JPH07333931A - Image forming device - Google Patents

Abstract

PURPOSE:To separate a transfer material in a fixed separation position for preventing a failure in transfer and to prevent the meandering of the transfer material by means of prevention of floating and the wrinkles of the transfer material generated after fixing by blowing air over the transfer material in the upper part of a carrying/guiding means and pressurizing the transfer material thereon. CONSTITUTION:An air blower means 4 blowing the air over the transfer material 10 from the upper part of the carrying/guiding means 2 and pressing the material 10 thereonto is provided. The air blower means 4 blows air over the material 10 in almost all areas in a direction nearly perpendicular to the transfer material 10 and the width direction over a fixing device 3 from the separation position 16 of the material 10 on a photoreceptor drum 5 with an air quantity so as not to scatter unfixed toner on the material 10. Especially, the air is blown over the guiding plate 15 of the carrying/guiding means 2 and the transfer material 10 is separated from the drum 5 at the fixed separation position 16 by the blowing of air and pressed onto the front surfaces of the carrying belt 14 of the carrying/guiding means 2 and the guiding plate 15, to be carried to the fixing device 3 without being floated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to an image forming apparatus in which a transfer material carrying an unfixed toner image is conveyed while being pressed by a conveying guide means by a blowing means. Regarding the device.

[0002]

2. Description of the Related Art In an image forming apparatus, when a toner image is transferred from a photosensitive drum carrying a toner image onto a transfer material for separation, a transfer failure may occur due to a delay in the separation position or the like. It is necessary to separate the transfer material from the photosensitive drum at a predetermined separation position by a separation corona (usually AC corona) so as not to cause such a transfer failure. On the other hand, it is necessary to prevent the wrinkle from occurring in the transfer material when the transfer material after separation is conveyed and fixed. In particular, A2
An image forming apparatus such as a copying machine that handles a large-sized sheet as described above may not be used when the transfer material is separated because of the paper size and thickness of the transfer material, or the weakness of stiffness caused by the paper size. Is likely to be disturbed or lost due to poor transfer, or wrinkles or the like may occur when the tip of the transfer material comes into contact with the roller portion of the fixing device or the like.

For example, as shown in FIG. 3, the toner image formed on the photosensitive drum 5 is transferred onto the transfer material 10 by the transfer corona discharger 9, and then an alternating current or a separated corona discharge in which a direct current is superposed on the alternating current is discharged. The electricity is removed from the back side of the transfer material 10 by the electric device 11. After that, the transfer material 10 is separated by the separating claw 17.
The spur 18 separates the transfer material from the photosensitive drum 5 while preventing the transfer material 10 from floating.

Further, since the transfer material 10 separated from the photosensitive drum 5 carries an unfixed toner image on its upper surface, the transfer material cannot be conveyed by sandwiching the transfer material with rollers or the like. Only the lower surface of the transfer material is brought into contact with a transport roller or the like and is transported to the fixing device 3. Further, a suction fan 21 is provided in the conveyor belt 14 or is connected via an appropriate duct to convey the transfer material 10 to the fixing device 3 while sucking the transfer material 10 onto the conveyor belt 14.

Further, as one of the means for preventing wrinkles, a guide plate 15 is provided on the front side of the fixing device 3 to guide the transfer material 10 to the fixing device 15. This guide plate 1
5 has a center portion curved upward, and the transfer material 10
First, the vicinity of the central portion of the tip of is contacted with the roller portion of the fixing device 3, and the contact is propagated toward both ends. According to this, the contact of the transfer material 10 with the roller portion of the fixing device 3 gradually goes from the center in the width direction to both ends. For this reason, the transfer material 10 is sent to the roller portion cleanly and wrinkles are suppressed.

[0006]

In the apparatus having the above-mentioned structure, a transfer failure is likely to occur due to the type of transfer material used and changes in the surrounding environment. As shown in FIG. In some cases, they separate as they go along. Therefore, a retransfer phenomenon occurs in which the toner once transferred to the transfer material 10 moves to the photosensitive drum 5 side again. In particular, when the transfer material 10 has a small thickness or when the humidity is low, the above-mentioned transfer failure is likely to occur.

Further, as shown in FIG. 3, the separation claw 17 is provided to separate the transfer material 10 from the photosensitive drum 5.
Is provided in contact with. Therefore, the surface of the photosensitive drum 5 is damaged by the sliding friction between the rotating photosensitive drum 5 and the separating claw 17. Further, a spur 18 is rotatably provided near the photosensitive drum 5 to prevent the transfer material 10 separated from rising. However, since the spur 18 presses the transfer material 10, the unfixed toner image on the transfer material 10 is damaged and a good transferred image cannot be obtained.

The transfer material separated from the photosensitive drum 5 is conveyed by a conveyor belt 14 serving as a conveyance guide means, and a suction fan 21 for preventing the transfer material from floating and meandering due to the conveyance is provided therein, or is suitable. The transfer material 10 is conveyed while being sucked so as to be fixed on the belt. Providing the suction fan 21 inside the conveyor belt 14 having a drive mechanism involves complicated design and steps, and is expensive.

In order to obtain a good transfer material without wrinkles in the fixing step, the transfer material 10 is prevented from floating above the guide plate 15, and the transfer material 10 is fixed from the vicinity of the center in the width direction of the fixing device. 3 and the guide plate 15 must be adjusted to the proper position and angle. Further, along with the adjustment of the guide plate 15, the fixing device 3 is also required to have mechanical precision and the like, and the work of adjusting these is complicated.

The present invention has been made in view of the above problems, and prevents a transfer failure of a transfer material with a simple structure, and damages the photosensitive drum due to a separating claw and a toner image on the transfer material due to spurs. Provided is an image forming apparatus capable of preventing damage to a sheet, preventing meandering of a transfer material conveyed on a conveyor belt, and eliminating a need for adjustment of a guide plate and a fixing device to obtain a good transferred image without image defects. The task is to do.

[0011]

In order to solve the above-mentioned problems, the present invention provides an image forming apparatus having a conveyance guide means for conveying a transfer material separated from an image carrier to a fixing device after image formation. It is characterized in that the material is provided with air blowing means for blowing air from above the conveying guide means and for causing the conveying guide means to press the transfer material.

Further, the carrying guide means includes a guide plate for guiding the transfer material to the fixing device, and the air blowing means blows air from above the guide plate to almost the entire widthwise direction of the transfer material. And the transport guide means,
It is characterized in that it includes a conveyor belt for guiding the transfer material to the fixing device, and blows air from above the conveyor belt to almost the entire area of the transfer material in the width direction.

Further, the air volume by the air blowing means is an air volume which does not fly unfixed toner formed on the transfer material. With the air blowing by the air blowing means to the conveyance guide means, It is characterized in that air is blown so as to separate the image carrier and the transfer material.

[0014]

In such a structure, the air blower blows air from the separating position of the transfer material on the photosensitive drum to the fixing device in a direction substantially perpendicular to the transfer material and almost in the entire width direction, so that unfixed on the transfer material. The air is blown in such an amount that the toner is not scattered. In particular, air is blown to the guide plate of the conveyance guide means. By this air blowing, the transfer material is separated from the photosensitive drum at a predetermined separation position, and the transfer material is pressed against the upper surfaces of the transfer belt and the guide plate of the transfer guide means, and the transfer material is transferred to the fixing device without floating.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing an image forming apparatus according to the present invention, which is roughly composed of an image forming section 1, a transfer material conveyance guide means 2, and a fixing device 3. An air blower fan 4 as an air blower for moving the transfer material while pressing the transfer material against the transfer guide means 2 is arranged above the transfer guide means 2 located between the separating position 16 of the image forming unit and the fixing device 3 which will be described later. ing.

As is well known, as the image forming section 1, a corona charger 6 for uniformly charging the surface of the photosensitive drum 5 with the photosensitive drum 5 as a center, and an original image is projected to form a latent image on the photosensitive drum 5. An optical projection device 7 for developing the latent image, a developing device 8 for developing the latent image, and a transfer corona for transferring the visualized toner image onto a transfer material 10 fed from a paper feed unit loaded with unillustrated roll paper or cut paper. The discharger 9, the AC separation corona discharger 11 for separating the transfer material 10 from the photosensitive drum 5, the cleaner 12 for removing the developer remaining on the surface of the photosensitive drum 5 after transfer, and the uniform surface potential on the surface of the photosensitive drum 5. And an eraser lamp 13 for operating the photosensitive drum 5 in sequence.

Further, between the vicinity of the separating corona discharger 11 and the fixing device 3, a transfer guide means 2 for conveying and guiding the transfer material 10 separated by the separating corona discharger 11 to the fixing device 3. Belt 14 and guide plate 15
Are arranged. At the tip of the guide plate 15, a fixing device 3 that fixes the toner image on the transfer material 10 as a permanent image is arranged.

The blower fan 4 is preferably located above the guide plate 15 and preferably blows air in a direction substantially perpendicular to the transferred transfer material 10 and over substantially the entire width direction of the transfer material. The wind from the blower fan 4 is mainly guided to the guide plate 15 or the guide plate 15
Hit 0. Further, this wind flows along the transfer material 10 or the guide plate 15 and is blown onto the conveyor belt 14. Further, the wind reaches the separation position 16 where the transfer material 10 is separated from the photosensitive drum 5 by the separation corona discharger 11. The amount of air blown by the blower fan 4 is preferably such that the toner formed on the transfer material 10 does not scatter, and the bias voltage opposite to the polarity of the toner is applied to the transfer belt 14 or the guide plate 15 so that the transfer material 10 is transferred. The toner scattering can be suppressed, and the air volume can be controlled.

The operation of the transfer material 10 will be described. When the optical image is projected on the photosensitive drum 5 charged by the corona discharger 6 by the optical projection device 7 as described above, the latent image corresponding to the optical image is projected. An image is formed on the surface of the photosensitive body of the photosensitive drum 5. This latent image is developed by the developing device 8 to form a toner image, and the toner image is transferred onto the transfer material 10 by the action of the transfer corona discharger 9. The transfer material 10 is then separated from the photosensitive drum 5 by the separation corona discharger 11. At the time of this separation, the air sent from the blower fan 4 flows between the photosensitive drum 5 and the transfer material 10, and the transfer material 10 can be separated at a predetermined separation position 16.

Next, the transfer material 10 is transported by a transport belt 14 configured by arranging a plurality of belt-shaped or single endless belts in the transport direction in order to transport the transfer material 10. At the time of this conveyance, the air blown from the blowing fan 4 flows from above the transfer material 10, and the transfer material 10 is pressed against the conveyance belt 14. The wind prevents the transfer material 10 from floating on the conveyor belt 14 and prevents the transfer material 10 from meandering. Further, a suction fan may be provided inside the conveyor belt 14 and used together.

The transfer material 10 transported by the transport belt 14 passes through the upper surface of the guide plate 15 and is guided to the fixing device 3. At this time, the air sent from the blower fan 4 flows from above the transfer material 10, and the transfer material is guided by the guide plate 15.
Is pressed by. This wind prevents the transfer material 10 from floating on the guide plate 15. That is, the transfer material 10 is guided to the fixing device 3 with a uniform surface without any bending. Therefore, the guide plate 15 may be formed on a flat surface. Next, the transfer material 10 guided to the fixing device 3 is fixed in the above-described favorable state, and a copy image having no transfer defects and no wrinkles is discharged to the outside of the device.

The fixing device 3 is composed of a fixing roller 19 and a pressure roller 20 which are arranged so as to be in relative pressure contact with each other as shown in FIG. May be Further, in order to prevent the temperature of the heater of the fixing device 3 from lowering due to the blowing of the blowing fan 4, the transfer material 10 has the separating position 16, the conveying belt 14, and the guide plate 1.
The air may be blown only when it is located at any one of the positions. Further, although the case where the photosensitive drum 5 is used is shown as an example, the same effect can be obtained by using the photosensitive belt.

[0023]

The image forming apparatus of the present invention has a simple structure in which the air blowing means is provided above the conveying guide means and air is blown from above the transfer material being conveyed and guided. The transfer material is separated at a position to prevent transfer failure, and the transfer material is pressed against the upper surface of the conveyor belt of the conveyance guide means to prevent the transfer material from floating and to prevent the transfer material from meandering. By pressing the transfer material and guiding it to the fixing device, it is possible to prevent wrinkles of the transfer material that occur after fixing. Further, it is possible to use a guide plate having a flat surface without requiring a suction fan provided inside the conveyor belt. Furthermore, the mechanical precision of the guide plate and the fixing device can be relaxed,
There is no need for complicated adjustments.

[0022]

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment according to the present invention.

FIG. 2 is a side sectional view showing an example of a conventional example.

FIG. 3 is a side sectional view showing an example of a conventional example.

[Explanation of symbols]

 1 Image Forming Section 2 Conveying Guide Means 3 Fixing Device 4 Blower Fan 5 Photosensitive Drum 10 Transfer Material 11 Separation Corona Discharger 14 Conveyor Belt 15 Guide Plate 16 Separation Position 17 Separation Claw 18 Spurs 19 Fixing Roller 20 Pressure Roller

Claims (5)

[Claims] 1. An image forming apparatus having a transport guide unit for transporting a transfer material separated from an image carrier to a fixing device after image formation, wherein air is blown to the transfer material from above the transport guide unit, and the transport guide is provided. An image forming apparatus, characterized in that the means is provided with a blowing means for pressing the transfer material. 2. The conveyance guide means includes a guide plate for guiding the transfer material to the fixing device, and blows air from above the guide plate to almost the entire width direction of the transfer material by the blowing means. The image forming apparatus according to claim 1. 3. The conveyance guide means includes a conveyance belt that guides the transfer material to the fixing device, and blows air from above the conveyance belt to almost the entire width direction of the transfer material by the blowing means. The image forming apparatus according to claim 1. 4. The image forming apparatus according to claim 1, wherein the air volume of the air blowing unit is such that the unfixed toner formed on the transfer material does not fly. 5. The image forming apparatus according to claim 1, wherein the air is blown so as to separate the image carrier and the transfer material when the air blower blows air to the conveyance guide means. .