JPH09127798A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a foreign matter from being caught between the tip part of a separation claw and a photoreceptor when the photoreceptor is reversely rotated and to maintain an excellent abutting state by separating the separation claw from the photoreceptor when the photoreceptor is reversely rotated. SOLUTION: When a printing button is depressed, a signal designating the normal rotation of the photoreceptor 1 is transmitted from a control substrate to a driving motor. The photoreceptor 1 starts to normally rotate and the separation claw 12 abuts on the photoreceptor 1. Thereafter, when an image forming stage is finished, a signal for designating to turn off a separation solenoid is transmitted, and the separation claw 12 is away from the photoreceptor 1. Then, the driving motor is stopped according to a photoreceptor stop signal. Immediately after that, a signal for reversely rotating the driving motor is transmitted, and the photoreceptor 1 is stopped after reversely rotating by a fixed distance. By controlling the separation claw 12 so as to be away from the photoreceptor at the time of reversely rotating the photoreceptor, the foreign matter stuck onto the separation claw is prevented from being caught between the photoreceptor and the separation claw.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a printer, and a FAX, and more specifically, a separation claw for separating a transfer paper which has been transferred from a photoconductor. In the image forming apparatus provided with the image forming apparatus, it is possible to prevent foreign matter such as toner, paper powder, and developer from being caught in the contact portion between the tip of the separation claw and the photoconductor, and maintain a stable contact state for a long time. Forming apparatus

[0002]

2. Description of the Related Art In an electrophotographic copying machine or the like, an electrostatic latent image is formed by irradiating an optical image information such as reflected light of a document on a photosensitive body which is uniformly charged in advance. An image is formed by converting the latent image into a visible image with a developer from a developing device, and then transferring and fixing the visible image on a transfer paper. In the transfer step,
Since the developed image is transferred onto the transfer paper by applying a bias having a polarity opposite to that of the developed image from the transfer means arranged opposite to the photoconductor with the transfer paper sandwiched therebetween, the transfer paper is once adsorbed on the surface of the photoconductor. However, the transfer paper is easily discharged and separated by corona discharge from the separation device arranged immediately after the transfer means. However, when the developed image is a solid black image, the photoconductor speed is high, the photoconductor drum has a large diameter (when the pole ratio is high), or when a transfer paper having low rigidity is used, Depending on the conditions, the separating force using the extreme value of the photoconductor drum becomes weak, and the leading edge of the transfer paper continues to adhere to the photoconductor surface even after passing through the separating device and is easily rotated. In preparation for such a case, a separation claw for forcibly separating the transfer paper is generally used, and the separation claw is in sliding contact with the surface of the photoconductor on the downstream side of the separation device. In order to forcibly separate the transfer paper that is in close contact with the photoconductor, it is necessary for the tip of such a separation claw to maintain a good contact state with the photoconductor.

However, if the separating claw is used for a long period of time, the toner will be fused to the tip of the separating claw that comes into contact with the photosensitive member, or paper powder or developer will be pinched, so that a good contact state can be obtained. I will not be able to. In this case, the transfer paper cannot be separated by the separation claw, causing a paper jam, or the toner accumulates on the tip of the separation claw and drops on the transfer paper, which significantly impairs the image quality. In order to solve such a problem, JP-A-2-96
In Japanese Patent No. 788, it is proposed that the contact between the separation claw and the photoconductor is released only during the sheet passing interval of the transfer paper so that the toner attached to the tip of the separation claw does not drop on the transfer paper. ing. However, it is difficult to reliably drop the toner between the sheets, and especially in the case of a high-speed machine, it is not possible to secure even the time for separating the separating claws. Further, once the toner or the like is fused to the separation claw, it can no longer be removed by the impact force. On the other hand, at the position further downstream of the separation claw,
The cleaning blade is in contact with the photoconductor, and the toner remaining on the photoconductor is collected. When such a cleaning blade is used for a long period of time, paper dust or the like is caught between the edge portion and the photoconductor,
Poor adhesion between the cleaning blade and the photosensitive member causes the cleaning function to deteriorate. In order to prevent this, it has been proposed that the photoconductor be rotated in the reverse direction after the photoconductor is stopped to remove the paper dust or the like that has been caught.

[0004]

However, when the separation claw remains in contact with the photoconductor when the photoconductor reverses, toner, paper dust, developer, etc. sneak into the tip of the separation claw, which causes the separation. It has been found that it becomes a new cause of poor contact between the nail and the photoconductor. On the downstream side of the separation claw, since the angle formed by the photosensitive member and the separation claw is acute, toner, paper powder developer, etc. easily sneak into the contact portion. In particular, the smaller the item, the easier it is to dig in. It was also found that even if the reverse rotation mechanism of the photoconductor is not provided, the photoconductor slightly reversely rotates due to its reaction immediately after the stop, so that it is easy for foreign matter to be caught at this time. The present invention has been made in view of the above problems, and an object thereof is to generate a situation in which foreign matter such as toner, paper powder, and a developer is caught between the tip of the separation claw and the photoconductor. It is an object of the present invention to provide an image forming apparatus capable of preventing the above and maintaining a good contact state.

[0005]

In order to achieve the above-mentioned object, the invention of claim 1 is provided with a drive mechanism for rotating the photoreceptor in the reverse direction and a separating claw for separating the transfer paper. 3. The image forming apparatus according to claim 2, wherein the separation claw is separated from the photoconductor when the photoconductor is reversed.
According to another aspect of the present invention, in the image forming apparatus having the separation claw for peeling off the transfer paper, the separation claw is separated from the photoconductor before the driving of the photoconductor is stopped.
According to another aspect of the present invention, in the image forming apparatus including the separation claw for peeling off the transfer paper, the separation claw is brought into contact with the photoconductor after the start of driving the photoconductor.

[0006]

In the present invention as described above, claims 1, 2
According to the invention, the separation claw is separated from the photoconductor when the photoconductor rotates in the reverse direction, so that the toner, the paper dust, the developer and the like enter from the rear and are not pinched during the reverse rotation. Behind the separation claw, the angle formed by the photoconductor and the separation claw is an acute angle, and in particular, a minute object is easily entangled. Further, even if the reverse rotation mechanism of the photoconductor is not provided, the photoconductor rotates slightly reversely due to its reaction immediately after the stop. Therefore, it is effective to release the separation claw during this period. According to the third aspect of the present invention, since the separation claw is brought into contact with the photoconductor after the photoconductor is started to drive, it becomes difficult for foreign matter on the photoconductor to be caught.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of an embodiment of the present invention, an outline of an image forming section of a copying machine to which the present invention is applied will be described based on FIG. The photosensitive drum 1, which is an image carrier, is rotationally driven in the direction of arrow A, and an electrostatic latent image is formed on the surface thereof by the electrostatic latent image forming means, which is visualized by the developing device 5. The toner image formed on the surface of the photosensitive drum is a pre-transfer charge erasing charger 1 which is a pre-transfer charge erasing unit.
The charge is removed by 0 to facilitate transfer separation. When this toner image reaches the transfer charger 6 which is the transfer means,
The transfer paper 11 is fed in synchronism with this, and the transfer charger 6 applies a charge having a polarity opposite to that of the toner from the back of the transfer paper 11 to transfer the toner image. After that, the transfer paper is charged with an alternating current biased by a direct current by a separation charger 7 which is a separation charge-eliminating means, and the charges applied to the transfer paper are erased or reduced. The transfer paper from which the charge is removed by the separation charger 7 is separated from the photosensitive drum by its rigidity and its own weight. Reference numeral 12 is a separation claw for forcibly separating the unseparated transfer paper from the photosensitive drum. Also, 9
Is a cleaning device for cleaning the toner remaining on the photosensitive drum, and has a cleaning blade 17 and the like.
FIG. 1 is a perspective view showing the structure of the separation claw 12. Separation claw 1
2 is composed of a metal plate whose tip forms an edge,
A holder -21 for holding this is rotatably supported by the support shaft 22. In addition, one end of the support shaft 22 is fixed by a screw 22a or the like, and a coil spring 23 wound around the support shaft imparts a rotational elastic force in a direction to bring the tip of the separation claw 12 into contact with the photoconductor 1. .

FIG. 2 is an exploded view of the separation claw contact / separation mechanism, and FIG. 3 is an explanatory view of an assembled state of the separation claw contact / separation mechanism. The shape of the separation claw and its holding means shown in FIG.
Although it is different from the one shown in FIG. 2, the separating claw etc. in FIG. 1 may be replaced with the separating claw etc. in FIG. 2 as it is, so that the one shown in FIG. 2 will be described here. That is, the support shaft 22 is attached to the main body of the apparatus via the brackets 24 and 25 so as to maintain the positional relationship parallel to the axial direction of the photoconductor 1. A lever 26 is attached to one end of the support shaft 22. When the signal of solenoid ON is sent from the control board 32 shown in FIG. 5, the plunger 28 of the solenoid 27 attached to the main body is pulled in, and the intermediate lever 29 rotatable about the central portion is the direction of the arrow. Turn to. When the other end of the intermediate lever 29 pushes the lever 26 in the direction of the arrow, the separating claw 12 contacts the surface of the drum 1 via the spring 23. Conversely, when the solenoid OFF signal is sent, the separation claw 12 is separated from the photoconductor 1 by the reverse operation.

A first embodiment of the present invention is characterized in that the separation claw is separated from the photoconductor when the photoconductor is reversed. That is, FIG. 5 shows the photosensitive member driving motor 3
3 is a timing chart of the separation claw contact / separation solenoid 27, and FIG. 6 is a block diagram showing a control system. When a print button 31 (not shown) provided on the main body of the image forming apparatus is pressed, a signal for instructing the photoconductor 1 to rotate normally is output from the control board (CPU, ROM, RAM, I / O port, etc.) 32. The photoconductor 1 starts to rotate forward.
Immediately after that, a signal instructing the separation solenoid to be turned on is sent from the control board 32 to the solenoid 27, and the separation claw 12 comes into contact with the photoconductor 1. After that, when the image forming process is completed, a signal for instructing the separation solenoid OFF is sent, and the separation claw 12
Is separated from the photoconductor 1. After that, the drive motor 33 is stopped by the photoreceptor stop signal. Immediately after that, a reverse rotation signal of the drive motor 33 is sent this time, and the photosensitive member 1 reversely rotates a predetermined distance and then stops. As described above, in the first embodiment of the present invention, the separation claw 12 is controlled so as to separate from the photoconductor when the photoconductor is reversed, so that the foreign matter attached to the separation claw is caught between the photoconductor and the photoconductor. Is prevented.

Further, in the second embodiment of the present invention, as shown in FIG. 4, before the normal rotation drive of the photosensitive member is stopped (t
3) Since the separation claw is configured to be separated from the photoconductor, it is possible to prevent foreign matter from sticking between the separation claw and the photoconductor even in an image forming apparatus having no photoconductor reversing mechanism. Further, in the third embodiment of the present invention, after the driving of the photoconductor is started (t2), the separation claw is brought into contact with the photoconductor, so that each of the above-mentioned form examples is driven even when the photoconductor is driven. The same effect of preventing foreign matter sticking can be exhibited.

[0011]

As described above, according to the first aspect of the present invention,
At least a photoconductor as a latent image carrier, a drive mechanism for rotating the photoconductor forward and backward, a developing device for visualizing an electrostatic latent image on the photoconductor, and a visible image on the photoconductor are transferred. In an image forming apparatus provided with a transfer means for transferring onto paper and a separation claw for separating transfer paper adsorbed on the surface of the photoconductor after the transfer, the separation claw is separated from the photoconductor when the photoconductor is reversed. Since it is configured as described above, it is possible to prevent foreign matter such as toner, paper dust, and developer from being caught between the tip of the separation claw and the photoconductor when the photoconductor is reversed, and maintain a good contact state. Is possible. According to the invention of claim 2, the separation claw is separated from the photoconductor before the driving of the photoconductor is stopped. Therefore, even in an image forming apparatus having no photoconductor reversing mechanism, The same effect as can be obtained. According to the invention of claim 3, since the separation claw is brought into contact with the photoconductor after the drive of the photoconductor is started, the same effect as in claim 1 can be obtained even when the photoconductor is driven. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a separation claw according to an embodiment of the present invention.

FIG. 2 is a view showing an example of a separation claw contact / separation mechanism of the present invention.

FIG. 3 is an overall view of a mechanism for bringing the separating claw into contact with and separating from a photoconductor.

FIG. 4 is a timing chart according to an embodiment of the present invention.

FIG. 5 is a block diagram according to one embodiment of the present invention.

FIG. 6 is a diagram showing a schematic configuration of an image forming unit of a copying machine to which the present invention is applied.

[Explanation of symbols]

12 separation claws, 17 cleaning blades, 22 support shafts, 26 levers, 27 separation claw solenoids, 31
Print button, 32 control board, 33 photoconductor drive motor.

Claims (3)

[Claims] 1. A photoconductor as at least a latent image carrier, a drive mechanism for rotating the photoconductor in the normal and reverse directions, a developing device for visualizing an electrostatic latent image on the photoconductor, and a photoconductor on the photoconductor. In an image forming apparatus provided with a transfer means for transferring a visible image to a transfer paper and a separation claw for peeling off the transfer paper adsorbed on the surface of the photoconductor after the transfer, the separation claw is used when the photoconductor is reversed. An image forming apparatus characterized in that it is configured to be separated from a photoconductor. 2. A photoconductor as at least a latent image carrier, a drive mechanism for rotating the photoconductor in the normal and reverse directions, a developing device for visualizing an electrostatic latent image on the photoconductor, and a photoconductor on the photoconductor. In an image forming apparatus equipped with a transfer means for transferring a visible image to a transfer paper and a separation claw for separating the transfer paper adsorbed on the surface of the photoconductor after the transfer, before stopping the driving of the photoconductor An image forming apparatus characterized in that the separation claw is configured to be separated from a photoconductor. 3. A photoconductor as at least a latent image carrier, a drive mechanism for rotating the photoconductor in the normal and reverse directions, a developing device for visualizing an electrostatic latent image on the photoconductor, and a photoconductor on the photoconductor. In an image forming apparatus provided with a transfer means for transferring a visible image to a transfer paper and a separation claw for peeling off the transfer paper adsorbed on the surface of the photoconductor after the transfer, after the driving of the photoconductor is started, An image forming apparatus having a structure in which a separation claw is in contact with a photoconductor.