JPH06236115A - Belt transfer device - Google Patents

Abstract

PURPOSE:To prevent the slip and vibration of a cleaning roller provided on a belt transfer device and the localization of a belt and to improve the durability of a scraper abutted on the cleaning roller. CONSTITUTION:In the belt transfer device 20, the belt 21 is extended over a driving roller 22, a paper electrifying roller 23 and a tension roller 21A and turned in the direction of the arrow. A transfer electrode 30 is provided on the upper side inside the belt 21, simultaneously, respective left and right cleaning rollers 24 and 25 are provided outside the belt 21 and a pressing spring is provided so as to obtain uniform pressing force on the surface of the belt 21 during rotation, as well. 2KV voltage is applied to the left cleaning roller 24 and the right cleaning roller 25 is electrically earthed and removes the toner stuck to the surface of the belt 21. The toner stuck to the left and right cleaning rollers 24 and 25 is removed by the scraper 26 whose abutting conditions are set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a cleaning member that is pressed against a belt of a belt transfer device provided in an image forming apparatus such as a copying machine or a printer, and an improvement of durability of a scraper member that contacts the cleaning member. .

[0002]

2. Description of the Related Art Generally, an electrophotographic image forming apparatus such as a copying machine is composed of a platen on which a document is placed, a document irradiation lamp reciprocating below the platen, a reflection mirror, and a fixed projection lens and a reflection mirror. Scanning optical system, a photosensitive drum which is charged with a predetermined potential by a band electrode and rotates, and toner is applied to the electrostatic latent image formed on the surface of the photosensitive drum by the scanning optical system to develop the electrostatic latent image. A developing device, a belt transfer device for transferring a toner image onto a recording paper surface which is a transfer material conveyed below the surface of the photoconductor drum, a removing electrode, and toner transferred onto the recording paper surface. It is composed of a fixing device for fixing an image and a cleaning device for removing toner, paper dust and the like remaining on the surface of the photoconductor after the transfer.

Then, desired toner images are successively recorded on the surface of the recording paper which is intermittently conveyed along a predetermined conveying path.

At least one cleaning roller presses and rotates on the outer peripheral surface of the belt stretched by a pair of rollers provided in the belt transfer device to clean the toner adhering to the belt surface and to keep the surface constantly. Keep it clean so that the back side of the recording paper is not contaminated with toner.

[0005]

However, since the linear velocity of the cleaning roller which presses and rotates against the belt surface is set to be 2.5 to 4% faster than the linear velocity of the belt in the related art,
If the load applied to the cleaning roller becomes large and the drive is driven only by friction with the belt, the drive force will be insufficient and slip will occur. Further, in order to compensate for this drawback, one roller (hereinafter referred to as a drive roller) that is drive-transmitted by a drive source (motor) out of a pair of rollers stretching a belt,
When the driving force is transmitted to the cleaning roller by a gear, the photosensitive drum is transmitted to the gear of the drive source through each gear when the cleaning roller slips or vibrates, and is further transmitted to the drive source by the drive source. However, there is a defect that pitch unevenness occurs in the image formed on the peripheral surface of the photosensitive drum.

Further, when the cleaning roller which presses against the surface of the belt is driven and transmitted to the drive roller by, for example, a gear, uniform pressing force is applied to both ends of the cleaning roller shaft on the drive transmitting side and the non-drive transmitting side. When applied, a reaction force required for drive transmission is generated on the drive transmission side, and the pressing force is reduced, and the pressing force on the drive transmission side and the non-drive transmission side becomes non-uniform when the cleaning roller is driven. However, there is a drawback that the operation becomes unsmooth due to the deviation of

Further, the scraper for scraping off the toner adhering to the peripheral surface of the cleaning roller is provided by a counter method in which the tip end portion of the scraper opposes and abuts in the rotation direction of the cleaning roller. Conventional scrapers have different materials, thicknesses, contact angles with cleaning rollers,
Since the contact length and the free length of the scraper that bends when contacting are not precisely determined, the durability is poor and cleaning defects occur, and the backside of the recording paper is contaminated with toner. is there.

The present invention solves such problems and prevents the occurrence of slipping, vibration, or belt deviation that occurs during rotation of the cleaning roller, and the durability of the scraper that abuts the cleaning roller. It is an object of the present invention to provide a belt transfer device that improves cleaning efficiency and does not cause cleaning failure.

[0009]

[Means for Solving the Problems]
This can be achieved by any of b and c.

(A) A belt transfer device of an image forming apparatus for transferring a toner image formed on an image carrier onto a transfer material conveyed by a belt stretched over at least one pair of rollers. The belt has at least one cleaning member to which a voltage for cleaning the belt by rotating by pressing is applied to the outer peripheral surface of the belt, and the linear velocity of the cleaning member is in the range of 0 to 10% with respect to the linear velocity of the belt. In addition, the drive transmission to the cleaning member is performed by at least one of the rollers that stretches the belt and is drive-transmitted from the drive source, and a friction member provided on the cleaning member. Belt transfer device.

(B) In item (a), the pressing force applied to the drive transmitting side support shaft portion having the friction member of the cleaning member is set in the range of 200 to 600 g, and the belt is not provided across the belt. A belt transfer device in which the pressing force applied to the drive transmission side support shaft is set in the range of 100 to 500 g, respectively.

(C) A belt transfer device of an image forming apparatus for transferring a toner image formed on an image carrier onto a transfer material conveyed by a belt stretched over at least one pair of rollers. And at least one cleaning member to which a voltage for cleaning the belt is pressed to rotate on the outer peripheral surface of the belt, and a scraper member that contacts the peripheral surface of the cleaning member to remove toner. The thickness of the scraper member is set in the range of 0.05 to 0.3 mm, the contact angle of the scraper member contacting the cleaning member is 20 to 60 °, and the contact length thereof is 0 to 5 mm. A belt transfer device in which the bendable free length is set in each range of 1 to 10 mm.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is a side sectional view showing the structure of the belt transfer device of FIG. 1, a perspective view showing a drive transmission mechanism of a cleaning member of FIG. 2, and a scraper abutting against the cleaning member of FIG. 4 will be described with reference to the side view showing the contact conditions and the side sectional view showing the configuration of the image forming apparatus in FIG.

However, the present invention is not limited to this embodiment.

As shown in FIG. 4, an electrophotographic image forming apparatus (hereinafter simply referred to as an image forming apparatus) 18 is provided with a platen glass P on which an original M is placed on the upper surface of the main body 1, and the platen glass P in the main body 1 is provided. A scanning optical device 2 is provided below. The scanning optical device 2 comprises a reciprocating document irradiation lamp 2a, a first mirror 2b, second and third mirrors 2c forming a V shape, a fixed projection lens 2d and a fourth mirror 2e. A photoconductor drum 3 is rotatably provided in the center of the inside of the main body 1 in the direction of the arrow, and in the periphery thereof, a belt electrode 4 for uniformly charging the photoconductor 3a along the rotation direction and a toner replenishing device. 5, toner is supplied by the developing device 6, and a developing sleeve 6a having a built-in developing sleeve 6a;
20, the static elimination electrode 9, and the cleaning device 10 are sequentially arranged. Two kinds of recording papers of different sizes are housed in the paper feed cassettes 11 and 11 'and set in the main body 1. Reference numeral 12 denotes a first paper feed roller that feeds the recording paper stored in the paper feed cassette 11 to a standby position before the second paper feed roller 13, and a belt is provided to prevent double feeding of the recording paper. It is composed of rotating rollers 12a, 12a and a stop roller (also referred to as a separating roller) 12b. Reference numeral 13 is an appropriate timing so that the recording paper fed by the first paper feed roller 12 is temporarily stopped at the standby position, and then the front end of the visible image on the photoconductor 3a and the front end of the recording paper are aligned at the transfer position. The second paper feed roller 14 that feeds paper again toward the transfer position at 14 is a guide plate for guiding the recording paper fed by the first paper feed roller 12 to the position of the second paper feed roller 13, It is opened and closed by operating a lever (not shown) so that the jammed paper can be taken out by inserting a hand. Reference numeral 15 is a conveying device that conveys the recording paper after transfer to a fixing position, and the fixing device 16 is a heating roller 16a and a pressure roller 16
b and. Reference numeral 17 denotes a paper discharge roller that discharges the recording paper after fixing to the outside of the main body.

When the copy button is operated in the above apparatus, the original M on the platen glass P is exposed and scanned by the scanning optical device 2, and an electrostatic latent image of the original M is formed on the photoconductor 3a of the photoconductor drum 3. It This electrostatic latent image is developed by the developing device 6.
A visible image is formed by the belt transfer device 20 on the recording paper fed from one of the paper feed cassettes 11 and 11 'of the main body 1. After the transfer, the recording paper is separated from the belt transfer device 20, conveyed to the fixing device 16 by the conveying device 15, fixed there, and ejected by the paper ejection roller 17. In this way, desired toner images are successively recorded on the recording paper surface.

Next, the belt transfer device 20 of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the belt transfer device 20 includes a drive roller 22 on the left side on which a belt 21 is stretched, and the drive roller 22.
22 and a plurality of tension rollers 21 provided above and below the inside of the belt 21.
A, a transfer electrode 30 provided inside the belt 21 so as to face the peripheral surface of the photosensitive drum 3 at a predetermined distance, and a belt 21.
A left cleaning roller 24 and a right cleaning roller 25, which face the driving roller 22 and the paper charging roller 23 across the sheet, and which are pressed against the peripheral surface of the belt 21, and left and right cleaning rollers.
A scraper that scrapes off the toner by abutting the peripheral surfaces of 24 and 25
26, a left cleaning roller 24 and a driving roller 22 shown in FIG. 2, and a driven side friction roller 24A and a driving side friction roller 24B provided on a right cleaning roller 25 and a paper charging roller 23 (not shown), respectively, and a drive transmission unit 27. And a left pressing spring 28A and a right pressing spring 28B which are hung on both ends of the support shafts of the left and right cleaning rollers 24, 25.

The belt 21 is an endless belt made of, for example, a flexible urethane rubber material and having a FLC coating on the surface thereof, and is recorded in the width direction of B4 size recording paper (direction perpendicular to the plane of FIG. 1). It has a length (in the direction perpendicular to the paper surface of FIG. 1) capable of transferring the formed image. The belt 21 is stretched by a drive roller 22, a paper charging roller 23, and tension rollers 21A provided at two upper and lower positions, and the stretched upper surface portion abuts on the peripheral surface of the photosensitive drum 3 and is shown in FIG. The nip width d shown is formed, and when the recording paper passes through the nip width d, the toner image formed on the peripheral surface of the photosensitive drum 3 is reliably transferred via the transfer electrode 30. .

As shown in FIG. 2, a drive gear 27C that meshes with a drive source gear 27D is integrally attached to the right end portion of the drive roller shaft 22a of the drive roller 22, and at a proper position on the left side thereof. A driving side friction roller 27B made of a synthetic resin material is integrally provided. Although not shown, the shaft of the paper charging roller 23 is also provided with a similar friction roller at a target position with the drive-side friction roller 27B. As shown in FIG. 1, the paper charging roller 23 is configured such that the rotation of the driving roller 22 is transmitted by a timing belt 22A wound around the driving roller 22 and the paper charging roller 23. The belt 21 includes a drive roller 22 that rotates via a drive source gear 27D and a drive gear 27C, and a timing belt 22.
A paper charging roller 23 that rotates via A rotates in the direction of the arrow.

As shown in the figure, a left cleaning roller 24 and a right cleaning roller 25 are provided on the outer side of the belt 21 so as to face the driving roller 22 and the paper charging roller 23. A conductive stainless steel (SUS) material is used. A scraper 26 is provided on the peripheral surface of each of the left and right cleaning rollers 24 and 25 in contact with each other by a counter method.

As shown in FIG. 2, a driven side friction roller 27A made of, for example, a urethane rubber material is integrally provided at the right end of the cleaning roller shaft 24a of the left cleaning roller 24 and abuts against the driving side friction roller 27B. The rotation is transmitted in the direction of the arrow. Therefore, in the present invention, instead of the conventional drive transmission by gears, the friction rollers 27A, 27
Drive is transmitted by B. Although illustration is omitted, the driven-side friction roller is also included in the right cleaning roller 25.
A friction roller similar to that of 27A is provided so that the rotation is transmitted by contacting the friction roller of the paper charging roller 25.

As shown in FIG. 2, the left cleaning roller 24 is located on the left side (non-drive transmission side) of the cleaning roller shaft 24a from below the cleaning roller shaft 24a toward the belt 21 surface.
The pressing spring 28A applied to the belt 21 and the right pressing spring 28B applied to the right side (drive transmission side) are pressed against the surface of the belt 21 and the friction roller 27B with a predetermined pressing force.

Although not shown, the right cleaning roller
The same pressing springs as the pressing springs 28A and 28B are also applied to 25 at the same position as the left cleaning roller 24 and pressed against the surface of the belt 21 and the friction roller of the paper charging roller 23.

The drive roller 22 is electrically grounded, and a voltage of about 2 KV is applied to the paper charging roller 23. On the other hand, a voltage of about 2 KV is applied to the left cleaning roller 24 and the right cleaning roller 25 is grounded. Therefore, the recording paper conveyed from the second paper feed roller 13 is charged by the paper charging roller 25, adsorbed on the surface of the belt 21 and conveyed in the arrow direction, and the toner image on the photosensitive drum is transferred by the transfer electrode 30. Then, the recording paper is continuously conveyed by the belt 21 which rotates in the direction of the arrow, and the belt 21 reaches the drive roller 22 and suddenly changes its direction along the curved surface, whereby the recording paper is separated from the surface of the belt 21 and the conveying device 15 And is sent to the fixing device 16.

According to the present invention, the left and right cleaning rollers 24, 25 which rotate by pressing against the surface of the belt 21 do not slip or vibrate so as to prevent the left and right cleaning rollers 24, 25 from rotating relative to the linear velocity of the belt 21. The linear velocity is set slow in the range of 0 to 10%, preferably about 5% to reduce the load so that slip and vibration do not occur.

As described above, the left and right cleaning rollers
Driven side friction roller 27A with elastic drive transmission for 24 and 25
Since it is transmitted by the drive side friction roller 27B, even if there is a small vibration, it is absorbed and is not transmitted to the photosensitive drum 3. Therefore, a normal toner image having no pitch irregularity is formed on the peripheral surface of the photosensitive drum.

Further, according to the present invention, the left and right cleaning rollers are provided.
In order to press the entire surface of the belt 21 with uniform pressing force during rotation of the belts 24 and 25, the pressing force is applied to the drive roller side cleaning roller shaft 24a having the driven side friction rollers 27A of the left and right cleaning rollers 24 and 25. Pressing force of spring 28B is 200
The pressure spring 28A to be set on the non-drive transmission side shown in FIG.
Pressing force of is set in the range of 100-500g, preferably about 35
Set to 0g. The pressing force on the right cleaning roller 25 is set in the same manner as the left cleaning roller 24.
By strongly setting the pressing force on the drive transmission side in this way, even if the pressing force is reduced by the repulsive force that the driven side friction roller 27A receives during drive transmission, the pressing force becomes the same as that on the non-drive transmission side. Cleaning rollers 24 and 25 are belts
It is possible to always press the surface 21 evenly and prevent the belt 21 from being biased.

The toner adhering to the surface of the belt 21 by the left and right cleaning rollers 24, 25 thus constructed is first transferred by suction to the left cleaning roller 24 to which a voltage is applied, and then scraped off by the scraper 26.
Then, since the toner remaining on the belt 21 that has passed the left cleaning roller 24 is converted to the opposite polarity, it is adsorbed and transferred to the grounded right cleaning roller 25, and then scraped off by the scraper 26, and the left cleaning roller 24 The toner scraped off is conveyed to the toner collection box.

In this way, the left and right cleaning rollers
24 and 25 and the belt 21 side are always kept clean.

Next, the contact condition of each scraper 26 contacting the peripheral surfaces of the left and right cleaning rollers 24, 25 is set as follows.

The scraper 26 is a PET sheet set to have a thickness of 0.05 to 0.3 mm, preferably 0.125 m.
Set to a thickness of m.

As shown in FIG. 3, the contact angle .theta. At which the scraper 26 contacts the peripheral surfaces of the left and right cleaning rollers 24, 25 is set in the range of 20 to 60.degree., Preferably about 40.degree .. The contact length a shown in the figure is set in the range of 0 to 5 mm, preferably about 1 mm.

The free length A shown in the bendable diagram of the scraper 26 supported by the scraper support 26A is 1 to 10 mm.
And preferably about 4 mm. By setting the contact condition of the scraper 26 in this manner, the toner adhered to each of the left and right cleaning rollers 24, 25 can be reliably removed, and the durability and reliability of the scraper 26 are ensured so that each of the left and right cleaning rollers is secured. Cleaning roller 2
Since 4 and 25 are always kept clean, the back side of the recording paper is not contaminated with toner.

Although the present invention has been described by taking a mono-black image forming apparatus as an example, the present invention is of course applicable to a color image forming apparatus.

[0036]

According to the present invention, the cleaning roller provided by pressing against the outside of the belt stretched by the belt transfer device of the present invention does not slip or vibrate during rotation, so that the photosensitive drum always has pitch unevenness. A normal toner image was formed, and deviation of the belt that occurred during rotation was prevented. In addition, since the contact conditions for the scraper that contacts the cleaning surface are set appropriately, the durability of the scraper is significantly improved and reliability is ensured.
Since the cleaning roller is always kept normal, the back side of the recording paper conveyed by the belt is not contaminated with toner.

[Brief description of drawings]

FIG. 1 is a side sectional view showing the structure of a belt transfer device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a drive transmission mechanism of a cleaning member according to an exemplary embodiment of the present invention.

FIG. 3 is a side view showing a contact condition of a scraper contacting a cleaning member according to an embodiment of the present invention.

FIG. 4 is a side sectional view showing the configuration of the image forming apparatus.

[Explanation of symbols]

 3 Photosensitive drum 18 Image forming device 20 Belt transfer device 21 Belt 22 Drive roller 23 Paper charging roller 24 Left cleaning roller 25 Right cleaning roller 26 Scraper 27A Driven side friction roller 27B Drive side friction roller 28A Non drive side pressure spring 28B Drive side Pressing spring 30 Transfer electrode θ Contact angle a Contact length A Free length

Claims (3)

[Claims] 1. A belt transfer device of an image forming apparatus for transferring a toner image formed on an image carrier onto a transfer material conveyed by a belt stretched over at least one pair of rollers. The belt has at least one cleaning member to which a voltage for rotating the outer peripheral surface of the belt is pressed to clean the belt, and the linear velocity of the cleaning member is in the range of 0 to 10% with respect to the linear velocity of the belt. At the same time, the drive transmission to the cleaning member is performed by at least one of the rollers that stretches the belt and is drive-transmitted from a drive source, and a friction member provided on the cleaning member. Belt transfer device. 2. The pressing force applied to the drive transmission side support shaft portion having the friction member of the cleaning member is set in a range of 200 to 600 g, and the belt is sandwiched between the cleaning member and the cleaning member. A belt transfer device in which the pressing force applied to the drive transmission side support shaft is set in the range of 100 to 500 g, respectively. 3. A belt transfer device of an image forming apparatus for transferring a toner image formed on an image carrier onto a transfer material conveyed by a belt stretched over at least one pair of rollers. The belt has at least one cleaning member to which a voltage for cleaning the belt is pressed to rotate on the outer peripheral surface of the belt, and a scraper member that contacts the peripheral surface of the cleaning member to remove toner. The thickness of the scraper member is set in the range of 0.05 to 0.3 mm, the contact angle of the scraper member contacting the cleaning member is set to 20 to 60 °, and the contact length is set to 0 to
A belt transfer device characterized in that the bendable free length at the time of contact is set to each range of 1 to 10 mm to 5 mm.