JPH09114258A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent irregularities in a toner image and to obtain an image having high printing quality by sucking the inside of a pipe opened in the vicinity of a photoreceptor by a suction fan, and sucking a material to be transferred carried along the surface of the photoreceptor to a suction port side so that the material to be transferred may be peeled from the photoreceptor. SOLUTION: Since the leading edge of paper 9 passing through a transfer device is unstable because there exists a small gap between the drum 2 and the paper, it comes closer toward the pipe 22 by the flow of air when it comes close to the pipe 22. At such a time, the flow by the fan 20 is interrupted by the paper 9, so that it is decreased, and further static pressure becomes high. Then, the static pressure near the pipe 22 becomes high and further the paper 9 comes close to the pipe 22, finally it is attracted to the pipe 22. The paper 9 attracted to the pipe 22 is gradually peeled from a photoreceptor drum 2 and carried to a fixing device 17 along a carrying guide 16. The toner image on the paper 9 is fixed on the paper 9 by the fixing device 17, and image forming is finished.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, multimedia has been increasingly used, and as for output devices, image forming apparatuses using various electrophotographic technologies such as color, high image quality, low price, small-sized electronic copying machines, laser beam printers, and the like. Needs are growing.

A conventional color image forming apparatus will be described below. FIG. 5 is a sectional view of a conventional color image forming apparatus,
FIG. 6 is a cross-sectional view of a main part of the conventional color image device during sheet conveyance after the transfer step.

In FIG. 5, reference numeral 1 is an image forming apparatus main body, 2
Is a photoconductor drum. 3 is a charging device, 4 is an exposure system for turning on / off a laser to form an electrostatic image on the photosensitive drum 2 based on information from a host, 5 is a developing device for converting the electrostatic image into a visible image, and 6 is a cleaner. Yes, each is provided around the photosensitive drum 2. Reference numeral 9 is a sheet of paper, and 10 is a peeling claw, which is in contact with the photosensitive drum 2 in order to peel off the sheet of paper 9 to be attracted to the photosensitive drum 2. Reference numeral 11 is a mounting shaft for mounting the peeling claw 10. The peeling claw 10 rotates about the mounting shaft 11 and separates from the photosensitive drum 2 when the paper 9 is not peeled. Further, the mounting shaft 11 is provided with a solenoid (not shown) that rotates the peeling claw 10 to contact the photosensitive drum 2.

A sheet cassette 12 and a sheet feeding roller 13 are provided below the image forming apparatus 1. 14 is a registration roller, 15 is a transfer device, 16 is a conveyance guide, 1
Reference numeral 7 is a fixing device, and 18 is a paper discharge roller, which are provided on the left side of the image forming apparatus 1. A paper discharge tray 19 is provided above the image forming apparatus 1. Transfer device 15
Are divided into two parts. The registration roller 14 side is the transfer device 15a, and the fixing device 18 side is the static eliminator 15b.

The operation of the color image forming apparatus configured as described above will be described below. When the image formation is started, the laser is turned on and off according to the information for each color sent from the host, an electrostatic image is formed for each color on the photosensitive drum 2, and the electrostatic image is developed by the developing device 5 for each color. It becomes a visible image, that is, a toner image, and these are combined into a color image. On the other hand, the paper 9 is fed from the paper cassette 12 by the paper feed roller 13 and conveyed to the registration roller 14. The registration roller 14 starts rotating in accordance with the position of the color image on the photosensitive drum 2, and sends the paper 9 to the transfer device 15.

The transfer device 15 starts corona discharge immediately before the paper 9 passes to the transfer position, and the color image on the photosensitive drum 2 is transferred to the paper 9. At the same time as the corona discharge of the transfer device 15, the solenoid is energized, and the peeling claw 10 rotates and comes into contact with the photosensitive drum 2.

The sheet 9 is charged due to the corona discharge of the transfer device 15. The charged paper 9 tends to be attracted to the photosensitive drum 2 due to static electricity. However, due to the action of the static eliminator 15b, a part of the electric charge on the paper 9 is removed, and the attraction force due to static electricity is reduced. Since there is a gap between the front end of the paper 9 and the photoconductor drum 2, the peeling claw 10 that is in contact with the photoconductor drum 2 enters into the gap and peels the paper 9. The sheet 9 is conveyed to the fixing device 17 along the conveyance guide 16. The conveyance state of the sheet 9 at this time is shown in FIG.

Finally, the toner image on the sheet 9 is fixed on the sheet 9 by the fixing device 17, and the sheet is ejected to the sheet ejection tray 19 by the sheet ejection roller 18 to complete the image formation.

[0010]

However, in the above-described conventional configuration, the charge removal amount of the toner on the paper reduces due to the effect of the static eliminator 15 and the toner image is disturbed, and the paper 9 is separated by using the peeling claw 10. The peeling claw 10 comes into contact with the toner image on the sheet 9 to cause rubbing marks, which deteriorates the printing quality.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide an image forming apparatus capable of preventing a toner image from being disturbed from a transfer unit to a fixing unit and obtaining an image of high print quality. To do.

[0012]

In order to achieve this object, an image forming apparatus of the present invention comprises a pipe arranged near a photoconductor and having a suction port, and a suction fan for sucking the inside of the pipe. The transfer target material is peeled off from the photosensitive member by sucking the transfer target material conveyed along the surface of the photosensitive member toward the suction port side.

A hood for restricting the flow of air is provided along the surface of the pipe opposite to the photoconductor.
Further, a rotating means for rotating the pipe in the same direction as the rotation direction of the photoconductor is provided.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is a photosensitive member carrying an electrostatic latent image, a developing device for forming a toner image on the photosensitive member, and a transfer target from the photosensitive member. A transfer means for transferring the toner image to the material, a fixing means for fixing the toner image transferred on the transfer material, a pipe provided in the vicinity of the photoconductor and having an inlet port, and a pipe inside the pipe. A suction fan for suctioning is provided, and the transfer material conveyed along the surface of the photoconductor is sucked toward the suction port side to separate the transfer material from the photoconductor. The material to be transferred can be reliably peeled off from the photoconductor by the flow of the air sucked therein. Therefore, the disturbance of the toner image can be prevented, and the separation claw can be eliminated, so that the image disturbance such as a scratch mark can be prevented and a high quality image can be obtained.

An embodiment of the present invention will be described below with reference to the drawings. 1 is a cross-sectional view of a color image forming apparatus according to a first embodiment of the present invention, FIG. 2 is a perspective view of the same paper peeling portion, and FIG. 3 is a partial cross-sectional view during paper conveyance after the completion of the transfer process. The same elements as those of the above-mentioned conventional example are designated by the same reference numerals and the description thereof will be omitted. 1 and 2, 20 is a suction fan provided in the vicinity of the transfer device 15, 21 is a duct connected to the suction fan 20 and made of resin, and 22 is a suction port 26 such as a round hole or a long hole.
The duct 21 is connected by a hollow pipe in which a plurality of are formed. The opposite side (the right end side in FIG. 2) of the pipe 22 is sealed by a sealing member (not shown). The pipe 22 is arranged along the surface of the photosensitive drum 2. Reference numeral 23 is a hood that regulates the flow of air near the pipe 22. The hood 23 is formed by cutting out a part of the tubular body, and is arranged along the surface of the pipe 22 on the opposite side of the photosensitive drum 2, and the suction port 26 is exposed to the photosensitive drum 2 side. doing.

The operation of the color image forming apparatus constructed as above will be described below. When the color image formation is started, the laser is turned on and off according to the information for each color sent from the host, and the photoconductor drum 2
An electrostatic image is formed for each color on the upper surface, and the electrostatic image becomes a visible image, that is, a toner image by the developing device 5 for each color, and these are combined to form a color image. On the other hand, the paper 9 is fed from the paper cassette 12 by the paper feed roller 13 and conveyed to the registration roller 14. The registration roller 14 starts rotating in accordance with the position of the color image on the photosensitive drum 2, and sends the paper 9 to the transfer device 15.

The transfer device 15 starts corona discharge immediately before the sheet 9 passes to the transfer position, and the color image on the photosensitive drum 2 is transferred to the sheet 9. The paper 9 is charged due to the corona discharge of the transfer device 15. The charged paper 9 tends to be attracted to the photosensitive drum 2 due to static electricity. However, since the front end of the paper 9 has a strong elastic force and is not completely attracted to the photoconductor drum 2, a slight gap is generated between the front end of the paper 9 and the photoconductor drum 2.

Further, the suction fan 20 causes a flow of air as shown by an arrow (FIG. 3). In the vicinity of the suction port 26 of the pipe 22, the air flows into the plural suction ports 2 of the pipe 22.
6 tries to flow into the pipe 22 evenly, but an air flow occurs in the suction port 26 of the pipe 22 on the opening side (right side in FIG. 3) of the hood 23, and the pipes 22 other than the opening of the hood 23. The air flow is regulated at the suction port 26 of. Therefore, the inflow air of the pipe 22 is reduced and the flow rate of the suction fan 20 is also reduced. In the suction fan 20, since the flow rate and the static pressure are in inverse proportion to each other, the suction fan 2
When the flow rate of 0 decreases, the static pressure increases. Due to these phenomena, at the suction port 26 facing the photoconductor drum 2, a high static pressure air flow is generated only in the direction in which the sheet 9 is separated from the photoconductor drum 2.

Since the front end of the paper 9 that has passed through the transfer device 15 is unstable because there is a slight gap between the front end of the paper 9 and the photoconductor drum 2, the front end of the paper 9 is moved to the pipe 22 by the air flow when it approaches the pipe 22. Get closer to the direction of. At this time, the flow rate of the suction fan 20 is reduced because it is blocked by the sheet 9, and the static pressure is further increased. Then, the static pressure in the vicinity of the pipe 22 also increases, and the paper 9 approaches the pipe 22 and finally the paper 9 is adsorbed by the pipe 22.

The sheet 9 adsorbed on the pipe 22 is gradually peeled off from the photosensitive drum 2 and conveyed to the fixing device 17 along the conveying guide 16. Finally, the toner image on the sheet 9 is fixed on the sheet 9 by the fixing device 17, and the sheet discharge roller 1
The sheet is discharged to the sheet discharge tray 19 by 8, and the image formation is completed.

Next, a color image forming apparatus according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a perspective view of a paper peeling portion of the color image forming apparatus according to the second embodiment of the present invention. In FIG. 4, 20 is a suction fan, 21 is a duct connected to the suction fan 20 and formed of resin, and 24 is a rotating member such as a bearing that can rotate independently on the outside and inside. The outer periphery of the rotating member 24 is connected to the periphery. Reference numeral 22 denotes a hollow pipe in which a plurality of suction ports 26 such as round holes and elongated holes are formed, and the outer circumference of the pipe 22 is connected to the inner circumference of the rotating member 24. The opposite side of the pipe 22 is sealed by a sealing member (not shown). A drive transmission member 25 such as a gear for transmitting drive from a drive means (not shown) such as a motor is fixed to the outer periphery of the pipe 22 on the side of the sealing member.

The operation of the color image forming apparatus constructed as above will be described below. When the paper 9 passes through the transfer device 15, the drive is transmitted from the drive means to the drive transmission member 25, and the pipe 22 moves to the photosensitive drum 2.
And rotate in the same direction. The peripheral speed at this time is set to be substantially the same as the peripheral speed of the photosensitive drum 2.

Since the front end of the paper 9 that has passed through the transfer device 15 is unstable because of a slight gap between the paper 9 and the photosensitive drum 2, it approaches the hood 23 and the suction port 26 of the pipe 22 facing the opening of the hood 23. By the flow of air having a high static pressure, the leading edge of the sheet 9 is adsorbed to the hood 23 and the suction port 26 of the pipe 22 on the opening side of the hood 23.

Since the pipe 22 is rotating, when the sheet 9 is conveyed to the left end of the opening of the hood 23 by the suction port, the sheet 9 and the suction port 26 of the pipe 22 are separated by the elastic force of the sheet 9. Immediately before this separation, at the right end of the hood 23, the next suction port 26 of the pipe 22 approaches the sheet 9 and adsorbs it.
By repeating a series of operations of suction, conveyance, separation, suction, conveyance, and separation on the sheet 9 in this manner, it is possible to stably separate the sheet 9 from the photosensitive drum 2 and convey it to the fixing device 17. You can

Finally, the toner image on the sheet 9 is fixed on the sheet 9 by the fixing device 17, and is ejected to the sheet ejection tray 19 by the sheet ejection roller 18, and the image formation is completed. Needless to say, the air that has passed through the suction fan 20 may be used for cooling the fixing device 17, the control board, etc., or for removing the ozone generated in the image forming apparatus main body 1.

[0026]

According to the present invention, the material to be transferred can be separated from the photosensitive member by the suction force of the suction port of the pipe, so that the peeling claw can be eliminated and the toner image on the material to be transferred after transfer is disturbed. Since it is conveyed to the fixing means without any need, high print quality can be realized. Further, by providing the rotating means for the hood and the pipe, the transferred material can be more surely peeled off from the photoconductor.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a sheet peeling portion of the color image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of the color image forming apparatus according to the first embodiment of the present invention during conveyance of a sheet after completion of a transfer process.

FIG. 4 is a perspective view of a sheet peeling portion of a color image forming apparatus according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a conventional color image forming apparatus.

FIG. 6 is a cross-sectional view of a main part of a conventional color image device during sheet conveyance after a transfer process.

[Explanation of symbols]

 1 image forming apparatus main body 2 photoconductor drum 9 paper 10 peeling claw 11 mounting shaft 15 transfer device 15b static eliminator 16 transport guide 17 fixing device 20 suction fan 21 duct 22 pipe 23 hood 24 rotating member 25 drive transmission member 26 suction port

Claims (3)

[Claims] 1. A photoconductor carrying an electrostatic latent image, a developing device for forming a toner image on the photoconductor, a transfer means for transferring the toner image from the photoconductor to a transfer material, and a transfer material. A fixing unit for fixing the toner image transferred to the photosensitive member, a pipe provided in the vicinity of the photosensitive member and having an opening for suction, and a suction fan for sucking the inside of the pipe are provided. An image forming apparatus characterized in that the transfer material is peeled off from the photosensitive member by sucking the transfer material conveyed by suction toward the suction port side. 2. The image forming apparatus according to claim 1, further comprising a hood that regulates a flow of air provided along a surface of the pipe opposite to the photoconductor. 3. The image forming apparatus according to claim 1, further comprising rotating means for rotating the pipe in the same direction as the rotating direction of the photosensitive member.