JP2000219361A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the carrying trouble of a recording medium by providing a guide rib on an inlet opening, and arranging at least the recording medium carrying directional upstream side part of the guide rib so as to retreat to a fan side from the guide surface of a guide member. SOLUTION: At least the recording medium carrying directional upstream side part 43A of a guide rib 43 is arranged in a position retreated to a fan 39 side from the guide surface 38 of a guide member 37. The recording medium carrying directional top stream end part 43C of the guide rib 43 is retreated to the fan 39 side from the guide surface 38, precisely from its flat surface 38A by the distance shown by G. Since the top end or reverse side of a recording medium passing an inlet opening 42 hardly makes contact with the guide rig 43, and the recording medium never makes contact with, particularly, the recording medium carrying directional upstream side part 34A, toner is hardly adhered to the top end or reverse side of the recording medium even if it is adhered to the guide rib 43, and the trouble of contaminating the recording medium with toner can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transferring a toner image formed on the surface of an image carrier to a recording medium surface at a transfer section, and using a guide member of a guide member on the back side of the recording medium passing through the transfer section. An image forming apparatus that conveys the recording medium to a fixing device while guiding the recording medium through the surface, and fixes the toner image transferred to the surface of the recording medium by the fixing device. The present invention relates to an image forming apparatus provided with a fan for sucking the back side of a recording medium through an intake opening formed in the guide member.

[0002]

2. Description of the Related Art In an image forming apparatus of the above-mentioned type configured as an electronic copying machine, various printers, facsimile machines, or a multifunction machine having at least two of these functions, a recording medium having an unfixed toner image on the surface thereof. Can be conveyed while suctioning from the back side by a fan, so that the problem that the surface of the recording medium comes into contact with an element provided in the image forming apparatus main body and the toner image on the surface is disturbed can be prevented. .

However, since the guide member is provided with a suction opening for sucking the recording medium by the fan, the leading end of the conveyed recording medium enters the suction opening, thereby causing a recording medium conveyance trouble. There is a possibility that. In order to prevent such a problem, a guide rib for preventing the leading end of the recording medium from entering the intake opening formed in the guide member is provided in the intake opening, and the recording medium passing through the intake opening is provided with a guide rib. It is conceivable that the guide rib is configured to be guided by the guide rib. In a state where the suction action through the intake opening is not impaired,
A guide rib is provided in the intake opening, and the recording medium is conveyed while the back surface of the recording medium is in contact with the guide rib, and the leading end of the recording medium is prevented from entering the intake opening.

However, when the above configuration is adopted, toner floating or flying up in the image forming apparatus main body adheres to the guide ribs, and the adhered toner is conveyed while contacting the guide ribs. There is a possibility that the recording medium adheres to the back surface and the recording medium is stained with toner.
Providing a guide rib at the intake opening has the advantage of suppressing the conveyance trouble of the recording medium, but also causes a new problem that the recording medium is stained by the toner attached to the guide rib.

[0005]

SUMMARY OF THE INVENTION The present invention has been made based on the above-described novel recognition, and an object of the present invention is to solve the problem of recording medium transport trouble caused by an intake opening provided in a guide member. An object of the present invention is to provide an image forming apparatus of the type described at the beginning, which can suppress the occurrence of the problem and effectively suppress the problem that the recording medium is soiled by the toner.

[0006]

According to the present invention, there is provided an image forming apparatus of the type described at the beginning, wherein a guide rib for preventing a leading end of a recording medium from entering the intake opening is provided. Provided at the intake opening, at least a portion of the guide rib on the upstream side in the recording medium transport direction,
An image forming apparatus is provided in which the guide member is disposed so as to be retracted closer to the fan than the guide surface of the guide member.

At this time, it is advantageous that the guide rib is inclined gradually from the upstream portion in the recording medium transport direction to the downstream portion in the recording medium transport direction so as to gradually approach the guide surface. (Claim 2).

The image forming apparatus according to claim 2, wherein the most downstream end of the guide rib in the recording medium transport direction is flush with the guide surface, or the guide rib is positioned closer to the fan than the guide surface. It is advantageous to protrude in the direction away (claim 3).

Further, in the image forming apparatus according to any one of claims 1 to 3, the flow velocity of the air flowing through a portion of the guide rib on the downstream side in the recording medium transport direction is set to be upstream of the guide rib in the recording medium transport direction. It is advantageous to position the fan such that it is lower than the flow rate of the air flowing through the part (claim 4).

The image forming apparatus according to any one of claims 1 to 4, further comprising a cleaning member for cleaning a surface of the image carrier after transferring the toner image to the surface of the recording medium, wherein the cleaning member is provided. The image carrier is supported so as to contact or separate from the surface of the image carrier, and the cleaning member contacts the surface of the image carrier before the fan starts operating. It is advantageous to provide a control means for controlling the operation of contacting and separating the cleaning member from the surface.

The image forming apparatus according to any one of claims 1 to 6, further comprising a cleaning member for cleaning the surface of the image carrier after transferring the toner image to the surface of the recording medium. The surface of the image carrier is supported so as to be in contact with or separated from the surface of the image carrier, and after the driving of the fan is stopped, the cleaning member is separated from the surface of the image carrier. It is advantageous to provide control means for controlling the operation of contacting and separating the cleaning member from the cleaning member (claim 6).

The image forming apparatus according to any one of claims 1 to 6, wherein the image carrier comprises an intermediate transfer member to which a toner image formed on the surface of the latent image carrier is transferred. When the transfer portion for transferring the toner image from the latent image carrier to the intermediate transfer member is a primary transfer portion, and the transfer portion for transferring the toner image from the intermediate transfer member to the recording medium is a secondary transfer portion, the toner image is formed on the surface of the recording medium. A cleaning member that cleans the surface of the intermediate transfer member after the transfer is performed, with respect to the moving direction of the surface of the intermediate transfer member, on the upstream side of the primary transfer portion,
Advantageously, it is located downstream of the secondary transfer portion and is supported so as to abut or separate from the surface of the intermediate transfer member (claim 7).

Further, in the image forming apparatus according to claim 7, the recording medium conveyed between the secondary transfer unit and the fixing device conveys the toner image with the surface on which the toner image has been transferred facing downward. Advantageously, the positions of the secondary transfer section, the fixing device, and the cleaning member are set such that the cleaning member is located below the recording medium conveyed (claim 8).

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic sectional view showing the internal structure of an image forming apparatus constructed as a color printer capable of forming a full-color image. The image forming apparatus shown here has an endless belt-shaped photosensitive member 2 which is an example of a latent image carrier disposed in the image forming apparatus main body 1, and the photosensitive member 2 is wound around rollers 3 and 4. It is hung.

During the image forming operation, the roller 4 is driven to rotate clockwise by a driving device (not shown), whereby the photosensitive member 2 is driven to rotate in the direction of arrow A. At this time, a sensor (not shown) detects the home mark provided on the photoconductor 2, and the image forming system starts operating based on the detected home mark. That is, the surface of the photosensitive member is subjected to a charge removing operation by the charge removing lamp 5, and then the surface of the photosensitive member is uniformly charged by the charging device including the charging charger 6.
Is exposed by the laser light L modulated by light emitted from
Is formed.

On the other hand, a rotary developing device 8 is provided inside the image forming apparatus main body 1 so as to face the photoconductor 2, and this developing device 8 includes a yellow developing device 9Y and a magenta developing device 9
M, a cyan developing unit 9C, a black developing unit 9BK, and a developing unit support 10 which detachably supports these developing units. Developing cases 11Y, 11M, 1 of each developing unit
1C and 11BK respectively contain yellow, magenta, cyan, and black developers, respectively. As the developer, various types of developers such as a powdery two-component developer having a toner and a carrier or a powdery one-component developer having no carrier can be used. Uses a powdery one-component developer (hereinafter, referred to as toner). Each developing device has developing rollers 12Y, 12M, 12C, and 12BK, and a toner supply roller that supplies toner to each of the developing rollers.

As described above, the first member formed on the photosensitive member surface
When the electrostatic latent image passes through the developing device 8, the first developing device, in this example, the yellow developing device 9 </ b> Y occupies the developing position facing the photoconductor 2. At this time, the developing roller 12Y of the yellow developing unit 9Y is rotated while being in contact with the photoconductor 2, and the first electrostatic latent image is converted into a yellow toner image by the yellow toner carried and conveyed by the developing roller 12Y. As a visible image.

On the other hand, an intermediate transfer member 15 which is an example of an image carrier is provided in the image forming apparatus main body 1, and the intermediate transfer member 15 of this embodiment is wound around two rollers 13 and 14. The intermediate transfer body 15 is constituted by an endless flexible belt, and one of the rollers 13 is rotationally driven by a driving device (not shown), whereby the intermediate transfer body 15 is rotationally driven in the direction of arrow B. The intermediate transfer member 15 and the photosensitive member 2 are in contact with each other in the primary transfer section 16, and a transfer brush 17, which is an example of a primary transfer unit, is in contact with the back side of the intermediate transfer member 15 in this portion. Instead of the belt-shaped intermediate transfer member, a drum-shaped intermediate transfer member can be used, and a latent image carrier composed of a drum-shaped photoreceptor can also be used.

When the yellow toner image formed on the surface of the photosensitive member 2 reaches the primary transfer portion 16 as described above, the toner image on the surface of the photosensitive member is transferred to the intermediate transfer member by the action of the voltage applied to the transfer brush 17. The primary transfer is performed on the surface of No. 15.
The transfer residual toner adhering to the photoconductor surface after the transfer of the toner image is scraped and removed by the cleaning member 18 pressed against the photoconductor 2, and the removed transfer residual toner falls into the cleaning case 19.

The photoreceptor surface whose surface has been cleaned as described above is again subjected to a neutralization operation by the neutralization lamp 5, and
The charged surface is uniformly charged by the charging charger 6, and then the charged surface is irradiated with the laser light L emitted from the laser writing unit 7 to form a second electrostatic latent image on the surface of the photoconductor. When the second electrostatic latent image passes through the developing device 8, the rotation of the developing device support 10 causes the second developing device, in this example, the magenta developing device 9M, to occupy the developing position facing the photosensitive member 2. Thus, the second electrostatic latent image is visualized as a magenta toner image in the same manner as in the case of the above-described yellow developing device 9Y. This toner image is also primary-transferred onto the surface of the intermediate transfer body 15 on which the yellow toner image has been previously transferred by being superimposed on the yellow toner image by the action of the transfer brush 17. The toner remaining on the surface of the photoconductor 2 after the transfer of the magenta toner image is also removed from the surface of the photoconductor by the cleaning member 18.

In exactly the same manner as described above, a cyan toner image and a black toner image are sequentially formed on the photoreceptor surface by a cyan developing device 9C and a black developing device 9BK facing the photoreceptor surface, respectively. The toner image is superimposed on the previously transferred toner image on the surface of the intermediate transfer body 15 and sequentially primary-transferred. The toner remaining on the surface of the photoreceptor is removed by the cleaning member 18 every time the toner image is transferred, and the surface is cleaned. Thus, a full-color toner image is formed on the surface of the intermediate transfer member 15.

On the other hand, a recording medium P made of paper or a plastic sheet is stacked on a paper cassette 20 set in the lower portion of the main body 1 of the image forming apparatus, and the recording medium P is rotated by rotation of a paper supply roller 21. Arrow C one by one
Fed in the direction. The recording medium P fed in this way is conveyed by the rotation of the conveying roller pair 22 and the registration roller pair 23, and the recording medium P is aligned with the full-color toner image formed on the surface of the intermediate transfer body 15 at the timing. The sheet is fed to a secondary transfer section 36 between the transfer roller 15 and a transfer roller 24 that constitutes an example of a secondary transfer unit opposed thereto. At this time, the full-color toner image on the surface of the intermediate transfer body 15 is electrostatically and collectively secondary-transferred onto the surface of the recording medium P by the action of the voltage applied to the transfer roller 24.

When the toner images of the respective colors sequentially formed on the photosensitive member 2 are primarily transferred onto the intermediate transfer member 15 as described above, the transfer roller 24 is so arranged that the toner image is not disturbed by the transfer roller 24. When the superposed toner image on the intermediate transfer member 15 is secondarily transferred onto the recording medium P, the transfer roller 24 is separated from the surface of the intermediate transfer member 15 by the transfer roller 24 via the recording medium P. The transfer roller is brought into contact with the front surface, and is rotated in a direction in which the transfer roller portion in contact with the intermediate transfer body 15 moves in the same direction.

As described above, after the recording medium P on which the full-color toner image has been secondarily transferred is separated from the intermediate transfer member 15,
The surface on which the toner image has been transferred, that is, the image surface faces downward, and is conveyed to the fixing device 25 as shown by an arrow D,
It passes between the fixing roller 26 and the pressure roller 27 of the fixing device 25. At this time, the toner image is fixed on the surface of the recording medium P by the action of heat and pressure. Fixing device 25
The recording medium P that has exited is discharged by the discharge roller pair 28 to the discharge stack unit 30 in the upper part of the image forming apparatus main body with the image surface facing downward as indicated by the arrow E.

On the other hand, the transfer residual toner remaining on the intermediate transfer member 15 after transferring the full-color toner image onto the recording medium P is removed by the cleaning device 31 for the intermediate transfer member, and the surface of the intermediate transfer member 15 is cleaned. You. The cleaning device 31 has one or a plurality of cleaning members, and in the illustrated example, has two cleaning members of a fur brush 32 and a cleaning blade 33 which are driven to rotate, and these cleaning members are intermediate transfer members. The transfer residual toner adhering to the surface of the transfer roller 15 is scraped off. Instead of providing two cleaning members, one or three or more cleaning members may be provided,
Also, other types of cleaning members, such as a magnetic brush roller, can be used. When the fur brush 32 and the cleaning blade 33 are collectively referred to, they are referred to as a cleaning member, and are denoted by reference numeral 29. The toner removed from the intermediate transfer body 15 by the cleaning member 29 falls into the cleaning case 34 of the cleaning device 31.

The cleaning member 29 is supported so as to be in contact with or separated from the surface of the intermediate transfer member. When each toner image is primarily transferred to the surface of the intermediate transfer member 15, the cleaning member 29 As shown by, it is away from the surface of the intermediate transfer member. When cleaning the toner remaining on the surface of the intermediate transfer member 15 after transferring the full-color toner image on the surface of the intermediate transfer member to the recording medium P, the cleaning member 2
Reference numeral 9 abuts on the surface of the intermediate transfer member to scrape and remove the transfer residual toner.

In the image forming apparatus shown in FIG. 1, the photosensitive member 2 and a cleaning member 1 for cleaning the surface thereof are provided.
A cleaning device having the cleaning unit 8 and the cleaning case 19, the intermediate transfer body 15, a cleaning device 31 for cleaning the surface of the intermediate transfer body 15, and the like are integrally incorporated in a unit case, and these constitute one image forming unit.

Here, as shown in FIGS. 1 to 3, the recording medium P passing through the secondary transfer unit 36 is fixed along the recording medium transport path between the secondary transfer unit 36 and the fixing device 25. A guide member 37 for guiding the device 25 is provided. The guide member 37 shown as an example in the figure has a hollow box shape inside, and its guide surface 38 is formed on the back surface of the recording medium P conveyed between the secondary transfer portion 36 and the fixing device 25, that is, The guide surface 38 is located opposite to the surface opposite to the surface on which the toner image has been transferred,
6 is guided on the back side of the recording medium P.

Although the entire guide surface 38 may be formed as a flat surface, in the illustrated example, as shown in FIG. 3, the guide surface 38 is formed integrally with the flat surface 38A. A plurality of ridges 3 slightly protruding from the surface
8B. Thereby, the contact area between the transported recording medium P and the guide surface 38 is reduced,
The frictional force acting on the recording medium P is reduced, and the recording medium P
Can be transported smoothly.

Since the unfixed toner image is carried on the surface of the recording medium P sent from the secondary transfer section 36 to the fixing device 25, the surface of the unfixed toner image is applied to the elements provided in the image forming apparatus main body 1. Upon contact, the unfixed toner image is disturbed. In particular, in the image forming apparatus shown in FIG. 1, the recording medium P carries an unfixed toner image and is conveyed with its surface facing downward, so that the leading end of the recording medium hangs down. In this case, the problem that the toner image is disturbed due to the contact of the surface of the recording medium with the element in the image forming apparatus main body is inevitable.

Therefore, in the image forming apparatus of the present embodiment, as shown in FIGS. 1 to 3, an appropriate number, in the example shown in FIG. The fans 39 are provided along a recording medium transport path between the secondary transfer unit 36 and the fixing device 25. These fans 39 have a cylindrical fan case 40 and an impeller 41 rotatably supported inside the fan case 40, and the impeller 41 is rotationally driven by a motor (not shown). As shown by an arrow F, air is taken in from one inlet opening 40A of the fan case 40, and the air is exhausted from the other outlet opening 40B of the fan case 40.

The fan 40 constructed as described above is assembled to the above-mentioned cleaning member 37, and its inlet opening 40A is formed on the back surface of the recording medium P conveyed between the secondary transfer section 36 and the fixing device 25. It is arranged facing the side.
Further, an intake opening 42 is formed at a portion of the guide member 37 facing the entrance opening 40A of each fan 39,
The opening 42 also faces the back side of the recording medium P conveyed between the secondary transfer unit 36 and the fixing device 25. A part of a plate part forming the guide surface 38 of the guide member 37 is cut out, and the cutout part is formed as the intake opening 42.

The recording medium P that has passed through the secondary transfer section 36 is
The back side is conveyed to the fixing device 25 while being guided by the guide surface 38 of the guide member 37. At this time,
The impeller 41 of the fan 39 is driven to rotate. For this reason,
The back side of the recording medium P conveyed between the secondary transfer unit 36 and the fixing device 25 is sucked by the fan 39 through the intake opening 42, and the recording medium P is guided to the guide surface 38 without hanging down. Then, the sheet is conveyed to the fixing device 25.

As described above, the image forming apparatus of the present embodiment transfers the toner image formed on the surface of the intermediate transfer member 15 which is an example of the image carrier to the transfer unit 36 on the surface of the recording medium.
The recording medium P is conveyed to the fixing device 25 while the back surface of the recording medium P that has passed through the transfer unit 36 is guided by the guide surface 38 of the guide member 37, and the fixing device 25 is
Thus, the toner image transferred to the surface of the recording medium is fixed on the surface of the recording medium.
A fan 39 is provided for sucking the back side of the recording medium P conveyed between the fixing device 25 and the fixing device 25 through an intake opening 42 formed in the guide member 37.

The recording medium P conveyed to the fixing device 25 as described above passes over the intake opening 42. When the leading end of the recording medium P passes through the intake opening 42, the leading end of the recording medium P If the recording medium falls into the suction opening 42 due to the suction action and enters the opening 42, a conveyance trouble of the recording medium occurs.

Therefore, each intake opening 42 is provided with an appropriate number of guide ribs 43, three in the illustrated example.
Each guide rib 43 of the present example is formed in a rod shape extending long along the conveyance path of the recording medium P, and each end in the longitudinal direction is integrally fixed to the guide member 37. By the operation of the fan 39, the air can be sucked into the guide member 37 through the space defined between the guide ribs 43 and the space defined between the guide rib 43 and the peripheral portion of the intake opening 42. Thus, the guide rib 43 is provided in the intake opening in a state where the suction operation through the intake opening 42 is not impaired.

Since the guide rib 43 is provided, when the leading end of the recording medium P passes through the intake opening 42, even if the leading end enters the intake opening 42, the guide rib 4
3, the leading end does not enter the intake opening 42, and the recording medium is reliably conveyed to the fixing device 25.

As described above, the recording medium P
Guide rib 4 for preventing the tip of
By providing 3 in the intake opening 42, it is possible to prevent the occurrence of the transport trouble of the recording medium P as described above. However, since the guide rib 43 is provided in the intake opening 42 where the air is sucked by the fan 39, the toner floating or flying up in the image forming apparatus main body 1 is
Riding on the air flow sucked by the fan 39, the intake opening 4
When passing through the guide rib 43, it is inevitable to adhere to the guide rib 43. When the recording medium P passes through the intake opening 42, the toner adhered to the guide ribs 43 may adhere to the leading end and the rear surface of the recording medium P, and may contaminate the recording medium P with the toner.

In particular, in the image forming apparatus shown in FIG. 1, the cleaning device 31 for the intermediate transfer member 15 is arranged near the secondary transfer portion 36, and the guide rib 43 is located immediately above the secondary transfer portion 36. The toner rising from the cleaning device 31 is drawn by the fan 39 and sucked into the intake opening 42, and the toner adheres to the guide rib 43 at this time. In addition, the cleaning device 31 for the intermediate transfer member 15 has the cleaning member 29 that comes into contact with and separates from the surface of the intermediate transfer member.
When the intermediate member 9 moves away from the surface of the intermediate transfer member, a large gap is formed between the cleaning member 29 and the surface of the intermediate transfer member 15, and the toner in the cleaning case 34 soars upward through the gap. Further, the toner soars due to an impact when the cleaning member 29 comes in contact with or separates from the cleaning member 29, and the toner easily adheres to the guide rib 43.

If the cleaning device 31 is disposed at a position far away from the secondary transfer section 36, the toner that has flown up from the cleaning device 31 will not easily adhere to the guide ribs 43. It is preferable to arrange at the position shown in 1,
When the cleaning device 31 is provided at the preferable position,
That is, the toner easily adheres to the guide rib 43.

Therefore, in the image forming apparatus of this embodiment,
As clearly shown in FIG. 2, at least a portion 43 </ b> A of the guide rib 43 on the upstream side in the recording medium transport direction is a guide member 37.
The guide surface 38 is located at a position retracted toward the fan 39. The most upstream end 43C of the guide rib 43 in the recording medium transport direction is retracted toward the fan 39 by a distance G from the guide surface 38, more precisely, the flat surface 38A. With such a configuration, the leading end and the back surface of the recording medium P passing through the intake opening 42 do not or hardly come into contact with the guide ribs 43. In particular, the recording medium P contacts the portion 43A on the upstream side in the recording medium transport direction. No longer. For this reason, even if toner adheres to the guide ribs 43, it is difficult for the toner to adhere to the leading end portion or the back surface of the recording medium P, thereby preventing a problem that the recording medium is contaminated with the toner or effectively reducing it. Can be.

Even if the portion 43 A of the guide rib 43 on the upstream side in the recording medium transport direction is largely retracted from the guide surface 38 toward the fan 39, there is no possibility that the transported recording medium P enters the intake opening 42. The portion 43B of the guide rib 43 on the downstream side in the recording medium transport direction can also be disposed at a position slightly retracted to the fan 39 side from the guide surface 38, but this portion 43B is larger than the guide surface 38 and is larger than the guide surface 38. If the recording medium P is located at a position closer to the side 39, the leading end of the recording medium P to be transported strongly hits the downstream side edge 42A of the intake opening 42, which may cause a recording medium P transport problem.

Therefore, in the image forming apparatus of this embodiment,
The guide rib 43 is gradually inclined from a portion 43A on the upstream side in the recording medium conveyance direction to a portion 43B on the downstream side in the recording medium conveyance direction so as to gradually approach the guide surface 38 side. As a result, the transported recording medium P is
2 when the guide rib 4
3 and the leading edge of the recording medium is
2 can be prevented from hitting the downstream edge 42A strongly.

In order to ensure the above effect, the most downstream end 43D of the guide rib 43 inclined as described above in the recording medium transport direction is connected to the guide surface 38 as shown in FIG.
It is preferable that the guide surface is flush with the fan 39 or that the guide surface slightly projects in a direction away from the fan 39. In the example shown in FIG. 2, the most downstream end 43D of the guide rib 43 in the recording medium conveyance direction is flush with the flat surface 38A of the guide surface 38, and the most downstream end 43D is shown in FIG. Guide ribs 4 so as to be flush with the top surface of the raised ridge 38B or, as described above, to project away from the fan 39 beyond the flat surface 38A or the top surface of the ridge 38B.
3 may be formed. With this configuration, it is possible to more effectively prevent the leading edge of the transported recording medium P from strongly hitting the downstream edge 42A of the intake opening 42, and the recording medium P can be transported smoothly.

In the image forming apparatus shown in FIG. 2, the center axis H of the impeller 41 of the fan 39 occupies a position closer to the upstream portion 43A of the guide rib 43 in the recording medium transport direction. Thus, when the fan 39 is operated, the flow velocity of the air flowing through the portion 43A of the guide rib 43 on the upstream side in the recording medium transport direction is reduced to the portion 4 on the downstream side in the recording medium transport direction.
It becomes faster than the flow velocity of the air flowing through 3B. That is, a portion 43 of the guide rib 43 on the downstream side in the recording medium transport direction.
The fan 39 is positioned so that the flow velocity of the air flowing through B is lower than the flow velocity of the air flowing through the portion 43A of the guide rib 43 on the upstream side in the recording medium transport direction.

According to the above configuration, the amount of air flowing to the upstream portion 43A of the guide rib 43 in the recording medium transport direction is
The amount becomes larger than the amount of air flowing through the downstream portion 43B in the recording medium conveyance direction, and the amount of toner adhering to the downstream portion 43B becomes smaller than the amount of toner adhering to the upstream portion 43A. For this reason, as described above, the guide rib 4
3 at the most downstream end 43D in the recording medium transport direction.
Is flush with the guide surface 38 or the guide surface 3
8, the amount of toner adhering to the end portion 43D is small even when the recording medium P conveyed contacts the end portion 43D. In addition, it is possible to prevent the toner from adhering to the back surface, or to minimize the amount of the adhering toner.

On the other hand, a large amount of toner adheres to the portion 43A on the upstream side in the recording medium transport direction, but since this portion is largely recessed on the side of the fan 39 rather than the guide surface 38, it is usually used here. Does not contact the recording medium P, and therefore, there is no possibility that the toner adhered to the portion 43A on the upstream side in the recording medium transport direction adheres to the recording medium P and stains the recording medium with the toner.

In the image forming apparatus illustrated in FIG. 1, as described above, the cleaning member 29 for cleaning the surface of the intermediate transfer member 15, that is, the surface of the image carrier after transferring the toner image onto the recording medium surface. , And the cleaning member 29 is supported so as to contact or separate from the surface of the image carrier. FIG. 4 shows an example of the timing at which the cleaning member 29 comes into contact with or separates from the surface of the image carrier made up of the intermediate transfer body 15.

In the example shown here, the cleaning member 29 first comes into contact with the surface of the intermediate transfer member 15 at time T1,
Next, at time T2, the fan 39 is driven by the motor, and the impeller 41 is rotationally driven. Subsequently, at time T3, a transfer voltage is applied to the transfer roller 24. In this way, the toner image on the intermediate transfer body 15 is secondarily transferred onto the surface of the recording medium P, and the recording medium P that has left the secondary transfer unit 36 is transferred to the fixing device 25 while being suctioned by the fan 39. Conveyed. After the end of the secondary transfer, T
At time point 4, the application of the transfer voltage to the transfer roller 24 is stopped, and the driving of the fan 39 is stopped. The drive of the impeller 41 by the motor is interrupted. At that time, the impeller 41 of the fan 39 continues to rotate due to its inertia even after the drive by the motor is cut off, and the rotation of the fan 39, more precisely, the rotation of the impeller 41 at the time indicated by T5. Stop. Next, at time T6, the cleaning member 29 is separated from the surface of the intermediate transfer member 15.

As described above, in the image forming apparatus of the present embodiment, the fan 39 starts operating after the cleaning member 29 comes into contact with the surface of the intermediate transfer member. FIG. 7 is a diagram for controlling the contact / separation operation of the cleaning member 29 with respect to the surface of the image carrier so that the cleaning member 29 contacts the surface of the intermediate transfer member 15 which is an example of the image carrier before the fan 39 starts operating. There is a control means not provided.

According to the above configuration, the cleaning member 29
Is in contact with the surface of the intermediate transfer member, and after the clearance between the cleaning member 29 and the surface of the intermediate transfer member 15 disappears, that is, after the toner in the cleaning case 34 does not flow up through the clearance, the fan 39 operates. Is started, the amount of toner adhering to the guide rib 43 can be reduced.

In the example shown in FIG. 4, after the driving of the fan 39 by the motor is stopped, the cleaning member 29 is stopped.
Are separated from the surface of the intermediate transfer member 15. That is, after the driving of the fan 39 is stopped, the cleaning member 2 with respect to the surface of the image carrier is so separated that the cleaning member 29 is separated from the surface of the intermediate transfer member 15 which is an example of the image carrier.
9 is provided with control means (not shown) for controlling the contact / separation operation. In particular, in the example shown in FIG. 4, after the fan 39 stops operating, that is, after the rotation of the impeller 41 completely stops at the time T5, the cleaning member 29 contacts the surface of the intermediate transfer body 15. It is configured as follows.

According to the above configuration, the motor 3
After the drive of the cleaning member 9 is stopped, especially after the impeller 41 is completely stopped, the cleaning member 29 is separated from the surface of the intermediate transfer body 15, and a gap is formed between the cleaning member 29 and the surface of the intermediate transfer body. You. That is, the driving of the fan 39 is stopped while the toner in the cleaning case 34 of the cleaning device 31 does not fly upward through the gap between the cleaning member 29 and the intermediate transfer body 15, whereby the guide rib 43 The amount of adhered toner can be reduced.

When the cleaning member 29 is separated from the surface of the intermediate transfer member, and there is a large gap between the cleaning member 29 and the surface of the intermediate transfer member, the impeller 41 of the fan 39 rotates at a high speed. When the toner soared upward from the cleaning case 34 through the gap reaches the air intake opening 42 by the air flow drawn by the fan 39, a large amount of the toner adheres to the guide rib 43, or the toner There is a possibility that it may adhere to the surface of the transfer body and appear on the image, but the configuration of the present example can prevent such a problem.

It has been described above that the cleaning device 31 for the intermediate transfer member 15 is preferably disposed near the secondary transfer portion 36. The reason will be described below.

As described above, if the cleaning device 31 is disposed at a position far away from the secondary transfer section 36, the cleaning device 31 is also far away from the suction opening 42, so that the toner soared from the cleaning device 31 is removed. It is possible to reduce the problem of being pulled by the fan 39 and adhering to the guide rib 43. Therefore, the cleaning device 3
1 is provided, for example, at a position downstream of the primary transfer unit 16 in the movement direction of the surface of the intermediate transfer member, and the cleaning device 31
And the intake opening 42 are greatly separated. However, in this case, the surface of the intermediate transfer body 15 after transferring the toner image onto the recording medium P is cleaned by the cleaning device 31.
In order to perform cleaning, the intermediate transfer body 15 must be caused to idle, and the image forming efficiency, that is, the image forming speed decreases.

On the other hand, the cleaning device 31 is
The cleaning member 29 is disposed at the position shown in FIG.
With respect to the direction of movement of the surface of the intermediate transfer member, if the intermediate transfer member is disposed upstream of the primary transfer portion 16 and downstream of the secondary transfer portion, the surface of the intermediate transfer member 15 is cleaned by the cleaning member 29. Immediately after that, the toner image on the photoreceptor 2 can be primarily transferred to the surface of the intermediate transfer member, so that the image forming speed can be increased and the image forming efficiency can be improved.

Further, while maintaining the positional relationship between the primary transfer unit 16 and the cleaning device 31 in the moving direction of the surface of the intermediate transfer member in the state shown in FIG. The cleaning device 31 and the suction opening 42 can also be moved to the downstream side in the moving direction of the transfer member surface.
However, in this case, the size of the image forming unit including the photoreceptor 2 and the intermediate transfer member 15 is increased, and the disadvantage that the entire image forming apparatus is enlarged is inevitable.

For the reasons described above, as shown in FIG. 1, the secondary transfer section 36 and the primary transfer section 16 are brought close to each other, and the cleaning device 31 is disposed therebetween, whereby the image forming unit and, consequently, the image forming apparatus Although the overall size can be reduced and the image forming speed can be increased, when the cleaning device 31 is disposed at such a position, the toner that has flown from the cleaning device 31 is applied to the guide rib 43 as described above. It becomes easy to adhere. However, even if toner adheres to the guide rib 43, the toner can be effectively prevented from adhering to the recording medium P by adopting the above-described respective configurations related to the guide rib 43.

As described above, each of the above-described configurations relating to the guide rib 43 can be particularly advantageously employed when the cleaning device 31 is provided at the position as shown in FIG.
That is, the configuration according to the present invention relating to the guide rib 43 exemplified above is such that the image bearing member transfers the toner image formed on the surface of the photosensitive member 2 which is an example of the latent image bearing member to the intermediate transfer member 15. The transfer unit that transfers the toner image from the latent image carrier to the intermediate transfer member 15 is the primary transfer unit 16, and the transfer unit that transfers the toner image from the intermediate transfer member 15 to the recording medium P is the secondary transfer unit 36. At this time, the cleaning member 29 for cleaning the surface of the intermediate transfer member after transferring the toner image onto the surface of the recording medium is located on the upstream side of the primary transfer portion 16 with respect to the moving direction of the surface of the intermediate transfer member. This is particularly effective when applied to an image forming apparatus that is located downstream of the intermediate transfer member 36 and is supported so as to contact or separate from the surface of the intermediate transfer body 15.

Further, in addition to the above configuration, the secondary transfer unit 3
The recording medium P conveyed between the fixing device 25 and the fixing device 25 is conveyed with the surface on which the toner image has been transferred facing downward, and the cleaning member 2 is provided below the conveyed recording medium P.
The present invention can be particularly advantageously applied to an image forming apparatus in which the positions of the secondary transfer unit 36, the fixing device 25, and the cleaning member 29 are set such that the position 9 is located. In this type of image forming apparatus, it is an essential requirement that the recording medium P conveyed from the secondary transfer unit 36 to the fixing device 25 does not sag downward. Advantageously, the cleaning member 29 is located below the intake opening 42, and the toner is easily sucked into the intake opening 42, so that the above-described respective configurations related to the guide ribs 43 can be particularly advantageously employed. .

As described above, the present invention can be advantageously applied to an image forming apparatus in which an image carrier is formed of an intermediate transfer member. However, the present invention is widely applied to various types of image forming apparatuses other than the image forming apparatus. it can. For example, a toner image is formed on the surface of an image carrier made of a photoreceptor, and the toner image is directly transferred to the surface of a recording medium facing upward, and in that state, the recording medium is transported to a fixing device, and the toner The present invention can also be applied to an image forming apparatus for forming a monochrome image for transferring an image.

[0064]

According to the first aspect of the present invention, the guide rib provided at the intake opening effectively prevents the leading end of the conveyed recording medium from entering the intake opening and causing the recording medium to have a transport trouble. And even if toner adheres to the guide ribs, it is possible to suppress the problem that the toner adheres to the recording medium.

According to the second aspect of the invention, it is possible to more effectively suppress occurrence of a recording medium transport trouble.

According to the third aspect of the invention, it is possible to more effectively suppress occurrence of a recording medium conveyance trouble.

According to the fourth aspect of the present invention, it is difficult for the toner to adhere to the portion of the guide rib on the downstream side in the recording medium transport direction where the transported recording medium is likely to come into contact, so that the recording medium is contaminated with the toner. Can be suppressed more effectively.

According to the fifth and sixth aspects of the present invention, the cleaning member comes into contact with and separates from the surface of the image carrier, so that the toner easily rises, but the toner is effectively prevented from adhering to the guide ribs. be able to.

According to the seventh and eighth aspects of the invention, the image forming speed can be increased, the size of the image forming apparatus can be reduced, and the toner adhered to the guide ribs can be hardly adhered to the recording medium. .

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is a perspective view of a guide member to which a fan is attached.

FIG. 4 is a timing chart showing an example of ON / OFF of fan driving and timing of contact / separation of a cleaning member with respect to an intermediate transfer member.

[Explanation of symbols]

 REFERENCE SIGNS LIST 15 intermediate transfer member 16 primary transfer portion 25 fixing device 29 cleaning member 36 transfer portion, secondary transfer portion 37 guide member 38 guide surface 39 fan 42 intake opening 43 guide rib 43A upstream portion in recording medium transport direction 43B downstream in recording medium transport direction Side part 43D Lowermost end P recording medium

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 DA38 ED24 ED27 EE02 EF09 ZA07 2H032 AA05 AA15 BA09 BA21 BA23 BA30 CA04 DA15 DA24 DA27 2H034 AA04 BD06 BD10 BF06 BF12 3F049 AA01 FB01 FC01 LA02 LA05 LA07 FC07 FC03 FC12 FC14 FC16 LA02 LB03

Claims (8)

[Claims] 1. A transfer unit transfers a toner image formed on a surface of an image carrier to a recording medium surface, and guides a back surface of the recording medium passing through the transfer unit by a guide surface of a guide member. An image forming apparatus that conveys a recording medium to a fixing device and fixes the toner image transferred to the surface of the recording medium by the fixing device, wherein the back side of the recording medium conveyed between the transfer unit and the fixing device An image forming apparatus provided with a fan that sucks the air through an intake opening formed in the guide member, wherein a guide rib for preventing a leading end portion of a recording medium from entering the intake opening is provided in the intake opening. An image forming apparatus, wherein at least a portion on the upstream side in the recording medium transport direction is retracted toward the fan from the guide surface of the guide member. 2. The guide rib according to claim 1, wherein the guide rib is gradually inclined from a portion on the upstream side in the recording medium conveyance direction to a portion on the downstream side in the recording medium conveyance direction so as to gradually approach the guide surface side. The image forming apparatus as described in the above. 3. The guide rib according to claim 2, wherein the most downstream end of the guide rib in the recording medium conveyance direction is flush with the guide surface or protrudes further away from the fan than the guide surface. Image forming device. 4. The positioning of the fan such that the flow velocity of air flowing on a downstream portion of the guide rib in the recording medium transport direction is lower than the flow velocity of air flowing on an upstream portion of the guide rib in the recording medium transport direction. Claims 1 to 3
The image forming apparatus according to any one of the above. 5. A cleaning member for cleaning a surface of an image carrier after transferring a toner image to a surface of a recording medium,
The cleaning member is supported so as to contact or separate from the surface of the image carrier, and before the fan starts operating, such that the cleaning member contacts the surface of the image carrier, 2. A control means for controlling an operation of bringing a cleaning member into and out of contact with the surface of the image carrier.
The image forming apparatus according to any one of claims 1 to 4. 6. A cleaning member for cleaning a surface of an image carrier after transferring a toner image to a surface of a recording medium,
The cleaning member is supported so as to be in contact with or separate from the surface of the image carrier, and after the driving of the fan is stopped, the cleaning member is separated from the surface of the image carrier. The image forming apparatus according to claim 1, further comprising a control unit configured to control an operation of moving the cleaning member toward and away from the surface of the image carrier. 7. The image carrier includes an intermediate transfer member for transferring a toner image formed on the surface of the latent image carrier, and a transfer unit that transfers a toner image from the latent image carrier to the intermediate transfer member. When a transfer portion for transferring the toner image from the primary transfer portion and the intermediate transfer member to the recording medium is a secondary transfer portion, a cleaning member for cleaning the surface of the intermediate transfer member after transferring the toner image to the recording medium surface is provided. With respect to the moving direction of the surface of the intermediate transfer member, it is located on the upstream side of the primary transfer portion and on the downstream side of the secondary transfer portion, and abuts or separates from the surface of the intermediate transfer member. Claim 1 supported by
7. The image forming apparatus according to any one of claims 1 to 6, wherein 8. A recording medium conveyed between the secondary transfer unit and the fixing device is conveyed with the surface on which the toner image has been transferred facing downward, and below the conveyed recording medium. The image forming apparatus according to claim 7, wherein the positions of the secondary transfer unit, the fixing device, and the cleaning member are set such that the cleaning member is located.