JPS61112217A - High voltage power supply for copying machine - Google Patents

Abstract

PURPOSE:To always perform the stable destaticization on the surface of a photosensitive body or the stable exfoliation of copy forms, by controlling a variable impedance circuit set inside of a conduction path of the DC component so that the DC component is kept at a prescribed level. CONSTITUTION:The DC component of a discharge current flowing to a corotron wire 22a is prevented by an electrostatic capacity C1 and therefore passes totally through an impedance Zd for detection of DC component. Most of the AC component passes through the capacity C1. The value of a DC component IDC of a corona discharge current is detected through the voltage Vdet at both ends of the impedance Zd and compared with the reference voltage Vref set previously by a control circuit 31. The circuit 31 controls the value of an impedance Zc to always keep the discharge current IDC at an optimum value IDCC. Thus the stable exfoliation characteristics are always secured despite the fluctuation of the discharge conditions of an exfoliating corotron 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-voltage power supply device for a copying machine, and in particular to a high-voltage power supply device for a copying machine, and in particular for eliminating residual charges on the surface of a photoreceptor in a copying machine or for photosensitive copying paper after transfer is completed. Peeling from the body is independent of fluctuations in discharge conditions (temperature and humidity inside the machine, distance between the corona discharge wire and photoreceptor, surface of the corona discharge wire/T5 loss, etc.).
To ensure stable operation at all times, the corona discharge current flowing out from the charger (corotron) is separated into a DC component and an AC component, a conduction path is set for each component, and the impedance value is set inside the conduction path for the DC component. Insert a variable impedance circuit that can arbitrarily adjust the impedance over a certain range,
The present invention relates to a high-voltage power supply device for a copying machine that adjusts a variable impedance circuit so that a DC component always maintains a predetermined value.

[Conventional technology]

Copying machines that obtain a copy image through the various steps of charging, exposing, developing, transferring, and fixing the surface of a photoreceptor are often equipped with a peeling corotron to smoothly peel off the copy paper after the transfer is completed. Various proposals have been made regarding the high-voltage power supply device in order to always promote stable peeling regardless of fluctuations in the discharge conditions of the corotron. This will be explained based on FIG.

In Fig. 4, 1 is an operation console equipped with switches, a display, etc., 3 is a platen glass on which the original 2 is placed, 4 is a scanning system, and the broken line shown therein is the light reflected from the surface of the original 2. means the route of Further, 5 is a photoreceptor drum, 6 is a charging corotron that charges the surface of the photoreceptor drum 5, 8 is an exposure slit, and 7 is a developer that visualizes the electrostatic latent image formed on the surface of the photoreceptor drum 5. 13 is a transfer corotron for transferring the visible image onto copy paper, 20 is the above-mentioned peeling corotron, 11 is a fixing unit, and lQa and 10b are paper feed trays for storing copy paper.

The peeling corotron 20 is equipped with two to
5kV (frequency is several hundred fiz, discharge current is lOμ~2
An alternating current voltage of 000 μA) is applied, and a direct current bias voltage of 0 to several hundred μA is further superimposed on this.

In Fig. 4, 22 is an AC voltage, 22 is a step-up transformer,
22a is the secondary winding, St, Sz, and S3 are low voltage terminals of the secondary winding 22a, S2 is the intermediate tap, and S3 is the high voltage terminal. The high voltage terminal S3 is directly connected to the corotron wire of the peeling corotron 20, and the low voltage terminal S
3 is connected to the zero potential point via a capacitor 28 (C,). The intermediate tap S2 is connected to the cathode of the rectifier diode 24a and the anode of the rectifier diode 24b, and the diode 24a,
The other poles of 24b are connected to both ends of sliding resistor 26, respectively. The sliding terminal 26a is grounded via a parallel connection of a capacitor 29 (C,) and a resistor 30 (R3). 12
The above-mentioned switch 1 23, sliding resistor 2
6, the central control unit (microcomputer) that controls the operation of each element of the copying machine inputs the human power data according to the control program stored in the human power interface 12a and the ROM 12b, which takes in each switch signal and each sensor signal inside the machine. A CPU 12d for processing, a RAM 12G for temporarily storing the intermediate data, and an output interface 12e for outputting the processing results to various parts in the aircraft.
Consisted of. Here, although the means for controlling the position of the sliding terminal 26a of the sliding resistor 26 is not directly shown, for example, a servo motor driven by the central controller 12 can be used.

Upper terminal of resistor R3 (in other words, sliding terminal 26a)
is connected to the input interface 12a of the central processing unit 12.

In the above configuration, the visible image (developed toner image) formed on the surface of the photosensitive drum 2 by light reflected from the surface of the original document 2 comes into contact with the copy paper at the position of the transfer corotron 13. The copy paper is charged with a charge opposite to that of the toner by direct current discharge from the transfer corotron 13, and the toner image is transferred to the copy paper. The copy paper is transferred to the transfer corotron 20, where it is neutralized by alternating current discharge. The copy paper is removed from the photosensitive drum 5 by this static electricity removal.
After being peeled off, it is fixed by the fixing unit 11 and discharged outside the machine.

Here, the voltage applied to the stripping orotron 20 (in other words, the output voltage of the high voltage power supply for the same corotron) is the output voltage of the secondary coil 22a of the step-up transformer 22 (terminal S3
and 82) and the DC voltage applied to the capacitor 128 (C,) (in other words, the bias voltage at the S3 terminal of the secondary coil 22a) are caused by the rectifier diodes 24a and 2
4b rectified voltage (both are half-wave rectified voltages). The polarities of the rectified voltages of these diodes are opposite to each other, and which one of them contributes more to the DC bias of the terminal S is determined by the position of the sliding terminal 26a of the sliding resistor 26.

For example, when the sliding terminal 26a is located at the upper end of the sliding resistor 26 (on the anode side of the rectifier 24a), the rectifier 26a
The rectified voltage at terminal a becomes dominant, and the voltage at terminal S.

The bias voltage of takes the maximum positive value. Similarly, sliding terminal 2
6b is located at the lower end of the sliding resistor 26 (on the cathode side of the rectifier 24b), the bias voltage at the terminal S1 takes the maximum negative value. Further, when the sliding terminal 26a is located at the center of the sliding terminal 26, the bias voltage of the terminal S1 becomes zero. That is, the bias voltage of the terminal S is the same as that of the sliding terminal 26a.
varies continuously between its positive and negative maximum values depending on the position of . Since the peeling corotron 20 itself has rectifying characteristics, and the AC high voltage applied to it has a DC bias voltage superimposed on it as described above, the discharge current of the peeling corotron 20 is mainly It is an alternating current, and it also contains some direct current components. Corotron 20 for peeling regardless of fluctuations in discharge conditions
In order for a to exhibit peeling characteristics, the DC component of its discharge current (
In other words, it is known that it is sufficient to keep the difference between the current values of the positive and negative half cycles at a constant value.

Once the discharge current of the peeling corotron 20 reaches the zero potential point, most of its alternating current components are due to the capacitance 28 (CI).
, and all of the DC component is returned to the terminal S of the transformer secondary coil 22a (in other words, the low voltage terminal of the high voltage power supply) via the resistor 30 (R3). Here, the resistance value of R3 is extremely small compared to the reactance of the capacitor C2 (29) and the resistance value of the sliding resistor 26. Therefore, the alternating current component (ripple component) included in the voltage across the resistor R, (30) can be ignored, and its value is the product of the direct current component of the discharge current of the stripping corotron 20 multiplied by R3). As is clear from FIG. 4, the voltage across R3 is input to the input interface 12a of the central controller 12.

The central controller 12 compares this value with the optimal value stored in the ROM 12b, and adjusts the sliding terminal 2 so that the two always match.
By controlling the position of 6a, the value of the discharge current of the peeling corotron 20 can be kept at an optimum value regardless of the discharge conditions, and stable peeling characteristics can always be realized.

[Problem that the invention seeks to solve]

However, according to this high-voltage power supply for copying machines,
,・! .

A central control device is always essential, and mechanical means such as servo motors are required to adjust the sliding resistor, which can result in a complex and expensive configuration.

In addition, as a method of controlling the DC component of the discharge current of the stripping corotron, in addition to the method of superimposing a DC bias voltage on the AC high voltage and adjusting its value, there are also methods to control the DC component of the discharge current of the stripping corotron. Method of adjusting (Duty Cycle)
2219, 1972-5438). In addition, there is a method that controls the output voltage waveform and amplitude of a high-voltage power supply every positive and negative half cycle, and this method also utilizes the magnetic saturation phenomenon of the step-up transformer core (Japanese Patent Application Laid-Open No. 54-1979-1). 1
249994), and 1 on the primary winding side of the step-up transformer.
Equipped with a circuit to control the positive and negative unbalanced amount of the secondary current (
JP-A-55-11257). In these systems, the waveform of one or both of the positive and negative half cycles of the output voltage of the high-voltage power supply has a half-sine wave shape in which the vicinity of the maximum value is flattened. Many of the above-mentioned methods have complicated circuit configurations, are troublesome to design to prevent biased excitation of the step-up transformer, and change the waveform of the output voltage along with the control, resulting in corona discharge. There are drawbacks such as the fact that even the alternating current component contained in the current changes.

Another method is to provide an independent DC power supply as the DC bias voltage and control its output voltage, but if the power supply is
Since it becomes a grid, it is expensive and has the disadvantage of increasing power loss.

[Means and effects for solving the problems] The present invention has been made in view of the above, and has a simple and economical structure that eliminates static electricity on the surface of the photoreceptor and peels off copy paper regardless of fluctuations in discharge conditions. In order to always be able to carry out the process easily, the discharge current flowing out from the charger (corotron) is separated into an AC component and a DC component, a conduction path is established for each component, and inside the conduction path for the DC component, A copy in which a variable impedance circuit that can continuously adjust the impedance value to #BI over a certain range is inserted, and the variable impedance circuit is adjusted so that the DC component of the discharge current maintains a predetermined constant value. The purpose is to provide a high-voltage power supply for aircraft.

Hereinafter, the high-voltage electric # device for a copying machine according to the present invention will be explained in detail.

〔Example〕

FIG. 1(a) and (bl show one embodiment of the present invention, fa
1 shows its block diagram, and (b) shows an example of its specific circuit groove. First of all, in FIG.
22 is a step-up transformer, 22a is the secondary winding, S I +
S! +33 are a low voltage terminal, an intermediate tap, and a high voltage terminal of the secondary winding 22a, respectively. The high-voltage terminal S3 is connected to the corotron wire 22a of the stripping corotron 20, and the low-voltage terminal S has a capacitance C, (as described later, serves to prevent discharge and DC components contained in the current, and its electrode The DC voltage appearing between them is connected to the zero potential point via the output voltage (which serves as a DC bias voltage for the output voltage). Moreover, the intermediate cup S2 is connected to the cathode and anode, respectively, of a pair of diodes D1 and D2 that are connected in opposite directions. Further, the anode of the diode D1 is connected to the DC current detection impedance Z via the resistor R1, and the cathode of the diode D2 is connected to the DC current detection impedance Z via the resistor R2 and the variable impedance circuit Zc.

The other terminal of is connected to the zero potential point. Further, the voltage VdoL applied to Z is proportional to the DC component of the discharge current, as will be described later, and is input to the control circuit 31 together with the reference DC voltage rQr. The control circuit 31 controls the difference between both input terminals (Vllll!L
It outputs a voltage proportional to vrer, and this amount is input manually to the variable impedance circuit Zc.

The ZCO value is controlled by the output of the control circuit 31.

The impedances of C5 and Z at the frequency of the AC component included in the output of the power supply device are extremely small, and can be ignored without causing any practical problems. Further, the impedance (ie, resistance value) of Zd with respect to the DC component is extremely small compared to R1 and R2. Further, 5 is a photosensitive drum whose shaft is connected to the zero potential point together with the corotron shield 22b.

In the above configuration, the voltage applied to the corotron wire 22a is the AC voltage between the terminals Sff and S of the secondary coil 22a superimposed with the DC bias voltage VCI applied to the capacitor C1. In the stripping corotron 22, the discharge current flowing through the corotron wire 22a and the shield 22b once flows into the zero potential point, and then returns to the high voltage voltage 'a' and g, or its DC component is connected to the capacitance C8. Therefore, all of it passes through the DC component detection impedance Zd, and a voltage proportional to the DC component is generated across it.

On the other hand, most of the alternating current components pass through volume 1c and are transferred to Z4.
Very few components are diverted to

On the other hand, the instantaneous value of the potential at the intermediate tap S2 of the secondary winding 22a is the sum of the instantaneous value VZS+-+ of the voltage between the terminals 5ZS1 and the DC bias voltage Vet (voltage between capacitors C1).

During the period when the potential of S2 is positive, diode D2 is in a conductive state and current flows from D2 toward R, , and Zc, and since diode D is in a non-conductive state, no current flows in R3. During the period when the potential of S2 is negative, diode D1 becomes conductive and current flows toward R, and since diode D2 is non-conductive, no current flows through R2 and ZC. The DC component IDC of the current flowing into the intermediate tap S2 is the temporal average value of the current flowing through the two branch paths. In addition, IDC is the direct current component of corona discharge current,
As is clear from FIG. 1 (al), it flows from the intermediate tap S2 to the peeling corotron 20 via the terminal S:l and forms a DC component included in the discharge current.Here, when R1<RZ +Zc The current component flowing from Ro to Dl has priority, ItlC flows in the direction of the arrow shown in FIG. 1 (al), and the DC bias voltage of Sl becomes positive (Vct>O).

When the value of Z decreases and R1>R2+ZC, the signs of IDC and VIC are inverted. In this way, the values of Inc and VIC can be changed arbitrarily within a certain range by changing the value of Zc.

As described above, the value of roe is detected through the voltage Vdot across the DC component detection impedance 24, and is compared with a predetermined reference voltage Vre in the control circuit 31. If the roc optimum value is I DCC, then Vraf
= Za locc . The control circuit 31 is as follows. .

-V. , (details will be described later), and the output voltage is zero (in other words, ■6.).

-V r e f). Therefore, the discharge current I. C always has one optimal value. , and even if the discharge conditions of the peeling corotron 20 change, stable peeling characteristics can always be imparted to the copy paper.

Figure 1 (bl) is a realization of Figure 1 (a) as a concrete circuit, and the contents of Zc, Za, and the control circuit 31 shown as a block diagram in Figure 1 (al) have been clarified. The impedance Z for DC component detection is configured as a parallel connection of a resistor R3 and a capacitance C2, and its constant is determined so that R3<<R1, R2 and Rff<1/ωC2. . ω is the angular frequency of the power supply output AC component. 33 (PC,) is a photocoupler consisting of a light emitting diode 33a and a phototransistor 33b, the photodiode 33a is connected to the control output circuit 31, and the phototransistor 33b is connected to a variable impedance circuit. Ql is a transistor that amplifies the emitter current of the phototransistor, R, and R5 are resistors of its bias circuit.
The winding 22b, the diode Dff+capacitance constitutes an auxiliary DC power supply for the photocoupler 33 (PC,) and the transistor Q1. phototransistor 33b,
Transistor Q1 resistors, R, , R, cooperate to form a variable impedance circuit Zc. 34 is an operational amplifier;
The load is a series connection of resistor R11 and light emitting diode 33a. Rs and Rq constitute a feedback circuit of the operational amplifier 34 together with the capacitance C3, the connection point of both resistors is connected to the operational amplifier input side e terminal, and the other terminal of the resistor R8 is connected to the reference voltage V ref . Here, R9 is determined by comparing it with the resistance value of R8 and the impedance value of C3.7□4. Stingray, □
07,. 11344 □ Functions as an opacity circuit. The input side terminal of the multiplier amplifier 34 is connected to Zd via a resistance value R7°. Light emitting diode 33a, differential amplifier 34. Resistors Ra, Rq.

Ro. , R1 and capacitance C3 cooperate to form a control circuit 31. IF means differential output current of the amplifier 34 (in other words, current supplied to the photodiode 33a). As in the case of FIG. 1(a), 21 is an AC power generation means (inverter, etc.) with several hundred cycles, and 32 is a DC power source that functions as a power source for the AC power generation means 21 and the photodiode 33a.

In the above configuration, the DC component included in the discharge current returned from the stripping corotron 20 passes through R3 in Za, and generates a DC voltage of Va-z=Zaloc=Rzloc across R3. Since the alternating current component slightly included in this current passes through 02 due to the condition of 1/ωC2 (R3), the voltage across Zd due to this can be ignored. The reference voltage v*!r is input to the input side terminal and the same θ terminal via R8.Therefore, the operational amplifier 34
The value of Vref is input, and the same crime 34 is V dat V
Voltage and current (IF
) is output. The light emitting diode 33a emits light in an amount corresponding to (1), and the light enters the transistor 33b.

In the variable impedance circuit Z, the phototransistor 33b receives the incident light from the light emitting diode 33a and becomes conductive, and its emitter current flows into the pace of the transistor Q1. The saturation current of the collector current of the transistor Q1 is due to the Haas current input from the phototransistor 33b, in other words, the output current of the differential amplifier 34 is
, controlled by . Figure 2 is ■. , > 0, (a) shows the potential of S2 (V 52-1 +V C1
, (b) shows the current flowing into ZC (current flowing from Dz toward R2), and (C) shows the instantaneous time of the current flowing through R1 as a function of time. ΔT1 is when the potential of Sz is positive (VS□-++Vc+>O)
During the period ΔT2, the potential of S2 is negative (Vsz-+ +
The period during which Vc+<O), and ΔT, is given by ΔT=ΔT, +ΔT2, and means one cycle of voltage and current fluctuations.

Also, the direction of the current is shown in Figure 1 (direction from top to bottom of bl (D
, to R5, and from D2 to Rz, Z c ) in the positive direction, and in evaluating the current value, the values of Rz and R4 are set to be negligibly small compared to R+ and Rz. First, to explain the instantaneous value of the current flowing through ZC with respect to Fig. 2 (bl), during the period of VSZ2-1+Vcl>0 (period of ΔT), diode D2 is in a conducting state, and 2. (therefore also R2) Current flows and Vsz-+
During the period +Vc+ < 0 (period ΔT2), the diode D2 is in a non-conductive state, so this current disappears.

Furthermore, if the value of ■3□-1+VC+ is small during the period ΔT, this current value is (Vsz-++Vc+)/
Although it is given by Rz, the value of VSZ-1+VC+ increases, and the current value of transistor Q increases.

When the collector current reaches the saturation value i3 of VS!, until the time Δt has elapsed. -1" Regardless of the value of V C1, the current maintains a constant value i5. Time ΔL
After , the collector current of transistor Q1 comes out of the saturated state, and the current value is again given by (VS2-1+VCI/R2. It can be seen that this current (and thus the value of 2.) is controlled by the load current IF of the light emitting diode 33a.

FIG. 2 (C1 illustrates the current flowing through R6, VS2-1
"If Vc+>O, it is zero; if VSZ-1+VCI<O, it is given by (Vsz-+ + Vc+)/R+.The DC component of the current flowing into the middle tap S2 of the cotton 22a is the second-order The algebraic sum of figures (b) and (C) is 1
This can be obtained by averaging over the period ΔL and inverting the sign (the sign is inverted depending on how the positive direction of I and D is determined).

The IDC is at the optimum value ■ due to variations in the discharge conditions of the peeling corotron 20. 6. When the deviation is more, V dot Vre
f+0, and the control circuit 31 outputs a signal (in this case, the optical signal of the light emitting diode 33a) proportional to the time integral of this amount, and this signal is transmitted through the variable impedance 1
, are received by the phototransistor 33b of the switch circuit Zc. The phototransistor 33b controls the saturation value of the collector current of the transistor Q1 according to the amount of received light, so that the value of the variable impedance circuit ZC becomes V ant
The magnitude of Vrer changes in a decreasing direction. Vd
When the condition of ot = Vref + is reached, ■daL
The time integral values of Vr and f remain unchanged, and the control circuit 3
1 outputs a constant amount continuously, and Zc also maintains a constant value. Therefore, the condition of a posteriori Vat ==V□f is continuously maintained, and Vaet = Rx IDCl Vrer = R3
IDC-IDCC is obtained from the relationship [occ (IDCC: optimum value)], and the peeling corotron 20 always shows constant peeling characteristics. In this case, the transistor Q of Zc
The base current of 1 is returned to Sl' of the third winding 22b, and Z
There is no possibility of passing 6. Therefore, there is no possibility that the ZC control will be disturbed by this current.

The group of curves shown in FIG. 3C shows how the VCI IDC characteristics change when the discharge conditions of the stripping corotron 20 change. The practical maximum and minimum values of the DC bias voltage value Vel are respectively V c + (
max) and V c+ (min), this high-voltage power supply device brings the IDC to the optimum value ■. In order to be able to maintain cc at ■c1, V c+ (min) ~
Due to the circuit characteristics of this device, it is necessary to design the device so that it can be adjusted within the range of V c+ (max).

In FIG. 3, Vel=VSZ-1tm), Vc+
= Vsz-+lff1゜(Vsz-1(1%)
is the maximum value of VSZ-1), and the two parallel lines in the horizontal direction indicate the upper and lower limits of It is included in the range between two curves running at the left end and right end. i: S If the area surrounded by two parallel lines and two curved lines is expressed as Δrpa, then this A rea
Dot inside (Tocc.

V C, (max) ), (I DCC, V c+ (
R,, R2, V3□- so that min)) is included.
By setting a value of 1, the above objective can be achieved. FIG. 1(C) is a modification of the basic configuration of FIG. 1(al).
The middle tap S2 of the next winding is set to capacitance C1, and the low voltage terminal S
3 is connected to the variable impedance circuit Z, the other circuit configuration, basic operation, and effects are as shown in
There is no substantial difference in the basic configuration of l. In addition, Figure 1 (a
The connections of ZC and Zd in l and fcl may be reversed from those shown.

Figure 1 (dl) shows another modification of the basic configuration of Figure 1 (a), and Figure 1 (e) specifically illustrates the circuit configuration. It is possible to directly detect and control the components.

FIG. 1 (fl shows a modified example of the embodiment shown in FIG. 1 (bl), in which the polarities of the diodes D, D, and D3 in FIG. The connection between the emitter and collector electrodes of the transistor 33b and the connection between the input side e and the e terminal of the operational amplifier 34 are reversed.In this case, the direction of the current controlled by the variable impedance circuit 2 is determined by the various circuits described above. The opposite is true for .

Furthermore, instead of the photocoupler 33 (Pct) used in the above embodiments, it is also possible to use a combination of a light-dependent resistor and a light emitting diode (Japanese Patent Laid-Open No. 54-5438).

Further, in the above-described embodiments, an output circuit of a high current/high voltage output circuit shown in FIG. 1fgl can be added to the secondary winding 22a of the step-up transformer to supply the output to other loads.

Further, in the embodiments described above, the discharge current I,.

can be controlled over both positive and negative polarities, but if the type of stripping corotron allows unipolar polarity, Dl and R1 can be omitted in the above embodiments.

Furthermore, in the embodiments described above, the reference voltage is built into the power supply device, but it may be provided externally as a target value setting command signal.

In addition, although the variable impedance circuit Z is exemplified as one that operates in an analog manner, it is possible to control the DC component using a switching element (or asynchronous) that is synchronized with (or asynchronous to) the AC component of the power supply. It is also possible to achieve the goal. This approach has the potential to reduce power losses and improve efficiency.

〔Effect of the invention〕

As explained above, according to the high-voltage power supply device for a copier of the present invention, the corona discharge current flowing out from the charger (corotron) is separated into a DC component and an AC component, a conduction path is set for each component, and the DC component is A variable impedance circuit that can arbitrarily adjust the impedance value over a certain range is inserted inside the conductive path, and the variable impedance circuit is adjusted so that the DC component always maintains a predetermined value. With a simple and economical structure, it is now possible to always and stably eliminate static electricity on the surface of a photoreceptor or peel off copy paper, regardless of fluctuations in the discharge conditions of the charger (corotron).

[Brief explanation of the drawing]

Fig. 1 (al~(gl) - - An explanatory diagram showing an embodiment of the present invention. Fig. 2 (a) - (c) - - An explanatory diagram for explaining the operating principle of a variable impedance circuit. Fig. 3 ---A diagram showing the relationship between the DC high-ass voltage and the DC component of the discharge current. FIG. , 2------manuscript,
3-m--- platen, 4----- one scanning system, 5---- one photosensitive drum, 6--
A charged corotron? --------Development section,
8...---111 slotted throat, 9------1 cleaning section, 10a, fob --1 paper feed tray,
1 t---- fixed attachment part, 12--1--- central processing unit, 12a---=- doujinshi interface,
12b---all ROM, 12c---all RAM
, 12d --- All CPV, 12e --- Same output interface, 20-
- Separation corotron, 20a - Corotron, wire, 20b - All shields, 21 - AC power supply, 22
---Step-up transformer, 22a, 22b 2, 3
Next winding, 23--Power switch, 24a, 24b--One rectifying element (Taioh F), 26
...--Sliding resistor, 28-------Capacitance (C1), 29---Capacitance (C2), 30-
--m-resistor (R3), 3]---control circuit,
32-----DC power supply, 33--Photocoupler (PC,), 33a----All light-emitting diodes, 33b----All phototransistors, 34--
・-Operation amplifier. Patent Applicant Fuji Xerox Co., Ltd. Representative Patent Attorney Shin Matsuhara 2 Seiji Muraki Tadao Hirata Jun Ueshima - Same Lead powder Hitoshi Figure 1 ((I) Figure 2 tσ-no.

Claims (1)

[Claims] Outputting an AC high voltage with a DC bias voltage superimposed thereon and applying it to a charger, detecting a DC component included in a corona discharge current of the charger or its photoreceptor current component, In a high-voltage power supply device for a copying machine that controls the amount of charge or the amount of static electricity removed from the charger by adjusting its output so that the discharge current remains at a predetermined value, a means for separating the body current component into a conductive path for each of them, and a means installed inside the conductive path for the DC component or the photoreceptor current component, and continuously changing its input impedance value over a certain range. a means for detecting the DC component or the photoconductor current component; and means for detecting the DC component or the photoconductor current component; 1. A high-voltage power supply device for a copying machine, comprising: controlling means.