JP2001350384A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent cleaning failure of a cleaning means, which removes a substance such as talc and toner remaining on an intermediate transfer belt in a high speed monochrome image forming device using the intermediate transfer body. SOLUTION: In the image forming device having a belt-like image carrier, onto which a toner image corresponding to image information is formed or transferred, and the cleaning means, which removes matter sticking to the surface of the image carrier, the image carrier is constituted so as to be reversely rotated only by a predetermined amount at predetermined timing.

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 such as a copying machine, a printer, and a facsimile.
In particular, the present invention relates to a black-and-white image forming apparatus using an intermediate transfer member such as an intermediate transfer belt.

[0002]

2. Description of the Related Art Conventionally, this type of image forming apparatus such as a copying machine or a printer uniformly charges the surface of a photosensitive drum to a predetermined potential and then performs image exposure on the surface of the photosensitive drum. Forming a toner image by forming an electrostatic latent image corresponding to the image information, and visualizing the electrostatic latent image with a developing device, and transferring and fixing the toner image on recording paper. Thus, an image is formed.

In such an image forming apparatus, in order to increase the number of recording sheets on which an image can be formed per unit time and to increase the speed, it is necessary to increase the rotation speed of the photosensitive drum and to increase the transport speed of the recording sheet. Must be set high, and the toner images sequentially formed on the photosensitive drum must be transferred and fixed onto recording paper that is continuously conveyed at short paper intervals.

[0004]

However, the prior art described above has the following problems. That is, in the above-described conventional image forming apparatus, when the toner image formed on the photosensitive drum is directly transferred onto the recording paper, a substance such as talc contained in the recording paper adheres to the surface of the photosensitive drum. Contamination, and image quality defects occur.

[0005] In particular, in the above conventional image forming apparatus,
In order to increase the speed, it is necessary to increase the rotation speed of the photosensitive drum and to set the recording paper transport speed high, and the load applied to the roll pair for transporting the recording paper, etc. To increase. Therefore, the recording paper is rubbed by a pair of rolls having a high applied load, and a substance such as talc adheres to the surface of the photosensitive drum not only from the end face of the paper but also from the entirety of the paper, as shown in FIG. Thus, the problem that image quality defects occur becomes significant.

Accordingly, the present invention firstly provides an image forming apparatus which can solve the above-mentioned problems and can prevent substances such as talc contained in recording paper from adhering to the surface of a photosensitive drum. The purpose is to:

In order to achieve the above object, the present inventors have changed the idea and invented an apparatus using an intermediate transfer member even for a high-speed black and white dedicated image forming apparatus. Was.

In an image forming apparatus using such an intermediate transfer member, after a toner image formed on a photosensitive drum is primarily transferred onto an intermediate transfer belt, the toner image transferred onto the intermediate transfer belt is It is configured to form an image by secondary transfer onto recording paper.

As described above, after the toner image formed on the photosensitive drum is primarily transferred onto the intermediate transfer belt, the toner image transferred onto the intermediate transfer belt is secondarily transferred onto recording paper. In this case, the photosensitive drum does not come into direct contact with the recording paper, so that talc or the like contained in the recording paper is prevented from adhering to the surface of the photosensitive drum, thereby reducing image quality defects. Can be prevented.

However, according to the study of the present inventors, as described above, the toner image formed on the photosensitive drum was primarily transferred onto the intermediate transfer belt and then transferred onto the intermediate transfer belt. When the toner image is configured to be secondarily transferred onto the recording paper, the recording paper comes into contact with the intermediate transfer belt when the toner image transferred onto the intermediate transfer belt is secondarily transferred onto the recording paper. . Therefore, in an image forming apparatus using the intermediate transfer belt, when the speed is increased, the amount of the substance such as talc and the residual toner included in the recording paper adhered to the intermediate transfer belt increases. A material such as talc and residual toner adhered to the intermediate transfer belt are configured to be removed by a cleaning blade. However, when the amount of material such as talc and residual toner adhered to the intermediate transfer belt increases, cleaning is performed. It has been found that there is a problem that substances such as talc and residual toner that have been rubbed off and residual toner accumulate on the back side of the edge portion of the blade, resulting in poor cleaning. As described above, when the cleaning failure of the intermediate transfer belt occurs, the amount of the substance such as talc and the toner remaining on the intermediate transfer belt increases, which causes a problem of causing an image quality defect.

Therefore, a second object of the present invention is to provide a high-speed black-and-white high-speed image forming apparatus using an intermediate transfer member, in which cleaning is performed to remove substances such as talc and toner remaining on the intermediate transfer belt. An object of the present invention is to provide an image forming apparatus capable of preventing occurrence of a cleaning failure.

[0012]

That is, according to a first aspect of the present invention, there is provided an image carrier for forming a toner image corresponding to image information in a black and white image forming apparatus for forming only a black and white image. A primary transfer means for primary-transferring the toner image formed on the image carrier onto a belt-shaped intermediate transfer body, and a state in which the toner image primary-transferred from the image carrier by the primary transfer means is carried And a secondary transfer means for secondary-transferring a toner image primarily transferred on the belt-shaped intermediate transfer member onto a recording medium. An image forming apparatus.

According to a second aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein the process speed is set to 200 m / s or more.

Further, according to a third aspect of the present invention, there is provided a belt-shaped image carrier on which a toner image corresponding to image information is formed or transferred, and an adhering substance adhered to a surface of the belt-shaped image carrier. An image forming apparatus comprising: a cleaning unit for removing the toner image; wherein the belt-shaped image carrier is reversed by a predetermined amount at a predetermined timing. Note that, for example, a belt-shaped intermediate transfer member is used as the belt-shaped image carrier, but a belt-shaped photoconductor may be used as the belt-shaped image carrier.

[0015] Still further, the invention described in claim 4 is:
4. The cleaning device according to claim 3, wherein the cleaning unit is configured by a blade made of an elastic body, and the blade is disposed near an upstream side of a driving roll that rotationally drives the belt-shaped image carrier. An image forming apparatus.

Further, the invention described in claim 5 is characterized in that the amount of reversal of the belt-shaped image carrier is set to be at least equal to the bite amount of the blade. Image forming apparatus.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 2 shows a black-and-white high-speed copying machine as an image forming apparatus according to Embodiment 1 of the present invention.

In FIG. 2, reference numeral 1 denotes a main body of the copying machine. An automatic document feeder 3 for automatically feeding the originals 2 in a separated state one by one is provided above the main body 1 of the copying machine. A document reading device 4 for reading an image of the document 2 conveyed by the automatic document conveying device 3 is provided.
The original reading device 4 illuminates the original 2 placed on the platen glass 5 with a light source 6 and reflects a reflected light image from the original 2 on a full rate mirror 7 and a half rate mirror 8.
9 via a reduction optical system consisting of
Scanning exposure is performed on the image reading element 11 made of D or the like, and the image reading element 11 reads the reflected light image of the document 2 at a predetermined dot density (for example, 16 dots / mm).

The reflected light image of the document 2 read by the document reading device 4 is sent to an image processing device 12 as black and white document reflectance data.
Shading correction for the reflectance data of Document 2
Predetermined image processing such as positional deviation correction, gamma correction, frame erasure, and moving editing is performed.

The image data subjected to the predetermined image processing by the image processing apparatus 12 as described above is converted into ROS 13 (Raster Output Sc) as original gradation data.
The ROS 13 performs image exposure using laser light in accordance with the original gradation data.
The high-speed copying machine is configured to also function as a printer, and when the high-speed copying machine functions as a printer, image data is input to the image processing apparatus 12 from a host computer such as a personal computer. After predetermined image processing is performed by the image processing apparatus 12, the image is output to the ROS 13 as original gradation data.

Inside the copying machine main body 1, an image forming means A capable of forming a black and white toner image is provided. The image forming means A mainly includes a photosensitive drum 17 as an image carrier on which an electrostatic latent image is formed, and a monochrome toner image formed by developing the electrostatic latent image formed on the photosensitive drum 17. And a developing device 18 as a developing means capable of forming the image.

As shown in FIG. 2, the ROS 13 modulates a semiconductor laser (not shown) according to original gradation data, and emits a laser beam LB from the semiconductor laser according to gradation data. The laser light LB emitted from the semiconductor laser is deflected and scanned by the rotary polygon mirror 14 and is scanned and exposed on the photosensitive drum 17 as an image carrier via the f · θ lens 15 and the reflection mirror 16.

The photosensitive drum 17 on which the laser beam LB is scanned and exposed by the ROS 13 is driven to rotate at a predetermined speed in a direction indicated by an arrow by driving means (not shown). In this embodiment, a high-speed black-and-white copying machine is used. The process speed, which is the rotational speed (peripheral speed) of the photosensitive drum 17, is, for example, 420.
It is set at a much higher speed such as mm / s.
The surface of the photosensitive drum 17 is charged in advance to a predetermined polarity (for example, a negative polarity) and a potential by a scorotron 19 for primary charging, and is then scanned and exposed to laser light LB in accordance with original gradation data. Thus, an electrostatic latent image is formed. The electrostatic latent image formed on the photosensitive drum 17 is reversely developed by a black-and-white developing device 18 using, for example, a toner charged to a negative polarity having the same polarity as the charged polarity of the photosensitive drum 17, and a black-and-white toner It becomes an image. The toner image formed on the photosensitive drum 17 is charged with a negative polarity or the like by a pre-transfer charger 20 as necessary, and the charge amount is adjusted.

The black-and-white toner image formed on the photosensitive drum 17 is transferred onto an intermediate transfer belt 21 as an intermediate transfer member disposed below the photosensitive drum 17 as a primary transfer means as a first transfer means. The image is transferred by the transfer roll 22. The intermediate transfer belt 21 includes a driving roll 23, a driven roll 24a, a driven roll 24b, a tension roll 2
4c, a driven roll 24d and a backup roll 25 as an opposing roll constituting a part of the secondary transfer means are rotatably supported along the arrow direction at the same moving speed as the peripheral speed of the photosensitive drum 17. I have.

A black and white toner image formed on the photosensitive drum 17 is transferred to the intermediate transfer belt 21 by a primary transfer roll 22. The toner image transferred onto the intermediate transfer belt 21 is transferred onto a recording paper 26 as a recording medium conveyed to a secondary transfer position at a predetermined timing.
Backup roll 25 supporting intermediate transfer belt 21
Then, the image is transferred by the pressing force and the electrostatic force of the secondary transfer roll 27 which constitutes a part of the secondary transfer means that is pressed against the backup roll 25. As shown in FIG. 2, the recording paper 26 includes a plurality of paper feed cassettes 28,
Sheets of a predetermined size from any one of 9, 30, and 31 are fed by feed rolls 28a, 29a, 30a, and 31a. The fed recording paper 26 is transported by a plurality of transport rolls 32 and registration rolls 33 to the secondary transfer position of the intermediate transfer belt 21 at a predetermined timing. As described above, the black and white toner image is transferred from the intermediate transfer belt 21 to the recording paper 26 by the backup roll 25 and the secondary transfer roll 27 as the secondary transfer unit. I have.

The recording paper 26 onto which the black and white toner image has been transferred from the intermediate transfer belt 21 is separated from the intermediate transfer belt 21 and then conveyed by a vacuum conveying belt 34 to a fixing device 35, where the fixing is performed. The toner image is fixed on the recording paper 26 by heat and pressure by the device 35,
In the case of one-sided copying, the image is directly discharged onto the paper discharge tray 36 and the image copying process is completed.

On the other hand, in the case of double-sided copying, the recording paper 26 on which a black-and-white image is formed on the first side (front side) is not discharged onto the discharge tray 36 as it is, but is turned downward by a reversing gate (not shown). The conveyance direction is changed, and the three rolls are once conveyed to the reversing passage 39 by the tri-roll 37 and the reversing roll 38 pressed against each other. Then, the recording paper 26 is conveyed to a two-sided passage 40 by a reversing roll 38 which is reversed this time, and once conveyed to a registration roll 33 by a conveying roll 41 provided in the two-sided passage 40 and stopped. The recording paper 26 synchronizes with the toner image on the intermediate transfer belt 21 and again
3, the recording paper 26 is discharged onto the discharge tray 36 after the toner image is transferred and fixed to the second surface (back surface) of the recording paper 26.

In this embodiment, a cleaning device 42 is provided for removing residual toner, paper dust and the like from the surface of the photosensitive drum 17 after the completion of the transfer process. Further, the intermediate transfer belt 32 after the transfer process is completed is disposed near the driving roll 23 of the intermediate transfer belt 21.
A cleaning device 50 for removing residual toner, paper dust, and the like from the surface of the printer is provided.

In FIG. 2, reference numeral 43 denotes a manual feed tray.

FIG. 3 is a block diagram showing the image forming means A of the copying machine.

In this copying machine, as described above, after the surface of the photosensitive drum 17 is uniformly charged to a predetermined potential by the scorotron 19 for primary charging, the surface of the photosensitive drum 17 Black and white image LB
Is exposed to form an electrostatic latent image. The electrostatic latent image formed on the surface of the photosensitive drum 17 is developed by the developing device 18, and a black and white toner image T is formed on the surface of the photosensitive drum 17.

The black and white toner image T formed on the photosensitive drum 17 is transferred to the photosensitive drum 17 and the intermediate transfer belt 2.
In the primary transfer position where the photosensitive drum 1 contacts
7 is transferred onto the surface of the intermediate transfer belt 21 from above. At this primary transfer position, a semi-conductive primary transfer bias roll 22 is disposed on the back side of the intermediate transfer belt 21. The intermediate transfer belt 21 is moved by the primary transfer bias roll 22 to the photosensitive drum. 17 comes into contact with the surface. The bias roll 22 for primary transfer includes
A voltage having a polarity opposite to the charging polarity of the toner is applied, and the toner image T formed on the photosensitive drum 17 is transferred onto the intermediate transfer belt 21 by a pressing force and an electrostatic force. In addition, of the rolls supporting the intermediate transfer belt 21,
The tension roll 24b is pressed against the intermediate transfer belt 21 by a spring S, and is configured to apply a certain tension to the intermediate transfer belt 21.

The unfixed toner image T primarily transferred to the intermediate transfer belt 21 in this manner is conveyed to a secondary transfer position facing the conveyance path of the recording paper 26 with the rotation of the intermediate transfer belt 21. You.

The recording paper 26 is fed from feed rollers 28a, 29a, 30a, and 31a from predetermined paper feed cassettes 28, 29, 30, and 31 as described above.
The intermediate transfer belt 21 is fed between the secondary transfer roll 27 and the intermediate transfer belt 21 at a predetermined timing by the registration roll 33.

On the back side of the intermediate transfer belt 21 at the secondary transfer position, a backup roll 25 serving as a counter electrode of the secondary transfer roll 27 is provided. At the secondary transfer position, the semiconductive secondary transfer roll 27 is pressed against the intermediate transfer belt 21 at a predetermined timing, and a voltage having the same polarity as the charged polarity of the toner is applied to the backup roll 25 to thereby perform the intermediate transfer. The unfixed toner image T transferred onto the belt 21 is electrostatically secondarily transferred onto the recording paper 26 at the secondary transfer position.

In this embodiment, as shown in FIG.
Instead of directly applying a voltage having the same polarity as the charge polarity of the toner to the secondary transfer roll 27, the transfer bias is applied by the bias roll 45 to the backup roll 25 pressed against the secondary transfer roll 27 via the intermediate transfer belt 21. A voltage having the same polarity as the charging polarity of the toner is applied from a transfer bias high voltage power supply (not shown) as a voltage applying unit. However, it is a matter of course that the secondary transfer roll 27 may be configured to directly apply a voltage having a polarity opposite to the charge polarity of the toner.

Then, the recording paper 26 to which the unfixed toner image has been transferred is separated from the intermediate transfer belt 21, and is discharged by the vacuum transport belt 34 through the neutralizing electrode 48 disposed downstream of the secondary transfer portion. The toner image is sent to the fixing device 35 and the fixing process of the unfixed toner image T is performed.

The intermediate transfer belt 21 is made of polyimide,
An appropriate amount of a conductive agent such as carbon black is dispersed in a synthetic resin such as polycarbonate, polyester, or polypropylene, or various rubbers, so that the volume resistivity is 10 ⁶ -1.
Is formed by adjusting the film-like belt such that 0 ¹⁴ Ω · cm. The thickness of the intermediate transfer belt 21 is set to, for example, 0.1 mm. The circumference of the intermediate transfer belt 21 is set to an integral multiple (for example, three times) of the circumference of the photosensitive drum 17.

The secondary transfer roll 27 is provided so as to be capable of coming in contact with and separating from the intermediate transfer belt 21 as necessary. When the image forming operation is started, the secondary transfer roll 27 is used.
7 is configured to be in pressure contact with the intermediate transfer belt 21.

Further, the secondary transfer roll 27 has a surface layer made of a urethane rubber tube in which carbon is dispersed, and an inner layer made of foamed urethane rubber in which carbon is dispersed. Is coated with fluorine. The secondary transfer roll 27 is formed such that its volume resistivity is set to 10 ³ to 10 ¹⁰ Ω · cm, and the roll diameter is φ28 mm.
The hardness is set to, for example, 30 ° (Asuka C).

On the other hand, the backup roll 25 has a surface layer made of a blended rubber tube of EPDM and NBR in which carbon is dispersed, and an inner layer made of EPDM rubber, and has a surface resistivity of 10 ⁷ to 10 ⁷ . 10 ¹⁰ Ω
/ □, formed so that the roll diameter is φ28 mm,
The hardness is set to, for example, 70 ° (Asuka C).

FIG. 4 is a configuration diagram showing a cleaning device according to an embodiment of the present invention.

In FIG. 4, reference numeral 50 denotes a cleaning device. The cleaning device 50 is disposed near the upstream side of the driving roll 23 for driving the intermediate transfer belt 21 of the copying machine. The cleaning device 50
Is a cleaning blade 5 that presses against the surface of the intermediate transfer belt 21 to remove the residual toner and paper powder (such as talc) attached to the surface of the intermediate transfer belt 21.
1 is provided. As the cleaning blade 51, for example, an elastic body such as polyurethane having a thickness of 2 mm is used. However, the thickness and the material of the blade 51 are not limited to this. The cleaning blade 51 has a cross section substantially L
The cleaning blade 51 is fixed to the V-shaped sheet metal 52 by bonding or the like.
Reference numeral 2 is attached to a frame (not shown) by means such as welding or bolting. Further, on the upstream side of the cleaning blade 51, a cleaning brush 53 is provided as necessary, for removing attached matter such as residual toner and paper powder (such as talc) adhered to the surface of the intermediate transfer belt 21. The cleaning brush 55 need not be provided.

Further, the cleaning device 50 has a storage section 54 for storing the deposits such as residual toner and paper dust removed by the cleaning blade 51. The storage section 54 has a substantially U It is formed in a character shape. Further, when a certain amount of deposits such as residual toner and paper dust removed by the cleaning blade 51 is accumulated in the storage unit 54, the attachments are rotated at a predetermined timing, so that the accumulated attachments are rotated. An auger 55 for transporting the kimono to the outside of the cleaning device 50 is provided.

The cleaning blade 51 is a so-called doctor blade as shown in FIG. Here, as shown in FIG. 5, the doctor blade is such that the leading end of the blade 51 is pressed against the upstream side in the moving direction of the intermediate transfer belt 21 and the rear end side of the blade 51 is located downstream in the moving direction of the intermediate transfer belt 21. And the rear end side of the blade 51 is inclined with respect to the surface of the intermediate transfer belt 21. Since the cleaning blade 51 is made of an elastic material such as polyurethane, when the cleaning blade 51 is pressed against the surface of the intermediate transfer belt 21 by a predetermined amount, as shown in FIG. When pressed against the surface, it has a curved shape that curves downward.

In this embodiment, as described above, the cleaning blade 51 is a polyurethane blade, and as shown in FIG.
Thickness t = 2 mm, width l = 15 mm, free length L = 10 m
m, the length is formed to be substantially the entire width of the intermediate transfer belt 21, the contact angle thereof is set to 17 °, and the amount of biting into the intermediate transfer belt 21 is set to 1.1 mm. However, the contact angle and bite amount of the cleaning blade 51 may of course be set to other values. Further, as described above, a sheet metal 52 made of stainless steel, aluminum, or the like is fixed to the surface side of the base end portion of the cleaning blade 51 by bonding or the like. By being attached to the pressing plate 53, the contact angle is set to the above-mentioned contact angle in a state of being pressed against the intermediate transfer belt 21.

By the way, in this embodiment, the belt-shaped image carrier is reversely rotated by a predetermined amount at a predetermined timing.

In this embodiment, the cleaning means is constituted by an elastic blade.
The blade is disposed near an upstream side of a driving roll that rotationally drives the belt-shaped image carrier.

Further, in this embodiment, the amount of reverse rotation of the belt-shaped image carrier is set to be at least equal to or greater than the blade biting amount.

FIG. 6 shows a drive system of the image forming apparatus according to the first embodiment.

In FIG. 6, reference numeral 17 denotes the photosensitive drum. The photosensitive drum 17 includes a driving stepping motor 60 and a driving stepping motor 60.
A pinion gear 61 fixed to the drive shaft of the first motor, a first intermediate gear 62 meshing with the pinion gear 61,
Second intermediate gear 6 fixed to the same shaft as the intermediate gear 62
3 and a final stage gear 65 fixed to a rotating shaft 64 of the photosensitive drum 17 meshing with the second intermediate gear 63.

In the drawing, reference numeral 66 denotes a bearing for supporting the rotating shaft 64 of the photosensitive drum 17 and the like.

In this embodiment, the drive roller 23 for driving the intermediate transfer belt 21 is provided with the pinion gear 6 fixed to the drive shaft of the drive stepping motor 60.
1, a third intermediate gear 67 meshed with the pinion gear 61, a fourth intermediate gear 68 fixed to the same shaft as the third intermediate gear 67, and a fourth intermediate gear 68 A fifth intermediate gear 69, a fifth intermediate gear 70 fixed to the same shaft as the fifth intermediate gear 69, and a rotating shaft 7 of the drive roll 23 meshed with the fifth intermediate gear 70.
It is configured to be rotationally driven by the final-stage drive gear 72 fixed to 1.

In the above-described configuration, the image forming apparatus according to this embodiment can prevent a substance such as talc contained in the recording paper from adhering to the surface of the photosensitive drum in the following manner. I have. In the image forming apparatus according to this embodiment, a material such as talc and toner remaining on the intermediate transfer belt are removed in a high-speed black-and-white image forming apparatus using an intermediate transfer body as follows. It is possible to prevent the occurrence of defective cleaning in the cleaning means to be performed.

That is, in this embodiment, as shown in FIGS. 2 and 3, a toner image corresponding to the image of the original is formed on the photosensitive drum 17 and the toner image formed on the photosensitive drum 17 is formed. After the image is primarily transferred onto the intermediate transfer belt 21, the toner image T primarily transferred onto the intermediate transfer belt 21 is secondarily transferred onto a recording paper 26 by
An image is formed.

The copying machine is designed to operate at a higher speed. The rotating speed of the photosensitive drum 17 is increased, and the conveying speed of the recording paper 26 is set higher. For this reason, the load applied to the pair of rolls 32 for conveying the recording paper 26 increases, and the recording paper 26 is rubbed by the pair of rolls 32 with a high applied load. A substance such as talc adheres to the surface of the intermediate transfer belt 21 from the entire sheet.

The substance such as talc and the adhered matter 75 such as residual toner adhered to the surface of the intermediate transfer belt 21 are shown in FIG.
As shown in FIG. 4 and FIG. 4, the cleaning blade 51 and the cleaning brush 52 remove the toner.
As shown in (b), a fine substance 75 of particles such as talc removed by the cleaning blade 51 adheres,
accumulate.

Accordingly, in this embodiment, after an image is formed on a predetermined number of recording sheets 26, the photosensitive drum 17
At a predetermined timing such as after the number of rotations reaches a predetermined number of times or immediately after the power of the copying machine is turned on, as shown in FIG. 7, the intermediate transfer of the toner image formed on the photosensitive drum 17 is performed. Primary transfer onto the belt 21 and recording paper 26 of the toner image primarily transferred onto the intermediate transfer belt 21
After the upward secondary transfer is completed, the drive motor 60 for driving the photosensitive drum 17 and the intermediate transfer belt 21 is rotated in reverse for a predetermined time T. Therefore, as shown in FIG. 1, the intermediate transfer belt 21 moves in a reverse direction by a predetermined amount and stops when the drive motor 60 rotates in the reverse direction. The amount by which the intermediate transfer belt 21 is moved in the reverse direction is, for example, set to be equal to or greater than the amount of biting of the cleaning blade 51. In this embodiment, the photosensitive drum 17
Is 5 mm, and the amount of movement of the intermediate transfer belt 21 is 3.
It is set to 5 mm.

At this time, since the cleaning blade 51 is pressed against the surface of the intermediate transfer belt 21 in the vicinity of the upstream side of the driving roll 23 for driving the intermediate transfer belt 21, the intermediate transfer belt 21 is moved in the reverse direction. When you move it,
The tension of the intermediate transfer belt 21 decreases momentarily, and the pressing force of the cleaning blade 51 causes the intermediate transfer belt 21 to rotate.
However, as shown in FIG. 1 (c) and FIG. 8 (b), it is deformed into a bent state. When the drive roll 23 is rotated in the reverse direction in this state, the intermediate transfer belt 21 moves in the reverse direction by a predetermined amount in a state where the back side of the edge of the cleaning blade 51 is in contact with the surface of the intermediate transfer belt 21.
Therefore, fine substance 7 such as talc or the like adhered and deposited on the back surface side of the edge portion of the cleaning blade 51
5 is rubbed by the intermediate transfer belt 21, removed from the back side of the edge of the cleaning blade 51, and transferred to the surface of the intermediate transfer belt 21. A substance 7 having fine particles such as talc transferred to the surface of the intermediate transfer belt 21.
5 is a cleaning blade 51 that moves the intermediate transfer belt 21 in the forward direction during the next image formation.
Will be removed.

On the other hand, the driving roll 23 during the reverse rotation
Is not downstream of the cleaning blade 51,
As shown in FIG. 9, when the drive roll 23 is reversed, the cleaning blade 51 is located on the upstream side of the drive roll 23, and thus the tension of the intermediate transfer belt 21 is applied to the intermediate transfer belt 21 by the reverse rotation of the drive roll 23. In addition, the intermediate transfer belt 21 at the position where the cleaning blade 51 is in pressure contact is not bent. Therefore, when the driving roll 23 is not located downstream of the cleaning blade 51 at the time of the reverse rotation, the intermediate transfer belt 21 at the position where the cleaning blade 51 is in pressure contact does not bend even if the driving roll 23 is rotated in the reverse direction. A substance 75 having fine particles such as talc adhered and deposited on the back side of the edge portion of the blade 51,
It cannot be removed efficiently.

As described above, in the above embodiment, the toner image formed on the photosensitive drum 17 is configured to be transferred onto the recording paper 26 via the intermediate transfer belt 21. Does not come into contact with the recording paper 26, so that a substance such as talc contained in the recording paper 26 can be prevented from adhering to the surface of the photosensitive drum 17 as shown in FIG.

In the above embodiment, the intermediate transfer belt 21 is moved in the reverse direction at a predetermined timing. Therefore, in the high-speed black-and-white copying machine using the intermediate transfer body 21, the intermediate transfer belt 21 is used. It is possible to prevent the cleaning blade 51 that removes substances such as talc and toner remaining on the belt 21 from causing cleaning failure.

[0064]

As described above, according to the present invention,
An image forming apparatus capable of preventing a substance such as talc contained in recording paper from adhering to the surface of the photosensitive drum can be provided.

Further, according to the present invention, in a high-speed black-and-white image forming apparatus using an intermediate transfer member, the cleaning means for removing substances such as talc and toner remaining on the intermediate transfer belt has a cleaning failure. It is possible to provide an image forming apparatus capable of preventing occurrence of the image.

[Brief description of the drawings]

FIGS. 1A to 1C are explanatory views showing main parts of an image forming apparatus according to an embodiment of the present invention; FIG.

FIG. 2 is a configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating an image forming unit of the image forming apparatus according to the embodiment of the present invention;

FIG. 4 is a configuration diagram illustrating a cleaning device of the image forming apparatus according to the embodiment of the present invention.

FIGS. 5A and 5B are explanatory views respectively showing a state of attachment of a cleaning blade.

FIG. 6 is a configuration diagram showing a drive system of the image forming apparatus according to one embodiment of the present invention.

FIG. 7 is a timing chart showing a driving state of the image forming apparatus according to one embodiment of the present invention.

FIGS. 8A and 8B are explanatory views respectively showing a driving state of the image forming apparatus according to the embodiment of the present invention.

FIGS. 9A and 9B are explanatory views showing comparative examples of the driving state of the image forming apparatus.

FIG. 10 is a graph showing the relationship between the transfer system of the image forming apparatus and the amount of talc attached.

[Explanation of symbols]

17: photosensitive drum, 21: intermediate transfer belt (belt-shaped image carrier), 23: drive roll, 50: cleaning device, 51: cleaning blade, 60: drive motor.

Continued on the front page (72) Inventor Makoto Ochiai 2274 Hongo, Ebina-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Satoshi Matsuzaka 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. F-term (reference) 2H032 AA05 BA09 BA23 BA30 2H034 BA05 BF07 BF09

Claims (5)

[Claims] An image forming apparatus exclusively for black and white forming only a black and white image, an image carrier on which a toner image corresponding to image information is formed, and a toner image formed on the image carrier are belted. A primary transfer means for primary transfer onto an intermediate transfer member having a belt shape, a belt-shaped intermediate transfer member moving while carrying a toner image primarily transferred from an image carrier by the primary transfer means, and a belt-like intermediate member. An image forming apparatus comprising: a secondary transfer unit for secondary-transferring a toner image primary-transferred onto a transfer member onto a recording medium. 2. The image forming apparatus according to claim 1, wherein the process speed is set to 200 m / s or more. 3. An image comprising: a belt-shaped image carrier on which a toner image corresponding to image information is formed or transferred; and a cleaning means for removing an attached matter on the surface of the belt-shaped image carrier. An image forming apparatus, wherein the belt-shaped image carrier is reversed by a predetermined amount at a predetermined timing. 4. The cleaning device according to claim 1, wherein the cleaning unit includes an elastic blade, and the blade is disposed near an upstream side of a driving roll that rotationally drives the belt-shaped image carrier. The image forming apparatus according to claim 3. 5. The image forming apparatus according to claim 3, wherein an amount of reversing the belt-shaped image carrier is set to be at least equal to a bite amount of the blade.