JPS63271488A - Paper guide apparatus for electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent a toner transfer failure from a photosensitive body to a form, by providing a conductive from guide plate in the vicinity of the photosensitive body and a transfer charger, and connecting it to a grid of a scorotron charger or a part of the same potential as this grid. CONSTITUTION:Conductive paper guide plates 14-16 are provided in the vicinity of a photosensitive body 2 and a transfer charger 7, and the guide plates are connected to the grid 3 of a scorotron charger 4 or the same potential part as the grid through a switch 30. According to this constitution, when a form 12 has humidity, the surface resistance drops, but when a movable contact point 33 of the switch 30 is connected to a contact point 31, a Zener element 28 holds a constant-voltage and a charge generated in the paper 12 is not escaped, and the transfer failure of toner is prevented. At the time of drying, the movable contact point 33 is connected to a contact point 32 and the guide plates 14-16 are grounded directly, and an unnecessary electrification of the guide plate is leaked quickly to a frame member 27, and exerts no influence on an operation of a valley part.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a paper guide device for an electrophotographic apparatus.

The principle of conventional electrophotographic equipment is that in the process of rotating the photoreceptor once,
First, an electrostatic latent image is formed on the outer periphery of the photoconductor, this electrostatic latent image is developed by a developing section, paper is sent between the transfer charger and the photoconductor, and the toner on the photoconductor is transferred using the transfer charger. This transfers the toner onto the paper, and finally fixes the toner on the paper. On the other hand, a guide plate is provided to guide the paper between the photoreceptor and the transfer charger. If this guide plate is made of an insulating material, charges from the photoreceptor, transfer charger, and paper will accumulate on the guide plate and will eventually be discharged, affecting each operation and image. uses a conductive guide plate, which is grounded to allow the charge to leak.

Problems to be Solved by the Invention As mentioned above, a high voltage is applied to the transfer charger in order to transfer the toner on the photoconductor to the paper, but when the humidity is high, the surface resistance of the paper decreases, so the paper The electric charge generated in the guide plate is grounded through the guide plate, which impairs the toner transfer effect onto the paper, causing problems such as differences in shading and deterioration of sharpness in print.

Means for Solving Interlayer Points A scorotron charger, a laser emitting section, a developing section, and a transfer charger are arranged along the outer periphery of a rotatable photoreceptor, and this A conductive guide plate is provided to guide the sheet between the two, and this guide plate is connected to the grid of the scorotron charger or a portion having the same potential as the grid.

Effect: Therefore, when the paper is damp, the surface resistance of the paper decreases, but since a constant voltage is always applied to the guide plate by the grit of the Scorotron charger, leakage of charge from the paper is suppressed. This ensures the voltage necessary for transfer at the transfer position, and prevents defective toner transfer from the photoreceptor to the paper.

Example An embodiment of the present invention will be described based on the drawings.

(2) is a housing, and this housing 1 is rotatably provided with a photoreceptor 2 driven by a motor (not shown), and on the outer periphery of this photoreceptor 2 is a scorotron charger 4 having three grits; Laser emitting section 5, developing section 6, and transfer charger 7
and a cleaning section 9 having a doctor blade 8;
A static eliminator 1O is arranged.

The housing 1 also includes a paper feed cassette 11 located at the bottom and detachably mounted, a paper feed roller 13 that pulls out the paper 12 in the paper feed cassette 11, and a conductive guide plate 14. Conductive guide plates 15 and 16 are provided opposite to the guide plate 14 with a predetermined spacing therebetween. Paper feed rollers 17 and 18 are provided on the paper path formed by these guide plates 14, 15, and 16, and a manual feed tray 19 is provided on the side surface of the housing 1 to feed the paper toward the paper feed roller 18. .

Further, the housing 1 includes a guide plate 20 for guiding the paper 12 passing through the transfer charger 7, a guide plate 21 facing the end of this guide plate 20, and a guide plate 20, 21 for guiding the paper 12 passing through the transfer charger 7. A discharge path 22 for discharging the paper 12 is provided. A peeling roller 23 is provided near the end of the guide plate 20, a heat roller 24 and a press roller 25 are provided in contact with each other in the middle of the guide plate 20, and a paper ejection roller 23 is provided in the ejection path 22. 26 are provided.

The scorotron charger 4 has its corona wire connected to the negative side of a 4 to 5 KV battery 27, the metal frame 4a grounded, and the grid 3 connected to the anode side of the Zener diode 28 to generate a negative 700V voltage. It is maintained at a potential. The cathode side of the Zener diode 28 is grounded. Further, the charger 7 has its corona wire connected to the negative side of the battery 29, and the metal frame 7a is grounded. Therefore, the guide plates 14, 15, 16 are connected to the grid 3 of the scorotron charger 4.
Alternatively, a switch 30 is provided to connect to a portion having the same potential as the grid 3. That is, this switch 30 includes a contact 31 connected to the anode side of the Zener diode 28, a grounded contact 32, and guide plates 14, 15 .
16, and a movable contact 33 connected to the contact 31 or 32. The movable contact 33 is connected to either of the contacts 31 and 32.

In such a configuration, in the process of rotating the photoreceptor 2 once, the outer periphery of the photoreceptor 2 is first negatively charged by the scorotron charger 4, and a laser beam from the laser emitting unit 5 is scanned over this charged portion. An electrostatic latent image is formed on the outer periphery of the photoreceptor 2, and the positively charged toner in the developing section 6 is attracted to the outer periphery of the photoreceptor 2, and the electrostatic latent image is visualized and developed. On the other hand, the paper feed cassette 11
The paper 12 inside is pulled out by a paper feed roller 13, and then conveyed between the transfer charger 7 and the photoreceptor 2 by feed rollers 17 and 18. Then, since a negative electric field is applied to the paper 12 by the transfer charger 7, the toner on the photoreceptor 2 is attracted to the paper 12. The paper 12 is further conveyed while being separated from the outer periphery of the photoconductor 2 by a peeling roller 23, is held between a heat roller 24 and a press roller 25, the toner on the paper 12 is fixed, and then is discharged to the outside by a discharge roller 26. be done. Further, after the transfer, the toner adhering to the outer periphery of the photoreceptor 2 is wiped away by the doctor blade 8, and the electrostatic latent image is also erased by the light beam from the static eliminating section 10.

Printing is performed on the paper as described above, but if the paper 12 is damp, the surface resistance of the paper 12 is reduced, but if the movable contact 33 of the switch 30 is connected to the contact 31, Since the Zener diode 28 maintains a constant voltage, the charge generated on the paper 12 is not missed, and defective toner transfer from the photoreceptor 2 to the paper 12 is prevented. In addition, when drying, by connecting the movable contact 33 of the switch 30 to the contact 32 and directly grounding the guide plates 14, 15, 16, unnecessary electrical charge as noise on the guide plates 14, 15, 16 is quickly removed from the frame. It is leaked to member 27. This does not affect the operation of each part. Furthermore, grit 3 of Scorotron charger 4
Since the potentials of the guide plates 14, 15, and 16 can be maintained constant using , the circuit does not become complicated.

Note that instead of the Zener diode 28, an electric resistor including a variable resistance element such as a varistor may be used. Since these electric resistors suppress charge leakage, the voltage of the paper is maintained at a certain level or higher even if the paper becomes moist, and therefore, defective toner transfer from the photoreceptor 2 to the paper 12 is prevented. Can be done. Alternatively, the grid 3 may be connected to a power source that maintains a constant voltage. In this case as well, the same objective can be achieved.

Effects of the Invention Since this invention is constructed as described above, the surface resistance of the paper decreases when the paper is damp, but a constant voltage is always applied to the guide plate by the grit of the Scorotron charger. Therefore, the leakage of electric charge from the paper is suppressed, and thereby the voltage necessary for transfer can be secured at the transfer position, thereby preventing defective toner transfer from the photoreceptor to the paper. In addition, by selecting the setting value of the grid potential of the scorotron charger, when the paper is dry, it is possible to leak unnecessary charges as noise from the guide plate, so that the operation of each part can be controlled. It is possible to prevent the image from being affected, and the grid of the scorotron charger can be used to maintain the potential of the guide plate at a constant level, so the circuit does not become complicated. have an effect.

[Brief explanation of the drawing]

The drawing is a longitudinal side view showing an embodiment of the present invention.

Claims (1)

[Claims] A scorotron charger, a laser emitting section, a developing section, and a transfer charger are arranged along the outer periphery of a freely rotatable photoreceptor, and a sheet of paper is guided near the photoreceptor and the transfer charger toward between them. 1. A paper guide device for an electrophotographic apparatus, characterized in that a conductive guide plate is provided, and the guide plate is connected to a grid of the Scorotron charger or a portion having the same potential as the grid.