JPH0519594A - Electrophotographic device - Google Patents

Abstract

(57) [Abstract] [Purpose] In an electrophotographic apparatus using a power source in which polarity is switched to the contact charging unit or AC is superimposed on DC, 2
An object of the present invention is to reduce the size and cost by using one of the power supplies as a voltage generating element instead of the power supply that requires more than one power supply. [Structure] A voltage generating element 6 is connected between a stabilizer or a grid of a corona discharge corotron 2 and a ground, and a voltage of the voltage generating element 6 is generated by a current of a high voltage power source 4,
By applying the voltage combined with the voltage of the DC power supply or the AC power supply 5 to the contact charging unit 3, the components are simplified and downsized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus using a contact charging section.

[0002]

2. Description of the Related Art Conventionally, a roller or brush is pressed directly against a photoconductor, a voltage is applied in close proximity to the photoconductor, or toner is discharged from a developing device to the photoconductor without using a corona discharge corona for charging. The electrophotographic apparatus having a contact voltage applying section for moving the toner to the copy sheet or transferring the toner from the photoconductor to the copy sheet has a structure as shown in FIG.

In FIG. 7, 11 is a photoreceptor, 12 is a corona discharge corotron for charging, 13 is a contact charging unit for development or transfer, and 14 is a high voltage for applying a high voltage to the wire of the corona discharge corotron 12. A power source, 15 is a power source, and since positive output and negative output are taken out internally, 15d and 15h
Transformer, 15c and 15g rectifying diode, 15
The smoothing capacitors b and 15f and the discharging resistors 15a and 15e are incorporated. The circuit on the primary side is omitted. 1
7 is a grid for stabilizing the surface potential of the photoreceptor 11, 16
Is a voltage generating element for determining the potential of the grid 17.

The method of applying a voltage to the contact charging section 13 of FIG. 7 is as follows. First, when applying a positive voltage, the power source 1
5, the circuit on the primary side of the transformer 15d is operated, and the primary side of the transformer 15h is not operated. The AC output of the transformer 15d is rectified and smoothed by the diode 15c and the capacitor 15b, and a positive voltage is applied to the contact charging section 13. The current flows from the contact charging unit 13 through the photoconductor 11, the ground, the resistor 15e, and the transformer 15d.
Next, when a negative voltage is applied, the negative voltage is applied by operating the transformer 15h without operating the transformer 15d.

When applying a voltage in which a direct current is superimposed on an alternating current, one of the power supplies inside the power supply 15 becomes an alternating current power supply, and a voltage in which a direct current is superimposed on an alternating current is applied.

[0006]

In such a conventional configuration, since the polarity of the DC power source is switched, two transformers, a secondary side rectifying circuit, and a primary side control circuit are required for all two circuits. A circuit for switching is also required, the circuit becomes complicated, and the power supply 15 is increased in size and cost. Further, when superimposing an alternating current on a direct current, a direct current power source and an alternating current power source are required, and the power source becomes large and the cost is increased.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks and provide a small-sized and inexpensive electrophotographic apparatus.

[0008]

In order to solve this problem, the present invention is directed to either a positive voltage or a negative voltage generated in a voltage generating element placed between a ground plate and a stabilizer plate or grid of a corotron for corona discharge. And a direct current power source is connected so that the polarity is opposite to the polarity of the voltage generated in the alternating current power source or the voltage generating element, and the voltage is applied to the contact charging section.

[0009]

The function of this technical means is as follows.

That is, the voltage generated in the stabilizer of the corona discharge corotron or the voltage generating element placed between the grid and the ground is used as either a positive or negative power source and is applied to the contact charging section. To do. Further, when a voltage in which AC is superimposed on DC or a voltage having a polarity opposite to the voltage generated in the voltage generating element is applied, the DC power supply or the AC power supply is operated.

With the above-described structure, it is possible to switch the polarity of the voltage applied to the contact charging section or switch the voltage in which direct current and direct current are superimposed on alternating current.

[0012]

【Example】

(Embodiment 1) FIG. 1 is a circuit diagram of an electrophotographic apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a photoconductor, 2 is a charging corona discharge corotron, 3 is a contact charging part, 4 is a high voltage power supply for applying a high voltage to the wire of the corona discharging corotron 2, and 5 is a contact charging part. A DC power source connected to the resistor 3 has a resistor 5a, a capacitor 5b, a diode 5c, and a transformer 5d built therein. The circuit on the primary side of the DC power supply 5 is omitted. Reference numeral 6 is a Zener diode as a voltage generating element.

The operation of FIG. 1 is as follows. When a high voltage of the high voltage power supply 4 is applied to the wire of the corona discharge corona discharge 2, a current flows from the wire of the corona discharge corotron 2 toward the stabilizer through the voltage generating element 6 by the corona discharge. A voltage is generated in the voltage generating element 6 by this current. At this time, if the DC power supply 5 is not operated,
The voltage generated in the voltage generating element 6 is applied to the contact charging unit 3 via the resistor 5a. Generally, the current flowing from the contact charging section 3 to the photoconductor 1 is about several μA, and even if the impedance of the resistor 5a is large, the voltage drop due to the resistor 5a is small and does not pose a problem.

Next, when the DC power supply 5 is operated and the voltage generated by the voltage generating element 6 has a reverse polarity and a large absolute value, a voltage having a difference between the absolute values is applied.

For example, if + 500V is generated by the voltage generating element 6 and the DC power supply 5 is not operating, about + 500V is applied to the contact charging section 3. Next, the DC power supply 5 is operated, and if the voltage of the DC power supply 5 is -1000V, a voltage of about -500V is applied to the contact charging section 3.

Further, if the output voltage of the DC power supply 5 is continuously varied, it is possible to apply to the contact charging section 3 a voltage in which a positive to negative voltage is continuously varied.

In this embodiment, the Zener diode is taken as an example of the voltage generating element 6, but other semiconductors, constant voltage elements, resistors, variable resistors, or a combination thereof may be used.

(Embodiment 2) FIG. 2 shows an embodiment in which a grid is added between the corotron and the photosensitive member to stabilize the surface potential of the photosensitive member. In FIG. 2, 1 is a photosensitive member and 2 is a charging member. Corona discharge for corona discharge for 3
Is a high voltage power supply, 5 is a DC power supply, 6 is a voltage generating element, and 7 is a grid.

In the operation of FIG. 2, the high voltage of the high voltage power supply 4 is applied to the wire of the corona discharge corona discharge 2, and the voltage generator 6 is generated by the current flowing through the stabilizer and the grid 7 of the corona discharge discharge corona discharge 2 by the corona discharge. Is generated and the voltage is applied to the contact charging unit 3, and the other points are the same as in the embodiment of FIG.

(Embodiment 3) FIG. 3 is an embodiment in which the voltage applied to the contact charging section and the voltage of the grid are provided differently. In FIG. 3, 1 is a photoreceptor and 2 is for corona discharge. Corotron, 3 is a contact charging unit, 4 is a high voltage power supply, 5 is a DC power supply, 6 is a voltage generating element, 7 is a grid, and 8 is a second voltage generating element.

The operation of FIG. 3 is the same as the operation of FIG. 2, but the second voltage generating element 8 is the corona discharge corotron 2.
Connected between the stabilizer and the grid 7, the voltage of the grid 7 and the voltage applied to the contact charging unit 3 are absolute values, and the voltage applied to the contact charging unit 3 becomes large.

(Embodiment 4) FIG. 4 shows another embodiment in which the voltage applied to the contact charging section and the voltage of the grid are provided differently. In FIG. 4, 1 is a photoconductor and 2 is a corona. A discharging corotron, 3 is a contact charging unit, 4 is a high voltage power supply, 5 is a DC power supply, 6 is a voltage generating element, 7 is a grid, and 8 is a second voltage generating element.

The operation of FIG. 4 is the same as the operation of FIG. 2, but two voltage generating elements are connected in series, and the voltage at the connection point is applied to the contact charging unit 3. Therefore, the voltage applied to the grid 7 and the voltage applied to the contact charging section 3 are large in absolute value.

(Embodiment 5) FIG. 5 is an embodiment in which a Zener diode of a voltage generating element is combined with a variable resistor. In FIG. 5, 1 is a photosensitive member, 2 is a corona discharge corotron, and 3 is a contact electrification. Part, 4 is high voltage power supply, 5 is DC power supply, 6
Is a voltage generating element, 7 is a grid, and 9 is a variable resistor.

The operation of FIG. 5 is the same as the operation of FIG. 2, but the voltage applied to the contact charging section 3 can be arbitrarily changed by the variable resistor 9, and the voltage of the DC power supply 5 can be changed. The same effect as when changing is obtained.

(Embodiment 6) FIG. 6 shows an embodiment in which a voltage in which alternating current is superimposed on direct current is applied to the contact charging section.
In FIG. 6, 1 is a photoconductor, 2 is a corotron for corona discharge, 3 is a contact charging unit, 4 is a high voltage power source, 5 is an AC power source, 6
Is a voltage generating element.

In the operation of FIG. 6, when the AC power supply 5 is off, the DC voltage generated in the voltage generating element 6 is applied to the contact charging section 3 via the winding of the AC power supply 5. When the AC power supply 5 is turned on, a voltage in which the AC voltage generated by the AC power supply 5 is superimposed on the DC voltage generated by the voltage generation element 6 is applied to the contact charging unit 3.

[0028]

As described above, according to the present invention, two DC power sources or two DC power sources and an AC power source are conventionally required, but one DC power source or an AC power source is used. Since it can be configured with one or one set of voltage generating elements, the circuit can be simplified, downsized, and the cost can be reduced. Also, in an electrophotographic device that uses a grid,
It is necessary to connect a voltage generating element or a DC power supply between the grid and the ground to determine the potential of the grid. Since the voltage generating element or the DC power source can be shared, further downsizing and cost reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an electrophotographic apparatus according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a second embodiment of the present invention.

FIG. 3 is a circuit diagram of a third embodiment of the present invention.

FIG. 4 is a circuit diagram of a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram of a fifth embodiment of the present invention.

FIG. 6 is a circuit diagram of a sixth embodiment of the present invention.

FIG. 7 is a circuit diagram of a configuration of a conventional electrophotographic apparatus.

[Explanation of symbols] 1 photoconductor 2 Corona discharge for corona discharge 3 Contact electrification part 4 high voltage power supply 5 DC power supply or AC power supply 5a resistance 5b capacitor 5c diode 5d transformer 6 Voltage generation element 7 grid 8 Voltage generation element

Claims (2)

[Claims] 1. A grounded photoconductor, a corona discharge corotron arranged to face the photoconductor, a high-voltage power supply for applying a high voltage between the wire of the corona discharge corotron and the ground, and the photoconductor. A contact voltage applying unit arranged close to or in contact with the body, connecting a voltage generating element between the stabilizer of the corona discharge corotron and the ground, and contacting the stabilizer of the corona discharge corotron with the contact. An electrophotographic device in which a power source is connected between the power supply section and the power source. 2. A grounded photoconductor, a corona discharge corotron arranged to face the photoconductor, a high-voltage power supply for applying a high voltage between the wire of the corona discharge corotron and the ground, and the photoconductor. A contact charging unit arranged close to or in contact with the body, a grid is provided between the photoreceptor and the corona discharge corotron, and the stabilizer of the corona discharge corotron is grounded or not. Alternatively, an electrophotographic apparatus is connected to the grid, a voltage generating element or a power source is connected between the grid and the ground, and a power source is connected between the grid and the contact charging unit.