JP3309579B2 - High voltage power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a color image forming apparatus such as an electrophotographic color printer or a color copying machine, and is used for supplying a high voltage such as a developing bias voltage to a developing device. It is about.

[0002]

2. Description of the Related Art As a color image forming apparatus to which this type of high-voltage power supply device is applied, for example, there is the following one. That is, as shown in FIG. 11, the color image forming apparatus uniformly charges the surface of the photosensitive drum 100 to a predetermined voltage by the primary charger 101 and then applies the first color to the surface of the photosensitive drum 100. To form an electrostatic latent image corresponding to the first color image. Then, the first-color electrostatic latent image formed on the photosensitive drum 100 is developed by the first-color developing device 102 to form a first-color toner image.

Next, the photosensitive drum 100 on which the toner image of the first color has been formed enters a second rotation cycle without passing through a transfer step or a cleaning step, and the surface of the photosensitive drum 100 is once again reprimed. After being uniformly charged by the charger 101, the second color image exposure and the developing process by the second color developing device 103 are performed to form a second color toner image on the surface of the photosensitive drum 100.

Further, in the same manner as above, the third and fourth rotations of the photosensitive drum 100 are cycled to expose the third and fourth colors of the image on the surface of the photosensitive drum 100, and the third and fourth rotations are performed. Fourth color developing units 104, 10
5 to form a color toner image in which four color toner images are superimposed on the surface of the photosensitive drum 100.

Then, while the photosensitive drum 100 rotates four times as described above, the four color toner images formed on the photosensitive drum 100 are transferred onto the transfer paper 107 by charging of the transfer charger 106. Along with these 4
The transfer paper 107 on which the color toner image is transferred is separated from the photosensitive drum 100 by charging of the separation charger 108, and the color toner image is fixed on the transfer paper 107 by a fixing device (not shown) to form a color image. End the process.

As described above, in the color image forming apparatus configured as described above, the toner images of four colors are sequentially formed on the photosensitive drum 100 while the photosensitive drum 100 rotates four times, so that the color image is formed. Since an image is formed, it is necessary to develop a toner image of the next color without disturbing the toner images sequentially formed on the photosensitive drum 100.

For this reason, each of the developing devices 102 to 105 of the color image forming apparatus includes a DC voltage in which an AC voltage necessary for performing good development is superimposed on one developing device during development. A predetermined DC voltage for preventing the toner from adhering to the photosensitive drum 100 is applied to the other three developing units to which the developing bias voltage is applied and the developing is not performed.
A high voltage power supply for applying a voltage is used.

For example, as shown in FIG. 11, the high-voltage power supply device includes four high-voltage power supply units 110 to 113 provided corresponding to the four developing units 102 to 105, respectively. All of the parts 110 to 113 have the same configuration. The high-voltage power supply units 110 to 113 include:
It comprises an AC voltage generator 114 for generating an AC voltage and a DC voltage generator 115 for generating a DC voltage. The AC voltage generation unit 114 includes an AC switching control unit 116 on the primary side of the step-up transformer T.
The switching control unit 116 turns on and off the voltage applied to the primary side of the step-up transformer T, thereby generating a high AC voltage on the secondary side of the step-up transformer T. In the AC voltage generator 116, a voltage monitor 117 and an overcurrent monitor 118 are provided on the secondary side of the step-up transformer T in order to enable constant voltage output and control of overcurrent.
The voltage monitor 117 and the overcurrent monitor 118 detect the output voltage and the output current, so that the AC switching control unit 116 controls the voltage applied to the primary side of the step-up transformer T on and off, and outputs The voltage is kept constant and overcurrent control is performed.

On the other hand, the DC voltage generating section 115 has a DC switching control section 119 on the primary side of the step-up transformer T, and turns on and off a voltage applied to the primary side of the step-up transformer T by the DC switching control section 119. As a result, a high voltage is generated on the secondary side of the step-up transformer T. Then, after the high voltage generated on the secondary side of the step-up transformer T is rectified by the rectifier circuit 120 including a diode or the like, the DC high voltage is output via the DC output control unit 121.

In the above high voltage power supply, each high voltage power supply 11
The AC voltage generated by the AC voltage generator 114 and the DC voltage generated by the DC voltage generator 115 are superimposed on each other and output to the corresponding developing devices 102 to 105.

However, in the above-mentioned conventional high-voltage power supply device, four high-voltage power supply units 11 correspond to the developing units 102 to 105, respectively.
0 to 113, and each of the high-voltage power supply units 110 to 113
A developing bias voltage composed of a DC voltage on which an AC voltage is superimposed is applied to one of the developing devices 102 to 105 at a predetermined timing, and the other developing devices 102 to 105 are not performing development. The configuration is such that only a predetermined DC voltage is applied to one developing device. Therefore, in the above-mentioned conventional high-voltage power supply device, it is necessary to separately provide the high-voltage power supply units 110 to 113 corresponding to the number of the developing devices as loads, so that the configuration of the device becomes complicated and the cost increases. was there.

In order to solve the problems of the conventional high-voltage power supply, Japanese Patent Laid-Open Publication No. Hei.
32358, JP-A-1-308128, JP-A-1-308129, JP-B-4-14759, JP-A-61-59460, JP-A-62-1
No. 60073 has already been proposed.

The high-voltage supply device disclosed in Japanese Patent Application Laid-Open No. 3-32358 is an image forming apparatus using an electrophotographic process, wherein at least two high-voltage loads are connected to one high-voltage power supply via respective resistors. A load current detection resistor is connected to one of the two high-voltage loads, and a switching control unit that keeps the load current constant by an output comparing a detection voltage of the detection resistor with a reference voltage is connected to an input side of the high-voltage power supply. It is configured so that

The power supply device according to the above-mentioned Japanese Patent Application Laid-Open No. 1-308128 is a power supply device that outputs high voltages having different output timings to a plurality of loads. Comprising a step-up transformer, a voltage doubler rectifier circuit and an output control element connected in front of the voltage doubler rectifier circuit, and having a plurality of output circuits connected to the secondary side of the step-up transformer. It is.

Further, in the power supply device according to the above-mentioned Japanese Patent Application Laid-Open No. 1-308129, a power supply device that outputs high voltages having different output timings to a plurality of loads is a single unit in which a predetermined alternating current is applied to the primary side. A step-up transformer, a voltage doubler rectifier circuit, an output control element connected upstream of the voltage doubler rectifier circuit, and a superimposing circuit that superimposes an AC generated at a control point by the output control element on an output of the voltage doubler rectifier circuit And a plurality of output circuits connected to the secondary side of the step-up transformer.

Further, the image forming apparatus according to Japanese Utility Model Publication No. 4-14759 includes developer conveying members for supplying a developer to the electrostatic latent image carrier while facing the electrostatic latent image carrier. In the image forming apparatus having a plurality of developing units, one high-voltage power supply is provided for applying a developing bias to the developer conveying member of each of the developing units, and the developer conveying member of each of the developing units and the high-voltage power supply are provided. Is connected via a switch means, and the high-voltage power supply is supplied to the developer conveying member of the developing device designated to apply the developing bias voltage after the switching means for the developer conveying member of the developing device is closed. The developing bias voltage is applied by energizing, and the switch means is opened after the high-voltage power supply is deenergized.

Further, the high voltage power supply for charging according to Japanese Patent Application Laid-Open No. 61-59460 is used in an electrophotographic process having a transfer corona discharger and a pre-cleaning corona discharger. A transformer is provided in parallel, a common DC power supply and a switching element are connected to the primary side, a load current flowing through a load connected to the secondary side of one boosting transformer is detected, and the conduction time of the switching element is controlled. It is configured so that

Furthermore, the above-mentioned Japanese Patent Application Laid-Open No. Sho 62-160073
In the high-voltage power supply according to the publication, primary windings of a plurality of step-up transformers are connected in parallel, and one of the first connection points is used as a driving power supply,
A multi-output for connecting the other second connection point to the switching element, detecting the output of one boosting transformer, controlling the conduction ratio of the switching element according to the output value, and stabilizing the output of the boosting transformer. And a voltage effect means is provided between the first and second connection points of the primary winding of at least one step-up transformer.

[0019]

However, the prior art described above has the following problems. That is, in the case of the high-voltage power supply device disclosed in Japanese Patent Application Laid-Open No. 3-32358, which relates to a technology relating to a tracking circuit, the tracking circuit itself can supply a high voltage to a plurality of loads with one transformer. There is a problem that the supply is performed at the same timing with respect to the load.

In the case of the power supply according to the above-mentioned Japanese Patent Application Laid-Open Nos. 1-308128 and 1-308129, a plurality of voltage doubler rectifier circuits are provided in one boosting transformer to constitute a tracking circuit. In addition, by connecting the output control element to a stage preceding the voltage doubler rectifier circuit, a high voltage can be supplied to a plurality of loads at different timings. However, in the case of this power supply device, it is necessary to use a high-voltage component as the output control element because the output of the high voltage is switched by the output control element provided on the secondary side of the step-up transformer. In addition, there has been a problem that the size of the output control element becomes large and expensive.

Further, in the case of the image forming apparatus disclosed in Japanese Utility Model Publication No. 4-1759, the output of the high-voltage power supply is supplied in order to supply the developing bias voltage to a plurality of developing units at independent timing by one high-voltage power supply. Since the switch section is provided at the end, the switch section has a high voltage, and has a problem that the elements constituting the switch section are expensive and large.

Further, the high voltage power supply according to the above-mentioned Japanese Patent Application Laid-Open Nos. 61-59460 and 62-160073 has a plurality of step-up transformers for a plurality of loads.
Since a common DC power supply and a switching element are connected to the primary side, there is a problem that ON / OFF of an output to a load becomes the same timing.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a low-cost device capable of supplying a high voltage to a plurality of loads at different timings. Another object of the present invention is to provide a small high-voltage power supply.

[0024]

Means for Solving the Problems Claim 1 of the present invention
High-voltage power supply device according to the section corresponding input voltage to the plurality of loads
A plurality of step-up transformers for stepping up and supplying an AC voltage;
A single DC power supply for supplying DC voltage,
Provided on the secondary side of the transformer, from the single DC power supply
Controls the supplied DC voltage based on input information and controls
The resulting DC voltage is transferred to the secondary side of the step-up transformer.
A plurality of direct current output controllers superimposed on the current voltage.
Is constructed sea urchin.

Further, the high voltage power supply according to claim 2 of the present invention boosts an input voltage corresponding to a plurality of loads and
Multiple step-up transformers that supply AC voltage and DC voltage
Supply a single DC power supply,
Provided on the secondary side and supplied from the single DC power supply
The DC voltage is controlled based on the input information, and the DC
Voltage to the AC voltage generated on the secondary side of the step-up transformer.
A plurality of DC output control units for folding,
Provided on the primary side of the power supply, and based on the input control signal.
A plurality of switch means for turning on and off the input voltage;
Commonly connected to the primary side of a plurality of step-up transformers,
A single switch that switches the input voltage
And a control unit . Further
The high voltage power supply according to claim 3 of the present invention
The plurality of loads are a plurality of developing units, and the switch means
Is ON and output from the DC control unit corresponding to the developing unit under development
DC voltage corresponding to the remaining developing units
To a value different from the DC voltage output from the
It is configured.

[0026]

In the high voltage power supply according to the first aspect of the present invention, the input voltage is boosted and exchanged corresponding to a plurality of loads.
Multiple step-up transformers that supply
And a plurality of step-up transformers.
Provided on the secondary side and supplied directly from the single DC power supply.
Current based on the input information, and the DC
Voltage is superimposed on the AC voltage generated on the secondary side of the step-up transformer
And a plurality of DC output control units.
Power supply, a single DC power supply
And apply high voltage to multiple loads at different times.
Low-cost and compact high-voltage power supply that can be supplied
Can be provided.

Further, in the high-voltage power supply according to claim 2 of the present invention, the primary of the plurality of step-up transformers
And the input power based on the input control signal.
A plurality of switch means for turning on and off the pressure;
Common to the primary side of the
A single switching control unit for switching
So that a single switch
Supports multiple loads that supply AC voltage using only the power control unit
It can be turned on independently by multiple switch means,
Can be turned off, so that multiple loads can be
Voltage and supply AC voltage to multiple switches.
It can be turned on and off independently by switch means,
A high voltage can be supplied to a plurality of developing devices at different timings, and the switch means is provided on the primary side of the step-up transformer. It is possible to use a small-sized one with a low withstand voltage, and it is possible to reduce the cost and size of the device.

Further, in the high-voltage power supply according to claim 3 of the present invention, the plurality of loads are controlled by the plurality of developing devices.
Yes, corresponding to the developing device with the switch means turned on and developing
The DC voltage output from the DC controller is sent to the remaining developing units.
A value different from the DC voltage output from the corresponding DC controller
Therefore, by supplying a DC voltage different from the DC voltage of the developing device to the developing device other than the developing device during the developing process to the developing device other than the developing device during the developing process, the developing device other than the developing device during the developing process is supplied. Accordingly, it is possible to reliably prevent the toner from adhering to the image carrier such as the photosensitive drum.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment.

FIG. 2 shows a color image forming apparatus to which an embodiment of the high voltage power supply according to the present invention is applied.

In FIG. 2, reference numeral 1 denotes a photosensitive drum as an image bearing member. As is well known, the photosensitive drum 1 has a photoconductive thin layer such as an organic photosensitive layer on its surface. ing. The photosensitive drum 1 is driven to rotate at a predetermined rotational speed along a direction indicated by an arrow by driving means (not shown). Around the photosensitive drum 1, a scorotron charger 2 for uniformly charging the surface of the photosensitive drum 1, a laser exposure device 3, and a developer of each color of yellow, magenta, cyan, and black were accommodated. Four color developing units 4a, 4b, 4c, 4
d, transfer charger 5a, separation charger 5b, and static eliminator 9
And a cleaner 7 having a blade 7a which is separated from the photosensitive drum 1 during image formation and comes into contact with the photosensitive drum 1 during cleaning, and a static elimination lamp 8 are sequentially arranged along the rotation direction of the photosensitive drum 1. I have. Further, in the vicinity of the photosensitive drum 1, a toner image is transferred from the surface of the photosensitive drum 1 to melt and fix the toner image on a recording paper 10 as a recording medium separated from the photosensitive drum 1. Is provided.

The scorotron charger 2 for uniformly charging the surface of the photoreceptor drum 1 is designed to stably and uniformly charge even the second and subsequent images.
It is desirable to use a scorotron charger using two or more discharge wires.

The color developing units 4a, 4b, 4
As c and 4d, for example, a two-component developing device having a known configuration can be used. In particular, the tips of the ears of the two-component developer including the toner and the carrier are formed on the surface of the photosensitive drum 1 and the second color. The two-component developer supported on the developing roll is arranged so that the spikes of the two-component developer are opposed to the surface of the photosensitive drum 1 via a gap so as not to contact the subsequent toner image formed on the photosensitive drum 1. Is used.

In the color image forming apparatus configured as described above, a color image is formed by sequentially forming four color toner images on the photosensitive drum 21 while the photosensitive drum 1 rotates four times. Therefore, it is necessary to develop the toner image of the next color without disturbing the toner images sequentially formed on the photosensitive drum 1.

For this reason, each of the developing units 4a to 4d of the color image forming apparatus is composed of a DC voltage on which an AC voltage necessary for good development is superimposed for one developing unit under development. A high-voltage power supply device that applies a predetermined DC voltage for preventing the toner from adhering to the photosensitive drum 1 is used for the other three developing units to which the developing bias voltage is applied and the developing is not performed. .

More specifically, in the image forming process of the color image forming apparatus, the functions desired for the high-voltage power supply for the developing units are the first to fourth developing units 4a to 4d.
Can be turned on / off independently, that is, when development is being performed in a certain developing device, the remaining three
It is required to prohibit the supply of the AC output to the two developing units. Also, when development is being performed in a certain developing device,
It is necessary to supply a DC voltage equivalent to the surface potential of the photosensitive drum 1 to the remaining three developing units.

Next, a description will be given of a high-voltage power supply for a developing device for satisfying the above conditions. In order to satisfy the above conditions, it is necessary to first have a step-up transformer for AC output and DC output, and to have a function that can be turned on / off independently. Further, the DC output needs to be able to independently control the output from the outside.

FIG. 1 shows a first embodiment of a high-voltage power supply used in the color image forming apparatus.

As shown in FIG. 1, this high-voltage power supply unit
Four high-voltage power supply units 11 to 14 are provided corresponding to the four developing units 4 a to 4 d.
To 14 have the same configuration. The high-voltage power supply units 11 to 14 include an AC voltage generation unit 1 that generates an AC voltage.
5 to 18 and a DC voltage generator 19 to generate a DC voltage
22. AC voltage generator 15 to
Reference numeral 18 includes four AC output transformers T1 to T4 provided corresponding to the four developing units 4a to 4d, respectively.
One AC switching control unit 23 having an AC switching element is connected in series to the primary windings of these four AC output transformers T1 to T4. And
The AC switching control section 23 turns on and off the voltage applied to the primary side of the step-up transformers T1 to T4, thereby generating a high AC voltage on the secondary side of the step-up transformers T1 to T4. The AC switching control unit 23 includes a voltage monitor 2 on the secondary side of the step-up transformers T1 to T4 to enable constant voltage output and overcurrent control.
4 to 27 and overcurrent monitors 28 to 31
These voltage monitors 24-27 and overcurrent monitor 2
The output voltage and the output current are detected by 8 to 31 to control the voltage applied to the primary side of the step-up transformers T1 to T4 by the AC switching control unit 23 so that the output voltage is kept constant and the overcurrent is maintained. Control is performed.

On the other hand, the DC voltage generators 19 to 22
The DC switching control unit 32 is provided on the primary side of the common step-up transformer T5.
By turning on and off the voltage applied to the primary side of the step-up transformer T5 by 2, a high voltage is generated on the secondary side of the step-up transformer T5. And the step-up transformer T5
After rectifying the high voltage generated on the secondary side by a rectifier circuit 33 composed of a diode or the like, the DC output control units 34 to
A high DC voltage is output via 37.

In the high-voltage power supply device, each high-voltage power supply 11
The AC voltage generated by the AC voltage generators 14 to 18 and the DC voltage generators 19 to 22 are superimposed on the DC voltage and output to the corresponding developing devices 4a to 4d.

In this embodiment, the switching elements SW1 to SW4 are connected between the primary side of the step-up transformers T1 to T4 of the AC voltage generators 15 to 18 and the input line + DC.
Are provided, and the switching elements SW1 to SW
4, the step-up transformers T1 to T for each AC output
4 can be turned on / off independently. As the switching elements SW1 to SW4, any switching elements such as transistors, FETs and relays can be used, and these switching elements SW1 to SW4 are step-up transformers T1 to T4.
Since it is connected to the primary side of T4, it may be of low withstand voltage.

As for the DC output, the DC output control units 34 to 37 are provided at the point where the DC output is superimposed on the secondary side of the step-up transformer T5 for AC output.
Step-up transformer T5 for C output, DC switching control unit 3
2 at least one is provided, and an arbitrary value is set for each AC
It can be superimposed on the output.

In the above configuration, the high-voltage power supply according to the first embodiment is a low-cost and small-sized high-voltage power supply as follows, and supplies a high voltage to a plurality of loads at different timings. It is possible to do. FIG. 3 is a timing chart when the high-voltage power supply according to the first embodiment is used in the image forming process.

First, during the charging of the photosensitive drum 1 and the image exposure, as shown in FIG.
The N / OFF line becomes active (active low in this case), and the AC switching control unit 23 and the DC switching control unit 32 start the switching operation. At this time, the switching element S of each of the high-voltage power supply units 11 to 14
W1 to SW4 are, as shown in FIGS.
Each of the developing devices 4a to 4d remains in the FF state,
As shown in (a) to (d), no AC output is generated and D
Only the DC output is generated by the C output control units 34 to 37.

Next, the switching element SW1 becomes active in the developing process by the first developing device 4a (FIG. 3).
(F)), an AC + DC voltage output is generated only from the output terminal DB1 (FIG. 3A), and only a DC output is generated from the output terminals DB2 to DB4 (FIG. 3).
(B)-(d)).

Further, when the developing process by the first developing device 4a is completed, the switching element SW1 becomes non-active (FIG. 3 (f)), and the switching element S
W1 to SW4 are all turned off (FIG. 3F)
(I)), no AC output is generated, and only DC output is generated (FIGS. 3A to 3D).

Thereafter, similarly, in the second rotation of the photosensitive drum 1, the switching element SW2 becomes active (FIG. 3 (g)), and development is performed by the second developing device 4b (FIG. 3 (b)). In the third cycle, the switching element SW3 becomes active (FIG. 3 (h)), development is performed by the third developing device 4c (FIG. 3 (c)), and in the fourth cycle, the switching element SW4 becomes active (FIG. 3 (c)). 3 (i)), development is performed by the fourth developing device 4d (FIG. 3 (d)), and a color toner image is formed on the photosensitive drum 1.

As described above, the step-up transformers T1 to T4 are provided corresponding to the four developing units 4a to 4d, respectively, and the input lines can be independently turned ON / OFF on the primary side of the step-up transformers T1 to T4. Switching element SW1
To SW4, the step-up transformer T1 provided corresponding to the four developing devices 4a to 4d.
To T4 are replaced by switching elements S provided on the primary side thereof.
By turning on / off by W1 to SW4, 4
A high voltage can be supplied to the two developing units 4a to 4d at different timings, and the switching element S
Since W1 to SW4 are provided on the primary side of the step-up transformers T1 to T4, the switching elements SW1 to SW4
As 4, a low-cost, small-sized, low-withstand-voltage device can be used, and the device can be reduced in cost and reduced in size.

FIG. 4 shows a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals. 2
ON / O of AC voltage and DC voltage for one developing unit
The configuration is such that the value of the DC voltage applied to the two developing units as well as the FF can be switched.

That is, in this embodiment, as shown in FIG. 5, a predetermined high voltage is supplied to each of the two developing units 50 and 51. Outputs DB1 and DB2 correspond to 51, respectively. As shown in FIG. 4, step-up transformers T1 and T2 for AC output are provided for these two developing units 50 and 51, respectively. One ends of the primary windings N11, N21 of the step-up transformers T1, T2 are both connected to the switching elements Q1, Q2 via the inductance L1. The other ends of the primary windings N11 and N21 of the step-up transformers T1 and T2 are
+ DC / 2 (R1 = R2), which is half of the DC power supply voltage + DC, is applied via the switching elements SW1 and SW2, respectively. Here, when the switching element SW1 is ON and the switching element SW2 is OFF, one end of the primary winding N21 of the step-up transformer T2 is open because the switching element SW2 is OFF, and the switching elements Q1 and Q2 are switched. Does not occur at the output terminal DB2. The other output terminal DB1 is in a state where both ends of the primary winding N11 of the step-up transformer T1 are connected,
An AC output is generated.

On the other hand, similarly, the switching element SW1
When the FF and the switching element SW2 are ON, no AC output is generated at the output terminal DB1, and A is output at the output terminal DB2.
A C output is generated.

Next, the DC output will be described. Using a known RCC circuit, a voltage several hundred volts higher than the potential superimposed on the AC output is generated at point A. Also,
Shunt regulators 52 and 53 are connected in series to the output terminals DB1 and DB2, respectively. Depending on the values of the remote REMOTE-DC1 and REMOTE-DC2, points B and C which are DC voltages to be superimposed on the AC output are provided.
The configuration is such that the potential of the point can be controlled from outside.

In this embodiment, a high-voltage power supply for supplying a bias voltage including an AC voltage to a capacitive load such as a developing device of the color image forming apparatus is connected in series to the capacitive load. An inductance forming an LC series resonance circuit together with a capacitive load, a first switching circuit capable of controlling an energizing time for energizing the LC series resonance circuit in a positive direction, and energization termination by the first switching circuit A first energizing circuit provided with a first diode that regenerates subsequent series resonance energy, an energizing time-controllable second switching circuit that energizes the LC series resonant circuit in a negative direction, A second diode provided with a second diode that regenerates the series resonance energy after the end of the energization by the second switching circuit; and a second energizing circuit for the first and second energizing circuits. It is configured to control the output voltage by controlling the energizing time.

FIG. 6 shows the main part of the AC voltage generating section of the high-voltage power supply according to the second embodiment, and shows only the configuration of one boosting transformer.

In FIG. 6, T denotes a step-up transformer, and the primary winding N1 of the step-up transformer T has:
A voltage + DC / 2, which is half of the DC power supply + DC of a predetermined voltage, is applied. Further, the step-up transformer T
A first switching element Q1 is connected in series to the primary winding N1, and a second switching element Q2 is connected in parallel to the load side of the first switching element Q1. I have. Further, the first switching element Q1 and the second switching element Q2 include:
Opposite first and second diodes D1 and D2, which are parasitic diodes such as FETs, that constitute the first switching element Q1 and the second switching element Q2, are connected in parallel. Further, on the load side of the second switching element Q2, an inductor L forming a series LC resonance circuit together with a capacitive load.
1 is connected in series to the positive electrode side of the primary winding N1. A large-capacity first capacitor C1 is connected to the positive terminal of the DC power supply + DC between the negative terminal of the primary winding N1 and the negative terminal of the primary winding N1. A second capacitor C2 having a capacity is connected in parallel.

The secondary winding N of the step-up transformer T
2 is connected to a developing device as a load. Since the developing device as a load includes a developing sleeve made of a metal cylinder arranged to face the conductor of the photosensitive drum 1, the load is , A capacitive load that acts like a capacitor.

Further, the first switching element Q1
The second switching element Q2 is configured to be turned on / off at a predetermined timing by a control circuit.

As the first and second switching elements Q1 and Q2, switching elements such as transistors and FETs can be used.

FIG. 7 shows a first-order equivalent circuit of the high-voltage power supply.

In the drawing, L1 is the inductance of the inductor L1 connected to the primary winding N1 of the step-up transformer T, L0 is the exciting inductance of the step-up transformer T,
Ls indicates the leakage inductance of the primary winding N1 and the secondary winding N2, and Cload indicates the capacitance of the developing device as a load.

The conditions for establishing the first-order equivalent circuit are as follows: C3> Load, C2> Load × (N
2 / N1) ² , L0> L1, Ls must be satisfied. Here, L1 + Ls = L.

The AC voltage generator of the high voltage power supply according to this embodiment outputs an AC bias voltage as follows. That is, in the AC voltage generating section of the high-voltage power supply device, as shown in FIG. 8, in the “mode 0” in which the first and second switching elements Q1 and Q2 are both in the off state, the diodes D1 and D2 are reverse-blocked. State, the current iL flowing through the inductor L1 maintains the state of 0, and at the same time, the load
The voltage Vc of ad becomes a predetermined value Vc (0). Therefore, the voltage at the point P is equal to the voltage Vc of the capacitor Cload, which is a load, and the voltage 1/2 Vcc of the second capacitor C2.
, Ie, 1/2 Vcc + Vc (0).

Mode 1 Next, in "mode 1" in which the second switching element Q2 is turned on for a predetermined time, as shown in FIG. 8 (f), the second switching element Q2 is turned on via the second switching element SW2. Accumulated in the capacitor C2 flows as a current iL, the second capacitor C2, the load capacitance Cload, the leakage inductance Ls of the step-up transformer T, and the inductor L1.
The series resonance operation of the series resonance circuit including the second switching element Q2 and the second switching element Q2 starts, and the state changes as in the following equation. Here, ω = 1 / LC, γ = [V (0) / (1 /
2Vcc)].

Then, the current iq2 (t) flowing through the second switching element Q2 becomes the current i flowing through the inductor L.
If L (t) is taken in the direction shown by the solid line in FIG. 7, it can be expressed as: q2 (t) = − iL (t) = (１ ／ Vcc + V (0)) · C / L · sinωt (FIG. b)). On the other hand, the AC voltage Vc (t) applied to the load is as follows: Vc (t) = (1 / 2Vcc + V (0)) cosωt−1 / 2Vcc = [(1 + γ) cosωt−1] × 1 / 2Vcc.

If the second switching element Q2 is turned on as it is, the state changes as shown by the broken line A in FIG. 8 (a). Continue. However, in this embodiment, the second switching element Q2 is turned off when Vc (t) = 0, that is, when the voltage at the point P becomes 1/2 Vcc. That is, the time t for turning off the second switching element Q2 is Vc (t) = [(1 + γ) cosωt-1] × １ ／ V
Since cc = 0, the second switching element Q2 is set to be turned off when the time t becomes t = 1 / ωcos ⁻¹ {1 / (1 + γ)}.

Mode 2 In "mode 2" in which the second switching element Q2 is turned off, Vc (t) at the end of "mode 1" and the second
The value of the current iq2 flowing through the switching element Q2 of
That is, from the above, the initial value of “mode 2” is Vc (t) = 0 iL (t) = iq2 (t) = (） Vcc + V (0)) · C / L · sin ｛ω
cos ^-1 [1 / (1 + γ)]｝.

The state of each part is expressed by the following equation. That is, when the second switching element Q2 is turned off,
The excitation energy stored in the inductor L1 and the leakage inductance Ls is supplied to the power supply Vcc via the diode D1.
Is returned to the side. Therefore, the current iD1 (t) flowing through the first diode D1 and the voltage Vc (t) of the load are iD1 (t) = − (（Vcc + V (0)) · C /
L · sin {ω (t-cos ⁻¹ [1 / (1 + γ)]} Vc (t) = {1− (1 + γ) cos [ω (t-cos
^-1 {1 / (1 + γ)]} × 1/2 Vcc.

This "mode 2" continues until the current iD1 flowing through the first diode D1 becomes 0, as shown in FIG. That is, t = cos ^-1 ｛1 / (1+
γ)]｝, and when this time t has elapsed and the current iD1 flowing through the first diode D1 becomes 0, the load voltage Vc (t) is charged to a polarity opposite to that of “mode 1”. , Vc (t) = − V (0). Therefore, P
The voltage at the point is, as shown in FIG.
V (0).

Mode 3 Next, after the “mode 2” ends, when both the first and second switching elements Q1 and Q2 are turned off, the “mode 2”
Vc (t) =-V (0) at the end of
As shown in FIG. 8A, the voltage at the point is Ｖ Vcc-
The state of V (0) is maintained.

Mode 4 Thereafter, in "Mode 4" in which the first switching element Q1 is turned on for a predetermined time, basically, the second switching element Q2 is turned on for a predetermined time.
The operation is the same as that of the "mode 1", except that the current flowing from the DC power supply Vcc via the first switching element Q1 is
, The polarity of the value of the current iL flowing through the inductance and the output voltage Vc (t) are inverted with respect to the case of the “mode 1”. That is, the value of the current iL flowing through the inductance is iq1 (t) = iL (t) =-(1 / 2Vcc + V (0)). C / L.sinωt, as shown in FIG. On the other hand, the AC voltage Vc (t) applied to the load
Vc (t) =-(1 / 2Vcc + V (0)) cos.omega.t-1 / 2Vcc =-[(1 + .gamma.) Cos.omega.t-1] .times.1 / 2Vcc.

If the first switching element Q1 is turned on as it is, the state changes as indicated by the broken line B in FIG. 8A, and if the loss of each part is neglected, the free oscillation by the LC series resonance circuit is achieved. Followed by However, in this example,
Vc (t) = 0, that is, P
It is turned off when the voltage at the point becomes 1/2 Vcc. That is, the time t during which the first switching element Q1 is turned off is set to t = 1 / ωcos ^-1 {1 / (1 + γ)} as in “mode 1”.

Mode 5 This "mode 5" basically operates in the same manner as "mode 2", but the output voltage Vc (t) and the value of the current iL flowing through the inductance are different from those in "mode 2". The polarity is reversed.

That is, the first switching element Q
In “mode 5” in which 1 is turned off, the value of Vc (t) at the end of “mode 4” and the value of the current iq1 flowing through the first switching element Q1, that is, the initial value of “mode 5” are
From the above, Vc (t) = 0−iL (t) = iq2 (t) = (１ ／ Vcc + V (0)) · C / L · sin ｛ω
cos ^-1 [1 / (1 + γ)]｝. In addition, the current i flowing through the second diode D2
D2 (t) and the voltage Vc (t) of the load are “mode 2”.
The case is reversed.

This "mode 5" continues until the current iD2 flowing through the second diode D2 becomes 0, as shown in FIG. 8 (e). That is, t = cos ^-1 ｛1 / (1+
γ)]}, and when this time t has elapsed and the current iD2 flowing through the second diode D2 becomes 0, the load voltage Vc (t) becomes Vc (t) = V (0). Therefore, the voltage at the point P is １ ／, as shown in FIG.
Vcc + V (0).

Mode 6 This "mode 6" basically operates in the same manner as "mode 0", except that the output voltage Vc (t) has an inverted value of + Vc ( 0).

Thereafter, "mode 1" to "mode 6" are sequentially repeated.

As described above, since the AC bias power supply device according to the above embodiment operates as described above, the ON time of the second switching element Q2 in "mode 1" and the first switching in "mode 4" By setting the on-time of the element Q1 so that Ton = (1 / ω) cos ^-1 {1 / (1 + γ)]} as described above, the load capacitance Cloa is obtained.
The peak-to-peak voltage Vcpp of the AC voltage applied to d is given by Vcpp = 2V (0) = 2γ · (1/2) Vcc = γ · Vcc, as is apparent from FIG. . That is, by setting the control parameter to γ, the ON time Ton of the first switching element Q1 and the second switching element Q2 is set to Ton = (1
/ Ω) cos ^-1 {1 / (1 + γ)]}, the peak-to-peak voltage Vcpp of the output voltage is controlled by Vcpp = γ · Vcc as a first-order equivalent amount of the equivalent circuit.

FIG. 9 is an oscilloscope graph showing an AC voltage generated by one embodiment of the AC bias power supply device according to this embodiment.

In this embodiment, since a series LC resonance circuit including a capacitive load is formed, conventionally, the charge to the load is repeated while the charge is repeatedly accumulated and released to the load. Although the power was consumed by the movement of the capacitor, the capacitive load itself constitutes a part of the series LC resonance circuit. Therefore, the consumed power is only the resistance component of the series LC resonance circuit, and the static load of the load is reduced. Since the capacitance does not depend theoretically, high efficiency can be achieved by reducing the power loss.

Next, a detailed circuit configuration of the high-voltage power supply will be described with reference to FIG.

As shown in FIG. 4, this high-voltage power supply
There are provided two high-voltage power supply units 52 and 53 provided corresponding to the two developing units 50 and 51, respectively.
2, 53 have the same configuration. The high-voltage power supplies 52 and 53 are composed of AC voltage generators 54 and 55 for generating an AC voltage and a common DC voltage generator 56 for generating a DC voltage. AC voltage generator 5
Reference numerals 2 and 53 include two AC output transformers T1 and T2 provided corresponding to the two developing units 50 and 51, respectively.
One AC switching control unit 57 having AC switching elements Q1 and Q2 is connected in series to the next winding. The AC switching control unit 57 turns on and off the voltage applied to the primary side of the step-up transformers T1 and T2, thereby generating a high AC voltage on the secondary side of the step-up transformers T1 and T2. The AC switching control unit 57 includes voltage monitors 58 and 59 and overcurrent monitors 60 and 61 on the secondary side of the step-up transformers T1 and T2 in order to output a constant voltage and a constant current. By detecting the output voltage and the output current by the voltage monitors 58 and 59 and the overcurrent monitors 60 and 61, the AC switching control unit 57 controls the voltage applied to the primary side of the step-up transformers T1 and T2 to be on and off. , The output voltage and the output current are kept constant.

On the other hand, the DC voltage generating section 56 has a DC switching control section 62 on the primary side of the common step-up transformer T10, and a voltage applied to the primary side of the step-up transformer T10 by the DC switching control section 62. To generate a high voltage on the secondary side of the step-up transformer T10. Then, the step-up transformer T1
After rectifying the high voltage generated on the secondary side of 0 by a voltage doubler rectifier 63 comprising a diode and a capacitor, a DC output controller 64 comprising a shunt regulator circuit,
A high voltage of DC is switchably output through 65.

In the above high voltage power supply device, each high voltage power supply 52
The AC voltage and DC voltage generated by the AC voltage generators 54 and 55 and the DC voltage generator 56 are superimposed and output to the corresponding developing devices 50 and 51.

In this embodiment, the switching elements SW1 and SW2 are connected between the primary side of the step-up transformers T1 and T2 of the AC voltage generators 54 and 55 and the input line + DC.
Are provided, and the switching elements SW1, SW
2, the step-up transformers T1, T
2 can be turned on / off independently. As the switching elements SW1 and SW2, any switching elements such as transistors, FETs and relays can be used, and these switching elements SW1 and SW2 are step-up transformers T1 and SW2.
Since it is connected to the primary side of T2, a low withstand voltage device may be used.

Further, with respect to the DC output, the DC output control sections 64 and 65 are provided at the point where the DC output is superimposed on the secondary side of each AC output step-up transformer T10.
By providing at least one DC output boosting transformer T10 and DC switching control unit 62, any value can be superimposed on each AC output.

More specifically, the AC voltage generator 54,
55 step-up transformers T1, T2
As described above, + DC / 2, which is half of the DC power supply + DC of a predetermined voltage, is applied to 1. Also, the primary winding N11 of the step-up transformers T1, T2,
A first switching element Q1 is connected in series to 21, and a second switching element Q2 is connected in parallel to the load side of the first switching element Q1. Further, the first switching element Q
The first and second switching elements Q2 include a first diode D1 and a second diode D2,
Are connected in parallel. Further, on the load side of the second switching element Q2, an inductor L1 that forms a series LC resonance circuit together with a capacitive load
Are connected in series to the positive electrode side of the primary winding N1.
A large-capacity first capacitor C1 is connected to the positive terminal of the DC power supply + DC between the negative terminal of the primary winding N1 and the negative terminal of the primary winding N1. A second capacitor C2 having a capacity is connected in parallel.

The secondary windings N13 and N23 of the step-up transformers T1 and T2 have developing devices 50 and 5 as loads.
1 are connected, and the developing devices 50, 5
As described above, since the developing sleeve 1 is provided with the developing sleeve made of a metal cylinder arranged to face the conductor of the photosensitive drum 1, the load is a capacitive load acting similarly to the capacitor. .

Further, the high-voltage power supply unit is capable of outputting a constant voltage and a constant current.
2 are provided with voltage monitors 58 and 59 and overcurrent monitors 60 and 61 on the secondary side.
8 and 59 and the overcurrent monitors 60 and 61 detect the output voltage and output current, and the AC switching control unit 57 controls the first and second switching elements Q
1. The on / off of Q2 is controlled to maintain the output voltage and output current at constant values.

Each of the voltage monitors 58 and 59 is constituted by a rectifier circuit composed of a diode and a capacitor. The voltage monitors 58 and 59 are connected in series via a resistor R3 to a variable resistor VR1 connected in series for detecting a voltage. And the variable resistor VR1
Is the regulator IC 6 of the AC switching controller 57.
6 terminal 1.

The overcurrent monitors 60 and 61 are
The overcurrent monitors 60 and 61 are configured by a rectifier circuit including a diode and a capacitor, an amplifying transistor, and the like. The overcurrent monitors 60 and 61 are connected to the terminal 9 of the regulator IC 66 of the AC switching control unit 57, the diode D, and the resistor R5. It is connected to the terminal 16 of the regulator IC 66.

Further, the DC output control units 64, 65
Is constituted by a shunt regulator circuit, and remote terminals REMOTE-DC1 and REMOTE
-By switching the voltage applied to DC2, D
The value of the DC voltage output to the point B and the point C of the output of the C voltage can be switched.

As the regulator IC 66 of the AC switching control unit 57, for example, TL493, TL494 and TL495 manufactured by Texas Instruments are used.

In the above configuration, in the high-voltage power supply according to the second embodiment, a developing bias voltage is supplied to the first and second developing units as follows.

First, in the high-voltage power supply device shown in FIG.
As shown in (c), the ON / OFF line becomes active (here, active low) and the remote terminal RE
When an arbitrary value is input to Mote-DC1, (FIG. 10
(F)) The regulator IC 66 operates, and the switching elements Q1 and Q2 start switching operation. Also,
The switching element Q10 of the DC voltage generator 56 also starts the switching operation and generates a DC output (FIG. 10A).
(B)). At this time, the switching elements SW1, SW2
Is OFF (FIGS. 10D and 10E), and the output terminal DB
1, AC output is not generated from DB2, and the remote terminal R
A DC output determined by the value V1 of EMOTE-DC1 and REMOTE-DC2 is generated as shown in FIGS.

Next, when the process of developing the toner of the first developing unit 50 on the photosensitive drum 1 is started, FIG.
As shown in (d), when the switching element SW1 is turned ON (active low in this case) and an arbitrary value V2 is input to the remote terminal REMOTE-DC1, the remote terminal REMO is output from the output terminal DB1.
An AC output on which the DC voltage determined by the value V2 of TE-DC1 is superimposed is generated (FIG. 10A). Also, since the switching element SW2 remains OFF (FIG. 10)
(E)), no AC output is generated at the output terminal DB2, and the remote terminal REMOTE-DC is supplied to the second developing device 51.
2 generates a DC output determined by the value V1 of FIG.
0 (b)). Developing device 5 other than the developing device in the developing state
The DC output voltage supplied to 1 is set to a value equal to the surface potential of the photosensitive drum 1 (for example, -500 to 600 V).

Thereafter, the switching element SW1 is turned off.
(FIG. 10 (d)), and the remote terminal REMOTE-
An arbitrary value V1 enters DC1. At this time, the switching elements SW1 and SW2 are OFF (FIG. 10D).
(E)), no AC output is generated from the output terminals DB1 and DB2, and the remote terminals REMOTE-DC1 and REMO
A DC output determined by the value V1 of TE-DC2 is generated (FIGS. 10A and 10B).

Next, when the process of developing the toner in the second developing unit 51 on the photosensitive drum 1 is started, the switching element SW2 is turned on (here, it is set to active low) (FIG. 10 (e)). ), Remote terminal REMO
When an arbitrary value V2 is input to TE-DC2, an AC output in which a DC voltage determined by the value of remote terminal REMOTE-DC2 is superimposed is generated from output terminal DB2 (FIG. 10B). Also, the switching element SW1
Remains OFF, no AC output is generated at the output terminal DB1, and the value V1 of the remote terminal REMOTE-DC2 is
A DC output is determined as shown in FIG.
(A)).

Thereafter, the switching element SW2 is turned off.
(FIG. 10 (e)), and the remote terminal REMOTE-
An arbitrary value V1 enters DC2. At this time, the switching elements SW1 and SW2 are OFF, and the output terminals DB1,
No AC output is generated from DB2 and the remote terminal REM
A DC output determined by the value V1 of OTE-DC1 and REMOTE-DC2 is generated (FIG. 10A).
(B)).

In the high-voltage power supply, FIG.
As shown in (c), the ON / OFF line becomes non-active, the regulator IC 66 stops, the switching operation of the switching element Q10 also stops, and all outputs stop.

The above is a series of operations of the high-voltage power supply for the developing device according to the present embodiment when one color copy of two colors is taken.

As described above, in the high-voltage power supply according to the second embodiment, as shown in FIG.
Step-up transformer T for supplying AC voltage corresponding to 0 and 51
1 and T2, and the step-up transformer T
1, ON / OFF of the input line independently on the primary side of T2
Since the switching elements SW1 and SW2 are provided, the two developing devices 50 and 51 are provided.
Is turned on / off by the switching elements SW1 and SW2 provided on the primary side of the step-up transformers T1 and T2, so that high voltages can be supplied to the two developing units at different timings. Since the switching elements SW1 and SW2 are provided on the primary side of the step-up transformers T1 and T2, the switching elements constituting the switching elements SW1 and SW2 are low-cost, small-sized, low-withstand-voltage switching elements. Can be used, and the cost and size of the device can be reduced.

Further, in the second embodiment, as shown in FIG. 4, a DC output controller 6 capable of individually switching the value of the DC voltage supplied to the two developing units 50 and 51.
4 and 65, when the developing bias voltage in which the DC voltage is superimposed on the AC voltage is supplied to one developing unit and the developing is performed, the switching elements SW1 and SW2 are used to control the other developing units. The AC voltage supply is turned off and the DC supply to the other remaining developing units is performed.
By changing the voltage value to be applied to the remote terminals REMOTE-DC1 and REMOTE-DC2 of the DC output control units 64 and 65, the D value of the developing device during development is changed.
Since the DC voltage value is configured to be different from the DC voltage value of the developing device being developed, the DC voltage value is different from the DC voltage value of the developing device being developed. It is possible to reliably prevent toner from adhering to the photosensitive drum 1 from other developing devices.

In the second embodiment, the case where the number of the developing devices is two has been described. However, it is needless to say that the number of the developing devices may be three or more.

The other constructions and operations are the same as those of the first embodiment, and their description is omitted.

In the first and second embodiments, the case where the present invention is applied to a power supply for supplying a developing bias voltage to a developing unit has been described. However, it is needless to say that the present invention can be used as a power supply for other chargers and the like. is there.

[0107]

According to the present invention, there is provided a high-voltage power supply device according to the first aspect, which boosts an input voltage corresponding to a plurality of loads to reduce an AC voltage.
A plurality of step-up transformers for supplying and a unit for supplying DC voltage
One DC power supply and the secondary side of the step-up transformers.
The DC voltage supplied from the single DC power supply.
Control based on the input information and control the DC voltage
Multiple superimposed on the AC voltage generated on the secondary side of the step-up transformer
And a DC output control unit.
Therefore, only one DC power supply for supplying DC voltage is required.
Supply high voltage to multiple loads at different times
To provide a low-cost and compact high-voltage power supply capable of
Can be

Further, in the high-voltage power supply according to claim 2 of the present invention, the primary of the plurality of step-up transformers
And the input power based on the input control signal.
A plurality of switch means for turning on and off the pressure;
Common to the primary side of the
A single switching control unit for switching
So that a single switch
Supports multiple loads that supply AC voltage using only the power control unit
It can be turned on independently by multiple switch means,
Can be turned off, so that multiple loads can be
Voltage and supply AC voltage to multiple switches.
It can be turned on and off independently by switch means,
A high voltage can be supplied to a plurality of developing devices at different timings, and the switch means is provided on the primary side of the step-up transformer. It is possible to use a small-sized one with a low withstand voltage, and it is possible to reduce the cost and size of the device.

Further, in the high-voltage power supply device according to claim 3 of the present invention, the plurality of loads are controlled by the plurality of developing devices.
Yes, corresponding to the developing device with the switch means turned on and developing
The DC voltage output from the DC controller is sent to the remaining developing units.
A value different from the DC voltage output from the corresponding DC controller
Therefore, by supplying a DC voltage different from the DC voltage of the developing device to the developing device other than the developing device during the developing process to the developing device other than the developing device during the developing process, the developing device other than the developing device during the developing process is supplied. Accordingly, it is possible to reliably prevent the toner from adhering to the image carrier such as the photosensitive drum.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a high-voltage power supply device according to the present invention.

FIG. 2 is a configuration diagram showing one embodiment of a color image forming apparatus to which the high-voltage power supply device according to the present invention is applied.

FIG. 3 is a timing chart showing the operation of the high-voltage power supply according to the first embodiment of the present invention.

FIG. 4 is a circuit diagram showing a second embodiment of the high-voltage power supply device according to the present invention.

FIG. 5 is a schematic view showing a color image forming apparatus to which a high-voltage power supply according to a second embodiment of the present invention is applied.

FIG. 6 is a circuit diagram showing a main part of the circuit shown in FIG. 4;

FIG. 7 is an equivalent circuit diagram of the circuit shown in FIG. 6;

FIG. 8 is a waveform diagram showing an operation of the high-voltage power supply according to the second embodiment of the present invention.

FIG. 9 is a waveform diagram showing an output waveform of the circuit shown in FIG.

FIG. 10 is a timing chart showing the operation of the high-voltage power supply according to the second embodiment of the present invention.

FIG. 11 is a block diagram showing a conventional high-voltage power supply device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoconductor drum, 11-13 High voltage power supply part, 15-1
8 AC voltage generator, 19-22 DC voltage generator, T
1 to T4 step-up transformer, SW1 to SW4 switching means.

Continuation of front page (56) References JP-A-1-308128 (JP, A) JP-A-5-95630 (JP, A) JP-A-62-10073 (JP, A) JP-A-61-59460 (JP, A) JP-A-3-32358 (JP, A) JP-A-1-308129 (JP, A) JP-A-1-304514 (JP, A) JP-A-4-115168 (JP, A) 5-9138 (JP, U) Jikken Hei 4-14759 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J 3/00-5/00 G03G 15/02

Claims (3)

(57) [Claims] An input voltage corresponding to a plurality of loads is boosted.
A plurality of step-up transformers for supplying an AC voltage, a single DC power supply for supplying a DC voltage, and a plurality of step-up transformers provided on the secondary side of the plurality of step-up transformers;
DC voltage supplied from DC power supply based on input information
And the DC voltage of the control result is
Multiple DC output controllers superimposed on AC voltage generated on the secondary side
And a high-voltage power supply device. 2. The method according to claim 1, wherein the input voltage is boosted corresponding to a plurality of loads.
A plurality of step-up transformers for supplying an AC voltage, a single DC power supply for supplying a DC voltage, and a plurality of step-up transformers provided on the secondary side of the plurality of step-up transformers;
DC voltage supplied from DC power supply based on input information
And the DC voltage of the control result is
Multiple DC output controllers superimposed on AC voltage generated on the secondary side
When provided on the primary side of the plurality of step-up transformer, the input
A plurality of switches for turning on and off the input voltage based on a control signal;
A switching means and a common side connected to the primary side of the plurality of step-up transformers;
Single switching system that switches between different input voltages
High-voltage power supply apparatus characterized that you and a control unit. 3. The plurality of loads are a plurality of developing devices,
When the switch means is turned on, it corresponds to the developing device under development.
DC voltage output from the flow control unit to the remaining developing units.
To a value different from the DC voltage output from the corresponding DC controller.
3. The high-voltage power supply according to claim 2, wherein the power supply is made different.
Place.