JP2000232729A - Power supply device and power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise and improve efficiency. SOLUTION: At transfer, a change-over circuit 12 is controlled to drive one of a transfer voltage control unit 14 and a transfer current control unit 16 and one of the primary input voltage, and the primary input current of a transformer 50 is controlled to be constant to obtain a prescribed value of the output of a half-wave rectifying circuit 51. A transfer current bypass switch 25 is turned on according to the current of the secondary side of the transformer 50, which is detected by a transfer output current detection unit 24 and a reverse-bias discharge resistance 20 is short-circuited. At non-transfer, the primary side input of a current transformer 60 is controlled by a reverse-bias voltage control unit 26 and a reverse-bias output voltage detection unit 28, to cause a positive output to be generated in a half-wave rectifying circuit 61 on the secondary side of the transformer 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device and a power supply system, and more particularly, to the first power supply circuit and the output side of a second power supply circuit which are connected in series by a bypass resistor. The present invention relates to a power supply device for selectively outputting power from a power supply circuit and a second power supply circuit, a power supply device for obtaining a power output by switching a power supply input by a switching unit, and a power supply system including these power supply devices.

[0002]

2. Description of the Related Art Image forming apparatuses such as printers and copiers form an electrostatic latent image on a photosensitive drum, develop it with toner to form a toner image, and use a contact transfer device (hereinafter referred to as a transfer device). And the toner image is transferred to the paper. The transfer device charges the transfer roll to the opposite charge (−) to the toner (+). That is, the transfer device supplies a negative high voltage output to the transfer roll. As described above, the toner (+) may adhere to the transfer roll supplied with the negative high-voltage output. If the toner adheres to the transfer roll, the toner adheres to the back of the sheet, and the sheet may be stained.
Therefore, it is necessary to clean unnecessary toner attached to the transfer roll. Therefore, during non-transfer, the transfer device applies a reverse polarity (plus high voltage output) to the transfer roll.

Power supply systems for applying voltages of different polarities include a circuit system in which positive and negative converters are connected in series (series) and a circuit system in which positive and negative converters are connected in parallel via switches. .

[0004] A circuit system for connecting a positive / negative converter to a series includes, for example, a power supply device for supplying a high voltage output obtained by increasing a low voltage input voltage to a load as described in Japanese Patent Publication No. 2-16659. The first and second high-voltage output sections provided on the low-pressure side and the first and second high-voltage output sections provided on the low-pressure side are selectively operated (one side O).
FF configuration), and an output switching device, which is provided in parallel with each output winding of the first and second high-voltage output units,
And a first and a second resistor connected to each other, provided in parallel with the output winding, respectively, and
There is a positive / negative switching high voltage power supply device comprising first and second resistors connected to each other, wherein the output switching device switches positive and negative high voltage output to a load. As a circuit system for connecting the positive and negative converters in parallel via a switch, there are devices described in JP-A-5-224541 and JP-A-1-292385.

As shown in FIG. 14, a power supply device for supplying power to the transfer device includes a switching element 70 for performing switching control of a primary-side input by using a booster circuit 50.
The output state detection circuit 80 detects the output state of the secondary side which has been increased in voltage by the booster circuit 50, compares the detected output state with a reference value, and determines the duty value of the PWM signal to be given to the switching element 70. Switching circuit 7 for controlling
A control circuit including a comparison circuit 74 and the like.

[0006] Such a power supply circuit is caused by a change in the impedance of the transfer device due to the environment of the transfer device (including a change in the temperature outside the machine), a change in the impedance of the paper, and a change in the impedance of the transfer device due to contamination of the transfer device. The output supplied to the transfer roll changes, and it may be difficult to maintain high image quality. Therefore, in order to reduce the influence of the environment and the like on the transfer performance, it is necessary to observe the state value of the transfer device, such as impedance, at appropriate times and to keep the output of the power supply supplied to the transfer roll constant.

As a general means, before performing the transfer,
The impedance of the transfer device is observed, and transfer parameters are determined from a table of transfer voltage and transfer current with respect to the impedance of the transfer device prepared in advance. Or
Appropriate transfer voltage and transfer current are obtained by calculation from the impedance of the transfer device to determine transfer parameters. Then, based on the transfer parameters, the input voltage and the input current on the primary side are switching-controlled to make the output of the power supply supplied to the transfer device constant.

[0008]

The circuit system in which the positive and negative converters are connected in series is an effective technique for reducing the size of the power supply device and reducing noise at the time of positive / negative switching. Depending on the output current and voltage, the power loss of the bypass resistor increases as the square of the current and voltage values.
The range of use of the circuit is limited. The circuit system in which the positive and negative converters are connected in parallel via a switch is an effective technique for increasing the efficiency of the power supply, increasing the output voltage, and increasing the power.However, noise is generated when the output is switched. Therefore, it is necessary to take measures against the device and peripheral devices, which increases the cost. In addition, since the size of the device is increased due to the switching device and noise countermeasures, and the switching speed is limited, the application is limited.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its first object to propose a power supply device and a power supply system which can be used in a wide range with low noise and high efficiency. I do.

Further, in the configuration including the switching circuit 72 and the comparison circuit 74 as described above, the switching time of the switching circuit 72 and the operation time of the comparison circuit 74 take time, so that the output after switching as a power source is stabilized. In the case of a high-speed machine or a case where switching time is severely required, image quality may be affected.

During the switching of the switching circuit 72, the reference value is indefinite, so that a period during which the output becomes unstable as a power supply occurs, an abnormal voltage is generated, and a circuit failure, a leak in the transfer device or a damage to the transfer device occurs. There is a possibility.

Since there is one comparison circuit 74, it is difficult to stably control the output over a wide range, which may affect the image quality.

The use of a mechanical relay or a semiconductor switch for the switching circuit increases the cost.

The present invention has been made in view of the above-mentioned circumstances, and it is a second object of the present invention to propose a power supply device and a power supply system capable of shortening a switching time when changing parameters according to the state of the power supply device. The purpose of.

[0015]

In order to achieve the first object, the invention according to claim 1 comprises a first power supply circuit and a second power supply circuit.
In the power supply device, the output sides of the power supply circuits are connected in series by a bypass resistor and selectively output from the first power supply circuit and the second power supply circuit. Bypass means for bypassing with a lower resistance value is provided on at least one output side of the first power supply circuit and the second power supply circuit.

As described above, when the output of each power supply circuit of the first power supply circuit and the second power supply circuit is off, the bypass means bypasses with a resistance value lower than the bypass resistance.
Internal loss can be reduced, high efficiency can be achieved, and noise is not generated at the time of switching because of such bypassing.

The bypass means may be a switching means for short-circuiting one of the divided resistors.

According to a third aspect of the present invention, there is provided a power supply apparatus for obtaining a power output by switching a power input by a switching means. And a plurality of control means including error amplification.

Thus, the driving of the switching means,
Since a plurality of control means including the reference value and the error amplification between the power supply output are provided, each of the plurality of control means compares each of the reference values with the power supply output, so that time for switching the reference value can be eliminated. Thus, it is possible to reduce the time for switching parameters according to the state of the power supply device.

From the above, the following invention is proposed. That is,
A first power supply device that obtains a power output by switching a power input by a switching means, and an output side of the first power circuit and a second power circuit connected in series by a bypass resistor;
A second power supply device for selectively outputting from a first power supply circuit and a second power supply circuit based on a power supply output from the power supply device.
The power supply device of the present invention is provided with a plurality of control means including the drive of the switching means, the amplification of the error between the reference value and the power supply output, the second power supply device, when the output of each power supply circuit is off, A power supply system is proposed in which bypass means for bypassing with a resistance value lower than the bypass resistance is provided on at least one output side of the first power supply circuit and the second power supply circuit.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In this embodiment, a power supply system that supplies power to a transfer device in an image forming apparatus such as a printer or a copying machine will be described as an example.

As shown in FIG. 1, the power supply system comprises:
The first to boost the primary input and generate a negative output
And a second transformer 60 and a half-wave rectifier circuit 61 for boosting a primary-side input to generate a plus output. Transfer voltage control on the primary side of the first transformer 50 for controlling the primary side input to a constant voltage and controlling the secondary side output to a predetermined voltage (a value corresponding to the first state of the transfer apparatus) The unit 14 and a transfer current control unit 16 for controlling the primary input to a constant current and controlling the secondary output to a predetermined voltage (a value corresponding to the second state of the transfer device) are connected. . Transfer voltage control unit 14 and transfer current control unit 1
6 is connected to a switching circuit 12 for switching between them. The switching circuit 12 receives a constant voltage / constant current select signal that drives (enables) either the transfer voltage control unit 14 or the transfer current control unit 16.

On the primary side of the second transformer 60, a reverse bias voltage control unit 26 for controlling the primary side input and controlling the secondary side output to a constant voltage (a voltage that can be cleaned) and a reverse bias voltage control unit 26 The output voltage detector 28 is connected.

The switching circuit 12 and the reverse bias voltage control section 26 are connected to a signal determination circuit 30 for inputting a transfer signal for transfer and a cleaning signal for cleaning. The transfer / cleaning select signal is input to the signal determination circuit 30.

The half-wave rectifier circuit 51 on the secondary side of the first transformer 50 is connected in parallel with the bypass resistor 18 for reverse bias current. A rush current suppression resistor 19 for transfer current bypass and a reverse bias discharge resistor 20 connected in series are connected in parallel to the half-wave rectifier circuit 61 on the secondary side of the second transformer 60. A transfer current bypass switch 25 is connected in parallel with the reverse bias discharge resistor 20. The resistors 18, 1
9 and 20 are connected in series. First transformer 50
The transfer output voltage detector 22 is connected to the output side (V _OUT ) of the second transformer 60. The above resistor 1
8, 19 and 20, a transfer output current detector 24 is further connected in series. The transfer output current detector 24 includes a transfer current bypass switch 25 and a transfer current controller 16.
, And the transfer output voltage detection unit 22 is connected to the transfer voltage control unit 14 and the monitor voltage correction circuit 32.

Next, the operation of the present embodiment will be described.

First, the transfer operation will be described. At the time of transfer, the signal determination circuit 30 outputs a transfer signal so as to output a transfer signal.
A transfer / cleaning select signal is input. The transfer signal is input to the switching circuit 12. The switching circuit 12 to which the transfer signal has been input inputs the drive signal to the transfer voltage control unit 14 or the transfer current control unit 16 based on the constant voltage / constant current select signal, so that the transfer voltage control unit 14 and the transfer current control One of the units 16 is driven. In the case where the primary input is controlled by the constant voltage, the transfer voltage control unit 14 is driven. As a result, the primary input is controlled at a constant voltage,
, A negative output is generated on the secondary side via the transformer 50 and the half-wave rectifier circuit 51. The reverse bias voltage control unit 26 is in a short-circuited state because the transfer current bypass switch 25 is ON although the reverse bias voltage control unit 26 is being driven.
An output is generated on the secondary side of the transformer 60, but is not supplied to the load side.

When a negative output is generated on the secondary side of the first transformer 50, as shown by the dotted lines, the resistors 18, 1
A current is about to flow through the transfer current 9 and 20. This current is detected by the transfer output current detection unit 24, and a detection signal is input to the transfer current bypass switch 25, which turns on the switch 25 and reverse biases it. Discharge resistor 20
Short circuit. Therefore, the reverse bias discharge resistor 2
0, no current flows during transfer. When a negative output is generated on the secondary side of the first transformer 50, the voltage on the secondary side is detected by the transfer output voltage detection unit 22, and the detection signal is input to the transfer voltage control unit 14 and the negative voltage is detected. A current associated with the output is detected by the transfer output current detection unit 24, and this detection signal is input to the transfer current control unit 16, and the transfer voltage control unit 14 and the transfer current control unit 16 determined by the constant voltage / constant current select signal. One of them controls the switching of the first transformer 50 by comparing it with the reference value that each has.

Next, the non-transfer time (cleaning) will be described. At the time of non-transfer, a transfer / cleaning select signal is input to the signal determination determination circuit 30 so that a cleaning signal is output. The cleaning signal is input to the reverse bias voltage controller 26. In this case, the switching circuit 12 does not output a drive signal to the transfer voltage control unit 14 and the transfer current control unit 16. Therefore, they are not driven. On the other hand, the reverse bias voltage control unit 26 to which the cleaning signal has been input controls the primary side input at a constant voltage. As a result, the second transformer 60 and the half-wave rectifier circuit 61 generate a positive output on the secondary side. At this time, the magnitude of the secondary side voltage is
8, and based on the detected value, the reverse bias voltage control unit 26 controls the primary side input so that the secondary side output becomes a predetermined voltage (a voltage that can be cleaned). When a positive output is generated on the secondary side of the second transformer 60, a current flows accordingly through the resistors 18, 19, and 20.

Here, referring to FIG.
The secondary side of the 0 and the second transformer 60 will be described in detail.
As shown in FIG. 3, the secondary sides of the first transformer 50 and the second transformer 60 are connected to the secondary power supply 50 of the first transformer.
A and the secondary power supply 50B of the second transformer are connected in series, and these can be considered to be configured to be connected in series by bypass resistors 18, 19, and 20.
As described above, the switch 25 is connected to the resistor 20 in parallel. A load is connected to the resistors 18, 19, and 20 in parallel. Here, conventionally, the configuration is the same as that of FIG. 3 except that the switch 25 is omitted.
Conventional and application-specific voltages Vo1, Vo2, first
The voltage V1 of the secondary power supply 50A of the transformer, the voltage V2 of the secondary power supply 50B of the second transformer, the resistors 18, 19,
The 20 losses Po1, Po2 are as follows.

Load-to-load voltage type At the time of transfer Conventional Vo1 = V1- (Z2 + Z3) × 11 Application Vo1 = V1-Z3 × 11 At the time of non-transfer Conventional Vo2 = V2-Z1 × 12 Application Vo2 = V2-Z1 × 12 Conversion-type At the time of transfer Conventional V1 = Vo1 + (Z2 + Z3) × 11 Present application V1 = Vo1 + Z3 × 11 Non-transferred Conventional V2 = Vo2 + Z1 × 12 Present application V2 = Vo2 + Z1 × 12 PowerLoss calculation formula During transfer Conventional Po1 = (Vo1 + (Z2 + Z3) × 11) ² ÷ Z1 + 11 ² × (Z2 + Z3) Application Po1 = (Vo1 + Z3 × 11) ² ÷ Z1 + 11 ² × Z3 ... SW ON Non-transferring Conventional Po2 = (Vo + Z1 × 12) ² ÷ (Z2 + Z3) +12 ² × Z1 Application Po2 = (Vo + Z1 × 12) ² ÷ (Z2 + Z3) +12 ² × Z1 ... SW OFF

FIG. 4 shows a state at the time of transfer in the configuration of FIG. The resistors 18, 19, and 20 are 100 MΩ, 100 kΩ, and 10 MΩ, respectively.
Then, consider the case where the output voltage on the secondary side, the output current, the transfer transformer generating voltage, and the transfer current bypass resistor voltage are as shown in the following table.

[0033]

[Table 1]

As shown in Table 1, an output current of 1300 μA or 1500 μA flows. Since the transfer current bypass switch 25 is turned on at the time of transfer, the resistor 20 (10 MΩ) is short-circuited to avoid an internal loss occurring in the resistor 20, and the loss in the resistors 18 and 19 is reduced to 0 in the worst state. .49W. Table 2 shows the results when the image is not transferred.

[0035]

[Table 2]

As described above, in the present embodiment, the switch 25 is turned on to bypass with a resistance value lower than the bypass resistance, so that the internal loss can be reduced and noise is generated at the time of switching. Can be prevented. That is, the following various effects can be obtained.

That is, since no noise is generated at the time of switching between the − output and the + output, no cost is required for measures for the device and the peripheral device. Even if the increase in the bypass resistance value switching device is anticipated, the cost of the entire device can be extremely reduced. Since the power loss of the bypass resistor increases as the square of the current value and the voltage value depending on the output current and the voltage, the additional device of the bypass resistance variable device is smaller than the power supply device corresponding to the power-up. is there. The switching speed at the time of the above switching can be made extremely high.

There are very few restrictions on the increase of the output voltage and the current value. (It is also possible to cope with high power.) Since the voltage of each (positive / negative) power supply device can be increased very little, the processing such as withstand voltage becomes unnecessary, and the cost and size can be reduced.

In the first embodiment described above, the transfer current bypass switch is turned on based on the transfer output current. However, the present invention is not limited to this. You can do so. That is, it may be determined whether or not the current time is the time of the transfer operation based on the outputs from the following various elements, and the transfer current bypass switch may be turned on.

That is, as shown in FIG. 5, the switch 25 may be turned on based on the detection signal of the transfer output voltage detecting section 22. As shown in (5), the switch 25 may be turned on based on a signal from the transfer voltage control unit 14.
On the other hand, when performing primary side constant current control, the switch 25 may be turned on based on a signal from the transfer current control unit 16 as shown in FIG. Further, as shown in FIG. 8, the switch 25 may be turned on based on a signal from the reverse bias voltage control unit 26. Further, as shown in FIG. 9, the switch 25 may be turned on based on a signal from the reverse bias output voltage detecting section 28.
It should be noted that, based on the signal from the signal determination circuit 30, the switch 2
5 may be turned on.

In the first embodiment described above, the reverse bias discharge resistor is short-circuited by the transfer current bypass switch. However, the present invention is not limited to this. The bypass resistor may be short-circuited by a switch. It is to be noted that the present invention is not limited to the case where a short circuit occurs, and the bypass may be performed with a resistor having a smaller value than the bypass resistor.

Next, a second embodiment of the present invention will be described. This embodiment has a configuration similar to that of the above-described first embodiment. Therefore, the same portions will be omitted, and different portions will be described.

As shown in FIG. 10, the switching circuit 12A according to the present embodiment is configured by arranging a plurality of transistors, in this embodiment, three stages of transistors.
This switching circuit 12A includes a reference voltage A / B corresponding to the constant voltage / constant current select signal in the first embodiment.
A switching signal is input. In the present embodiment, the impedance of the transfer device is determined, and based on the determined impedance, the reference voltage A / B switching signal indicating whether to set the reference voltage A or the reference voltage B to the switching circuit 12A.
Is input to In this case, when setting the reference voltage A,
The reference voltage A / B switching signal becomes High, and when the reference voltage B is set, the reference voltage A / B switching signal becomes Low.
State. Switching regulator ICs 14A and 16A are connected to the switching circuit 12A. The switching regulator IC 14A receives the V _OUT reference voltage A and the I _OUT reference voltage A. The reference voltage B for V _OUT and the reference voltage B for I _OUT are input to the switching regulator IC 16A. In the present embodiment, the output state detection circuit 80 (in the first embodiment, the transfer output voltage detection unit 22 and the transfer output current detection unit 24
). The V _OUT detection voltage and the I _OUT detection voltage from the output state detection circuit 80 are input to the switching regulator ICs 14A and 16A, respectively.
The switching regulator ICs 14A and 16A are connected to the base side of the switching element circuit 70, respectively. On the connector side of the switching element circuit 70,
The booster circuit 50 is connected.

Next, the operation of the present embodiment will be described. As described above, when switching to the reference voltage A based on the impedance of the transfer device, the reference voltage A / B switching signal is set to a high state. As a result, the first-stage transistor is turned on, and the second-stage connector side becomes Low and is input to the switching regulator IC 16A. Therefore, the switching regulator IC is in a non-driving state. Reference voltage A / B switching signal (High state)
Is input to the base side of the second-stage transistor,
The transistor in the second stage is turned on, and the connector side of the transistor in the second stage is low. When the second-stage transistor connector side becomes Low, the third-stage transistor is turned off, and the connector side of the third-stage transistor is VF.
As a result, the switching regulator IC 14A is driven into a High state, and is input to the switching regulator IC 14A. Switching regulator IC
14A, the V detected by the output state detection circuit 80 is
_OUT detection voltage and I _OUT detection voltage are input respectively,
Each is compared with the V _OUT reference voltage A, and based on the result, the switching element circuit 70 is controlled, and the primary side of the booster circuit 50 is controlled at a constant voltage.

On the other hand, when the impedance of the transfer device changes and the reference voltage B is selected, the reference voltage A
/ B switching signal is in the Low state. When the reference voltage A / B switching signal is in a low state, the characteristics are the opposite of those when the reference voltage A / B switching signal is in a high state, so that the switching regulator IC 14A is in a non-driving state and the switching regulator IC 16A is in a driving state. The V _OUT detection voltage and the I _OUT detection voltage detected by the output state detection circuit 80 and the V _OUT reference voltages B and I
_The reference voltage B is compared with the _OUT reference voltage B, and the switching element circuit 20 is controlled based on the comparison result.
The secondary input is controlled by constant voltage.

Thus, the switching regulator IC 14A for comparing the reference voltage A with the detected voltage,
A switching regulator IC for comparing the reference voltage B with the detected voltage is provided, and which of the switching regulator ICs is driven is selected based on the reference voltage A / B switching signal High or Low. The time for switching the reference value can be eliminated. That is, the following various effects can be obtained.

That is, the switching time of the switching circuit as shown in FIG. 14 and the operation time of the comparison circuit can be reduced, and the response time of output mode switching can be improved.

The state where the reference value during switching of the switching circuit becomes indefinite is eliminated, and the unstable output state at the time of switching can be improved.

Since a comparison circuit is provided for each output mode, output stabilization control suitable for output characteristics can be realized with a simple configuration.

Since no mechanical relay or semiconductor switch is used, the cost can be reduced. Next, a modification of the second embodiment will be described. In this modified example, as shown in FIG. 11, a booster circuit detects a switching element that periodically switches an applied voltage on a primary side of a transformer and an output state on a secondary side that is boosted by a booster circuit. At least a comparison circuit 84, a switching element drive circuit 14A, which controls the DUTY value of the PWM signal to be given to the switching element 70 by comparing the secondary side output with the target value.
16B are provided, and an external signal (reference voltage A) is provided between the subsequent stage of the comparison circuit 84 and the switching element driving circuit.
/ B switching signal), one of the two comparison circuits 84 and one of the switching element driving circuits 14A and 16B can be selectively operated. In fact, the control circuit generally uses a switching regulator I
C (for example, TL594 manufactured by TI) is used.

The detailed electric circuits of the first and second embodiments described above will be described with reference to FIGS. The electric circuits in FIGS. 12 and 13 are connected via A, B, C, and D, respectively.

As shown in FIG. 12, the switching circuit 12
As in the second embodiment (FIG. 10), a plurality of transistors are provided. The transfer voltage control unit 14 includes a switching regulator IC 14A as in the above-described second embodiment. The transfer current control section 16 includes a switching regulator IC 16A as in the second embodiment described above. The transfer voltage control unit 14 and the transfer current control unit 16 include a switching element 70 as in the second embodiment. The switching element 70 controls the booster circuit (first transformer) 50.

As shown in FIG. 13, the reverse bias voltage control section 26 includes a reverse bias current control section 28 and controls the second transformer 60. In this electric circuit, the transfer current bypass switch 25 is controlled based on a signal from the signal determination circuit 30, and the reverse bias discharge resistor 20 is short-circuited.

A determiner (not shown) determines the state (impedance, etc.) of the transfer device, and according to the determined state,
The switching circuit 12 supplies a constant voltage /
Input the constant current select signal.

That is, when the constant voltage control is performed (the transfer device is in the first state), a high-state constant voltage / constant current select signal is input, the transistor is turned on, and the switching of the transfer voltage control unit 14 is performed. The signal is input to the regulator IC 14A as an enable signal to be in an enabled state.
The secondary output from the secondary half-wave rectifier circuit 51 of the first transformer 50 is the operational amplifier 2 of the transfer output voltage detection unit 22.
A large signal corresponding to the value of the secondary output is input to the switching regulator IC 14A. The switching regulator IC 14A compares the reference signal A stored therein with the input signal, controls the switching of the switching element 70, and outputs the signal from the half-wave rectifier circuit 51 on the secondary side of the first transformer 50. The secondary output is controlled so that the transfer device has a magnitude corresponding to the first state.

On the other hand, when the constant current control is performed (the transfer device is in the second state), a low-state constant voltage / constant current select signal is input, the transistor is turned off, and the switching of the transfer current control unit 16 is performed. The signal is input to the regulator IC 16A as an enable signal to be in an enabled state.
The secondary output from the secondary half-wave rectifier circuit 51 of the first transformer 50 is the operational amplifier 2 of the transfer output current detection unit 24.
A signal that is input to 4P and indicates the value of the current flowing through the half-wave rectifier circuit 51 is input to the switching regulator IC 16A. The switching regulator IC 16A compares the reference signal B stored therein with the input signal, controls the switching of the switching element 70, and outputs the switching signal from the half-wave rectifier circuit 51 on the secondary side of the first transformer 50. 2
The secondary output is controlled so that the transfer device has a magnitude corresponding to the second state.

At the time of transfer as described above, a low-state transfer / cleaning signal is input to the signal determination circuit 30 via the input terminal 106. In this case, the signal determination circuit 30
Transistor 30C is turned off, the transfer current bypass switch 25 is turned on, and the reverse bias discharge resistor 20 is short-circuited.

On the other hand, at the time of non-transfer (at the time of cleaning),
The transfer / cleaning signal in the high state is input to the signal determination circuit 30 via the input terminal 106. This allows
The light emitting diode 30B emits light, and the photodiode 26A of the reverse bias voltage control unit 26 receives light, and enters an enabled state. The secondary output (voltage applied to the transfer roll) of the second transformer 60 is detected by the reverse bias output voltage detection unit 28 via the inductance 63, and a signal having a value corresponding to the secondary output is output from the transistor. 26B is input to the base side. Accordingly, the second transformer 60 is controlled in accordance with the magnitude of the secondary output, and the secondary output is controlled to a size that can be cleaned.

In the above-described embodiment, two types of transfer device states, a first state and a second state, have been described as examples. However, the present invention is not limited to this. Control may be performed according to a plurality of larger states. In this case, switching regulators having a plurality of states may be provided, and control may be performed in the same manner as described above.

[0060]

As described above, according to the first aspect of the present invention, when the output of each of the first power supply circuit and the second power supply circuit is off, the bypass means has a resistance value lower than the bypass resistance. In this case, the internal loss can be reduced, the efficiency can be increased, and noise is not generated at the time of switching.

According to the third aspect of the present invention, a plurality of control means including driving of the switching means and amplification of an error between the reference value and the power supply output are provided. Since the comparison with the power supply output is performed, the time required for switching the reference value can be eliminated, and the time required for switching the parameter according to the state of the power supply device can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment.

FIG. 2 is a diagram illustrating the operation of the first embodiment.

FIG. 3 is a schematic diagram illustrating a secondary side of a first transformer and a second transformer.

FIG. 4 is a detailed view of the electric circuit of FIG. 3;

FIG. 5 is a block diagram showing a first modification of the first embodiment.

FIG. 6 is a block diagram illustrating a second modification of the first embodiment.

FIG. 7 is a block diagram showing a third modification of the first embodiment.

FIG. 8 is a block diagram showing a fourth modification of the first embodiment.

FIG. 9 is a block diagram showing a fifth modification of the first embodiment.

FIG. 10 is a block diagram of a second embodiment.

FIG. 11 is a block diagram showing a modification of the second embodiment.

FIG. 12 is a part of a detailed electric circuit of the first embodiment and the second embodiment.

FIG. 13 shows the rest of the electric circuit of the first embodiment and the second embodiment.

FIG. 14 is a conventional electric circuit.

[Explanation of symbols]

50 first transformer (first power supply circuit) 51 half-wave rectifier circuit (first power supply circuit) 60 second transformer (second power supply circuit) 61 half-wave rectifier circuit (second power supply circuit) 18, Reference Signs List 20 resistance (bypass resistance) 25 switch (bypass means) 70 switching element (switching means) 12A switching circuit (control means) 14A, 16A switching regulator IC (control means)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 EA03 JA20 ZA01 2H032 BA23 5G065 AA00 AA01 DA07 EA01 FA05 GA03 HA01 HA18 JA01 KA02 KA05 LA01 LA02 MA09 MA10 NA02

Claims (4)

[Claims] 1. A power supply device in which the output sides of a first power supply circuit and a second power supply circuit are connected in series by a bypass resistor and selectively output from the first power supply circuit and the second power supply circuit. A power supply device, wherein bypass means for bypassing with a resistance lower than the bypass resistance when at least one output of the power supply circuit is off is provided on at least one output side of the first power supply circuit and the second power supply circuit. . 2. The power supply device according to claim 1, wherein the bypass unit is a switching unit that short-circuits one of the divided resistors. 3. A power supply apparatus for obtaining a power output by switching a power input by a switching means, wherein a plurality of control means including a drive of the switching means and an error amplification between a reference value and a power output are provided. Power supply features. 4. A first power supply device for obtaining a power output by switching a power supply input by a switching means, and an output side of the first power supply circuit and an output side of the second power supply circuit connected in series by a bypass resistor. A second power supply device for selectively outputting from a first power supply circuit and a second power supply circuit based on a power supply output from the power supply device, wherein the first power supply device comprises: A plurality of control means including driving the switching means and amplifying an error between a reference value and a power supply output, wherein the second power supply device is configured such that when an output of each power supply circuit is turned off, A power supply system, wherein bypass means for bypassing with a low resistance value is provided on at least one output side of the first power supply circuit and the second power supply circuit.