JPH06161187A - Paper powder eliminator - Google Patents

Abstract

PURPOSE:To prevent the reverse attachment of paper powder from the side of a scraper for eliminating paper powder by coming in sliding contact with a roller with the paper powder of a transfer sheet attached thereto even when the roller is reversely rotated in order to pull out the jammed transfer sheet, thereby avoiding the attachment of paper powder to the surface of a photosensitive body drum through the fed transfer sheet after jam disposal. CONSTITUTION:A paper powder eliminator is provided with a roller 23 positioned in a paper feed path 22 for conveying a transfer sheet to a transfer part around an image carrier 4 so as to come in contact with the transferred face of the fed transfer sheet, and a scraper brought into sliding contact with the surface of the roller 23. This scraper is supported in such a way as to be rotated onto the lower side around the same axis as that of the roller 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper dust preventive device for preventing a paper dust from adhering to the surface of an image carrier for forming an image in a copying machine or a printer for forming an image by an electrophotographic method. With regard to the above, in particular, a roller that is located in a sheet feeding path that conveys a transfer sheet to a transfer position around an image carrier and that is in contact with a transfer surface of a transfer sheet that is fed, and a scraper that is in sliding contact with the surface of the roller. The present invention relates to a paper dust removing device equipped with.

[0002]

2. Description of the Related Art In electrophotographic image forming, a transfer sheet is squeezed by a separating means or contacted with a sheet guide or the like of each part so as to follow a predetermined feeding or paper feeding path in order to avoid double feeding. Since the paper is conveyed while being conveyed, paper dust or the like is often raised on the surface of the transfer sheet due to the friction caused by the ironing and the contact.

When such a transfer sheet is fed as it is to the transfer section and comes into contact with the image carrier, the paper powder adheres to the surface of the image carrier, deteriorating the photosensitivity of the image carrier, or the image carrier. When cleaning the surface, the paper dust becomes agglomerates and hinders the cleaning effect. Further, a large amount of paper powder is mixed in the residual developer removed from the surface of the image bearing member by cleaning. Therefore, both adversely affect the image quality.

Japanese Patent Laid-Open No. 63-109485 and Japanese Patent Publication No. 62-52864 disclose a paper dust removing device using a combination of a roller and a scraper as described above in order to solve such a problem. There is.

When the roller provided in the paper feed path comes into contact with the transfer surface of the transfer sheet fed to the transfer section, the paper dust on the transfer surface adheres to the surface. The paper dust adhering to the surface of the roller is scraped off by the scraper that is in sliding contact with the surface of the roller, and is prevented from returning to the contact portion with the transfer sheet.

As a result, the amount of paper dust existing on the transfer surface of the transfer sheet fed to the transfer section is reduced, so that when the transfer sheet reaches the transfer section and receives the image transfer, it is not transferred to the surface of the image carrier. Adhesion of paper dust can be suppressed.

Further, in the one disclosed in the above publication, a dust collecting portion is provided below the tail end portion of the scraper for receiving and storing the paper dust removed from the roller by the scraper.

[0008]

However, the paper dust scraped from the roller by the scraper is accumulated on the portion between the scraping edge of the scraper and the roller and overflows from the scraping edge portion of the paper dust. Only the portion that loses stability and spontaneously drops toward the tail end of the scraper is collected in the dust collecting portion. Therefore, the paper dust just scraped remains between the scraping edge of the scraper and the roller.

By the way, when the transfer sheet is jammed in the paper feed path, the roller is sometimes rotated in the reverse direction to pull out the jammed transfer sheet. This reversal is particularly noticeable in an image forming apparatus having a main body of a type in which the paper feed path is not opened vertically.

In such a case, the remaining paper powder is reversely attached to the roller surface and is conveyed in the reverse direction of the roller. Therefore, when the transfer sheet is next fed, the paper powder that has been conveyed in the reverse direction on the roller surface remains at the same position or comes into contact with the transfer surface of the transfer sheet which is going to pass through the roller. Reversely adheres to this.

The paper powder thus reversely adhered to the transfer surface of the transfer sheet adheres to the surface of the image carrier when the transfer sheet reaches the transfer portion. Absent.

[0012] Therefore, an object of the present invention is to provide a paper dust removing device capable of solving such a problem.

[0013]

In order to achieve the above-mentioned objects, the present invention is directed to a transfer sheet which is located in a paper feeding path for conveying a transfer sheet to a transfer portion around an image carrier. In a paper dust removing device provided with a roller in contact with the surface to be transferred and a scraper in sliding contact with the surface of the roller,
The scraper is supported so as to be rotatable downward about the same axis as the roller.

[0014]

In the above-described structure of the present invention, paper dust is attached to the transfer surface of the transfer sheet to be fed, and the attached paper dust is scraped off by a scraper which is in sliding contact with the surface of the roller. Since the paper comes into contact with the transfer surface of the transfer sheet and removes the paper powder well, it is possible to prevent the paper powder of the transfer sheet from adhering to the surface of the image carrier at the time of transfer.

Moreover, since the scraper can rotate downward about the same axis as the roller, the scraping edge of the scraper is inclined downward as the sliding contact position of the scraper to the roller shifts to the lower side of the roller. Therefore, the paper dust remaining between the scraping edge and the roller can be dropped.

[0016]

EXAMPLE An example to which the present invention is applied will be described below.
It will be described in detail with reference to the accompanying drawings.

In this embodiment, as shown in FIGS. 1 and 2, a so-called main body is constituted by a lower frame 1 which is stationary and an upper frame 3 which is pivotally supported on the lower frame 1 by hinge pins 2 so as to be openable and closable. The figure shows the case of a clamshell type copying machine.

The upper frame 1 is equipped with an electrophotographic image forming mechanism 5 centering on the photosensitive drum 4. Although the image forming mechanism 5 is known, a detailed description thereof will be omitted, but an electrostatic latent image corresponding to an original image formed by image exposure on the photosensitive drum 4 is developed to form an image. Reference numeral 6 denotes an exposing means for this purpose, and 7 denotes a developing means.

The image forming mechanism 5 in this embodiment employs a mirror scan type exposure means 6, but the present invention is not limited to this.
Further, the developing means 7 has two developing devices 8 and 9 for developing with toners of different colors, but various developing devices can be adopted.

The lower frame 1 faces the surface of the photoconductor drum 1 after development and transfers the image formed on the photoconductor drum 1 onto a transfer sheet, and the transfer charger 11 and the photoconductor drum. A transfer mechanism for feeding a transfer sheet to the transfer section between the four, a conveyor 13 for conveying the transfer sheet after the transfer, and a fixing device 14 for fixing the transfer sheet after the transfer conveyed by the conveyor 13 are provided. ing. It should be noted that the lower frame 1 is also equipped with a fan 14 that cools or exhausts a key portion inside the body.

From the state in which the upper frame 3 is closed on the lower frame 1 in FIG. 1, when the upper frame 3 is rotated upward and opened as shown in FIG. The paper feeding mechanism 1
The sheet feeding / passing path 22 between the pair of separating rollers 21 and the fixing device 13 is opened.

As a result, even if the transfer sheet is jammed in the sheet feeding / passing path 22, it can be exposed to the outside by opening the upper frame 3 and processed without difficulty.

Immediately before the transfer portion of the paper feeding / passing path 22, a timing roller pair 23 for adjusting the timing of the transfer sheet fed to the transfer portion to align the leading edge with the image on the photosensitive drum 4. 24 are provided.

Of the pair of timing rollers 23 and 24, the upper timing roller 23 is pivotally supported by the upper frame 3 and the lower timing roller 24 is pivotally supported by the lower frame 1. As a result, when the upper frame 3 is opened upward, the upper timing roller 23 follows this movement and separates upward from the lower timing roller 24, which does not hinder the jam processing.

The transfer sheets are sent from the paper feed cassette 25 by the paper feed rollers 26, and then are separated one by one by the separation roller pair 21 to be used for transfer. When the transfer sheet is separated by the separating roller pair 21, the transfer sheet is ironed so that the paper powder is floated on the surface and a large amount of the paper powder is attached to the surface. The paper dust also floats when the transfer sheet comes in contact with each part of the sheet guide of the sheet feeding path 22.

When the paper dust on the surface to be transferred, which is opposed to the photosensitive drum 1 of the transfer sheet and receives the transfer of the image, is left as it is, the transfer sheet comes into contact with the photosensitive drum 4 at the time of transfer. At times, the paper powder adheres to the surface of the photoconductor drum 4 and deteriorates the photosensitivity of the photoconductor drum 4. Further, when the surface of the photoconductor drum 4 after the transfer is cleaned by the cleaning means 15, the paper dust adhering to the photoconductor drum 4 becomes an agglomerate to reduce the cleaning effect. Further, a large amount of paper powder is mixed in the residual developer removed from the surface of the photosensitive drum 4 by cleaning. These impair the quality of the formed image.

In the case of this embodiment, the upper timing roller 23, which is behind the separating roller pair 21 in which a large amount of paper dust is generated and immediately before the transfer section, is on the transfer surface of the transfer sheet fed to the transfer section. Paying attention to the point of contact, the surface of the upper timing roller 23 is in contact with the transfer surface of the transfer sheet, and the paper dust adhered thereto is slid on the surface of the upper timing roller 23 as shown in FIG. By scraping with the scraper 27 so as not to return to the transfer surface of the transfer sheet again, the paper dust adhering to the transfer surface of the transfer sheet fed to the transfer portion is removed. There is.

Therefore, by the upper timing roller 23 and the scraper 27, the paper dust on the transfer surface of the transfer sheet to be transferred adheres to the surface of the photosensitive drum 4 and the image quality deteriorates as described above. You can avoid that.

The method of providing the roller for removing the paper dust in contact with the transfer surface of the transfer sheet depends on whether the transfer surface of the transfer sheet is facing upward or downward, It may be variously determined according to the difference between the horizontal direction and the vertical direction, or the difference in the specific configuration of the sheet feeding mechanism 12 such as the arrangement of the rollers.

Further, in this embodiment, the upper timing roller 23 has a vinyl chloride tube 2 on the conductive core material 23a.
The lower timing roller 24 is a conductive roller. And the upper timing roller 23
A bias power supply 31 is connected to the surface of the device to apply a bias voltage, and the lower timing roller 24 is grounded.

As a result, when the insulating surface layer of the upper timing roller 23 is charged by the application of the voltage and comes into contact with the transfer surface of the transfer sheet, the paper dust adhering to the transfer surface is electrostatically charged. Since it is sucked and positively transferred to the surface side of the upper timing roller 23, the effect of removing the paper dust is remarkably improved.

The bias voltage is applied only while the transfer sheet passes through the timing roller pair 23, 24. Therefore, in addition to the main switch 32 in the middle of the voltage application circuit, a sheet detection switch 33 for detecting passage of the transfer sheet of the timing roller pair 23, 24 is also provided.
A switch 34 interlocking with is provided. However, the sheet detection switch 33 can directly turn the voltage application circuit on and off.

The sheet detection switch 33 has an actuator 33a whose front end faces the paper feeding / passing path 22 and a photocoupler 33b for detecting that the actuator 33a is pushed by a transfer sheet passing through the timing roller pair 23, 24. It has and.

The scraper 27, which is brought into sliding contact with the surface of the upper timing roller 23, is fixed to a part of the transfer portion front upper guide 35 of the paper feeding / passing path 22, and this transfer portion front upper guide 35.
At the same time, it is pivotally supported about the same axis as the upper timing roller 23 so as to be pivotable downward as shown in FIG.

Specifically, the transfer section front upper guide 35 is formed in a box shape as shown in FIG. 5, and the scraper 27 is fixed to the front surface of the tip wall 35a on the transfer section side by applying adhesive or screwing. is doing.

On both sides of the tip wall 35a of the transfer section front upper guide 35, a bifurcated part which is removably and rotatably fitted to a part of the rotary shaft 23c of the upper timing roller 23 through a groove 23d formed therein. A portion 35b is provided,
By fitting the bifurcated portion 35b and the rotary shaft 23c, the transfer portion front upper guide 35 can rotate downward about the same axis as the upper timing roller 23, and in the free state, the rear end wall 35c. The side has a habit of turning to a downward posture as shown in FIG. 4, and is stabilized in this downward posture. On the other hand, the transfer unit front lower guide 36 is fixed to the lower frame 1.

In the present embodiment, when the upper frame 3 is closed with respect to the lower frame 1 as shown in FIG. 1, the transfer unit front upper guide 35 tries to stabilize in the downward posture.
A protrusion 36 provided on a part of the lower front guide 36 of the transfer unit
By being abutted with a, it is pressed to a predetermined position and stabilized at the normal guide position shown in FIG.

On the other hand, when the upper frame 3 is opened upward as shown in FIG. 2, the transfer portion front upper guide 35 is lifted upward and rotated downward while contacting the protrusion 36a. Then, from a position far from the protrusion 36a, the posture becomes downward as shown in FIG. 4 and becomes stable.

When the transfer section front upper guide 34 is in the normal guide position in FIG. 3, the scraping edge portion 27a at the tip of the scraper 27 is slid upward and slidably contacts the side portion of the upper timing roller 23 on the side opposite to the transfer portion. ing. As a result, the paper dust scraped off and removed from the surface of the upper timing roller 23 by the scraper 27 first collects between the upper timing roller 23 on the upward scraping edge 24a, but when it overflows, the back surface of the scraper 27. Those that have become unstable beyond the angle of repose while wrapping around and accumulating on the side reach the back surface of the transfer unit front upper guide 35 and are deposited there.

Therefore, the paper dust scraped off and removed by the scraper 27 from the upper surface of the upper timing roller 23 is not returned to the surface of the upper timing roller 23, but is transferred to the transfer surface of the transfer sheet via the upper timing roller 23. The adhered paper dust can be effectively removed.

When the upper frame 3 is opened upward and the front lower guide 36 of the transfer portion is in the downward posture, as shown in FIG. 4, the scraping edge 27a of the scraper 27 is brought into sliding contact with the upper timing roller 24. The portion moves to the lower side of the upper timing roller 23, and the scraping edge 27a of the scraper 27 is inclined downward.

Therefore, the paper dust accumulated on the portion between the scraping edge 27a and the upper timing roller 23 falls off from the scraping edge 26a and falls on the pre-transfer upper guide 35, which is further transferred. The paper dust accumulated on the upper guide 35 falls on the rear end wall 35c which is the lower side of the pre-transfer upper guide 35.

In this embodiment, in order to collect the paper powder falling on the rear end wall 35c of the pre-transfer upper guide 35, the rear end wall 35c of the pre-transfer guide 35 is provided with a collecting pocket 35d. Whenever the transfer unit front upper guide 35 is in the vertical posture, the paper dust accumulated on the scraping edge portion 27a of the scraper 27 or the paper dust accumulated on the transfer unit front upper guide 35 is dropped into the pocket 35d. It is supposed to be collected. The paper dust collected in the pocket 35d can be discharged to a proper place and discarded by removing the pre-transfer upper guide 35 from the rotary shaft 23c.

When the upper frame 3 is opened upward to remove the transfer sheet jammed in the paper feeding / passing path 22 as described above, the pre-transfer upper guide 35 automatically moves in the hanging posture shown in FIG. 4 in conjunction with this. The scraping edge 27a and the upper timing roller 2 are slanted downward while the sliding contact position of the scraper 27 to the upper timing roller 23 of the scraping edge 27a shifts to the lower side.
Since the paper dust accumulated between the upper timing roller 23 and the upper timing roller 23 is reversely rotated, the paper dust accumulated between the upper timing roller 23 and the upper frame 3 is pulled upward and the jammed transfer sheet is pulled out. Since the paper dust does not collect between the timing roller 23 and the timing roller 23, the paper dust adheres to the surface of the upper timing roller 23 and is conveyed in the reverse direction. It is possible to avoid the adhesion.

In this embodiment, since the paper feeding / passing path 22 is opened by opening the upper portion of the upper frame 3, the upper timing roller 23 is unlikely to be reversed when the jammed transfer sheet is taken out. Also by this, it is possible to prevent the paper dust from adhering to the surface of the photosensitive drum 4 via the transfer sheet fed after the jam processing.

Further, in the present embodiment, the pre-transfer sheet guide 35 is automatically turned downward in conjunction with opening the upper frame 3 upward, but the present invention is not limited to this.
For example, in the case of a copier or printer of the type in which the paper feeding / paper passing path 22 is not opened, it may be rotated downward in conjunction with the opening operation of the main body door that is opened for jam clearance. If necessary, it may be manually pivotable downward. Also, the scraper 27 may be rotatable downward alone or at the same time as another appropriate one.

[0047]

According to the present invention, the scraper is rotated downward about the same axis as the roller in order to remove the paper dust on the transfer surface of the fed transfer sheet by the roller and the scraper which are in sliding contact with each other. Move it so that the scraping edge inclines downward, and the paper dust remaining between the scraping edge and the roller can be dropped, so the roller rotates in the reverse direction to pull out the jammed transfer sheet. Even if the paper is scraped, there is no paper dust between the scraping edge and the roller, and the paper dust is reversely attached to the roller surface from the scraper side and is conveyed backwards. It is possible to avoid the adhesion to the surface, and the image quality becomes stable.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a copying machine to which the present invention is applied in a state in which an upper frame is closed.

FIG. 2 is a cross-sectional view of a state in which an upper frame of the copying machine of FIG. 1 is opened.

FIG. 3 is an enlarged view of a transfer unit of the copying machine of FIG.

FIG. 4 is an enlarged view of a transfer unit of the copying machine of FIG.

5 is an exploded perspective view of a paper dust removing mechanism portion of the copying machine of FIG.

[Explanation of symbols]

 4 Photoreceptor Drum 22 Feeding / Paper Passing Path 23 Upper Timing Roller 23c Rotating Shaft 27 Scraper 27a Scraping Edge

Claims (1)

[Claims] 1. A roller, which is located in a paper feed path that conveys a transfer sheet to a transfer portion around an image carrier, and is in contact with a transfer surface of a transfer sheet that is fed, and a scraper that is in sliding contact with the surface of the roller. A paper dust removing apparatus comprising: a scraper supported on the scraper such that the scraper can rotate downward about the same axis as the roller.