JPH049301B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a paper conveyance device in a reversal development type copying machine.

For example, reversal development type copying machines are widely used to copy image information recorded on microfilm.

(Prior Art) FIG. 1 shows an example of such a conventional reversal development type copying machine. This copying machine uses a photosensitive drum 1 having a photosensitive member (photoconductor) provided on the surface of a metal drum. Photosensitive drum 1
When it rotates in the direction of arrow A, its surface is first charged by a charging corotron (not shown), and an electrostatic latent image is formed by exposure of this afterlight image. The electrostatic latent image is
At a location facing the developing device 2, reversal development is performed with toner. The toner image obtained in this way is
By the action of the transfer corotron 3, the image is transferred onto plain paper (not shown). Toner remaining on the surface of the photosensitive drum 1 after the transfer is removed by a cleaning device (not shown). After the transfer, the plain paper is sent to a fixing device (not shown), where it is fixed and a copied image is obtained.

In this copying machine, plain paper is conveyed between a transfer corotron 3 and a photosensitive drum 1 with its leading edge held by a gripper (not shown).
Next, a device for conveying this plain paper will be described. The gripper that holds the leading edge of plain paper is
It is attached to the chain 4 and moves together with it. The chain 4 is driven by a motor (not shown) and is guided by chain guides 5, 6, etc. to travel in the direction of arrow B. A bracket 7 is provided in front of the transfer corotron 3. A support plate 8 is attached to the upper surface of the bracket 7. A shaft 9 having a hexagonal cross section is rotatably attached to one support portion 8a of the support plate 8. Paper guides 10 and 11 are attached to both sides of the shaft 9, respectively. Further, a U-shaped connecting plate 12 is attached to one side of the shaft 9. A partially U-shaped operating member 14 is rotatably attached to the other support portion 8b of the support plate 8 via a shaft 13. One end of a link 16 is rotatably connected to the actuating member 14 via a pin 15. The other end of the link 16 is connected to the connecting plate 12 via a pin 17. Link 1 on the top surface of support plate 8
A U-shaped stopper 18 is attached below 6. The paper guides 10 and 11 are connected to the connecting plate 1
2 and is biased clockwise by the force of a spring (not shown), and is normally positioned at a position where the connecting plate 12 abuts one stopper portion of the stopper 18. Further, the actuating member 14 is biased counterclockwise by its own weight, and normally the link 16 is pressed against the stopper 18.
It is positioned at a position where it comes into contact with the other stopper part. In this state, the paper guides 10, 11
Each tip end of the actuating member 14 enters a paper conveyance path 19 indicated by a two-dot chain line.

When plain paper is conveyed in this copying machine, the gripper that grips the leading edge of the plain paper moves as the chain 4 moves in the direction of arrow B. When this moving gripper abuts the tip of the actuating member 14, the actuating member 14 is pushed by the gripper and rotates clockwise, allowing movement of the gripper.
When the actuating member 14 rotates clockwise, the link 1
6, the paper guide 1 along with the connecting plate 12
0 and 11 rotate counterclockwise, and the paper transport path 19
Exit from. When the gripper passes over the actuating member 14 and the paper guides 10, 11, the actuating member 14 and the paper guides 10, 11 are returned to their original states shown in FIG. 1 by the force of the spring. When the paper guides 10 and 11 return to their original states, their leading ends push up the leading end of the plain paper and bring it into contact with the surface of the photosensitive drum 1. The plain paper brought into contact with the surface of the photosensitive drum 1 receives a toner image transferred thereto at a location facing the transfer corotron 3. After the transfer, the plain paper is released from being held by the gripper, fixed, and discharged to a discharge tray (not shown).

By the way, in a reversal development type copying machine, the photosensitive drum 1
The photoreceptor is electrically charged, exposed to light to neutralize the portion corresponding to the image information, and charged toner adheres to the neutralized portion, thereby performing reversal development. Therefore, in such a copying machine,
Since there is no attraction force between different types of charges between the surface of the photosensitive drum 1 and the toner, the toner is in a state where it is easy to peel off. On the other hand, in such a copying machine, as described above, the paper guides 10 and 11 return to their original state after passing through the gripper, and the leading edge of the plain paper is brought into contact with the surface of the photosensitive drum 1. . For this reason, the leading edge of the plain paper is brought into sudden contact with the surface of the photosensitive drum 1, and the impact at this time may cause toner to fall off the surface of the photosensitive drum and transfer to the leading edge of the plain paper. When such a phenomenon occurs, abnormal transcription due to this and normal transcription by the transcription corotron 3 are performed. In other words, double transfer is performed, resulting in a decrease in image quality.

(Object of the Invention) The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a paper conveying device that does not cause double transfer.

(Means for Achieving the Object) In the present invention, an elastic buffle is provided between the paper guide and the photosensitive drum close to the photosensitive drum, and a preload is applied to this buffle to bias it toward the leading end of the paper guide. This prevents the leading edge of the paper from suddenly coming into contact with the surface of the photosensitive drum, thereby achieving the above-mentioned purpose.

The present invention will be explained in detail with reference to Examples below.

(Example) The same parts as in Fig. 1 are given the same symbols as in Fig. 2.
The figure shows the main parts of a paper conveying device in one embodiment of the present invention, and FIG. 3 shows a plan view of a part thereof.

In this device, a support plate 22 made of sheet metal is attached to the lower surface of a toner tray 21 via a long hole 23 and an adjusting screw 24 so that its position can be adjusted freely. The toner tray 21 is provided below the developing device 2, and is used to collect toner that spills from the developing device 2. At the tip of the support plate 22, a thin elastic buffle 25 made of polyethylene terephthalate film or the like is attached. The elastic baffle 25 is interposed between the paper guides 10, 11 and the photosensitive drum 1, and is given a preload by its own elasticity, so that it presses against the tip of the paper guides 10, 11 with an appropriate pressing force. I'm forced to.
The tip of the elastic buttful 25 is connected to the paper guide 1 in the latter stage.
It extends to the part closest to the surface of the photosensitive drum 1 . The width of the elastic buffle 25 is appropriately smaller than the width of the plain paper.

In this device, when the paper guides 10 and 11 return to their original state after passing through the gripper, their leading ends push up the leading end of the plain paper and bring it into contact with the lower surface of the elastic buffle 25. Since the elastic baffle 25 is biased by its own elasticity in the direction of pressing against the paper guides 10 and 11, the photosensitive drum 1 can be pushed up even if it receives a push-up force due to sudden contact with plain paper.
It does not reach the point where it comes into contact with the surface. The plain paper brought into contact with the lower surface of the elastic buffle 25 is further conveyed by the gripper, and is brought along the surface of the photosensitive drum 1, which is rotating in the direction of arrow A, from a substantially tangential direction. Since the conveyance speed of the plain paper by the gripper is the same as the peripheral speed of the photosensitive drum 1, the leading end of the plain paper is brought into smooth contact with the surface of the photosensitive drum 1. Therefore, the toner adhering to the surface of the photosensitive drum 1 does not transfer to the leading edge of the plain paper. Therefore, only normal transcription by the transcription corotron 3 is performed.

(Effects of the Invention) As described above, according to the present invention, the paper guide is provided between the paper guide and the photosensitive drum close to the photosensitive drum, and a preload is applied so as to bias the tip of the paper guide. Since the leading edge of the paper can be prevented from suddenly contacting the surface of the photosensitive drum by the elastic buffle, double transfer does not occur and the image quality is improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view showing an example of a conventional paper transport device, FIG. 2 is a longitudinal sectional front view showing main parts of a paper transport device in an embodiment of the present invention, and FIG. 3 is a partial plan view thereof. It is. 1...Photosensitive drum, 3...Transfer corotron, 1
0, 11...paper guide, 14...operating member, 1
9...Plain paper conveyance path, 21...Toner tray, 22
...Support plate, 25...Elastic buttful.

Claims (1)

[Claims] 1. A gripper that grips the leading edge of the paper and transports it between the photosensitive drum and the transfer corotron, a paper guide that is provided before the transfer corotron and brings the paper into contact with the surface of the photosensitive drum, and a paper guide that moves in conjunction with the movement of the gripper. means for moving the paper guide out of the movement path of the gripper and bringing the paper into contact with the surface of the photosensitive drum by the paper guide after passing the gripper; 1. A paper conveyance device comprising: an elastic buffle disposed adjacent to the paper guide and preloaded so as to be biased against the tip of the paper guide.