JP2000338832A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a fixing means and the carrying part of a transfer material from being soiled by the splash of toner caused at the cleaning means of an intermediate transfer body by providing the guide member of the carrying part arranged at the downstream side of a transfer part in the carrying direction of the transfer material with an aperture part, forming a duct means from the aperture part and coupling the duct means to a suction means. SOLUTION: The toner left on an intermediate transfer belt 5a is guided to a suction means holding member 20 coupled to the duct means 19 through the duct means 17-19 from the aperture part 12c formed at the carrying guide member 12b and sucked by the suction means 21 held by the holding member 20. The sucked toner is captured by a filter means arranged at the downstream side of the suction means 21. Therefore, since the toner suspending near the carrying part 12 is sucked by the suction means 21, it is prevented from being attached to the carrying part 12. As the result, the back surface of the transfer material is prevented from being soiled by the toner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic or electrostatic recording type image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a conventional image forming apparatus. In FIG. 1, a toner image formed by a developing device 104 is temporarily transferred onto an intermediate transfer belt 105 a temporarily on a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as “photosensitive drum”) 101 as an image carrier. The image forming apparatus A that forms the image by secondarily transferring the toner image transferred to the intermediate transfer belt 105a to the transfer material S sequentially transfers a plurality of component color images of color image information and multicolor image information. The present invention is effective as a color image forming apparatus that outputs an image formed product in which a color image or a multicolor image is synthesized and reproduced, or an image forming apparatus having a color image forming function or a multicolor image forming function.

An intermediate transfer belt 1 is used as the intermediate transfer member.
In the conventional image forming apparatus A provided with the image forming apparatus 05a, during image formation (at the time of secondary transfer), the residual toner not transferred to the transfer material S in the toner image on the intermediate transfer belt 105a is removed by a cleaning unit (cleaning unit). The intermediate transfer belt 105a is cleaned by applying an AC bias voltage by the charging roller 105f of 105e to apply a charge having a polarity opposite to that at the time of transfer and electrostatically attaching the charge to the photosensitive drum 101.

[0004]

The above-mentioned image forming apparatus A
In this embodiment, the cleaning of the intermediate transfer belt 105a is performed by applying an AC bias voltage by the cleaning unit 105e, so that a part of the toner on the intermediate transfer belt 105a is transferred to the downstream transport unit 112 by the AC bias voltage. There was a risk of scattering.

In this case, as the total number of prints increases, the toner scattered from the intermediate transfer belt 105a by the cleaning unit 105e accumulates in the transport unit 112, and the toner adheres to the back surface of the transfer material S, which may cause back contamination. There was also.

Further, the scattered toner adheres to the entrance 108 c of the fixing device 108 on the downstream side of the conveying section 112,
There was also a risk that the transfer material S was caught by the attached toner and jammed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of preventing the fixing means and the transfer material transporting portion from being contaminated by scattering of toner caused by the cleaning means for the intermediate transfer member.

[0008]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
The toner image formed on the image carrier is primarily transferred to an intermediate transfer member at a primary transfer portion, and the toner image on the intermediate transfer member is secondarily transferred to a transfer material at a secondary transfer portion to form an image. And an image forming apparatus including a cleaning unit that cleans residual toner remaining on the intermediate transfer body after the cleaning.
An opening is provided in the guide member of the transport unit disposed downstream of the secondary transfer unit in the transfer material transport direction, duct means is formed from the opening, and the duct means is connected to the suction means. Image forming apparatus.

According to another aspect of the present invention, a toner image formed on an image carrier is primarily transferred to an intermediate transfer member in a primary transfer portion, and the toner image on the intermediate transfer member is transferred to a secondary transfer portion. Cleaning means for cleaning residual toner remaining on the intermediate transfer body after secondary transfer to a transfer material to form an image, and a duct for releasing heat generated inside the image forming apparatus to the outside An image forming apparatus provided with a discharging means and an exhausting means, wherein an opening is provided in a guide member of a transport unit disposed downstream of the secondary transfer unit in the transfer material transport direction, and duct means is formed from the opening, and the duct An image forming apparatus is provided, wherein the image forming apparatus is provided with a second opening, connected to the means, and sucked by the existing exhaust means.

In the above invention, the cleaning means is of a type in which a charging member is brought into contact with the intermediate transfer member to apply an AC bias voltage.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

FIG. 1 shows a full-color laser beam printer which is an electrophotographic image forming apparatus as an embodiment of the present invention.

First, the overall configuration of the image forming apparatus A will be described with reference to FIG.

The image forming apparatus A shown in FIG. 1 includes a photosensitive drum 1 as an image carrier. The photosensitive drum 1 is driven to rotate in a direction indicated by an arrow R1 by a driving unit (not shown).

A charging device 2 for uniformly charging the surface of the photosensitive drum 1 is provided around the photosensitive drum 1, and an exposure device 3 for irradiating a laser beam based on image information to form an electrostatic latent image on the photosensitive drum 1. A developing device 4 for attaching toner to the electrostatic latent image to develop it as a toner image; an intermediate transfer belt unit 5 for secondarily transferring the toner image temporarily primary-transferred from the photosensitive drum 1 to the transfer material S; Cleaning device 6 for removing post-transfer toner remaining on the surface of photosensitive drum 1
And so on.

The cleaning device 6 including the photosensitive drum 1, the charging device 2, and the container 11 is integrally formed into a cartridge to form a process cartridge B, and is formed into an image forming apparatus main body (hereinafter, referred to as an apparatus main body) 14. It is removable.

A cassette feeding means 7 for feeding a transfer material S such as paper toward the intermediate transfer belt unit 5 and transporting the transfer material S, a secondary transfer unit 29, A fixing device 8 for fixing the toner image on the transfer material S after the transfer is provided.

The photosensitive drum 1 has, for example, an organic photoconductor layer (OP) on the outer peripheral surface of an aluminum cylinder having a diameter of 47 mm.
C photosensitive layer), both ends of which are rotatably supported by support members (not shown), and a driving force from a drive motor (not shown) is transmitted to one end. Is driven to rotate.

As the charging device 2, for example, a contact charging type can be used. In this case, the charging member is a conductive roller formed in a roller shape. The roller is brought into contact with the surface of the photosensitive drum 1 and a charging bias voltage is applied to the roller from a power supply (not shown). This is to uniformly charge the surface of the photosensitive drum 1.

The exposure device 3 has a polygon mirror 3a, and the polygon mirror 3a is irradiated with image light corresponding to an image signal from a laser diode (not shown). The polygon mirror 3a is a scanner motor (not shown)
The image light, which is rotated at a high speed and reflected by the
b, the surface of the charged photosensitive drum 1 is selectively exposed through the reflection mirror 3c and the like to form an electrostatic latent image.

The developing device 4 includes a rotary member 4A rotatable around a shaft 4d and four developing devices mounted on the rotary member 4A, that is, a developing device containing black, magenta, cyan, and yellow toners, respectively. Vessels 4Bk, 4C,
4M, 4Y.

When developing the electrostatic latent image on the photosensitive drum 1,
A predetermined developing device of a color to be attached to the electrostatic latent image is arranged at a developing position. That is, the predetermined developing device is stopped at the developing position facing the photosensitive drum 1 by the indexing rotation of the rotating body 4A, and the developing sleeve 4b of the developing device faces the photosensitive drum 1 with a small gap (about 300 μm). Then, the electrostatic latent image on the photosensitive drum 1 is developed.

This development is performed as follows. The toner in the developing device corresponding to the color to be developed is sent to the application roller 4a by a feeding mechanism, and the thinner layer of the toner is applied to the outer periphery of the rotating developing sleeve 4b by the rotating application roller 4a and the toner regulating blade 4c. Charge (frictional electrification). This developing sleeve 4b;
By applying a developing bias to the photosensitive drum 1 on which the electrostatic latent image is formed, toner is attached to the electrostatic latent image and developed as a toner image.

Each of the developing units 4Bk, 4C, 4M, 4Y
The developing sleeve 4b is connected to a high-voltage power supply (not shown) for developing each color provided in the apparatus main body 14 when each developing device is disposed at the developing position. Is selectively applied with a voltage. Each of the developing devices 4Bk, 4C, 4M, and 4Y is configured to be individually detachable from the rotating body 4A.

The intermediate transfer belt unit 5 is a unit for secondary-transferring a plurality of toner images, which are sequentially primary-transferred sequentially from the photosensitive drum 1 and are superimposed, onto the transfer material S collectively. The intermediate transfer unit 5 includes an intermediate transfer belt 5a that runs in the direction of arrow R5. The intermediate transfer belt 5a of this embodiment is an endless belt having a circumference of about 440 mm, and includes a driving roller 5b, a secondary transfer opposing roller 5c, and a driven roller 5d.
Are stretched over the three rollers.

The intermediate transfer belt unit 5 is provided with a primary transfer roller (pressing roller) 5j for transferring the toner image formed on the photosensitive drum 1 onto the intermediate transfer belt 5a.

The intermediate transfer belt unit 5 is placed on the drawer unit 30, and the intermediate transfer belt unit 5
Numeral 0 is attached to the apparatus main body 14 so as to be freely pulled out. The drawer unit 30 includes a manual feed conveyance unit 16 that conveys the transfer material S to the intermediate transfer belt unit 5 between the right side plate 22 and the left side plate (not shown). When the intermediate transfer belt unit 5 is housed in the apparatus main body 14, a coupling member (not shown) coaxial with the drive roller 5b engages with a positioning member (not shown) in the apparatus main body 14. The drawer unit 30
Is pressed leftward in the figure.

The secondary transfer unit 2 provided on the apparatus main body 14
9 is provided with a secondary transfer roller 29a for secondarily transferring the toner image primarily transferred to the intermediate transfer belt 5a to the transfer material S.

At a predetermined position outside the intermediate transfer belt 5a, there is provided a cleaning unit (cleaning means) 5e capable of coming in contact with and separating from the surface of the intermediate transfer belt 5a. The remaining secondary transfer residual toner is removed.

The cleaning unit 5e brings the charging roller 5f into contact with the intermediate transfer belt 5a to apply a charge to the toner having a polarity opposite to that of the transfer. The toner having the opposite polarity charge is electrostatically attached to the photosensitive drum 1, and thereafter,
The photosensitive drum 1 is collected by the cleaning device 6. The method of cleaning the intermediate transfer belt 5a is not limited to the electrostatic cleaning described above, but may be a mechanical method such as a blade or a fur brush, or a method using both of them.

After the toner developed on the photosensitive drum 1 by the developing device 4 is primary-transferred to the intermediate transfer belt 5a, the cleaning device 6 removes the transfer residual toner remaining on the surface of the photosensitive drum 1 without being primary-transferred. Is what you do. The transfer residual toner collected by the cleaning device 6 is accumulated in the cleaning container 11.

The cassette feeding / conveying means 7 includes a paper feed cassette 7a in which a plurality of transfer materials S are stored and which is loaded in a lower portion of the apparatus main body 14, and is provided between the intermediate transfer belt 5a and the secondary transfer roller 29a. The transfer material S is fed to the secondary transfer portion,
The transfer material S after the secondary transfer by the transport belt 12a of the transport unit 12
To the fixing device 8.

A pickup roller (half-moon roller) 7e, a retard roller 7f, a feed roller 7g, and a pair of conveyance rollers 7c of the cassette feeding / conveying means 7 are driven and rotated in accordance with an image forming operation, and transfer the transfer material S in the sheet cassette 7a. The sheets are guided one by one along the guide plate 7b and separated and fed. Transfer material S
Of the intermediate transfer belt 5a stops once, forms a loop, and synchronizes the rotation of the intermediate transfer belt 5a with the image writing position to obtain the registration roller pair 7d.
d, the intermediate transfer belt 5a and the secondary transfer roller 29a
The paper is re-supplied to the secondary transfer section between them.

The transfer material S stacked on the tray 16a is also conveyed from the manual feeder 16 of the drawer unit 30 by the conveying roller pairs 16b and 16c and the guide 16d, and the transfer material S is similarly subjected to the secondary transfer. The paper can be re-fed to the printer.

The fixing device 8 fixes a plurality of toner images after the secondary transfer to the transfer material S. The fixing device 8 is driven and rotated by a fixing roller 8b, and heat and pressure are applied to the transfer material S by pressing. And a pressure roller 8a for applying the pressure.
The pressure roller 8a and the fixing roller 8b have a heater (not shown) inside thereof. The transfer material S to which the toner image has been transferred by the fixing device 8 is conveyed by a fixing roller 8b, and heat and pressure are applied by a pressing roller 8a, so that the toner image is fixed on the surface of the transfer material S. You.

Next, an image forming operation of the image forming apparatus having the above configuration will be described.

First, the photosensitive drum 1 is rotated in synchronization with the rotation of the intermediate transfer belt 5a, the surface of the photosensitive drum 1 is uniformly charged by the charging device 2, and the exposure device 3 irradiates a black image with light. A black electrostatic latent image is formed on the drum 1. Simultaneously with the formation of the electrostatic latent image, the developing device 4 is driven to place the black developing device 4Bk at the developing position, and the charging on the photosensitive drum 1 is performed so that the black toner adheres to the electrostatic latent image on the photosensitive drum 1. A voltage having the same polarity as the polarity and substantially the same potential is applied to cause black toner to adhere to the electrostatic latent image for development.

Then, the intermediate transfer belt 5a is brought into contact with the photosensitive drum 1, and a voltage having a polarity opposite to that of the toner is applied to the primary transfer roller (pressing roller) 5j, thereby transferring the black toner image on the photosensitive drum 1 to the intermediate transfer. The primary transfer is performed on the belt 5a.

As described above, when the primary transfer of the black toner image is completed, the next developing device is rotated and positioned at the developing position facing the photosensitive drum 1, and the magenta and cyan colors are set in the same manner as in the case of black. Then, formation, development, and primary transfer of an electrostatic latent image are performed for each color of yellow, and four color toner images are superimposed on the intermediate transfer belt 5a.

During this time, the secondary transfer roller 29a is not in contact with the intermediate transfer belt 5a, and the charging roller 5f of the cleaning unit 5e is not in contact with the intermediate transfer belt 5a.

After the completion of the formation of the four color toner images on the intermediate transfer belt 5a, the secondary transfer unit 29 is pushed up by a displacement means (not shown), and the secondary transfer roller 29a is moved through the intermediate transfer belt 5a to the secondary transfer unit 29. It is pressed against the transfer facing roller 5c. Further, the transfer material S which has been waiting at a predetermined position near the registration roller pair 7d in synchronization with the rotation of the intermediate transfer belt 5a is transferred to the intermediate transfer belt 5a and the secondary transfer roller 29a.
To the secondary transfer section.

Here, a voltage having a polarity opposite to that of the toner is applied to the secondary transfer roller 29a.
The upper toner image is secondarily transferred onto the surface of the transferred transfer material S.

The transfer material S thus secondary-transferred is conveyed to the fixing device 8 via the conveyance belt 12a, and a toner image is transferred between the pressing roller 8a and the fixing roller 8b.
After being fixed by heating and pressing upward, the transfer material S on which the toner image is fixed is discharged to the paper discharge tray 10 by the paper discharge rollers 13, 15, and 9, and the image formation is completed.

Next, the transport unit 1 which is a characteristic part of the present invention is described.
2 to 4 will be described with reference to FIGS.

The residual toner on the intermediate transfer belt 5a scattered in the vicinity of the cleaning unit 5e of the intermediate transfer belt unit 5 passes through ducts 17, 18, and 19 from an opening 12c provided in the conveyance guide member 12b. It is guided to the suction means holding member 20 connected to the duct means 19 and is sucked by the suction means (exhaust means) 21 held by the suction means holding member 20. The sucked toner is captured by a filter (not shown) provided downstream of the suction unit 21.

Incidentally, the suction means 21 sucks air from the high-voltage power supply unit in order to suppress the temperature rise of the conventional high-voltage power supply unit (not shown), and further transfers the heat generated in the fixing device 8 to the developing device 4. Outside air is sucked by the duct means 19 so as not to be transmitted.

In this embodiment, a hole 19a for connecting with the newly provided duct means 18 is newly formed in the existing duct means 19, thereby securing the intake passage.

Accordingly, the toner scattered in the cleaning unit 5e of the intermediate transfer belt unit 5 and the toner floating near the transport unit 12 can be sucked by the suction unit 21 by the toner accumulation preventing mechanism of the transport unit 12, so that the toner can be sucked. Can be prevented from adhering to the transport unit 12, and as a result, the back surface of the transfer material S can be prevented from being stained by the toner.

Further, by sucking the toner in the vicinity of the transport section 12, it is possible to prevent the toner from adhering to the entrance 8c of the fixing device 8 further downstream, so that when the transfer material S enters the fixing device 8, In addition, it is possible to prevent the transfer material S from being caught on the attached toner and jamming.

[0050]

As is apparent from the above description, according to the image forming apparatus of the present invention, an opening is provided in the guide member of the transport unit disposed downstream of the secondary transfer unit in the transfer material transport direction. By forming a duct means from the opening, by connecting the duct means to the suction means, or by providing an opening in the guide member of the transport unit disposed downstream in the transfer material transport direction of the secondary transfer unit, Forming duct means from the opening;
The duct means is provided with a second opening and connected thereto, and the suction is performed by the existing exhaust means, so that the transfer material transporting section to the fixing means is contaminated by the scattering of toner caused by the cleaning means of the intermediate transfer body. Therefore, even when the total number of prints is increased, it is possible to prevent the toner from adhering to the back surface of the transfer material and to prevent the transfer material from being soiled, thereby forming a good image.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating the vicinity of a transport unit of the image forming apparatus of FIG. 1;

FIG. 3 is a rear view illustrating a transport unit, a duct, and a periphery thereof;

FIG. 4 is a plan view showing a transport unit, a duct, and its periphery.

FIG. 5 is a schematic configuration diagram illustrating an example of a conventional image forming apparatus.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum (image carrier) 5 intermediate transfer unit 5a intermediate transfer belt (intermediate transfer member) 5e cleaning unit 12 transport unit 12b transport guide member (guide member) 12c opening 17 duct unit 18 new duct unit 19 existing duct unit 19a Hole 21 suction means

Claims (3)

[Claims] 1. A toner image formed on an image carrier is primarily transferred to an intermediate transfer member at a primary transfer portion, and the toner image on the intermediate transfer member is secondarily transferred to a transfer material at a secondary transfer portion. An image forming apparatus including a cleaning unit that cleans residual toner remaining on the intermediate transfer body after forming an image by using a transfer unit disposed downstream of the secondary transfer unit in a transfer material transfer direction. An image forming apparatus, wherein an opening is provided in the guide member, and duct means is formed from the opening, and the duct means is connected to the suction means. 2. A toner image formed on an image carrier is primarily transferred to an intermediate transfer member at a primary transfer portion, and the toner image on the intermediate transfer member is secondarily transferred to a transfer material at a secondary transfer portion. Image forming apparatus, comprising: a cleaning unit for cleaning residual toner remaining on the intermediate transfer body after forming an image by using a duct unit for discharging heat generated inside the image forming apparatus to the outside; and an exhaust unit. In the apparatus, an opening is provided in a guide member of a transport unit disposed downstream of the secondary transfer unit in the transfer material transport direction, a duct is formed from the opening, and a second opening is formed in the duct. An image forming apparatus, wherein the image forming apparatus is provided, connected, and sucked by the existing exhaust means. 3. The image forming apparatus according to claim 1, wherein the cleaning unit is configured to apply an AC bias voltage by bringing a charging member into contact with the intermediate transfer member.