JP2503289Y2 - Paper guide device for electrophotographic device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sheet guide device for an electrophotographic apparatus.

2. Description of the Related Art The principle of an electrophotographic apparatus is that, in the process of rotating a photoconductor once, an electrostatic latent image is first formed on the outer periphery of the photoconductor, and the electrostatic latent image is developed by a developing unit. The paper is sent to and from the body, the toner on the photoconductor is transferred to the paper using a transfer charger, and finally the toner on the paper is fixed. On the other hand, a guide plate is provided to guide the paper between the photoconductor and the transfer charger. If this guide plate is formed of an insulating material, the charges of the photoconductor, transfer charger, and paper are accumulated in the guide plate, and finally discharge and affect each operation and image.Therefore, at least in the vicinity of the photoconductor and transfer charger. Holds both sides of a conductive guide plate by a conductive frame, and grounds via the frame to leak charges.

Problems to be Solved by the Invention As described above, a high voltage is applied to the transfer charger 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 electric charges generated in the sheet are grounded through the guide plate, which impairs the transfer action of the toner onto the paper, and causes problems such as a difference in shade in printing and a decrease in sharpness.

This invention provides a pair of left and right insulating support plates for holding both sides of a conductive guide plate for guiding a sheet between a photoconductor and a transfer portion, and one of the support plates is provided. A conductive plate sandwiched between the inner surface of the plate and one side of the guide plate is provided, and the conductive plate is grounded via a constant voltage element or a resistor.

Therefore, when the paper is damp, the surface resistance of the paper decreases, but since the guide plate is grounded via the conductive plate and the constant voltage element or resistance, the paper charge leaks. As a result, the voltage required for transfer is secured at the transfer position, and defective transfer of toner from the photoconductor to the paper is prevented. Further, the structure is simplified because the support of the guide plate, the insulation, and the formation of the ground circuit are simultaneously performed.

Embodiment An embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a photoconductor that is connected to a motor (not shown) and rotates. On the outer periphery of the photoconductor 1, an electrostatic latent image forming unit 4 including a charging charger 2 and a laser emitting unit 3 and a developing unit 5 are provided. When,
A transfer charger 6, which is a transfer unit, and a cleaning unit 7.
And the static eliminator 8 are arranged. The photoconductor 1, the electrostatic latent image forming unit 4, the developing unit 5, the cleaning unit 7, and the charge removing unit 8 are held by a frame (not shown) that can rotate upward.

Next, a paper feed unit 9 is provided at the bottom of the housing. That is, an insulating support plate 10 facing each other and a conductive plate 11 provided along the inner surface of one support plate 10 are provided. Conductive guide plates 12, 13 and 14 are fixed to these support plates 10 by screws 15, and projections 16 are formed on the inner surface of the support plate 10 on the side of the photoreceptor 1 and fitted into these projections 16. A guide plate 17 having a combined hole is held by the support plate 10. The conductive plate 11 has a plurality of holes fitted into the screws 15 and the protrusions 16 and is sandwiched between one support plate 10 and one side of the guide plates 12, 13, 14, and 17. Further, both ends of the cassette switch stay 18 are fitted to the support plate 10 and a notch 20 is formed to project the shaft portion of the paper feed roller 19 to the outside. A pressure contact roller 21 that elastically contacts the paper feed roller 19 is rotatably supported by a frame that rotates upward together with the photoconductor 1 and the like. Further, the support plate 10 has a pipe 22.
Both ends of are mated. Then, as shown in FIG. 2, the paper feed unit 9 is held in the frame 23 by screwing the screws 24 penetrating from the outside of the metal frame 23 facing each other at both ends of the pipe 22. Is held. The shaft portion of the paper feed roller 19 is supported by a bearing 25 fitted in the frame 23 and is prevented from moving in the axial direction by a retaining ring 26.

Then, the connector 28 fitted to the bending piece 27 formed in a part of the conductive plate 11 and the frame 23 are connected by a conductor wire 29, and a zener diode 30 which is a constant voltage element is provided in the middle of the conductor wire 29. Are connected. The Zener diode 30 has an anode side connected to the conductive plate 11 and a cathode side connected to the frame 23.

In such a configuration, in the process of rotating the photoconductor 1 once, first, the outer periphery of the photoconductor 1 is negatively charged by the charging charger 2, and the laser emitting section 3 is attached to the charged portion.
The electrostatic latent image is formed on the outer periphery of the photoconductor 1 by scanning the laser beam from the toner, and the toner of the developing portion 5 having a positive charge is attracted to the outer periphery of the photoconductor 1 to visualize the electrostatic latent image. And then developed. On the other hand, the paper in the paper feed cassette 31 is pulled out by the paper feed roller 32, or the paper is inserted from the manual insertion portion, and these papers are transferred to the transfer charger 6 and the photoconductor 1 by the roller 19 and the pressure contact roller 21. Be transported between. Then, since a negative electric field is applied to the paper by the transfer charger 6, the toner on the photoconductor 1 is attracted to the paper. The sheet is further sent to a fixing unit (not shown) to fix the transferred image, and then discharged to the outside.

Printing on the paper is done as above, but if the paper is damp, the surface resistance of the paper is reduced,
Since the Zener diode 30 maintains a constant voltage, the charge generated on the paper is not missed, and the toner transfer failure from the photoconductor 1 to the paper is prevented. By connecting the switch 33 in parallel with the Zener diode 30 and closing the switch 33 during drying, unnecessary charges as noises borne by the guide plates 12, 13, 14, 17 are quickly leaked to the frame 23. This does not affect the operation of each unit.

Instead of the Zener diode 30, an electric resistor including a variable resistance element such as a varistor may be used. These electrical resistors suppress the leakage of electric charge, so that the voltage of the paper can be maintained above a certain level even if the paper is moistened, thus preventing the transfer failure of the toner from the photoconductor to the paper. You can

Further, since the support plate 10 is formed of an insulating material and the conductive plate 11 is sandwiched between the one support plate 10 and the guide plates 12, 13, 14, 17 to form a ground circuit, the guide plate 12, The support of 13,14,17, the insulation and the formation of the ground circuit are simultaneously performed, and the structure is simplified.

Effect of the Invention Since the invention is configured as described above, the surface resistance of the paper is reduced when the paper is moist, but the guide plate is grounded through the conductive plate and the constant voltage element or resistance. Therefore, leakage of paper charge is suppressed, which
At the transfer position, it is possible to secure the voltage required for transfer and prevent toner transfer failure from the photoconductor to the paper.
Moreover, since the guide plate is supported, insulated, and the ground circuit is formed at the same time, the structure can be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show one embodiment of the present invention. FIG. 1 is a vertical sectional side view, and FIG. 2 is an exploded perspective view showing a supporting structure of a paper feeding unit. 1 ... Photoconductor, 6 ... Transfer part, 10 ... Support part, 11 ... Conductive plate, 12, 13, 14, 17 ... Guide plate, 30 ... Constant voltage element

Claims (1)

(57) [Scope of utility model registration request] 1. A pair of left and right insulating support plates for holding both sides of a conductive guide plate for guiding a sheet is provided between a photoconductor and a transfer portion, and one inner surface of the support plate and the guide plate. A sheet guide device for an electrophotographic apparatus, characterized in that a conductive plate sandwiched between one side and the other side is provided, and the conductive plate is grounded via a constant voltage element or a resistor.