JPH0734429Y2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an image forming apparatus such as a recording apparatus, a copying machine, a printer, etc., having a fixing unit for thermally fixing a toner image transferred onto a transfer paper.

[Conventional technology]

In a copying machine, as described in, for example, Japanese Patent Laid-Open No. 61-84663, the transfer paper after the toner image is transferred is pressed against the belt of the belt transfer device by a suction force and conveyed to the fixing unit. There is one as shown in FIG.

In this copying machine, the electrostatic latent image formed on the photosensitive drum 1 is converted into a visible image (toner image) by the developing device 2, and the toner image is transferred to the transfer paper P by the transfer charger 3, and then the transfer image is transferred. Is pressed against the belt by the suction force of the suction fan 4, and is conveyed to the fixing unit 6 by the belt conveying device 5,
Therefore, the toner image is thermally fixed on the transfer paper P by heat and the pressure applied by the upper and lower fixing rollers 6a and the pressure roller 6b.

A cleaning unit 7 for collecting the residual toner on the photosensitive drum 1 after the image transfer is arranged around the photosensitive drum 1.

[Problems to be solved by the device]

However, in the case of an image forming apparatus in which the transfer paper after the toner image is transferred in this manner is pressed against the belt transfer device by a suction force to be transferred, for example, the upper part of the apparatus main body 10 in FIG. If the air intake port 10a is formed in the transfer sheet P, the transfer paper P is sucked by the belt conveying device 5 even if the cleaning unit 7 is arranged near the fixing unit 6 which is a heat source in order to downsize the image forming apparatus. When not, the air from the outside flows in from the air intake port 10a in the direction of the arrow A, and the recovery tank 7a is cooled by the introduced air, so that the temperature of the toner inside it is fixed. It is possible to prevent the toner from sticking because the temperature does not exceed the predetermined temperature.

However, the transfer paper P is conveyed by the belt transfer device 5 during the transfer process.
At the position shown in FIG. 3 where all the suction ports 5a are closed, the cleaning unit 7 is not cooled sufficiently since the outside air hardly flows into the apparatus main body 10, and the temperature of the toner in the recovery tank 7a is not increased. May reach a certain temperature at which it sticks. Therefore, in such a case, the toner adheres.

Further, when the transfer sheet P is sucked into the belt transport device 5, a sufficient suction force is obtained at a position where the transfer sheet blocks all the suction ports 5a, but at a position where a part of the suction port 5a is opened, transfer is performed. Since the suction force acting on the paper P is reduced, in order to obtain a sufficient suction force even at such a position, a fan having a large size and a large capacity is required.

This invention was made in view of the above problems,
To prevent toner from sticking to the cleaning unit by preventing it from reaching a temperature higher than a predetermined temperature at which toner adheres to the cleaning unit, and at the same time, to curl the transfer paper in the carrying process by the carrying device to ensure stable carrying. The purpose is to

[Means for Solving the Problems]

In order to achieve the above-mentioned object, this invention has a fixing unit for thermally fixing a toner image transferred onto a transfer paper from a photoconductor in a main body of the apparatus, a conveying device for conveying the transfer paper to the fixing unit, and a transfer device for transferring the transfer paper. In an image forming apparatus including a cleaning unit for removing residual toner on the photoconductor, an external air passage is provided between the cleaning unit and the fixing unit and into an introduction air passage passing through a side surface of a toner recovery tank of the cleaning unit. In addition to introducing the air, the outside air introducing and blowing means is provided for blowing the introduced air so as to press the transfer sheet against the sheet conveying surface of the conveying device.

[Action]

According to the image forming apparatus thus configured, the outside air introduction spraying means introduces the cooled air from the outside of the apparatus main body into the introduction air passage between the cleaning unit and the fixing unit inside thereof to collect the toner in the cleaning unit. Since the tank is cooled from the outside, the temperature of the toner in the toner recovery tank does not rise to the temperature at which it adheres even if the cleaning unit is located near the fixing unit that is the heat source. Can be prevented from sticking.

Further, the air introduced from the outside to cool the cleaning unit is blown toward the paper transporting surface of the transporting device, so if the transfer paper transported by the transporting device is curled, The curled portion is pressed against the sheet conveying surface by the blown air, and the curl is conveyed while being corrected.

〔Example〕

Hereinafter, a specific description will be given based on an embodiment of the present invention.

FIG. 1 is an overall configuration diagram showing a recording apparatus as an image forming apparatus showing an embodiment of the present invention.

The recording apparatus includes a printer unit 20 including therein various units for executing various image forming processes, and a laser beam (laser diode) based on image data provided above the printer unit 20 to emit the laser beam onto the photosensitive belt 14. Laser light emitting part 15 for irradiation
Consists of.

The printer unit 20 includes a fixing unit 11 for thermally fixing the toner image transferred onto the transfer paper P from the photoconductor belt 14 in the apparatus body 30, and a belt transfer device 12 for transferring the transfer paper P to the fixing unit 11. A cleaning unit 13 for removing the residual toner on the photosensitive belt 14 after the transfer is provided, and the cleaning unit 13 is arranged close to the fixing unit 11 in order to downsize the apparatus.

Further, a fan 28 which introduces air from the outside of the apparatus main body 30 between the cleaning unit 13 and the fixing unit 11 and blows the introduced air so as to press the transfer paper P against the paper carrying surface 12a of the belt carrying device 12. Is provided.

The photoconductor belt 14 is composed of three rollers approximately in the center of the device body 30.
16, 17 and 18 are stretched, and a predetermined writing position Lp of the horizontally stretched portion is irradiated with laser light from the laser light emitting unit 15 to form an electrostatic latent image (for example, An image is formed where the light hits.

Around the photosensitive belt 14, a charging charger 19 and
A developing device 22 that develops the electrostatic latent image on the photoconductor belt 14 to form a visible image with toner, a registration roller 23, a registration sensor 24 arranged on the upstream side of the sheet feeding, a transfer charge 25, The above-mentioned cleaning unit 13 and the static eliminator 21 for erasing the residual electric cylinder on the photosensitive belt 14 are provided.

The cleaning unit 13 removes the toner remaining on the photosensitive belt 14 after the transfer is completed by the cleaning far brush 27 and the cleaning blade 26, and collects the recovered toner in the toner recovery tank 13a. Store.

The belt conveying device 12 has a conveying belt stretched between two conveying rollers 31 and 32 arranged at intervals in the paper feeding direction so as to be rotatable in the arrow B direction. Face 12
The transfer paper P is placed on a and conveyed to the fixing unit 11.

The fixing unit 11 is composed of a fixing roller 33 and a pressure roller 34 or the like which is pushed up by a pressure means (not shown) and is brought into pressure contact with a predetermined pressing force, and the space between the fixing roller 33 and the pressure roller 34. Transfer paper P with the toner image transferred to the surface with
While being heated and pressed, it is heat-fixed, and then discharged onto the discharge tray 40.

The fan 28 is, for example, a cross flow fan and is rotated by a fan motor (not shown). At the time of rotation, the fan 28 introduces air from the outside through an air intake 36 formed in the upper part of the left side surface of the apparatus body 30 and introduces the air. The dust is removed by a filter 37 having air arranged on the right side, and the dust is removed by the upper cover 38 of the fixing unit 11, the left side surface of the toner recovery tank 13a, and the front and rear thereof (both the front side and the back side in FIG. 1). ) Is blown onto the sheet conveying surface 12a of the belt conveying device 12 through the introduction air passage 39 which is a portion surrounded by the front and rear side plates (not shown) provided in (1).

In this embodiment, the fan 28 and the introduction air passage 39
And correspond to the outside air introducing and blowing unit that blows the introduced air from the outside so as to press the transfer sheet against the sheet conveying surface of the conveying device.

On the other hand, in the lower part of the apparatus main body 30, a paper feed cassette 41 that can be pulled out from the apparatus main body 30 is detachably attached to the front side in FIG. 1, and when it is inserted to a predetermined paper feed position, The bottom plate raising arm 42 raises the sheet sending end side of the transfer sheet P in the sheet feeding cassette 41 via the bottom plate 43, and presses the uppermost sheet against the sheet feeding roller 44.

The transfer sheet P in the sheet feeding cassette 41 is conveyed to the pair of rollers 46 and 47 through the turn conveying path 45 and then to the registration roller 23. Then, the rollers of the roller pair 46 and thereafter are inserted from the manual feed table 48, and
It is also commonly used in the case of manual transfer paper conveyance that is fed by 49.

Next, the operation of this embodiment configured as described above will be described.

When the paper is automatically fed from the paper feed cassette 41, it is inserted into a predetermined position shown in FIG. 1 and set. Further, when manually feeding, the transfer paper P is placed on the manual feeding table 48.
Insert it from above until its tip reaches the manual feed roller 49.

In this state, press the print switch (not shown)
While the photoconductor belt 14 starts rotating in the direction of arrow C in FIG. 1, the charging charger 19 uniformly charges the photoconductive surface (front side) of the photoconductor belt 14.

Then, laser light is emitted from the laser light emitting unit 15 to a predetermined writing position Lp according to image data (for example, input from an external image reading device or a printer via a connection interface), and thereby, the light is exposed. An electrostatic latent image is formed on the photosensitive surface of the body belt 14. Then, the electrostatic latent image is developed by the rotation of the photosensitive belt 14 in the direction of arrow C in FIG.
When it reaches 22, the developing roller forms a visible image (toner image).

Next, the transfer paper P is fed from the paper feed cassette 41 or the manual feed table 48 at a predetermined tongue, and the transfer paper P is fed to the registration roller.
After being temporarily stopped at 23, the toner image is conveyed at a predetermined timing, and when passing through the transfer charger 25, the toner image on the photosensitive belt 14 is transferred.

The transfer sheet P is sent onto the sheet transfer surface 12a of the belt transfer device 12, the toner image on the transfer sheet P is fixed by the fixing unit 11, and it is discharged onto the sheet discharge tray 40. .

When the transfer sheet P is fed onto the sheet conveying surface 12a of the belt conveying device 12, the air from the outside of the apparatus main body 30 is introduced into the inside through the air intake port 36 by the rotation of the fan 28. , It is blown onto the sheet conveying surface 12a of the belt conveying device 12 through the introduction air passage 39, so that the transfer sheet P is in a stable state while being pressed against the sheet conveying surface 12a by the air blown from above. Then it is transported to the fixing unit 11.

Therefore, even if the transfer paper P is curled, the curled portion is corrected by the air blown and pressed against the paper transport surface 12a of the belt transport device 12, so that it is stable. However, even small-sized paper such as postcards and paper with a low stiffness such as waste paper can be conveyed in a stable state.

Note that the toner on the transfer paper P is blown with air introduced from the outside, but the toner is electrostatically transferred to the transfer paper P.
Since it is firmly absorbed, it does not scatter or shift (unless it is rubbed).

Further, only the front end or the rear end of the transfer paper P is the paper transport surface 12
Even when the transfer paper P does not cover the entire paper transport surface 12a, as when the transfer paper P has partially reached a,
Since the wind pressure that blows on the transfer paper is always constant, suction is performed at the position where the transfer paper closes all the suction ports of the transfer device and the position where it does not, as in the case of the transfer device that uses the suction force that has been used in the past. There is no difference in force (it is necessary to use a large-capacity motor in consideration of the difference).

Therefore, according to this embodiment, it is possible to sufficiently satisfy the function with a driving motor for the fan 28 having a smaller capacity than that of the driving motor used for the conventional conveying device using the suction force. .

The air after being introduced from the outside and blown onto the sheet conveying surface 12a is the apparatus body below the belt conveying device 12.
It is discharged to the outside of the apparatus through louvers (not shown) formed on the front side and the back side in FIG.

The cool air from the outside of the apparatus main body 30 introduced by the fan 28 cools the toner recovery tank 13a of the cleaning unit 13 from its surface when passing through the introduction air passage 39, In order to cool the toner collected inside, the cleaning unit 13 is heated by the fixing unit 11, which is a heat source, because it is heated by it, but the temperature of the toner inside does not reach the temperature at which it adheres. Since it does not rise, toner adhesion is prevented.

The invention can be similarly applied to image forming apparatuses such as copying machines and printers other than the recording apparatus.

[Effect of device]

As described above, according to the present invention, the cleaning unit is cooled by the air introduced from the outside to prevent the temperature of the toner from rising to the temperature at which it adheres. Can be prevented.

Further, since the air introduced from the outside is blown onto the transfer paper transported by the transport device, even when the transfer paper is curled, the curled portion is pressed against the paper transport surface of the transport device and adheres closely. Since the curled portion is corrected, stable transportation can be performed.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a recording apparatus as an image forming apparatus showing an embodiment of the present invention, and FIG. 2 is provided with a conveying device for sucking and transferring a conventional transfer sheet to a belt by a suction force. FIG. 3 is a schematic configuration diagram showing an example of a copying machine, and FIG. 3 is a schematic configuration diagram for explaining inconvenience in a copying machine provided with a conveying device that uses suction force. 11 …… Fixing unit, 12 …… Belt transport device 12a …… Paper transport surface 13 …… Cleaning unit 14 …… Photosensitive belt, 19 …… Charging charger 22 …… Developer, 25 …… Transfer charger 28 …… Fun , 30 …… Main unit 36 …… Air inlet, 38 …… Upper cover 39 …… Introduction air passage, P …… Transfer paper

Claims (1)

[Scope of utility model registration request] 1. A fixing unit for thermally fixing a toner image transferred onto a transfer paper from a photoconductor in a main body of the apparatus, a conveying device for conveying the transfer paper to the fixing unit, and a residual toner on the photoconductor after the transfer. An image forming apparatus including a cleaning unit that removes the air from the outside of the apparatus main body to an introduction air passage that passes through a side surface of the toner recovery tank of the cleaning unit between the cleaning unit and the fixing unit. An image forming apparatus comprising: an outside air introduction spraying unit that sprays the introduced air onto the paper transport surface of the transport device so as to press the transfer paper.