9.

FIG. 7 is a timing chart showing operation waveforms of various parts of the circuit of FIG. In the figure, A indicates an output pulse signal (control pulse) output from the pulse width control circuit 4, and drives the transformer 5 by turning on the driver in the drive circuit 6 at a high (H) level.

In the figure, B indicates a control pulse signal output from the comparison circuit 9, and compares the voltage Vs2 from the output amount detection circuit 7 with a predetermined value inside the comparison circuit 9. Then, the gate switch circuit 10 is operated based on the comparison result. The output of the drive circuit 6 is turned off by a high (H) level pulse signal. The ON / OFF operation of the drive circuit 6 is performed by the control pulse signal output from the comparison circuit 9 in a cycle longer than the cycle of the output pulse signal (control pulse) output from the pulse width control circuit 4.

Further, in the figure, C is a gate signal (control pulse) of the driver 11 which is output from the gate switch circuit 10 and drives the transformer 5 inside the drive circuit 6, and is a high (H) level pulse. The driver 11 is turned on by a signal.

[Sixth Embodiment] FIG. 8 is a circuit diagram showing a configuration of a high-voltage power supply device according to a sixth embodiment. The same components as those in the first embodiment are denoted by the same reference numerals. In the figure, reference numeral 1 denotes a transformer for generating a high voltage. A rectifier circuit including a diode D1 for rectifying the high voltage generated in the transformer 1 and a capacitor C2 is connected to the secondary winding of the transformer 1, and the output of the rectifier circuit is the output of the high voltage output 1 via a resistor R4. It is led to the terminal. The output terminal of the high voltage output 1 is connected to a process element (for example, a charger) of the image forming apparatus.

A power supply + B is connected to one end of the primary winding of the transformer 1 via a resistor R1 and a capacitor C1. A drive circuit 2 for driving the transformer 1 is connected to the other end of the primary winding of the transformer 1.

An output amount detecting circuit 13 including a resistor R3 and detecting a high voltage output amount is connected to the rectifier circuit connected to the secondary winding of the transformer 1. In the present embodiment, the output amount detection circuit 13 detects a current as an output amount. The output amount detection circuit 13 is connected to the pulse width control circuit 4.

The pulse width control circuit 4 incorporates a pulse oscillator, and outputs a current I as an output amount of the output amount detection circuit 13.
s1 is compared with a predetermined value. In the present embodiment, when the current Is1 as the output amount is smaller than the predetermined value, the pulse width of the output pulse signal of the predetermined drive frequency from the pulse oscillator is increased. While increasing the output,
When the output amount is larger than the predetermined value, pulse width control is performed to reduce the output by reducing the pulse width of the output pulse signal of the predetermined drive frequency from the pulse oscillator to make the output amount constant.

The output pulse signal from the pulse width control circuit 4 is output to the drive circuit 2 and at the same time
Is also output. A drive circuit 6 is connected to one end of the primary winding of the transformer 5, and a power supply + B is connected to the other end of the primary winding of the transformer 5 via a resistor R5 and a capacitor C3. I have.

The secondary winding of the transformer 5 includes a transformer 5
A rectifier circuit composed of a diode D2 and a capacitor C4 for rectifying the high voltage generated by the rectifier circuit is connected, and the output of the rectifier circuit is led to the output terminal of the high voltage output 2 via the resistor R8. The output terminal of the high voltage output 2 is connected to a process element (for example, a charger) of the image forming apparatus.

The output rectifier circuit 17 connected to the secondary winding of the transformer 5 includes a resistor R7 and detects an output amount of high voltage. In the present embodiment, the output amount detection circuit 17 detects the current Is2 as the output amount.

The current Is2 as the output amount of the output amount detection circuit 17 is input to the comparison circuit 9 and used for controlling the input voltage of the transformer 5, and is controlled to a predetermined value.

The comparison circuit 9 compares the current Is2 as the output amount from the output amount detection circuit 7 with a predetermined value inside the comparison circuit 9, and outputs the comparison result to the gate switch circuit 10. . The current Is2 of the output amount detection circuit 17
Is larger than a predetermined value inside the comparison circuit 9, the gate switch circuit 10 operates to stop the output of the drive circuit 6, and Is2 of the output amount detection circuit 17 is predetermined inside the comparison circuit 9. If the value is smaller than the value, the gate switch circuit 10 operates to continue the output of the drive circuit 6, and is controlled so that the output amount of the high voltage output 2 becomes constant (see FIG. 7).

As described above, in the sixth embodiment, the output amount detection circuit 13 is a current detection circuit composed of the resistor R3 and the like, and the output amount detection circuit 17 is a current detection circuit composed of the resistor R7 and the like. Circuit.

Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations of the embodiments, and the functions described in the claims or the configurations of the embodiments are not limited to the embodiments. The present invention can be applied to any configuration as long as the function can be achieved.

For example, in each of the above-described embodiments, the case where only one of the voltage and the current is detected as the output amount has been described. However, the voltage and the current may be detected in combination. In each of the above embodiments, the case of two types of high-voltage outputs has been described. However, the case of three or more types of high-voltage outputs can be similarly applied.

Further, in the present invention, the technical elements of the above embodiments may be combined as needed.

The present invention may be applied to a case where all or a part of the configuration of the claim or the embodiment forms one device or is combined with another device. It may be an element constituting the device.

[0091]

According to the present invention, the operation of generating a plurality of high voltages can be performed by one pulse oscillator for driving the transformer, and the circuit can be simplified. Thus, the high-voltage power supply for electrophotography can be downsized.

Therefore, a plurality of high voltages corresponding to various processes can be generated with a small number of circuit components, and when mounted on an image forming apparatus, its size and cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a configuration of a high-voltage power supply device according to a first embodiment.

FIG. 2 is a circuit diagram illustrating a configuration of a high-voltage power supply device according to a second embodiment.

FIG. 3 is a circuit diagram illustrating a configuration of a high-voltage power supply device according to a third embodiment.

FIG. 4 is a circuit diagram showing a configuration of a series control circuit portion connected to a secondary winding of a transformer 5 by another connection method.

FIG. 5 is a circuit diagram illustrating a configuration of a high-voltage power supply device according to a fourth embodiment.

FIG. 6 is a circuit diagram illustrating a configuration of a high-voltage power supply device according to a fifth embodiment.

FIG. 7 is a timing chart showing operation waveforms of various parts of the circuit of FIG.

FIG. 8 is a circuit diagram illustrating a configuration of a high-voltage power supply device according to a sixth embodiment.

[Explanation of symbols]

 1, 5 Transformer 2, 6 Drive circuit 3, 7, 13, 17, 27, 37 Output amount detection circuit 4 Pulse width control circuit 8, 18, 28, 38 Series control circuit 9 Comparison circuit 10 Gate switch circuit 11 Driver D1 , D2 Diode C2, C4 Capacitor R2, R3, R6, R7 Resistance

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H003 BB11 DD03 EE11 2H027 EC06 ZA01 5G065 AA08 DA07 EA01 FA02 GA06 HA01 JA01 LA01 MA01 MA09 MA10 NA02 NA09 5H730 AA15 AS01 AS02 AS04 BB43 BB57 BB83 CC22 CC43 DD04 EE42 EE01EE FD31 FG05

Claims (12)

[Claims] 1. A power supply device comprising a first voltage output means for outputting a first voltage and a second voltage output means for outputting a second voltage, wherein the first voltage output means comprises an input voltage A first transformer for rectifying the output of the first transformer and outputting the rectified output as the first voltage, and a first output for detecting an output amount of the first voltage. Power detection means, pulse width control means for controlling a pulse width of an output pulse signal based on the detected output amount, and a first drive for driving the first transformer according to a pulse width of the output pulse signal. The second voltage output means comprises: a second transformer for boosting an input voltage; and the second voltage output means, in accordance with a pulse width of the output pulse signal supplied from the pulse width control means. Drive to drive the transformer Means, rectifying the output of the second transformer, and outputting the rectified output as the second voltage, second output amount detecting means for detecting the output amount of the second voltage, A power supply device, comprising: voltage control means for controlling the second voltage based on the detected output amount. 2. The voltage control means comprises a series control circuit connected to an input side winding of the second transformer and controlling a voltage applied to the input side winding. 2. The power supply device according to 1. 3. The first and second output amount detection means detects a voltage divided by a resistor connected to an output side of the first and second rectification means as the output amount. The power supply device according to claim 1 or 2, wherein: 4. The apparatus according to claim 1, wherein the first and second output amount detecting means detects a current flowing through a resistor connected to an output side of the first and second rectifying means as the output amount. The power supply device according to claim 1 or 2, wherein 5. The voltage control means according to claim 1, wherein said voltage control means comprises a series control circuit connected to an output side winding of said second transformer and controlling a voltage of said output side winding. Power supply. 6. The first and second output amount detecting means detects a voltage divided by a resistor connected to an output side of the first and second rectifying means as the output amount. The power supply device according to claim 5, wherein: 7. The second output amount detecting means includes:
The power supply device according to claim 5, wherein a current flowing through a resistor connected to an output side of the rectifier is detected as the output amount. 8. The voltage control means is connected to an output side winding of the second transformer, and
Comparing means for comparing the output amount of the second voltage detected by the output amount detecting means with a reference value, and switch means for performing an on / off operation of the second driving means according to the comparison result. 2. The power supply device according to claim 1, wherein the on / off operation of the second driving unit is performed in a cycle longer than a cycle of the output pulse signal supplied from the pulse width control unit. 3. 9. The second output amount detecting means, wherein
9. The power supply device according to claim 8, wherein a voltage divided by a resistor connected to an output side of the rectifier is detected as the output amount. 10. The first and second output amount detecting means detects a current flowing through a resistor connected to an output side of each of the first and second rectifying means as the output amount. The power supply device according to claim 8, wherein 11. The power supply according to claim 1, wherein the power supply is applied to a high-voltage power supply used in an image forming process of the image forming apparatus. 12. An output control method for a power supply device for outputting a first voltage and a second voltage from a first voltage output circuit and a second voltage output circuit, respectively, wherein the first voltage output circuit comprises: Rectifying the output of the first transformer for boosting the voltage and outputting the rectified output as a first voltage; detecting the output amount of the first voltage; and outputting an output pulse signal based on the detected output amount. Controlling the pulse width of the output pulse signal, and driving the first transformer in accordance with the pulse width of the output pulse signal. Accordingly, a step of driving a second transformer that boosts an input voltage, a step of rectifying an output of the second transformer and outputting the rectified output as the second voltage, and detecting an output amount of the second voltage. And a step of Based on the issued output amount, the output control method of the power supply apparatus characterized by a step of controlling the second voltage.