JPS59101668A - High voltage power source device of copying machine or the like - Google Patents

Abstract

PURPOSE:To execute easily and safely an adjustment of a corona discharge current by inserting a resistance between a secondary side low voltage end of an output transformer in a high voltage device and a ground, and measuring the voltage generated across this resistance by a monitor terminal. CONSTITUTION:A rectifying circuit consisting of a diode 18 and a capacitor 19 is provided on a secondary side winding 15b of an output transformer 15 in a high voltage power supplying circuit 14, and a connecting point of its diode 18 and the capacitor 19 is connected to a corona wire 20 of a corona discharger 3 arranged around a photosensitive drum 1. A resistance R is connected between a low voltage end (r) of the secondary side winding 15b of the output transformer 15 and a frame ground of a machine, and also a monitor terminal 23 is provided across this resistance R. The resistance R is a current detecting resistance for detecting a current flowing to it, and its resistance value is set by a value of a current to be detected, for instance, a current i(d) flowing to a photosensitive body, and a range of a measuring instrument which is connected to the monitor terminal 23 and used for a measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high voltage power supply device for a copying machine or the like.

In copying machines, a corona discharger is used that uses corona discharge to charge the photoreceptor, etc., as a means of charging the photoreceptor. This is not limited to copying machines that expose light and copy the original image onto paper; for example, it modulates the information to be recorded with a laser beam and irradiates it onto a photoreceptor using a rotating polygon mirror for deflection and scanning to print characters, etc. It is also used in electronic printing machines that print on paper.

Corona dischargers that utilize corona discharge as described above are used not only for charging photoreceptors, but also for applying charges to paper in order to transfer toner to the paper. Alternatively, there are various types of devices that can be used to remove static electricity by weakening the suction between residual toner and the photoconductor to make it easier to clean.For example, in an electrophotographic copying machine, the area around the photoconductor is generally charged, transferred, and
Equipped with one or more corona dischargers for separation and static elimination phases.

This type of corona discharger usually has a structure in which blocks made of electrical insulators are provided at both ends of an elongated box-shaped metal case, and a corona wire made of tungsten or the like is stretched between the blocks. This is arranged at a predetermined distance from the surface of the photoreceptor, and a DC or AC voltage of, for example, several kilovolts is applied to the corona wire to cause corona discharge.

Figure 1 schematically shows the area around the photoreceptor of a copying machine. As mentioned above, a corona discharger for each purpose is provided around the photoreceptor as necessary. The illustration shows two corona dischargers around the drum.

The photoreceptor drum (1) has a photoconductive material layer formed on a cylindrical conductive support, is attached to a drum shaft (2), and faces the surface of the photoreceptor drum (1). A corona discharger (3L) with the structure as described above.
(4> is installed. This corona discharger (31, (
41 are connected to a high-voltage power supply (7) for corona discharge via cords (51, (61), respectively, while the conductive support of the photoreceptor drum is connected to the frame ground of the machine, Corona discharge is caused by applying a high voltage from a high voltage power supply (7).

By the way, such a corona discharger +3)', +4)
The current f (Tor) flowing from is the current 1 flowing to the photoreceptor.
(d) and a current t(S) flowing through the metal case as a shield surrounding the corona wire as described above. Of these, the value of the above current i<dt is This is an important factor that greatly affects quality and paper jams near the photoreceptor.For this reason, the above current L(d
) must be adjusted so that the size of If the value of the above current 1(d) gradually changes over time due to changes in temperature and humidity, misalignment of the corona discharger and photoreceptor, etc., and it falls outside the above range, readjustment is necessary. Can be removed as needed.

Therefore, when adjusting the corona current i+a>, as shown in FIG. 2, the photoreceptor drum (1) is removed from the drum shaft (2) and a current measuring plate ( 8) can be used to adjust the current 1(d).

That is, the current measurement plate (8) has a mounting portion (9) formed of an electrical insulator and a mounting portion (9) formed of an electrically insulating material.
It is a jig consisting of an arc-shaped conductor part 0@ provided in the part <? a is fixed to the drum shaft (5), so that the surface of the arc-shaped conductor glS min α0) is at the same position as the surface of the photoreceptor drum (1) as shown in Figure 1 (2). It is configured.

When adjusting the corona discharger (3) using such a current measuring plate (8), as shown in FIG. Insert the ammeter αJ between the lead (lυ, conductive part α0 of the current measurement plate (8) from the 1st bottle) and the frame ground of the machine, and connect the high-voltage power supply (7
) is turned on and the current Z(cl) flowing through the ammeter α in this state is measured. There is a very strong correlation between this current Z(c) and the current t++n during the actual copying operation. Therefore, by changing the output of the high-voltage power supply (7) and adjusting the current Z(c) flowing through the ammeter α1 to a value of
The value of (d) can be set within a predetermined tolerance range of -4.

Since the current measuring plate (8) is rotatable around the drum shaft (2), the corona discharger (4) is next rotated around the drum shaft (2).
) can be similarly adjusted by facing the corona dischargers, and in this way adjustments can be made sequentially to other corona dischargers.

However, such an adjustment method requires a lot of effort, such as removing the photoreceptor drum (1) and inserting a jig such as the above-mentioned current measurement plate (8).

In addition, when copying at a slow copying speed, when adjusting the current z(d) flowing through the photoreceptor, it is necessary to adjust the current 1 (TOTI) flowing from the corona discharger as described above. In other words, in such a copier,
Since there is a correlation between the above current j [ToT) and current 1 (d), if the allowable range of current z (d) is wide, current 1 (d) can be adjusted by adjusting the current t (ToT). can be kept within the range. Therefore, if it is sufficient to adjust the TOTI, the current 7:
As shown in the figure, an ammeter α1 may be inserted between the output of the high-voltage power supply (7) and the corona discharger (3) for adjustment.

However, this adjustment method is dangerous because it involves inserting the measuring device into the high voltage circuit as described above, and the measuring device is likely to be damaged.

In this way (2.), it is not possible to easily adjust the corona discharge current with the adjustment method shown in Figure 2, and
The adjustment method shown in FIG. 3 has a problem in that the adjustment cannot be performed safely.

This invention was made in view of the above points,
By inserting a current detection resistor into the circuit that returns to the output capacitor C2 of the high-voltage power supply for corona discharge from the frame ground of a machine such as a copying machine, and by providing monitor terminals so that both ends of this resistor serve as check terminals. It is an object of the present invention to provide a high-voltage power supply device for a copying machine, etc., which allows adjustment of corona discharge current easily and safely.

Embodiments of the present invention will be described below based on the drawings.

FIGS. 4 and 5 respectively show the circuit configuration and external structure of an embodiment of the high voltage power supply device of the present invention. In FIG.
In a general high-voltage power supply circuit with DC positive output constant voltage control, the output voltage αQ and the primary winding of this output voltage αυ @(
15a) A transistor Tr for discharging the current flowing through the transistor 11
And the secondary winding (15b) of the output transformer (F?)
Volume VR to adjust the output taken from
This high-voltage power supply circuit tS includes a constant voltage control circuit (10, etc.) including a high-voltage power supply αη shown in FIG.
(2) The volume VR for adjusting the output is provided in the case so that it can be adjusted from the outside.

The secondary winding (15b) of the output voltage α in the high voltage power supply circuit 0 is provided with a rectifier circuit consisting of a diode 0 and a capacitor α9), and the diode α
The connection point between the capacitor and the capacitor is connected to the corona wire wire of a corona discharger (8) arranged around the photoreceptor drum (1). The metal case υ is connected to the low voltage end r of the secondary winding (15b) of the output transformer α9 through a dedicated line υ, and the corona discharger (31c7) gold J-J case G!υ The current 2 (s) flowing through the terminal is returned to the output transformer α■ side via this dedicated line.■.

Furthermore, the secondary winding (15b) of the above output transformer/1G
A resistor R is connected between the low voltage end r of the machine and the frame ground of the machine, and in the case of Fig. 4, this resistor R
Both ends C: Monitor terminals (C) are provided.

The above-mentioned resistor R is a current detection resistor for detecting the current flowing there, and its resistance value is the current to be detected (for example, the current flowing through the photoreceptor c current 1td) as described above.
It is set by the value of the above monitor terminal (c) (X) and the range of the measurement instrument used for measurement.
If the target value when adjusting the above current 1(d) to a value within a predetermined range is 100 μA, and the range of the measuring instrument as mentioned above is 2 V, the resistance value of the above resistor R is about 10Ω. And it is sufficient.

In addition, in order to easily check the voltage generated across the resistor R even under normal conditions, the monitor terminal (c) is connected to the high voltage power supply device (1) as shown in FIG.
It is attached to the case of 71. Therefore, the above resistance R
The voltage generated across the terminal can be measured from outside the power supply.

Next, we will explain the case where the corona discharge current of the corona discharger (3) is adjusted by using the device of the above embodiment. If a measuring device is connected to the monitor terminal and the volume VR of the high voltage power supply q is adjusted so that the voltage generated at the monitor terminal becomes the specified value, the output of the high voltage power supply αη is changed. Current 1 flowing through the photoreceptor (
The value of d) can be set within a predetermined range. That is, in the case of the circuit shown in Fig. 4, the metal case e◇ of the corona discharger (3) is not connected to the ground, but is connected to the secondary winding @ (15b) of the output voltage α by the dedicated line (a). The current 1 (s) flowing through this metal case Qυ is returned without passing through the resistor R. Therefore, the conductive support of the resistor R is connected to the frame of the machine. Only current 1(d) flows through the photoreceptor of the photoreceptor drum (1) connected to the ground. Therefore, a voltage drop due to the current Z(s) does not occur across the resistor R, but a voltage drop corresponding to the voltage '/-(d) occurs, so the value of the voltage By measuring the current t+a+, the above-mentioned current t+a+ can be adjusted.

Since the adjustment can be made in this way, the photoreceptor drum (1) can be removed (
There is no need to use a special jig for inserting the drum shaft (instead of that), the adjustment can be easily made, and moreover, it can be adjusted easily in the high voltage circuit as shown in the adjustment method shown in Figure 3. Adjustments can be made safely because there is no need to insert a measuring device.Furthermore, the monitor terminal (
c) (2) Therefore, the above current 't at f2 during normal operation
It is possible to easily check whether or not (d) is within the allowable range.

In the illustrated example, the metal goose tube η of the corona discharger (8) is connected to the low voltage end T via the dedicated line 4, and the current flowing to the metal case Qη or the grid is connected to the resistor R.
However, in the case of a copying machine with a slow copying speed, the dedicated line (the metal case I21 above) should be connected to the ground once instead of using two lines. is also possible.

That is, as mentioned above, the current 'L(
When adjusting d), if it is sufficient to adjust the current j (ToT) flowing from the corona discharger (3),
The current 1 (ror) is caused to flow through the resistor R,
In this case, it is also possible to measure the voltage generated across the resistor R and adjust the current 1 (S) flowing through the photoreceptor, and the adjustment method is to measure the voltage generated across the resistor R. Since this is the same as when connecting the measuring device in c), it is possible to make adjustments easily and safely.

Therefore, as mentioned above, the output voltage α of the high voltage power supply is 2
By providing a resistor R between the next-side low-voltage end r and the ground, and making it possible to measure the voltage generated across this resistor 8 from outside the high-voltage power supply α using a monitor terminal, the current t+d+ or the current 1 (TOT' ) Does it make it easier for you to make any adjustments?

It can be done safely. Further, according to this configuration, even if the output of the high-voltage power supply is AC, it is sufficient to simply set the monitor terminal (c) (=the measuring instrument to be connected to the AC measurement range).

FIG. 6 shows a high-voltage power supply device (1η) in another embodiment of the present invention. In this embodiment, the voltage generated in the above-mentioned resistor R is outputted via a buffer amplifier. This can be measured using the monitor terminal (c).

In other words, the input impedance of a digital multimeter that is generally available on the market is about IMΩ to IOMΩ, which is sufficiently large compared to the resistance value of the resistor R mentioned above, but the input impedance of an analog meter is about IMΩ to IOMΩ. There are hundreds of ohms.

Therefore, if the meter used is of this kind, a measurement error will occur, so once the output is output via a Puffer amplifier (incorporated) as shown in Figure 6, it is necessary to
Errors due to instrument impedance can be prevented.

In this way, the voltage of the resistor R is adjusted to the buffer amplifier (c).
If the configuration is such that the corona discharge current can be taken out and measured through the instrument, it is possible to easily and safely adjust the corona discharge current as described above, and at the same time, the adjustment can be made without being affected by the input impedance of the meter being used. It is also possible to prevent adjustment errors caused by this.

FIG. 7 shows the main part of the high-voltage power supply α force in still another embodiment of the present invention, and in this embodiment, t is
If you want to install a rectifying and smoothing circuit consisting of an amplifier (converter) and an amplifier (a) between the above-mentioned resistor R and the monitor terminal (c), and use a DC-only measuring instrument,
It is designed so that the AC output can be output via this rectifying and smoothing circuit.

FIG. 8 shows the circuit configuration of a high voltage power supply αη according to still another embodiment of the present invention. In this embodiment, the secondary low voltage end r of the output transformer α$ is connected to one side of the amplifier. and connect the other input terminal to the ground, and connect the above-mentioned resistor R for current detection between one input terminal and the output terminal of the above amplifier. C so that the output of the output terminal can be measured with the monitor terminal.
Two have been.

In this embodiment, by using the current-voltage conversion circuit with the above configuration, the same effects as in the embodiment shown in FIG. It can have a simple configuration.

That is, unlike FIG. 4, the control signal used for constant voltage control is a dividing signal that divides the output of a rectifier circuit consisting of a diode and a capacitor provided on the secondary side of the output transformer αG. It can be formed using signals taken from the connection points of the resistors R, , R2.

As mentioned above, corona dischargers are used not only in copying machines but also in electronic printing machines and the like, so the present invention can be applied to such cases as well.

As described above, the present invention inserts a resistor between the secondary low voltage end of the output transformer and the ground in a high voltage device that supplies high voltage to a corona discharger, and monitors the voltage generated across the resistor. Since measurements can be made from outside the high-voltage power supply, the corona discharge current can be adjusted easily and safely, and the value of the corona discharge current can be easily checked even during normal operation. It has features such as:

[Brief explanation of drawings]

Figure 1 is a perspective view schematically showing the area around the photoreceptor of a copying machine, Figure 2 is a perspective view for explaining the method of adjusting the corona discharge current, and Figure 8 is for explaining other adjustment methods. FIG. 4 is a circuit diagram showing the circuit configuration of one embodiment of the high voltage power supply device of the present invention, FIG. 5 is a perspective view showing the external affairs of the high voltage power supply device, and FIG. FIG. 7 is a circuit diagram showing the main part of the circuit structure of another embodiment of the present invention. FIG. 8 is a circuit diagram showing the main part of the circuit structure of still another embodiment of the present invention. It is a circuit diagram showing the circuit configuration of the high-voltage power supply device. Symbol explanation (3)...Corona discharger α motion...High voltage power supply circuit αU...Output transformer αη・・
...High voltage power supply (A) ...Monitor terminal γ ...Secondary side low voltage end R ...Resistance patent applicant Fuji Xerox Co., Ltd. 1 Figure 1 Figure 2 Figure 3 Figure 14 Figure 4 Prisoner 5 Figure 6

Claims (1)

[Claims] In a copying machine etc. that has a corona discharger, a resistor is inserted between the secondary low voltage end of the output transformer of the high voltage power supply for corona discharge and the ground, and a monitor terminal is installed to measure the voltage generated across this resistor. A high-voltage power supply device for a copying machine, etc., characterized by the following: