JPH0636887A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To eliminate the high potential charge of paper at reverse printing and prevent the scattering of toner and the turbulence of an image thereby in an electrophotographic device having double printing mechanism. CONSTITUTION:An electrophotographic device has a static eliminating brush 36 is provided in such a manner as to be movable to the position approaching the paper after transfer and the position leaving it. The static eliminating brush 36 is controlled so as to be situated in the leaving position at printing on the surface of the paper and situated in the approaching position at printing on the reverse side of the paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus provided with an antistatic brush for destaticizing a paper after transfer.

[0002]

2. Description of the Related Art In an electrophotographic apparatus such as a laser printer or a copying machine, in order to peel off a sheet of paper after transfer from a photoconductor, it is necessary to bring a charge-eliminating brush into contact with the back surface of the paper after transfer to discharge electric charge. It is already known from Japanese Utility Model Publication No. 61-44212.

In an electrophotographic apparatus equipped with a double-sided printing mechanism,
In double-sided printing, when a charge is applied when transferring to the back surface after transferring to the front surface of the paper, the electric potential of the paper becomes several times as large as that at the time of front surface transfer and sometimes reaches several KV. As a result, when the highly charged paper comes into contact with the transport guide plate or the like, the toner transferred onto the paper is scattered and the image is disturbed. Even in the case of a general electrophotographic apparatus, this image distortion may occur at low temperatures.

[0004]

The above problem can be solved by fixing the static elimination brush to the position of the paper after transfer, if the potential of the paper is simply lowered. However, in order to bring the transferred paper into close contact with the transfer guide plate for transfer, it is desirable that the paper has a certain electric potential.
This is because if the paper after transfer is not brought into close contact with the transport guide plate,
This is because it causes fixing wrinkles and the like, and therefore it is necessary to electrostatically adhere the paper to the conveyance guide plate.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems of image disturbance and fixing wrinkles due to toner scattering in an electrophotographic apparatus having a double-sided printing mechanism.

Another object of the present invention is to prevent the occurrence of image distortion at low temperatures in a general electrophotographic apparatus.

[0007]

According to the present invention, the above-mentioned object is provided so that the static elimination brush can be moved between a position closer to and a position away from the paper after transfer, and the static elimination brush is provided on the surface of the paper. The problem can be solved by providing means for controlling so that when printing on the paper, the position is set to move away, and when printing on the back surface of the paper, the position is set to approach.

In order to solve the above-mentioned problems, the present invention proposes that the static elimination brush is formed in a shape having brushes at both ends of the main body, and the rotation is controlled by the means.

Further, the present invention has a problem that even when the surface is transferred, when the paper charged to a high potential comes into contact with the conveying guide plate or the like, the toner transferred onto the paper is scattered at a low temperature, and the image is disturbed. In order to solve the problem, a temperature sensor is provided inside the apparatus, and the static elimination brush is mounted so as to be movable between a position closer to the paper after transfer and a position away from the paper after transfer, and the static elimination brush is normally located at the position away from the sheet. It is proposed to provide means for controlling the temperature to approach the position when the temperature detected by the temperature sensor reaches a predetermined set value.

[0010]

In the electrophotographic apparatus provided with the double-sided printing mechanism and provided with the static elimination brush for eliminating static electricity after the transfer, the static elimination brush is provided so as to be movable between a position approaching the transfer sheet and a position away from the transfer sheet. And a means for controlling the static elimination brush so that the static elimination brush moves away from the surface when printing on the front surface of the paper and the static elimination brush moves closer to the position when printing on the back surface of the paper. As a result, when the paper comes into contact with the conveyance guide plate, etc., the high potential that causes the toner to scatter and the image is disturbed is eliminated, and the electric potential that is electrostatically adhered to the conveyance guide plate is maintained. become.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser printer having a double-sided printing mechanism shown in the drawings will be described below as an embodiment of the present invention.

In the laser printer 1 shown in FIG. 1,
The latent image of the image formed on the belt-shaped photoconductor 3 by the laser writing device 2 is made into a toner image by a predetermined electrophotographic process. The papers fed one by one from the paper feed tray 4 are supplied to the photoconductor 3 by the registration roller 5 at a predetermined timing, and the toner image is transferred onto one surface of the photoconductor 3 under the action of the transfer charger 6. The paper on which the toner image is transferred is fixed by the fixing device 7 and then sent to the reversing unit 10.

Inside the reversing unit 10, a so-called three-roller reversing roller 11 and a reversing guide 12 are provided. In the reversing unit 10, the paper is ejected to the sorter or the paper ejection tray 13 outside the machine without reversing it, or the reversing guide 12 is fed upward to eject the reversed paper to the reversing ejection tray 14, or the reversing guide 12 It is possible to make a selection as to whether or not to move the paper backward and feed it below the reversing unit 10 into the duplex unit 20 provided at the bottom of the printer body. When performing double-sided printing, double-sided unit 20
Inward delivery is selected.

A stacker 21 for temporarily stacking the fed papers is provided in the duplex unit 20 so that the leading edge of the papers is aligned with the leading end of the stacker 21 regardless of the size of the papers. Re-feeding conveyance path 22 and guide plate 23 whose discharge ports can be switched according to size
Is provided. When a specified number of sheets of paper are stacked,
The calling roller 24 is pressed against the leading end of the stacked sheet bundle, and is fed one by one to the registration roller 5 of the printer 1 in accordance with the back side image forming signal, and printing is performed on the back side of the sheet.
The paper on which the back side printing is completed is discharged from the reversing unit 10 to the sorter, the paper discharge tray 13 or the reverse discharge tray 14.

In FIG. 2, the static elimination brush 36 is a support plate 37.
The support plate 37 is fixedly supported by the support plate 37 and is pivotally mounted around the support point 37a. One end of the support plate 37 has a solenoid 38
Is pivotally attached to the actuator 38a, and one end of a spring 39 is locked to the other end. FIG. 2 shows the state of the static elimination brush 36 when printing on the surface of paper. Since the solenoid 38 is energized to pull in the actuator 38a, the charge removal brush 36 is located away from the position where the paper is discharged, that is, away from the belt-shaped photoconductor 3. At this position of the static elimination brush 36, no electrostatic action occurs on the paper after transfer. Reference numeral 40 is a conveyance guide plate.

FIG. 3 shows the state of the static elimination brush 36 when printing the back side of the paper. At this time, the urging of the solenoid 38 is interrupted, and the action of the spring 39 causes the actuator 38 to operate.
“A” projects from the solenoid 38, and the support plate 37 rotates clockwise. The static elimination brush 36 is located at a position close to the paper after transfer, and neutralizes the paper after transfer.

FIG. 4 shows a structure which is normally used as the above-mentioned static elimination brush 36.

On the other hand, FIG. 5 shows a static elimination brush 41 constructed according to the present invention. This static elimination brush 41 is formed in a shape having brushes 42 on both side ends of its main body 41a. As shown in FIG. 6, the static elimination brush 41 is rotation-controlled. When printing on the surface of the paper, the static elimination brush 41 is in the position indicated by A in FIG.
The brush 42 is located away from the paper. When printing on the back side of the paper, the static elimination brush 41 is rotated 45 °
That is, the brush 42 comes close to the paper and is a position where the static elimination action is performed. The rotation control of the static elimination brush 41 is performed under the angle control by the stepping motor 43 shown in FIG.

The present invention can also be applied to the prevention of toner scattering, which is likely to occur at low temperatures. Therefore, a temperature sensor is arranged inside the device. Normally, the static elimination brush is set at a position far from the paper after transfer, and when the temperature detected by the temperature sensor reaches a predetermined set value, the static elimination brush is positioned so as to be close to the paper after transfer. To do.
This configuration can be applied regardless of single-sided printing or double-sided printing on paper.

[0020]

EFFECTS OF THE INVENTION In an electrophotographic apparatus having a double-sided printing mechanism, static electricity of high potential generated on paper during backside printing is eliminated to prevent toner scattering after transfer and eliminate image disturbance.

By constructing the static elimination brush according to the second aspect, the life of the static elimination brush can be almost doubled.

According to the third aspect of the present invention, it is possible to prevent toner scattering, which is likely to occur at low temperatures, and to eliminate image disturbance.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a laser printer to which the present invention is applied.

FIG. 2 is an explanatory view showing a static elimination brush constructed according to the present invention in a non-static elimination state.

FIG. 3 is an explanatory view showing that the static elimination brush is in a static elimination state.

FIG. 4 is a front view of a normal charge eliminating brush.

FIG. 5 is a front view of a static elimination brush constructed according to the present invention.

FIG. 6 is an explanatory diagram showing an applied configuration of the static elimination brush shown in FIG.

FIG. 7 is a perspective view of the static elimination brush according to the present invention.

[Explanation of symbols]

 1 Laser Printer 3 Belt-Shaped Photosensitive Member 6 Transfer Charger 20 Double-sided Unit 36, 41 Static Elimination Brush 42 Brush A Non-Static Elimination Brush B B Static Elimination State

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03G 15/00 108 7369-2H 21/00 116

Claims (3)

[Claims] 1. An electrophotographic apparatus having a double-sided printing mechanism and provided with an antistatic brush for destaticizing the paper after transfer, wherein the antistatic brush is movable between a position approaching the paper after transfer and a position away from it. And a means for controlling the static elimination brush so that it is moved away from the surface of the paper when printing on the front surface of the paper, and is moved toward the back surface of the paper when printing on the back surface of the paper. apparatus. 2. The electrophotographic apparatus according to claim 1, wherein the static elimination brush is formed in a shape having brushes at both ends of the main body, and is rotation-controlled by the means. 3. An electrophotographic apparatus provided with a static elimination brush for eliminating static electricity from a sheet of paper after transfer, wherein a temperature sensor is provided inside the apparatus, and the static elimination brush is movable between a position closer to and a position away from the sheet of paper after transfer. And a means for controlling the static eliminator brush so that the static elimination brush is normally located at the distant position, and that when the temperature detected by the temperature sensor reaches a predetermined set value, the static elimination brush is brought to the approaching position. Characteristic electrophotographic device.