JP3125336B2 - Electrophotographic equipment - Google Patents

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 unit.

[0002]

2. Description of the Related Art Conventionally, a roller or a brush is directly pressed against a photoreceptor or a voltage is applied by bringing the roller or brush close to the photoreceptor.
An electrophotographic apparatus having a contact charging unit for transferring toner from a developing device to a photoreceptor and transferring toner from the photoreceptor to copy paper had a configuration as shown in FIG.

In FIG. 6, 11 is a photoreceptor, 12 is a corona discharge corona for charging, 13 is a contact charging section for development or transfer, and 14 is a high voltage which applies a high voltage to the wire of the corona discharge 12 for corona discharge. A power supply 15 is a power supply, and internally 15d and 15d are provided for taking out a positive output and a negative output.
h transformer, 15c and 15g rectifying diodes, 1
Smoothing capacitors 5b and 15f and discharge resistors 15a and 15e are built in (note that the primary side circuit is omitted). Reference numeral 17 denotes a grid for stabilizing the surface potential of the photoconductor 11, and 16 denotes a voltage generating element for determining the potential of the grid 17.

[0006] The method of applying a voltage to the contact charging section 13 in FIG. 6 is as follows. First, when a positive voltage is applied, the power supply 1
5 operates the primary side circuit of the transformer 15d, and does not operate the primary side of the transformer 15h. 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 unit 13. The current flows from the contact charging unit 13 through the photoconductor 11, passes through the ground, passes through the resistor 15e, and returns to the transformer 15d.
Next, when a negative voltage is applied, a negative voltage is applied by operating the transformer 15h without operating the transformer 15d.

[0005]

In such a conventional configuration, the polarity of the DC power supply is switched, so that the transformer 15 is required.
d, 15h, the secondary rectifier circuit and the primary control circuit are all 2
Circuits are required, and a circuit for switching the polarity is also required, which complicates the circuit and increases the size and cost of the power supply 15.

SUMMARY OF THE INVENTION An object of the present invention is to provide a small and inexpensive electrophotographic apparatus which eliminates the above-mentioned conventional disadvantages.

[0007]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention is directed to a positive or negative voltage generated in a voltage generating element inserted between a stabilizer or a grid of a corona discharge corotron and a ground. And a DC power supply for generating a voltage having a large absolute value, which is opposite to the polarity of the voltage generated in the voltage generating element, is connected to apply a voltage to the contact heating unit.

[0008]

The operation of this technical means is as follows.

That is, the voltage generated in the stabilizer or the voltage generating element inserted between the grid and the ground of the corona discharge corona is used as a positive or negative power source and applied to the contact charging section. I do. When a voltage having a polarity opposite to that of the voltage generated in the voltage generating element is applied, the DC power supply is operated.

With the above configuration, it is possible to switch the polarity of the voltage applied to the contact heating section.

[0011]

FIG. 1 is a circuit diagram of an electrophotographic apparatus according to an embodiment of the present invention. In Figure 1, 1 is a photoreceptor, 2 corona discharge corotron for charging, 3 contact pressure conductive portion, 4 is a high-voltage power supply for applying a high voltage to the wire of the corona discharge corotron 2
is there. Reference numeral 5 denotes a stabilizer and voltage generator for the corotron 2 for corona discharge.
The contact point with the raw element (Zener diode) 6
A DC power supply connected between the electrical parts 3 and internally having a resistor 5a;
A capacitor 5b, a diode 5c, and a transformer 5d are built in. The circuit on the primary side of the DC power supply 5 is omitted.
You.

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 corotron 2, a direct current flows from the wire of the corona discharge corotron 2 toward the stabilizer through corona discharge through the voltage generating element 6. This current generates a voltage in the voltage generating element 6. At this time, unless the DC power supply 5 is 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 photoreceptor 1 is about several μA. Even if the impedance of the resistor 5a is large, the voltage drop due to the resistor 5a is small and causes no problem.

Next, when the DC power supply 5 is operated and the absolute value of the voltage generated by the voltage generating element 6 is opposite to that of the voltage generated by the voltage generating element 6, a voltage having a difference between the absolute values is applied.

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

If the output voltage of the DC power supply 5 is continuously varied, a voltage in which a positive to negative voltage can be continuously varied can be applied to the contact heating section 3.

In this embodiment, a Zener diode is used as an example of the voltage generating element 6. However, another semiconductor, a constant voltage element, a resistor, a variable resistor, or a combination thereof may be used.

Embodiment 2 FIG. 2 shows an embodiment in which a grid 7 is added between a corotron and a photoconductor to stabilize the surface potential of the photoconductor.
In FIG. 2, 1 is a photoreceptor, 2 is a corona discharge corona for charging, 3 is a contact charging unit, 4 is a high voltage power supply, 5 is a DC power supply, and 6 is a voltage generating element . 7 is a grid,
This is connected to the stabilizer of the coronatron 2 for Rona discharge.
The voltage generating element 6 is connected between the point and the ground.

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 corotron 2 and the voltage generated by the voltage generation element 6 by the current flowing through the stabilizer 7 and the grid 7 of the corona discharge corotron 2 by corona discharge. 1 and a voltage is applied to the contact heating section 3, and the rest is the same as the embodiment of FIG.

(Embodiment 3) FIG. 3 shows an embodiment in which a difference is provided between the voltage applied to the contact charging unit and the voltage of the grid. In FIG. Corotron, 3 is a contact heating 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, except that the second voltage generating element 8 is a corona discharge corotron 2.
The voltage of the grid 7 and the voltage applied to the contact heating unit 3 are absolute values, and the voltage applied to the contact heating unit 3 increases.

(Embodiment 4) FIG. 4 shows another embodiment in which a difference is provided between the voltage applied to the contact charging section and the voltage of the grid. In FIG. Discharge corotron, 3 is a contact heating section, 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 in FIG. 4 is the same as the operation in FIG. 2, except that two voltage generating elements are connected in series, and the voltage at the connection point is applied to the contact charging section 3. Therefore, the voltage applied to the grid 7 and the voltage applied to the contact charging unit 3 in absolute value are large.

(Embodiment 5) FIG. 5 shows an embodiment in which a Zener diode of a voltage generating element is combined with a variable resistor. In FIG.
Reference numeral 2 denotes a corona discharge corotron, 3 denotes a contact charging unit, 4 denotes a high-voltage power supply, 5 denotes a DC power supply, 6 denotes a voltage generating element, 7 denotes a grid, and 9 denotes a variable resistor.

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

[0025]

As described above, according to the present invention, two DC power supplies are conventionally required, but one DC power supply and one or one set of voltage generating elements are used. This makes it possible to simplify the circuit, reduce the size, and reduce the cost. In an electrophotographic apparatus using a grid, it is necessary to connect a voltage generating element or a DC power supply between the grid and the ground in order to determine the potential of the grid. Since the voltage generating element or the DC power supply can be shared, the size and cost can be further reduced.

[Brief description of the 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 according to 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 configuration of a conventional electrophotographic apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor 2 Corona discharge for corona discharge 3 Contact applying part 4 High voltage power supply 5 DC power supply 5a Resistance 5b Capacitor 5c Diode 5d Transformer 6 Voltage generating element 7 Grid 8 Voltage generating element

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 15/02 102 G03G 15/06 101 G03G 15/16 103

Claims (2)

(57) [Claims] 1. A grounded photoconductor, a corona discharge corotron disposed opposite to the photoconductor, a high-voltage power supply for applying a high voltage between a wire of the corona discharge corotron and ground, and the photoconductor. Comprising a contact-applying unit disposed in proximity to or in contact with the body, and connecting a voltage generating element between the stabilizer and the ground of the corona discharge corotron,
The corona discharge corona ballast and voltage generating element
An electrophotographic apparatus in which a power source that generates a voltage having a large absolute value and a polarity opposite to that of the voltage generated in the voltage generating element is connected between the connection unit and the contact heating unit. 2. A grounded photoreceptor, a corona discharge corotron disposed opposite to the photoreceptor, a high voltage power supply for applying a high voltage between a wire of the corona discharge corotron and ground, A contact charging unit disposed close to or in contact with the body, a grid is provided between the photoreceptor and the corona discharge corona, and the stabilizer of the corona discharge corotron is grounded. Or, a voltage generating element is connected between the grid and the ground, and the grid is connected to the voltage generating element.
And connection part, wherein the voltage is a voltage generated in generating element in opposite polarity, electrophotographic apparatus connect the power to generate a large voltage absolute value between the contact pressure conductive portion.