JPH0634129B2 - Transfer paper separator - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for separating transfer paper from a photoconductor in an electrophotographic copying machine.

Configuration of Conventional Example and Problems There are conventional transfer paper separating devices by an electric treatment using a separation charger, a mechanical treatment using a separation belt, and an electric treatment using the separation charger and the splitting claw described above. There is also a combination of mechanical treatment.

Generally, an electrophotographic copying apparatus forms an electrostatic latent image by charging a photosensitive member formed in a drum shape or a belt shape with a charging charger and exposing it. Develop it with toner,
While the transfer paper is in contact with the developing surface, a corona discharge having a polarity opposite to the electric charge held by the toner is applied to the transfer paper by the transfer charger to transfer the developed toner image on the photoconductor to the transfer paper. Next, when the transfer paper on which the toner image is transferred is separated from the surface of the photoconductor, an extra charge having a polarity opposite to that of the toner is present on the transfer paper due to corona discharge for the transfer. The transfer paper is attracted to the photoconductor by this electrostatic attraction. Therefore, it becomes difficult to separate the transfer paper from the photoconductor. As one of the devices that easily separates this, a separation charger is provided separately from the transfer charger, which removes the charges that were added during transfer, and naturally separates it from the photoconductor by the rigidity and weight of the transfer paper. A so-called electrostatic separation device which is electrically processed so as to be used is used.

As described above, the electrostatic separation device must be provided with a separation charger separately from the transfer charger. Further, since AC (alternating current) corona discharge is used for the separation charger, it is necessary to provide an AC high voltage power supply.

On the other hand, in the separation belt device that mechanically processes the separation, as shown in FIGS. 1 and 2, the transfer paper 2 guided by the photoconductor drum 1 by the transfer guide 6 is exposed by the image forming means. The toner image formed on the surface of the body drum 1 is transferred by the transfer charger 5. At this time, one end A of the transfer paper 2 on one side is clamped by the separation belt 3 and the separation roller 4, and the end of the transfer paper 2 which is out of the image area along the transfer material transport passage end of the photosensitive drum 1 is The process proceeds without contacting the photosensitive drum 1. On the other hand, the portion of the image portion near the center other than the above-mentioned end portion is the photosensitive drum 1.
While the toner image is transferred by the transfer charger 5 while being in contact with the
Transfer and separation are performed.

As is clear from the above, the end portion of the transfer paper held by the separation belt exists separately from the image portion. Therefore, the end of the copied image (the part held by the separation belt)
Has the drawback that the image has been deleted and full copying is not possible.

There is also another separation device that uses a separation charger and a separation claw together.

This device uses a transfer guide 6 as shown in FIG.
The transfer paper 2 guided by the photosensitive drum 1 transfers the toner image formed on the surface of the photosensitive drum 1 by the image forming means by the transfer charger 5 and then separated by the separation charger 7. However, since the force for separating the transfer paper 2 from the photoconductor drum 1 is likely to change depending on the ambient environment conditions such as humidity, the transfer paper 2 may not be sufficiently separated from the photoconductor drum 1 or may not be separated at all. is there. In these cases, transfer paper 2
Is separated from the photosensitive drum 1 by the separating claw 8 in the direction of arrow b as shown by the chain line. However, in this case, there is a drawback that the unfixed toner image held on the surface of the transfer paper 2 is rubbed when coming into contact with the separation claw 8 and a trace thereof is formed on the toner image. Furthermore, since the separation claws are always in contact with the photoconductor and are rubbing, there is a problem in that the surface of the photoconductor is scratched.

FIG. 4 shows another conventional example. As shown in FIG. 4, the transfer paper 22 guided by the belt-shaped photoconductor 21 mounted on the photoconductor driving drum 21a and the photoconductor driven roller 21b by the transfer guide 23 is transferred to the belt-shaped photoconductor 21 by the image forming means. The toner image formed on the surface is transferred by the charging / transferring charger 24. Next, the transfer paper 22 and the belt-shaped photoconductor 21 move at the same speed, and the leading end of the transfer paper 22 moves to the photoconductor driven roller 2
When it reaches 1b, since the curvature of the photoconductor driven roller 21b is increased, the transfer paper 22 moves straight due to the rigidity of the transfer paper 22 due to this curvature, and the transfer paper 22 is transferred from the belt-shaped photoconductor 21 at this curvature portion. break away. Transfer paper 2
When the belt 2 and the belt-shaped photoconductor 21 advance, the front end of the transfer paper 22 moves downward due to the weight of the transfer paper 22 itself, comes into contact with the fixing guide 25, further advances, and is guided to the fixing device 26. The toner image is fixed on the transfer paper 22. However, when so-called double-sided copying is performed in which the transfer paper once copied is turned over and then copied again, the toner image on the belt-shaped photoreceptor 21 is transferred to the transfer paper 22 at the moment when the transfer paper 22 after transfer comes into contact with the fixing guide in FIG. There has been a problem that the transferred unfixed toner image is scattered and so-called image disorder occurs. Therefore, the current situation is that double-sided copying cannot be performed. This development does not occur in a conventional copying machine configuration in which the charge of the transfer paper and the toner after the transfer is removed by the separation charger. Further, the common construction of these copying machines in which the image disturbance occurs is to separate the transfer paper from the photoconductor without using a separation charger. For example, the separation belt, the separation claw, and the one prior art example described above. Increase the curvature of part of the photoconductor,
There is a method of naturally separating the transfer paper at that portion. The common point of these is that since the transfer paper after transfer is separated from the photoconductor without removing the charge, the transfer paper itself after transfer is charged by transfer. When the paper comes into contact with the fixing guide, the unfixed toner image on the transfer paper scatters, which causes image distortion, which makes it impossible to perform high-quality screen copying. The reason why image distortion occurs when performing double-sided copying is that the transfer paper after transfer is 1
Moisture is removed by the heat of the second fixing, and the resistance value of the transfer paper itself increases, and the charge amount increases. Therefore,
When this transfer paper is used as a double-sided copy paper, the amount of electric charge accumulated on the transfer paper increases remarkably as compared with the first transfer due to the second transfer. Therefore, the transfer paper is separated from the photoconductor. When the sheet comes into contact with the fixing guide, the charge on the transfer sheet is rapidly removed, and at that moment, the unfixed toner on the transfer sheet scatters to cause image disturbance. Therefore, the image disturbance does not occur in the first copy, but the image disturbance occurs in the second copy (double-sided copy). This is because there is a large amount of change in the electric charges that are removed by the contact with. Further, although the image distortion in the normal state occurs during double-sided copying, when a polyester sheet having a large resistance value is used as the transfer paper, the image distortion occurs even in the first copying. Therefore, in conventional copying machines, it is necessary to take measures such as limiting the resistance value of the transfer paper to be used. Had the drawbacks of high manufacturing cost.

As described above, the image disturbance is caused by the increase of the resistance value due to the drying of the transfer paper. On the other hand, an environmental test is carried out to put the copier into practical use, but in a high humidity (for example, 30
At a temperature of 90 ° C. and a relative humidity of 90%, a copying machine having a conventional configuration causes a transfer failure. The reason for this is that if the resistance value of the transfer paper drops significantly due to high humidity, even if the transfer charger tries to transfer, the resistance value of the transfer paper is low, so the potential applied to the transfer paper leaks through the fixing guide. Will end up. As a result, only a low potential is applied to the transfer paper, and most of the toner image formed on the surface of the photoconductor remains, so-called transfer failure occurs. To solve this, there is a method in which the fixing guide is completely insulated or a distance between the fixing guide and the transfer charger is made sufficiently large. However, if the fixing guide is completely insulated, the electric charge of the transfer paper itself after the transfer is accumulated in the fixing guide due to the contact of the transfer paper, which causes an image disturbance that disturbs the unfixed toner image on the transfer paper, or the electric charge of the fixing guide is changed. There is a drawback that the spark discharge may increase and the spark discharge may become noise, which may cause an electric circuit to malfunction. Further, if the distance between the fixing guide and the transfer charger is made sufficiently large, the copying machine becomes large, which is against the manufacture of a small and inexpensive product.

OBJECT OF THE INVENTION It is an object of the present invention to provide a transfer paper separating device capable of surely separating a transfer paper from a photoconductor without using a separation charger, a separation belt and a separation claw and preventing the unfixed toner image from being disturbed. It is what

In the transfer paper separating apparatus of the present invention, a separation auxiliary material composed of an insulator, a conductor, and a discharging brush is arranged in the vicinity of a place where the photoconductor roll and the transfer paper are separated. The conductor is arranged in an upper layer portion of the insulator so that the conductor occupies at least a smaller area than the insulator so as to contact the transfer paper,
The static elimination brush is attached to the downstream end surface of the insulator in the transfer paper advancing direction, and after the transfer paper after transfer comes close to the separation auxiliary material, the charge of the transfer paper itself causes the transfer paper to move first. A charge having a polarity opposite to that of the charge is induced in the conductor in the upper layer of the separation aid, and the transfer paper electrostatically attracts and contacts the conductor in the upper layer, and the charge charged on the transfer paper is the lower layer. When the transfer paper is separated from the photoconductor by discharging the electric charge charged on the transfer paper by contacting the insulator of the transfer paper and discharging the charge on the transfer paper, the transfer paper can be separated with a simple structure. The image disturbance can be removed and the entire image can be copied.

Description of Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 5 is a schematic block diagram of a copying machine in which a transfer paper separating device according to an embodiment of the present invention is implemented. In FIG. 5, reference numeral 51 is an endless belt type photoconductor (hereinafter referred to as a photoconductor) using an organic photoconductor, 51a is a photoconductor driving drum, and 51b is a photoconductor driven roll (hereinafter referred to as a photoconductor roll). , 52 is a transfer paper, 56 is a transfer guide, 59 is a charger for both charging and transfer, 60 is a two-layer structure of an insulator 60a and a conductor 60b, has a charge eliminating brush 60c, and has a fixing guide function. Reference numeral 61 is a cassette containing the transfer paper 52, 62 is a delivery roller, 63 is a pair of transport rollers, 64 is a developing device, 65 is an exposure device including an optical fiber lens 65a and a lamp 65b, and 66 is a photoconductor cleaning device. , 67 is a photoconductor charge eliminating lamp, 68 is a fixing device, and 70 is a paper discharge tray.

The operation of the transfer sheet separating apparatus of the present embodiment configured as described above will be described below.

The transfer paper 52 shown by a broken line in FIG. 6 is sent to the transfer guide 66 by a pair of transport rollers (not shown). Next, the transfer paper 52 is guided to the photoconductor 51 and electrostatically adheres thereto, and the toner image formed on the photoconductor 51 is transferred by the negative corona discharge charging and the transfer charger 59.

It is arranged so that the surface of the conductor 60b made of a stainless steel plate having a thickness of 0.15 mm is on the extension line of the tangent line of the contact point A between the transfer paper 2 and the photoconductor roll 66 shown by the broken line in FIG. The transfer paper 52 after transfer advances at the same speed as 51, and the front end of the transfer paper 52 approaches the conductive material 60b. By the way, the transfer paper 52 transfers the toner image of the photoconductor 51 to a negative transfer charger (not shown). , And as a result, the negative charge becomes an excess, and the transfer paper 52 is negatively charged.

When the transfer paper 52 approaches the conductor 60b, a positive charge having a polarity opposite to that of the transfer paper 52 is induced in the conductor 60b and electrostatically attracted to each other, resulting in the transfer paper 52b.
Is attracted to the conductor 60b, and the transfer paper 52 is separated from the photoconductor 51. At this time, the surface potential of the conductor 60b charges the conductor 60b because the transfer paper 52 itself has a large negative charge amount due to the adsorption of the transfer paper 52. Further, an insulator 60a made of acrylic resin is arranged below the conductor 60b so that the extension line opening on the upper surface of the insulator 60a enters the gap between the rollers of the fixing device 68. Furthermore, the static elimination brush 60c is grounded and arranged on the extension line opening of the insulator 60a. The conductor 60
When the transfer paper 52 separated by b advances, the insulator 6
After contacting with 0a, the charge is transferred to the fixing device 68 while contacting with the charge removal brush 60c to remove the charge of the transfer paper 52 after transfer.

As described above, the separation assisting material 60 including the conductor 60b, the insulator 60a, and the charge eliminating brush 60c is provided in the vicinity of the photoconductor roll 51b, and contributes to the separation of the separation assisting material 60 and the center of the photoconductor roll 51b. The practical gap between the line connecting the lines and the intersection G of the photoconductor 51 is 1 mm or less.

With the above-described configuration, the transfer paper 52 after transfer gradually approaches the conductor 60b and comes into contact with the conductor 60b in a minute area (a portion corresponding to the point E in FIG. 7), and the conductor of the transfer paper 52 is charged by the charge. 60b is charged (the electric potential of the transfer paper 52 decreases). In addition, the transfer paper 52 further advances and the electric charge of the transfer paper 52 itself continuously increases on the conductor 60b, but it is considered that when the transfer paper 52 is charged to a certain extent, it is naturally discharged from the portion other than the point E to the atmosphere. Further, the transfer paper 52 further advances,
The transfer paper 52 comes into contact with the insulator 60a, and the electric charge of the transfer paper 52 is transferred so as to reduce the potential difference between the transfer paper 52 and the insulator 60a to charge the insulator 60a (the potential of the transfer paper decreases). . Further, the transfer paper 52 advances and comes into contact with the static elimination brush 60c, all charges on the transfer paper 52 are removed, and the transfer paper 52 is guided to the fixing device 68 and fixed.

As described above, the transfer paper 52 after transfer comes into contact with each of the conductor 60b, the insulator 60a, and the charge removal brush 60c to gradually remove the electric charge of the transfer paper 52 itself. It has become possible to eliminate the disturbance of the.

EFFECTS OF THE INVENTION As is clear from the above description, the present invention provides an insulator, a conductor, and the vicinity of a place where a photoconductor roll and a transfer paper are separated from each other
A separation auxiliary material including a static elimination brush is disposed, and in the separation auxiliary material, the conductor is disposed in the upper layer portion of the insulator so that the area occupied is at least smaller than that of the insulator so that the conductor contacts the transfer paper. Is attached to the downstream end face of the insulator in the transfer paper traveling direction,
When the transfer paper after transfer comes close to the separation auxiliary material, the electric charge of the transfer paper itself induces the electric charge of the opposite polarity to the electric charge of the transfer paper to the conductor in the upper layer of the separation auxiliary material to electrostatically transfer it. The paper attracts and contacts the conductor of the upper layer, and then the charge charged on the transfer paper contacts and discharges the insulator of the lower layer, and further the charge charged on the transfer paper is discharged by the static elimination brush. By separating the transfer paper from the photoconductor, stable transfer paper separation can be performed with a simple structure, the disturbance of the unfixed toner image can be removed, and the entire image quality can be copied cleanly.

[Brief description of drawings]

FIG. 1 is a perspective view of a conventional transfer paper separating device, FIG. 2 is a side view thereof, FIGS. 3 and 4 are side views of another example of the conventional transfer paper separating device, and FIG. FIG. 6 is a schematic side view of a copying machine in which an embodiment of the present invention is implemented, FIG. 6 is a side view of a main part of an example of the transfer paper separating device of the present invention, and FIG. 7 is an enlarged side view of the main part. 51: photoconductor, 51b: photoconductor roll, 60: separation aid, 68: fixing device

Claims (1)

[Claims] 1. A separation auxiliary material composed of an insulator, a conductor, and a charge eliminating brush is arranged in the vicinity of a place where a photoconductor roll and a transfer paper are separated, and in the separation auxiliary material, the conductor is transferred to the transfer paper. The occupying area is arranged at least in the upper layer portion of the insulator so as to be in contact with the insulator, and the static elimination brush is attached to an end face of the insulator downstream in the transfer paper traveling direction, When the transfer paper of (1) comes close to the separation auxiliary material, the electric charge of the transfer paper itself firstly induces the electric charge of the opposite polarity to the electric charge of the transfer paper to the conductor of the upper layer portion of the separation auxiliary material, and the transfer paper is electrostatically charged. The transfer sheet is attracted and brought into contact with the upper layer conductor, and then the charge charged on the transfer sheet is brought into contact with the lower layer insulator to be discharged. Further, the charge charged on the transfer sheet is discharged by a static elimination brush to transfer the transfer sheet. Separate from the photoreceptor Transfer paper separating device according to symptoms.