JP3413786B2 - Stripping device in multiple transfer device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a peeling device for peeling a sheet from a transfer drum in a multiple transfer device using a transfer drum, and more particularly to a transfer film for the transfer drum when the sheet is peeled from the transfer drum. The present invention relates to a peeling device in a multiple transfer device including a pushing-up member that locally pushes up the sheet from the inside to deform the sheet so that the leading edge of the sheet floats up.

[0002]

2. Description of the Related Art For example, in a color image forming apparatus, a multiple transfer apparatus using a transfer drum is used. This transfer drum is provided with a pair of disc-shaped members arranged at a predetermined interval and a drum-shaped transfer film supported between the pair of disc-shaped members.

FIG. 6 is a schematic sectional view showing an example of a color image forming apparatus used by a multiple transfer device using a transfer drum.

In the color image forming apparatus shown in FIG. 6, the photosensitive drum 1 is charged by the charging device 2 and exposed by the exposure device 3 to form a black latent image on the photosensitive drum 1 at a predetermined position. Next, the latent image is developed by the black developing unit 4K of the developing device 4.

On the other hand, the paper is conveyed along the paper chute 19 and electrostatically adsorbed on the surface of the transfer film 9a of the transfer drum 9 by the suction corotron 11 or by the transfer corotron 12 without the suction corotron 11. .
The toner image on the photoconductor drum 1 is transferred by the transfer corotron 12 to the sheet adsorbed on the transfer film 9a. A transfer corotron 12 is disposed inside the position of the transfer drum 9 facing the optical body drum 1, and the charge of the opposite polarity (in the example of the figure) of the toner from the back surface of the paper (negative in the example of the figure). By applying (plus), the toner on the photosensitive drum 1 is electrostatically transferred onto the paper P. The residual toner on the photoconductor drum 1 is removed by the cleaning device 7.

Similarly, in synchronism with the rotation of the transfer drum 9, yellow, magenta,
A cyan toner image is sequentially formed, and the paper rotates while being electrostatically adsorbed on the transfer film of the transfer drum 9, and each time the transfer drum 9 makes one rotation, the paper is rotated to the same position on the paper. The toner images of the respective colors are sequentially transferred from the photoconductor drum 1 to form a multicolor image on the paper. The paper P on which the multicolor image has been formed is peeled off from the surface of the transfer film 9a of the transfer drum 9 by the peeling device 50, and then undergoes a fixing process.

The peeling device 50 comprises a transfer film pushing member 51 and a peeling claw 14. The transfer film pushing-up member 51 locally pushes up the transfer film 9a of the transfer drum 9 from the inside so that the leading end of the paper P is lifted from the transfer film 9a, and the leading end of the peeling claw 14 is attached to the leading end of the paper P lifted. Is inserted and a peeling operation is performed to mechanically peel the paper P electrostatically attracted to the transfer film 9a.

[0008]

The transfer film pushing-up member 51, which is a constituent element of the peeling device 50 and locally pushes up the transfer film 9a from the inside, normally stands by at a position close to or in contact with the back surface of the transfer film 9a. Therefore, there is a problem that the transfer film 9a is charged by being influenced by the charge on the back surface of the transfer film 9a, disturbs the toner image at the front end of the paper P immediately after peeling, and causes an image quality defect.

The reason why the image quality defect occurs due to the transfer film pushing member 51 will be described with reference to FIG. As described above, in order to transfer the negatively charged toner on the photosensitive drum 1 to the paper P, the transfer film 9
A positive charge is given to the back surface of a. This positive charge moves as the transfer drum 9 rotates, and approaches or contacts the transfer film pushing-up member 51. For this reason,
The tip of the transfer film pushing member 51 is positively charged. Therefore, the toner having a negative charge on the sheet P is attracted to the positive charge on the surface of the transfer film pushing-up member 51, and the streak-like toner scattering corresponding to the operation time of the transfer film pushing-up member 51 is caused in the sheet feeding direction. It occurs in the opposite direction.

Especially in a low humidity environment, for example, 30% relative humidity
In the following, due to the influence of the electrostatic charge on the back surface of the transfer film, a remarkable image quality defect occurs at the front end of the paper immediately after peeling. This is because in a low humidity environment, the current flowing into the transfer film decreases due to the increase in the surface or volume resistance accompanying the drying of the paper, and the electrostatic force that attracts the toner from the photoconductor drum 1 to the paper P decreases. Therefore, in the low humidity environment, it is necessary to increase the transfer current as compared with the environment of normal temperature and normal humidity and high temperature and high humidity (for example, 28 ° C. and 85%). More than. For this reason, the transfer film pushing-up member 51 is charged by the charge on the back surface of the transfer film or charged by the frictional charge of peeling, so that the positive charge increases in a low humidity environment as compared with a room temperature and normal humidity and a high temperature and high humidity environment. For this reason, the scattering of toner is also remarkable.

An object of the present invention is to provide a multiple transfer device using a transfer drum, when peeling a sheet from the transfer drum,
This is to prevent the transfer image on the paper from being disturbed due to the scattering of toner caused by the charging of the push-up member that locally pushes up the transfer film from the inside to deform it and lift the tip of the paper.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a transfer film formed in a drum shape is electrostatically attracted to a sheet to perform multiple transfer, and after the multiple transfer, the transfer film is transferred from the inside of the transfer film. In a peeling device of a multi-transfer device that pushes up with a push-up member to peel the paper from the transfer film,
When the member comes into contact with the transfer film,
Is it a charge series material that is charged in the opposite polarity to the charge of the film?
It is characterized by being configured from .

[0013]

Further, the present invention is characterized in that the transfer film pushing member is a negatively charged resin.

Further, the present invention is characterized in that the transfer film pushing-up member is a fluorine resin or a resin containing a fluorine component.

[0016]

[0017]

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of an image forming apparatus to which the present invention is applied. In FIG. 1, a charging device 2, an exposure device 3, a developing device 4, a transfer device 5, a pre-cleaning corotron 6, a cleaning device 7, a discharge lamp 8 and the like are sequentially arranged around a photosensitive drum 1 which is an image carrier. Has been done.

The developing device 4 is provided with four color developing units 4K, 4Y, 4M and 4C corresponding to four colors of black, yellow, magenta and cyan, and any one color developing unit is selectively exposed to light. The electrostatic latent image on the surface of the photosensitive drum 1 is brought into contact with the body drum 1 and developed with color toner.

The transfer device 5 is provided with a transfer drum 9 which is a transfer material carrier that comes into contact with the photosensitive drum 1. Around the transfer drum 9, a transfer material sheet is transferred at the suction portion. A suction roll 10 and a suction corotron 11 for adsorbing the toner image on the surface of the photoconductor drum 1 onto a sheet on the transfer drum 9, and
A transfer corotron 12 for adhering the paper to the surface of the transfer drum 9 when there is no suction roll 10 or a suction corotron 11, a peeling corotron 13 and a peeling claw for removing the toner image on the surface of the paper from the surface of the transfer drum 9. 14,
A static eliminator 15 for eliminating residual charges on the transfer drum 9 and a transfer body cleaning device 16 for cleaning the surface of the transfer drum 9 are arranged.

To the transfer device 5, the paper in the paper feed tray (not shown) is sent out by the paper feed roll 17 and the surface of the suction roll 10 and the transfer drum 9 through the paper chute 19 by the transport roll 18. Sent between and.

Next, the basic operation of the above-mentioned image forming apparatus will be described.

The photosensitive drum 1 is uniformly charged by the charging device 2 in the charging cycle, and a black latent image is formed at a predetermined position on the photosensitive drum 1 by the laser light emitted from the exposure device 3. Next, the developing device 4 rotates, the black developing unit 4K moves to a position facing the photoconductor drum 1, and a predetermined bias voltage is applied. As a result, the charged toner is selectively transferred to the photosensitive drum 1, and the latent image is developed. At this time, the laser light is adapted to write the image portion, and the toner having the same polarity charge as the surface potential polarity of the image carrier 1 charged by the charging device 2 is the laser light irradiation portion on the photosensitive drum 1. To form a toner image.

On the other hand, the paper is conveyed along the paper chute 19 and discharged when passing through the position where the suction corotron 11 and the suction roll 10 face each other, so that the paper is electrostatically attached to the peripheral surface of the transfer drum 9. Be adsorbed. Alternatively, if the adsorption corotron 11 is not present, the transfer corotron 12
As a result, the sheet is electrostatically attracted to the peripheral surface of the transfer drum 9. The toner image on the photosensitive drum 1 moves to a position facing the transfer drum 9, contacts the paper adsorbed on the peripheral surface of the transfer drum 9, and is transferred by the action of the transfer corotron 12. The residual toner on the photoconductor drum 1 is adjusted by the pre-cleaning corotron 6 to an appropriate charge amount, and then removed by the cleaning device 7. Also,
The residual charge on the photoconductor drum 1 is removed by the static elimination lamp 8. Next, as the second cycle, after the photoconductor drum 1 is recharged by the charging device 2, the laser beam from the exposure device 3 causes the laser beam corresponding to the yellow image to reach a predetermined position on the photoconductor drum 1. Is irradiated. On the other hand, the developing device 4 is rotated and the yellow developing unit 4 is rotated.
While Y moves to a position facing the photoconductor drum 1, a bias voltage is applied, and the yellow toner is transferred to the laser light irradiation portion of the photoconductor drum 1 and development is performed. The developed toner image is transferred so as to be superposed on the black image on the sheet carried on the transfer drum 9.

After that, similarly, after a magenta image forming step as a third cycle and a black image forming step as a fourth cycle, black, yellow, magenta, and cyan toners are formed on the paper carried on the transfer drum 9. A multicolor toner image is formed by superimposing the images. The paper on which this multicolor image is formed is the peeling corotron 13 and the peeling nail 1.
After being separated from the transfer drum 9 by 4, the toner image is fixed by being heated and pressed by a fixing device (not shown) to form one copy image. Further, the transfer drum 9 is moved to the sheet suction position again after the charge removal device 15 removes excess charges on the front surface and the back surface of the transfer drum 9 and the transfer drum cleaning device cleans the charges.

FIG. 2 shows a transfer drum built-in assembly arranged inside the transfer drum 9 used in the image forming apparatus shown in FIG. The transfer drum built-in assembly 20 includes, as main components, a fixed shaft 21, a pair of circular support plates 22 and 23 mounted on the fixed shaft 21 with a predetermined space, and a pair of support plates 22 ,. A rotary shaft 2 having a rectangular cross section in which a transfer film pushing member 24 is attached to an intermediate position of the rotary film 23 so as to be freely rotatable.
5, transfer corotron rail 26, image writing reference signal generation sensor 27, transfer corotron baffle movable member 2
8, a static elimination corotron high-voltage circuit 29, an internal pressing member positioning member 30, and the like.

3 (a) and 3 (b) are a side view and a front view showing the structure of the transfer film pushing member 24 used in the transfer drum built-in assembly 20 shown in FIG. 2 as a single unit.

The transfer film pushing-up member 24 is composed of a wedge-shaped support arm 31 having a rounded tip, and a roll 33 rotatably supported by a metal shaft 32 at the tip of the support arm 31. ing. A rectangular mounting hole 34 that fits into the rotary shaft 25 having a rectangular cross section is formed in the base end portion of the support arm 31, and the support arm 3 is fitted with the rotary shaft 25 in the mount hole 34.
The support arm 31 is fixed to the rotating shaft 25 by screwing 1 onto the rotating shaft 25 via the screw holes 35. The rotary shaft 25 is elastically urged by a spring (not shown) in a direction in which the tip of the support arm 31 is separated from the transfer film 9a, and a solenoid (not shown) provided in the transfer drum built-in assembly 20. Thus, it is rotationally driven in a direction in which it comes into pressure contact with the transfer film 9a via a link mechanism or the like.

In this embodiment, the roll 33 has a diameter of 8 mm, and the radius of curvature of the rounded end of the support arm 31 is 3.
The diameter is 5 mm, and the roll 33 at the tip has a diameter larger by 0.5 mm. This is because only the rotating roll is brought into direct contact with the inner surface of the transfer film so that only rolling friction with less friction is generated and the triboelectric charge amount of the roll 33 is suppressed as much as possible.

Further, as the material of the roll 33, a negative charging type resin is used. For example, a fluororesin such as Teflon or PFA, or a resin containing a fluorine component can be used. The latter is, for example, a polyacetal resin containing 10% or more of fluorine. Further, not only the roll 33 but also the support arm 31 may be made of the above material.

Further, as a means for suppressing the charge amount of the roll at the tip, as shown in FIG.
6 may be brought into contact with the roll 33 to remove the charge.

Conventional wedge type lifting member (material: PO
The transfer film at the position of M) and the push-up member is charged with a voltage of plus 2000 V or more, but the surface potential is about minus 500 to 2000 V depending on the material, shape, and addition of the static elimination brush. This is a comparison of relative potentials, and toner scattering can be prevented by increasing the charge amount of the minus component and suppressing the charge amount of the plus component.

[0034]

As described above, according to the present invention, the transfer film pushing-up member is provided with a means for suppressing the accumulation of charges generated by the influence of the transfer film, for example, a roll charged with a negative charge. , Charge the transfer film pushing member to the positive side. As a result, it is possible to prevent the transfer image from being disturbed on the sheet due to the scattering of toner caused by the charging of the transfer film pushing member.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an image forming apparatus to which the present invention is applied.

FIG. 2 shows a transfer drum built-in assembly arranged inside a transfer drum used in the image forming apparatus shown in FIG.

3A and 3B are a side view and a front view showing the structure of a transfer film pushing member used in the transfer drum built-in assembly 20 shown in FIG.

4 is a sectional view showing a single roll used in the transfer film pushing-up member shown in FIG.

FIG. 5 is a side view showing an example of a transfer film pushing member.

FIG. 6 is a schematic cross-sectional view showing an example of a color image forming apparatus used by a multiple transfer apparatus using a transfer drum.

[Explanation of symbols]

1 ... Photosensitive drum, 2 ... Charging device, 3 ... Exposure device, 4 ...
Developing device, 4K, 4Y, 4M, 4C ... Color developing unit, 5 ... Transfer device, 6 ... Corotron before cleaning, 7
... cleaning device, 8 ... static elimination lamp, 9 ... transfer drum, 10 ... suction roll, 11 ... suction corotron, 12 ...
Transfer corotron, 13 ... Peeling corotron, 14 ... Peeling claw, 15 ... Static eliminator, 16 ... Transfer body cleaning device,
17 ... Paper feeding roll, 18 ... Conveying roll, 19 ... Paper chute 20 ... Transfer drum built-in assembly, 21 ... Fixed shaft,
22, 23 ... Support plate, 24 ... Transfer film pushing member, 25 ... Rotating shaft, 26 ... Transfer corotron rail, 27
... Image writing reference signal generation sensor, 28 ... Transfer corotron baffle movable member, 29 ... Static elimination corotron high-voltage circuit, 30 ... Internal pressing member positioning member, 31 ... Support arm, 32 ... Metal shaft, 33 ... Roll, 34 ... Mounting hole Three
5 ... Screw hole

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Fumio Furusawa 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Zerox Co., Ltd. (56) Reference JP-A-4-215678 (JP, A) (58) Fields investigated ( Int.Cl. ⁷ , DB name) G03G 15/16 G03G 15/14 101

Claims (3)

(57) [Claims] 1. A transfer film formed in a drum shape is electrostatically attracted to a sheet to perform multiple transfer, and after the multiple transfer, the transfer film is pushed up by a transfer film pushing member from the inside of the transfer film to push the sheet. In a peeling device in a multiple transfer device for peeling from a transfer film, the transfer film pushing-up member is
Contact with the transfer film, it has a polarity opposite to that of the charge on the transfer film.
A peeling device in a multiple transfer device, characterized in that it is composed of a charge series material that is charged to the inside . Wherein said transfer film lifting member is Mai
The peeling device in the multiple transfer device according to claim 1, wherein the peeling device is an eggplant-type resin . Wherein the transfer film lifting member is fluoride
It must be a base resin or a resin containing a fluorine component.
DOO peeling device in the multi-transfer apparatus according to claim 2, wherein.