JPH1124341A - Image forming device - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide an image forming apparatus capable of reliably peeling a transfer material from a traveling member constituting a transfer means and preventing discharge when the transfer material is peeled. With the goal. The present invention has an image forming means (K) for forming a toner image on a photoreceptor (1), and a transfer belt (12) running between a pair of support rollers (10) and running endlessly. A transfer device 5 that transports the paper P to the photoreceptor 1 to transfer the developer image onto the paper P by traveling, and a large-diameter portion formed on a support roller 10 located on the downstream side in the transport direction of the paper P 10a and a small diameter portion 10b.

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 applied as, for example, an electrophotographic apparatus.

[0002]

2. Description of the Related Art In recent years, digitalization has been advanced in electrophotographic apparatuses, and digital copying machines have become widespread. In a digital copying machine, a reversal development method is mainly used, and in a transfer process, the polarity of a photosensitive member and the polarity of a transfer member such as a transfer corona have different polarities. For this reason, the polarity of the transfer object such as paper and the photoreceptor are also reversed, and both attract and attract. Therefore, it is necessary to devise a method of separating the transfer target from the photoreceptor.

Conventional laser printers and the like often have a slow process speed and require a small diameter photoconductor.
The paper is separated by the waist of the paper, and a peeling charger is provided downstream of a transfer corona or the like as an auxiliary means, and the paper is neutralized so that the image is not disturbed.

However, in a digital copying machine, the process speed is high, so that the diameter of the photoreceptor becomes large. For this reason, it is difficult to separate the paper by the waist. In view of this, a method has been proposed in which a belt is used as a transfer member, paper is electrostatically attracted to the belt side, and the paper is conveyed and transferred.

[0005]

However, when a belt is used as the transfer member, there is a problem that the sheet cannot be peeled off from the belt satisfactorily. That is, in the case of a paper having a weak stiffness and a high resistance, for example, a 50 g tracing paper, it may not be able to be peeled off even if it is attracted to the belt and reaches the most downstream side of the belt, and may be jammed.

Further, even when the paper is peeled from the belt, there is a disadvantage that the halftone image is disturbed by the discharge at the time of peeling, and the image quality is deteriorated. The present invention has been made in view of the above circumstances, and provides an image forming apparatus capable of reliably peeling a transferred material from a traveling member of a transfer unit and preventing discharge when the transferred material is peeled. With the goal.

[0007]

According to the present invention, in order to solve the above-mentioned problems, an image forming means for forming a developer image on an image carrier and a pair of support rollers are provided. Transfer means for transferring the transfer-receiving member to the image carrier and transferring the developer image, and a downstream side in the transfer direction of the transfer-receiving member. And a large-diameter portion and a small-diameter portion formed on the support roller located at the position (1).

According to a second aspect of the present invention, there is provided an image forming means for forming a developer image on an image carrier, and a running member which runs between a pair of support rollers and runs endlessly. A transfer means for transferring the developer image by transferring the transfer object to the image carrier, and a large-diameter portion formed at both ends of a support roller positioned downstream in the transfer direction of the transfer object; And a small-diameter portion formed at the center.

According to a third aspect of the present invention, there is provided an image forming means for forming a developer image on an image carrier, and a traveling member which runs between a pair of support rollers and runs endlessly. By means of a transfer means for transferring the transferred object to the image carrier to transfer the developer image, a large-diameter portion and a small-diameter portion formed on a support roller positioned downstream in the transfer direction of the transferred object A fitting member fitted and fixed to the small-diameter portion of the support roller and having an arc surface having the same curvature as the curvature of the large-diameter portion, and abutting on the arc surface of the fitting member via the traveling member. And a removing member for removing the developer adhered on the traveling member.

According to a fourth aspect of the present invention, there is provided an image forming means for forming a developer image on an image carrier, and a running member which runs between a pair of support rollers and runs endlessly. A transfer unit that transfers the developer image by transferring the transfer target to the image carrier, and a support roller that is provided near a support roller that is positioned downstream in the transfer direction of the transfer target; Push-up means for pushing up the part.

According to a fifth aspect of the present invention, there is provided an image forming means for forming a developer image on an image carrier, and a running member which runs between a pair of supporting rollers and runs endlessly. A transfer unit that transfers the developer image by transferring the transfer target to the image carrier, and a support roller that is provided near a support roller that is positioned downstream in the transfer direction of the transfer target; A push-up roller that pushes up the section and rotates as the travel member travels.

According to a sixth aspect of the present invention, there is provided an image forming means for forming a developer image on an image carrier, and a traveling member which runs between a pair of support rollers and travels endlessly. The transfer means for transferring the transfer object to the image carrier and supplying the transfer voltage to the traveling member to transfer the developer image, and slidably contact the transfer object discharged from the transfer means. While guiding in a predetermined direction,
And a guide member that is frictionally charged to the same polarity as the charge of the transfer target by the transfer unit during the guide.

According to a seventh aspect of the present invention, there is provided an image forming means for forming a developer image on an image carrier, and a running member which runs between a pair of support rollers and runs endlessly. The transfer means for transferring the transfer object to the image carrier and supplying the transfer voltage to the traveling member to transfer the developer image, and slidably contact the transfer object discharged from the transfer means. While guiding in a predetermined direction,
At the time of this guide, a guide member frictionally charged to the same polarity as the charge of the transfer target body by the transfer unit, and the developer image is fixed by passing through the transfer target member guided by the guide member. Fixing means.

According to another aspect of the present invention, there is provided an image forming means for forming a developer image on an image carrier, and a traveling member which runs between a pair of support rollers and travels endlessly. The transfer means for transferring the transfer object to the image carrier and supplying the transfer voltage to the traveling member to transfer the developer image, and slidably contact the transfer object discharged from the transfer means. While guiding in a predetermined direction,
At the time of this guide, the guide member is frictionally charged to the same polarity as the charge of the transfer object by the transfer means, a discharge means for discharging the charge accumulated in the guide member, and the guide member guided by the guide member. Fixing means for fixing the developer image by passing through the transfer medium.

According to the present invention, a large-diameter portion and a small-diameter portion are formed on the support roller on the downstream side in the transport direction of the transfer object, so that the traveling member stretched over the support roller is formed on the large-diameter portion and the small-diameter portion of the support roller. To form a gap between the sheet and the transfer target.

Thus, the adhesion between the running member and the transfer member is reduced, so that the transfer member can be smoothly separated from the transfer member. In addition, by pushing up the running member in the vicinity of the support roller by a push-up means (push-up roller), the running member stretched over the support roller is deformed into an uneven shape. Due to this deformation, a gap is formed between the transfer member and the running member, and the adhesion between the running member and the transfer member is reduced, so that the transfer member can be smoothly separated from the running member.

Further, a fitting member having an arc surface having the same curvature as that of the large diameter portion at both ends is fitted into a small diameter portion formed at the center of the support roller, and a running member is inserted into the arc surface of the fitting member via a traveling member. By contacting the removing member, the developer attached on the traveling member can be removed.

Further, when the guide means for guiding the transferred object carried out of the transfer means is guided, the transferred object is frictionally charged to the same polarity as the polarity charged by the transfer means, so that the transferred object is separated from the traveling member. The transfer member is neutralized to reduce its charge amount, thereby making it difficult to discharge.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to a first embodiment shown in the drawings. FIG. 1 is a configuration diagram illustrating the image forming unit K. In the figure, reference numeral 1 denotes a photoconductor as an image carrier, and a peripheral portion of the photoconductor 1 is provided along a rotation direction thereof.
A charging charger 2 for uniformly charging the surface of the photoconductor 1 to a surface potential of -500 to -800 V, an exposure unit 3 for forming an electrostatic latent image on the surface of the photoconductor 1, and an electrostatic latent A developing device 4 for visualizing the image, a transfer device 5 for transferring the visible image to a sheet P as a material to be transferred, a cleaning device 6 for removing residual toner on the photoconductor 1, and a residual potential on the photoconductor 1 Is provided. The transfer device 5 includes a belt unit 9. The belt unit 9 has a transfer belt 12 as a running member that is stretched between the support rollers 10 and 11. Transfer belt 12
Is an elastic belt having a volume resistance of 10 ⁸ to 10 ¹² Ω · cm. The elastic belt runs while being pressed against the photoreceptor 1 and conveys the sheet P as a transfer target. Reference numeral 10 denotes a driving roller (hereinafter, the supporting roller 10 is referred to as a driving roller). The driving of the driving roller 10 causes the transfer belt 12 to run at substantially the same moving speed as the photosensitive member 1.

A power supply roller 14 facing the photoreceptor 1 is in contact with the back side of the transfer belt 12. Feed roller 1
Reference numeral 4 denotes a conductive elastic roller having a volume resistance of 10 ² to 10 ⁷ Ω · cm, and a bias (+300
To 5 kV) is connected.

At the time of image formation, the surface of the photoconductor 1 is uniformly charged to a surface potential of -500 to -800 V by the charging charger 2, and the surface of the charged photoconductor 1 is electrostatically charged by the exposure unit 3. An image is formed. The electrostatic latent image is sent to the developing device 4 by the rotation of the photoconductor 1, and the electrostatic latent image is visualized by supplying negatively charged toner from the developing device 4.

On the other hand, at this time, the paper P is fed between the photosensitive member 1 and the transfer belt 12, and the bias (+300 to +300) is applied to the transfer belt 12 by the high voltage power supply 15.
5 kV) is applied. As a result, the visible image on the photoconductor 1 is transferred to the sheet P, and the visible image is transferred to the sheet P.
Is carried out by the movement of the transfer belt 12 and sent to a fixing device (not shown) which is the next process.

FIG. 2 is a perspective view showing the drive roller 10 around which the transfer belt 12 is wound. The drive roller 10 is made of aluminum having a total length of 322 mm and is grounded, and has a large-diameter portion (outer diameter 16 mm) 10a at both ends and a central portion (width 40m).
m) is formed with a small diameter portion (outer diameter 8 mm) 10b.

Therefore, when the transfer belt 12 is stretched over the driving roller 10, as shown in FIG.
When the sheet P is conveyed to the unloading end side of the transfer belt 12, the sheet P is deformed along the recess of the transfer belt 12, and a gap is formed between the sheet P and the transfer belt 12. Is formed.

As a result, the sheet attracting force of the transfer belt 12 is weakened, and the sheet P is reliably separated from the transfer belt 12. By the way, at the time of image formation, since the developer may adhere to the transfer belt 12 and become dirty, after the paper P is carried out from the transfer belt 12, the transfer belt 1
It is necessary to remove the developer on the second. For this reason, a cleaning blade 23 is in contact with the lower side of the drive roller 10 via the transfer belt 12.

However, since the driving roller 10 is formed with the small diameter portion 10b, it cannot be brought into contact with the same strength over the entire width of the transfer belt 12 simply by bringing the cleaning blade 23 into contact. .

Therefore, as shown in FIG.
The fitting member 18 is fitted in the small diameter portion 10b of the zero. As shown in cross section in FIG. 5, the fitting member 18 has an arcuate surface 18 having the same curvature as the large diameter portion 10a of the drive roller 10.
a. The fitting member 18 is formed of acrylic, and the arc surface 18a is coated with Teflon. The fitting member 18 is fitted in a range from 90 degrees to 225 degrees.

If the fitting angle of the fitting member 18 exceeds 270 degrees, the curvature of the transfer belt 12 due to the difference in the outer diameter of the drive roller 10 does not become small, and the peeling performance of the paper P cannot be improved.

Similarly, the fitting member 18 is moved from 0 degree to 90 degrees.
Even if the sheet P is inserted at the right position, the peeling performance of the sheet P cannot be improved for the same reason. The shafts 19 of the drive roller 10 are rotatably supported by support frames 20 on both sides, and the fitting member 18 is fixed to the support frame 20 via a stay 21. Therefore, the driving roller 10 rotates, but the fitting member 18 fitted in the small diameter portion 10b does not rotate.

The fitting member 18 fitted as described above.
A cleaning blade 23 as a removing unit is in contact with the transfer belt 12 via the transfer belt 12. Therefore, the cleaning blade 23 can be satisfactorily contacted over the entire width of the transfer belt 12, and the residual toner on the transfer belt 12 can be reliably removed.

In practice, the contact position of the cleaning blade 23 is preferably about 180 degrees. At a position where the fitting member 18 is not fitted, there is a step in the axial direction of the driving roller 10. Cleaning cannot be performed.

FIGS. 6 to 10 show a second embodiment of the present invention. The same portions as those described in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the second embodiment, as shown in FIG. 6, a push-up roller 31 as push-up means is provided near the drive roller 10, that is, 30 mm upstream of the drive roller 10.

FIG. 7 shows the push-up roller 31.
The push-up roller 31 has a shaft portion 32 having a diameter of 8 mm and a length of 322 mm, and a shaft portion 32 having a diameter of 12 mm rotatably attached to a central portion of the shaft portion 32 through a bearing 33.
And a roller portion 34 having a width of 10 mm.

FIG. 8 shows the drive mechanism 36 of the push-up roller 31. Both ends of the shaft portion 32 of the push-up roller 31 are held in the middle of the rotating levers 38,38.
One end of each of the rotating levers 38, 38 is rotatably supported by a support shaft 39, and the other end of an operating element 41 of a solenoid 40 is provided at the other end.
Is connected. A spring 44 is connected to an intermediate portion of the rotating levers 38, 38 and is urged downward. The other end of the rotating lever 38 contacts the positioning member 43 to maintain a horizontal state.
At this time, the lifting roller 34 is moved from the transfer belt 12 by 5
mm.

When tracing paper of 50 g or less is used as the paper P, the solenoid 40 is energized and excited. When the solenoid 40 is excited, as shown in FIG.
Rotates upward around the support shaft 39 against the urging force of the spring 44, moves the lifting roller 34 to the upper limit position, and pushes up the transfer belt 12.

When the paper P is other than tracing paper, the solenoid 40 is demagnetized, and the urging force of the spring 44 causes the rotation lever 38 to rotate downward as shown in FIG. It moves downward, contacts the positioning member 24, and is horizontally positioned at the lower limit position.

FIG. 10 is a perspective view showing a state where the transfer belt 12 is pushed up by the push-up roller 34. The central portion of the transfer belt 12 rises in a convex shape, and the transfer belt 12
The paper P conveyed by the transfer belt 12 is deformed along the convex portion of the transfer belt 12, and a gap is formed between the paper P and the transfer belt 12.

As a result, the sheet attracting force of the transfer belt 12 is weakened, and the sheet P is reliably separated from the transfer belt 12. The ON / OFF of the solenoid 40 is
This is performed by a user operating a switch on a control panel (not shown).

FIGS. 11 and 12 show a third embodiment of the present invention. Note that the same parts as those in the above-described first and second embodiments are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, a guide member 47 is provided between the discharge side of the transfer belt 12 and the fixing device 46 as a fixing means for guiding the sheet carried out of the transfer belt 12 toward the fixing device 46. ing.

At the time of image formation, the paper P on which the toner image is transferred from the photoreceptor 1 and peeled off is charged to the same polarity as the photoreceptor 1. The guide member 11 is formed of an insulating material that charges the paper P with the same polarity.

When the paper is positively charged with ordinary paper, OHP or the like, the material of the guide member 47 may be aniline / formalin resin, polyformaldehyde resin, polymethyl methacrylate resin, ethyl cellulose resin, nylon, melamine -Formalin resin or the like is suitable, and if the paper is negatively charged, Teflon, PF, etc. are suitable.

For example, the sheet positively charged at the transfer section is separated from the transfer belt 12 and then comes into contact with the guide member 47 to be charged to a negative polarity, so that the charge is removed. However, when continuous printing is performed, the guide member 11
When the positive charges accumulate on the sheet and the positive charges are saturated, the effect of negatively charging the sheet is lost.

Therefore, as shown in FIG. 12, an electrode 49 as a discharge member grounded to the guide member 11 is brought into contact with the guide member 11.
Discharge is performed between the passage of a sheet and the passage of the next sheet.

In this embodiment, the guide member 47 comprises a metal plate 47a and a sheet material 47b of a positively charged material adhered to the upper surface of the metal plate 47a. The electrode 49 is brought into contact with the metal plate 47a of the guide member 47 to discharge the electric charge of the guide member 47.

[0047]

As described above, according to the present invention, since the large-diameter portion and the small-diameter portion are formed on the support roller on the downstream side in the transport direction of the transfer object, the traveling member stretched over the support roller is large. It is deformed along the diameter portion and the small diameter portion, and a gap is formed between the traveling member and the transfer object. Therefore, the degree of adhesion between the transfer object and the traveling member is reduced, the transfer object can be smoothly separated from the traveling member, and clogging of the transfer object can be reliably prevented.

Further, since the central portion of the traveling member is pushed up by the lifting means in the vicinity of the support roller, a gap is formed between the traveling member and the transfer object at the convex portion of the traveling member. Therefore, the degree of adhesion between the transfer object and the traveling member is reduced, the transfer object can be smoothly separated from the traveling member, and clogging of the transfer object can be reliably prevented.

Further, a fitting member having an arc surface having the same curvature as that of the large diameter portion is fitted into the small diameter portion of the support roller, and the removing member is brought into contact with the arc surface of the fitting member via the traveling member. The developer attached to the member can be reliably removed.

Further, since the guide means for guiding the transfer object discharged from the transfer means is formed of a material which is frictionally charged to the same polarity as the transfer object charged by the transfer means, it is transferred from the traveling member. The transferred material to be transferred can be discharged to reduce the amount of charge, make it difficult to discharge, and maintain good image quality.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an image forming unit according to an embodiment of the invention.

FIG. 2 is a perspective view showing a driving roller of a transfer belt.

FIG. 3 is a perspective view showing a transfer belt stretched over a driving roller.

FIG. 4 is a perspective view showing a state in which a fitting member is fitted into a small diameter portion of the drive roller.

FIG. 5 is a sectional view showing a fitting member of a small diameter portion of the driving roller.

FIG. 6 is a configuration diagram of an image forming unit according to a second embodiment of the present invention.

FIG. 7 is a perspective view showing a push-up roller.

FIG. 8 is a cross-sectional view illustrating a state in which the transfer belt is not pushed up by a push-up roller.

FIG. 9 is a cross-sectional view illustrating a state where the transfer belt is pushed up by a push-up roller.

FIG. 10 is a perspective view showing a state where a transfer belt is pushed up by a push-up roller.

FIG. 11 is a configuration diagram illustrating an image forming unit according to a third embodiment of the present invention.

FIG. 12 is a perspective view showing a guide member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photoreceptor (image carrier) 2 ... Charging charger 3 ... Exposure means 4 ... Developing device 10 ... Drive roller (supporting roller) 14 ... Conductive elastic roller 15 ... High voltage power supply 18 ... Insertion member 19 ... Shaft 21 ... Stay 23: Cleaning member (removal member) 31: Push-up roller 32: Shaft 34: Roller part 46: Fixer (fixing means) 47: Guide member 47b: Sheet material 49: Electrode (discharge member)

Claims (8)

[Claims] An image forming means for forming a developer image on an image carrier; and a running member which runs between a pair of support rollers and runs endlessly. Transfer means for transferring the developer image to the image carrier to transfer the developer image; and a large-diameter portion and a small-diameter portion formed on a support roller positioned downstream of the transfer target in the transport direction. An image forming apparatus comprising: 2. An image forming means for forming a developer image on an image carrier, and a running member which runs between a pair of support rollers and runs endlessly. A transfer unit for transferring the developer image by transferring the developer image to the image carrier; and a large-diameter portion and a central portion formed at both ends of a support roller positioned downstream of the transfer target in the transport direction. An image forming apparatus comprising: a small-diameter portion; 3. An image forming means for forming a developer image on an image carrier, and a traveling member which runs between a pair of support rollers and runs endlessly, and the traveling member moves the transfer target member. Transfer means for transferring the developer image by transferring to the image carrier; a large-diameter portion and a small-diameter portion formed on a support roller positioned downstream of the transfer target in the transport direction; and a small-diameter of the support roller. A fitting member fitted and fixed to the portion, having an arc surface having the same curvature as the curvature of the large-diameter portion; and abutting the arc surface of the fitting member via the traveling member, on the traveling member. An image forming apparatus, comprising: a removing member that removes an attached developer. 4. An image forming means for forming a developer image on an image carrier, and a traveling member which runs between a pair of support rollers and runs endlessly, and the traveling member travels to transfer an object to be transferred. Transfer means for transferring the developer image by transferring to the image carrier, provided near a support roller positioned on the downstream side in the transfer direction of the transfer target, and a push-up means for pushing up a central portion of the traveling member; An image forming apparatus comprising: 5. An image forming means for forming a developer image on an image carrier, and a traveling member which runs across a pair of support rollers and runs endlessly, and the traveling member travels to transfer an object to be transferred. A transfer unit that transfers the developer image by transferring the developer image to the image carrier; a transfer roller that is provided near a support roller positioned downstream of the transfer target in the transfer direction; An image forming apparatus, comprising: a push-up roller that rotates as a member travels. 6. An image forming means for forming a developer image on an image carrier, and a traveling member which is stretched between a pair of support rollers and runs endlessly. A transfer unit that transfers the developer image by supplying a transfer voltage to the traveling member while conveying the transfer member to the image carrier; and guides the transfer target body discharged from the transfer unit in a predetermined direction while slidingly contacting the transfer target body. An image forming apparatus, comprising: a guide member that is frictionally charged to the same polarity as the polarity of the transfer target when the guide is charged by the transfer unit. 7. An image forming means for forming a developer image on an image carrier, and a running member which runs between a pair of support rollers and runs endlessly. A transfer unit that transfers the developer image by supplying a transfer voltage to the traveling member while conveying the transfer member to the image carrier; and guides the transfer target body discharged from the transfer unit in a predetermined direction while slidingly contacting the transfer target body. A guide member frictionally charged to the same polarity as the charge of the transfer target by the transfer means during the guide; and a developer image fixed by passing the transfer target guided by the guide member. An image forming apparatus comprising: 8. An image forming means for forming a developer image on an image carrier, and a traveling member which runs between a pair of support rollers and runs endlessly. A transfer unit that transfers the developer image by supplying a transfer voltage to the traveling member while conveying the transfer member to the image carrier; and guides the transfer target body discharged from the transfer unit in a predetermined direction while slidingly contacting the transfer target body. At the time of this guiding, the guide member is frictionally charged to the same polarity as the charge of the transfer target body by the transfer means, a discharging means for discharging the charge accumulated in the guide member, and guided by the guide member. Fixing means for fixing the developer image by passing through the transfer-receiving member.