JPH06102779A - Paper guiding device for image forming device - Google Patents

Abstract

PURPOSE:To set a paper holding state with reference to a transfer drum in a good state, as to a color electrophotographic copying machine provided with.a transfer drum for electrostatically holding the paper with reference to a photosensitive drum. CONSTITUTION:A counter attracting roll 3 for pressurizing the paper P is arranged on a position for feeding the paper P with reference to the transfer drum 2 arranged corresponding to the photosensitive drum, and an elastic guiding film 20 for eliminating the curved state of the paper fed from a resist roll device 10 in the width direction is arranged. The elastic guiding film 20 is constituted so that it may be rocked by a solenoid 24, and the pressing force by the elastic guiding film 20 is set small for a small-sized paper based on information from a controller, and the paper is sent out while giving an stroking work toward the part of the transfer drum 2 to which the paper is stuck, and then, the paper is stuck on the surface of the transfer drum 2 and held.

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 full-color copying machine for transferring color toner images formed on a photosensitive drum in an overlapping manner while supporting a sheet on a transfer drum. The present invention relates to a guide unit that can perform a pressing action of a sheet of paper on the surface of the transfer drum in a good state when the sheet of paper is attached and held to the transfer drum, and prevents unevenness and the like from occurring on the sheet.

[0002]

2. Description of the Related Art In a full-color copying machine, for example,
As shown in JP-A-57-137246,
One in which one photosensitive drum is arranged is used for the transfer drum that holds the paper. In the above-mentioned conventional example, a plurality of developing devices are arranged on the photosensitive drum, and each time one color toner image is formed on the photosensitive drum,
A method of transferring the toner image by rotating the transfer drum once is used. Then, in order to hold the paper with respect to the transfer drum, a gripper or the like is provided on the transfer drum so that the front end of the paper can be accurately held, and the transfer is performed according to the operation in which the color toner image is formed. It uses a mechanism that superimposes and transfers a color toner image on a sheet held on a drum.

Further, there are many cases where a transfer drum is used in which a sheet is electrostatically held on the surface of the transfer drum without providing a gripper on the transfer drum. For example, in the example disclosed in Japanese Patent Application Laid-Open No. 2-6983, an adsorption corotron is arranged at a portion where a sheet is attached to a transfer drum, and the sheet is electrostatically attracted and held by the discharge from the corotron. A mechanism is provided. When a mechanism for electrostatically supporting the paper on the surface of the transfer drum is used, the number of mechanical parts such as grippers can be reduced, so that the mechanism of the transfer drum can be simplified, and It is possible to exert the advantage that the supporting action of the paper can be easily performed.

As shown in the above-mentioned conventional example, an apparatus provided with a mechanism for electrostatically holding a sheet on a transfer drum is constructed, for example, as shown in FIG. In the color electrophotographic copying machine shown in FIG. 5, a mechanism for forming a toner image using an electrophotographic system is arranged around the photosensitive drum 1 as in the case of the conventional example. In addition to the charging device, the exposure device, and the cleaning device, a developing device for developing four color toner images (black, magenta, cyan, yellow) and the like are arranged.

Then, one of the four developing devices is arranged at a position corresponding to the photosensitive drum 1, a color toner image is formed on the photosensitive drum 1, and the image is supported on the transfer drum 2. The transferred paper P is transferred. After that, the developing device that creates another color toner image is moved to the position corresponding to the photoconductor drum, and the steps of transferring the color toner images of different colors to the paper are repeated in sequence, and a large number of colors are printed on the paper. After the color toner images are overlapped and carried, they are fixed through a fixing device to form a color copy.

The transfer drum 2 arranged corresponding to the photosensitive drum is formed by winding a drum-shaped insulating film made of thin PET (polyethylene terephthalate) or PVdF (polyvinylidene fluoride) around the drum frame. I am using one. As shown in the drawing, a cleaning device 8 and the like are arranged on the outer peripheral portion and the inner side of the transfer drum 2 in addition to the suction facing roll 3, the transfer corotron 5, the charge eliminating corotron 6, the peeling corotron 7, and the drum charge eliminating corotron 9. ing. The cleaning device 8
Is composed of a fur brush or the like, and cleans the surface of the film on the transfer drum.

The suction facing roll 3 is made of a conductive material and is connected to the ground, and is supported by a mechanism that contacts and separates from the surface of the transfer drum 2.
A function of pressing a sheet sent through the registration roll device 10 arranged in the sheet conveying path against the surface of the transfer drum 2 is performed. An adsorption corotron 4 and a discharge regulation baffle 11 are arranged at a position corresponding to the suction facing roll 3, and a charge having a polarity opposite to the polarity of the toner transferred to the paper is applied to suck the paper onto the surface of the transfer drum. Hold it. The discharge restriction baffle controls the amount of discharge from the corotron 4 so that the amount of charge on the drum 2 can be controlled.

Then, the color toner image formed on the photosensitive drum 1 is transferred onto the paper by discharging the transfer corotron 5 while rotating the transfer drum holding the paper. After the color toner images of the respective colors are transferred onto the paper in an overlapping manner, the charge holding the paper on the transfer drum is removed by the charge eliminating corotron 6, and the paper is peeled off by the discharge from the peeling corotron 7 and the fixing device is set. Send it out and complete as a color copy. Further, the suction-opposing roll 3 used for pressing the paper against the transfer drum 2 is retracted from the pressing position after adhering the paper to the surface of the transfer drum and is ready for feeding the next paper. Held in the standby position.

When the paper P is absorbed by the resist roll device 10 and the suction facing roll 3 for feeding the paper to the transfer drum as described above, the leading end of the paper is widthwise. It may be wavy. Then, such a sheet is transferred to the transfer drum 2.
When entering the nip position between the suction-adhesive roll 3 and
The thin film member forming the surface of the transfer drum may be deformed by the uneven pressing action by the corrugated paper. Therefore, if the paper is held on the transfer drum in a state of unevenness, the toner image is not transferred uniformly, and there is a problem that image unevenness occurs.

Therefore, in order to solve the above-mentioned problems, it has been proposed to use a sheet guide means as shown in FIG. 6, for example. In the example shown in FIG. 6, the guide plate 12 and the elastic guide film 13 are arranged to face each other between the resist roll device 10 and the suction facing roll 3, and the paper P sent out by the resist roll device 10 is The sheet is curved by the tip of the elastic guide film 13 when passing between the members. Then, before being attached to the transfer drum 2, the guide plate 12 and the elastic guide film 1 are applied to the paper P.
By means of 3, an ironing action is applied to the paper at the two points of the guide plate pressing portion A and the film pressing position B, whereby the bending of the water-containing paper in the width direction is eliminated, and the paper is transferred to the transfer drum 2. Thus, the function of pressing by the suction facing roll 3 can be satisfactorily exhibited.

[0011]

As shown in FIG. 6, a mechanism for bending a sheet is arranged between the registration roll device 10 and the suction facing roll 3, and the sheet has two action points A and B. Conventionally, the apparatus is constructed for the maximum size of paper used in an electrophotographic copying machine when it is bent. In that case, the wavy state in the width direction of a large size paper is canceled by the pressing action of the tip end portion of the elastic guide film, and the elastic guide film can exert a pressing force sufficient to attach the paper to the transfer drum. I am trying to do it.

However, when the elastic guide film has a wide width corresponding to a large size sheet, it causes an excessive pressing force to a small size sheet. When a small-sized sheet is fed toward the transfer drum, it is strongly pressed by the elastic guide film, so that the state in which the sheet is largely curved is delayed, and the time when the sheet reaches the transfer drum is delayed. Occurs,
Checkout delay etc. occurs. In addition, small-sized paper with a high water content has a problem in that the paper is stiff and weak, so that the paper is not normally fed toward the transfer drum. It was

[0013]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional paper feeding mechanism, and corresponds to the size of the paper with respect to the elastic guide film provided between the registration roll device and the transfer drum. An object of the present invention is to provide a device that constitutes a mechanism for applying a pressing force and can exhibit a normal paper feeding action even for small-sized and weak paper.

[0014]

According to the present invention, a transfer drum is arranged corresponding to a photosensitive drum for forming a color toner image, and a sheet is electrostatically carried on the surface of the transfer drum. A mechanism for superposing and transferring the color toner images formed on the photoconductor drum is configured, and a suction facing roll and a charging unit are arranged at a position for sucking and holding the paper with respect to the transfer drum. The present invention relates to an image forming apparatus using a means for supporting while pressing the surface of a transfer drum. In the present invention, the elastic guide film is arranged corresponding to the position where the paper is pressed on the transfer drum, and the elastic guide film is provided with a means for controlling the pressing force against the paper, so as to respond to the information of the paper size. Thus, the pressing force of the elastic guide film on the paper can be adjusted.

Further, in the paper guide device of the image forming apparatus of the present invention, the base portion of the elastic guide film is supported by the guide plate, and the guide plate is provided so as to be swingable via the support shaft, and the guide plate is supported with respect to the guide plate. Drive means is provided so that the drive means for the guide plate can be operated according to the information on the paper size. In addition to the above configuration, in the present invention, the guide plate is provided at a fixed position, and a slit is provided at a position corresponding to the width of the paper with respect to the elastic guide film supported by the guide plate so as to correspond to the paper size. It is possible to configure a mechanism capable of exerting a pressing force by the elastic guide film.

As described above, when a mechanism for oscillating the elastic guide film arranged in the paper feeding portion is arranged to reduce the pressing force of the elastic guide film for a small size sheet, Since the elastic guide film can be driven according to the sheet size information obtained from the paper feed tray or the like, the pressing force against the elastic guide film can be easily controlled. Further, in the case where the elastic guide film is provided with slits, it is possible to exert a pressing force corresponding to the paper size without providing special adjusting means. Therefore, by pressing the paper according to the size of the paper, eliminating the curved state due to the water content of the paper, and causing the adhesive action toward the transfer drum, the paper is transferred to the transfer drum. Since it is possible to uniformly attach and hold the same on the surface of the sheet, it is possible to prevent inconvenience such as uneven transfer of an image from occurring.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet guide device for an image forming apparatus according to the present invention will be described with reference to the illustrated example. The example shown in FIG. 1 shows a case where the support mechanism of the elastic guide film is changed and the swinging mechanism is arranged with respect to the elastic guide film in the sheet feeding portion shown in FIG. Further, the transfer drum 2 and the respective constituent members arranged to be attached to the transfer drum are
It can be configured in the same manner as in the case of FIG. Also,
In the present invention, as shown in FIG. 1, the guide plate 12 and the elastic guide film 20 are arranged between the registration roll device 10 and the suction facing roll 3 arranged at the paper adhering portion of the transfer drum 2. However, the tip of the elastic guide film 20 is arranged so as to enter a position very close to the nip between the transfer drum 2 and the suction facing roll 3. Then, the front end of the elastic guide film 20 presses the sheet toward the surface of the suction facing roll 3, and the pressing action at the contact portion D imparts a squeezing action to the sheet, so that the sheet is uneven in the width direction. To eliminate
A function of uniformly adhering the paper to the surface of the transfer drum 2 is added.

The elastic guide film 20 is supported by a guide plate 21 as shown in the drawing, and the guide plate 21 is swingably provided via a support shaft 22. A spring 22a is provided at an end of the guide plate 21, a wire 23 is connected to the other end, and a solenoid 24 is connected through the wire 23. Then, by the action of the spring 22a and the action of the solenoid 24 and the spring 25 which oppose it, the guide plate 21 is swung through the support shaft 22, so that the leading end portion of the elastic guide film is strong and the sheet is attracted to the opposing roll. It is configured such that a state of pressing toward 3 and a state of weakly pressing can be set. Further, in order to drive the solenoid, a paper size detection sensor 27 is connected to a CPU 26 provided in the control device, and information on the paper size obtained by the paper size detection sensor 27 is used to drive the solenoid. Is controlled. As the paper size detection sensor 27,
For example, the information from the paper size display means such as the paper feed tray or the paper feed cassette can be used, but in addition, the paper size detection information from the sensor arranged in the paper transport path can be used.

In the device constructed as shown in FIG. 1, the CPU of the control device sets the pressing state of the elastic guide film based on the information on the paper size obtained from the paper size detection sensor 27. For example, when the paper is a large size, the operation of feeding the paper toward the transfer drum is performed while maintaining the state of FIG. 1 and strongly pressing the paper toward the suction facing roll 3. To On the other hand, when the paper is of a small size, the CPU outputs a drive signal to the solenoid 24 to energize the solenoid 24 so that the wire 23 is used to move the guide plate 21 counterclockwise. It is rocked to the state shown in FIG.

In the state shown in FIG. 2, the leading end of the elastic guide film 20 is at the film pressing position D, and the state is set in which the paper is lightly pressed toward the suction facing roll 3. Therefore, since a small size sheet is not pressed with a large force, a curving action can be given according to the width of the sheet. Then, even in the case of a water-containing paper having a narrow width, the ironing effect is added while applying a pressing effect according to the width of the paper so that the registration timing is not delayed and the paper is fed toward the transfer drum. To enable that.

[0021]

[Another Example of Structure of Elastic Guide Film] As described above,
In addition to the means for adjusting the pressing force by swinging the elastic guide film, in the present invention, as shown in FIGS. A mechanism that causes the elastic guide film to exert a corresponding pressing force can be used. In the example shown in FIG. 3, the elastic guide film 30 is supported at a fixed position by the guide plate 33, and the tip end portion of the elastic guide film 30 extends near the nip position between the transfer drum 2 and the suction facing roll 3. Are configured as Then, the tip end portion of the elastic guide film 30 is pressed toward the surface of the suction facing roll 3 so that the curving action and the ironing action on the sheet can be imparted.

As shown in FIG. 4, the elastic guide film 30 is provided with slits 31 and 31a for each predetermined width to constitute a mechanism capable of controlling the pressing action on the paper. The width of the elastic guide film 30 is set corresponding to the width L of the maximum size sheet, for example.
Slits 31 and 31a are provided at positions of distances L1 and L2 from the end portion on the reference line side of sheet conveyance. The interval L1,
L2 can be configured to correspond to the widths of B5 size and A4 size papers, for example. In the case of A3 size paper, the entire width of the elastic guide film presses the paper, but for narrower paper, the elastic guide of the portion corresponding to the width of the paper is used. Since only the film gives the pressing action, no extra pressing action is applied to the paper.

Therefore, as shown in FIGS. 3 and 4, a slit is provided in the width direction of the elastic guide film 30 to set a state in which the leading end portion of the elastic guide film corresponding to the sheet size exerts a pressing action. As a result, the elastic guide film can exert a pressing force corresponding to the strength of the waist of the sheet even for a small size sheet. Therefore, when the sheet is attached to the transfer drum in a state of being bent by the elastic guide film and subjected to the ironing action, it is possible to prevent a registration delay of the sheet from occurring. Further, since no curving or unevenness in the width direction of the paper is formed on the paper supported by the transfer drum 2, the function of superimposing and transferring the color toner images from the photoconductor drum can be performed in a good state. It will be possible.

In the paper guide device of the image forming apparatus of the present invention configured as described above, the elastic guide film disposed between the registration roll device 10 and the attachment position of the transfer drum 2 is sent out from the registration roll device 10. Guide the folded paper in the direction to bend it. Then, thereafter, the sheet is guided against the suction facing roll 3 at the suction position C while being pressed against the roller surface, and the sheet is squeezed so that the unevenness in the width direction of the sheet is eliminated. To do. Therefore, by curving the paper by the elastic guide film, and at the same time, by applying the ironing action corresponding to the width of the paper, the curving state of the paper in the width direction is eliminated, and the adhering state of the paper on the transfer drum 2 is improved. Can be set.

As described above, the elastic guide film having the adjustable pressing force is arranged at the position where the paper is attached to the transfer drum, and the paper is moved by the tip of the elastic guide film to the suction facing roll. By providing the mechanism for pressing toward the surface, the paper fed toward the transfer drum is attached to the surface of the transfer drum with a uniform pressing force in the width direction. Further, since the paper does not exert an excessive pressing action on the film arranged as the paper holding member on the surface of the transfer drum, it is possible to prevent the film member from being deformed. Therefore, in the apparatus of the present invention, in parallel with the action of the sheet being supported by the transfer drum, when the first color toner image is transferred and then the second color toner image is transferred, the pressing force of the suction facing roll is increased. Even if the problem is solved, the position of the paper does not change, and it is possible to prevent a deviation or the like from occurring between the color toner images transferred in an overlapping manner.

In the embodiment of the present invention, the sheet pressed by the film or the like is curved to a position close to the guide plate 12, and even at the pressing position A against the plate, the ironing action is performed. It is also possible to configure so that it can be given. In addition, the guide plate 12 that acts as a guide mechanism for the paper in the paper feeding unit is
It is necessary to set the paper so that it can be guided normally. Further, as the elastic guide film, a PET film or any other film member can be used, and by appropriately selecting the thickness of the film, the action of pressing the paper toward the suction facing roll can be obtained. Can be demonstrated.

[0027]

Since the paper guide device of the image forming apparatus of the present invention is constructed as described above, a mechanism for swinging the elastic guide film arranged in the paper feeding portion is arranged to provide a small size. When a mechanism for reducing the pressing force of the elastic guide film is applied to the paper, the elastic guide film can be driven by the information on the paper size obtained from the paper feed tray or the like. The pressing force on the film can be easily controlled. Further, in the case where the elastic guide film is provided with slits, it is possible to exert a pressing force corresponding to the paper size without providing special adjusting means. Therefore, by pressing the paper according to the size of the paper, eliminating the curved state due to the water content of the paper, and causing the adhesive action toward the transfer drum, the paper is transferred to the transfer drum. Since it is possible to uniformly attach and hold the same on the surface of the sheet, it is possible to prevent inconvenience such as uneven transfer of an image from occurring.

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of an apparatus of the present invention.

FIG. 2 is an explanatory view of a state in which the pressing force of the elastic guide film is reduced by the device of FIG.

FIG. 3 is a side view of the second embodiment of the present invention.

FIG. 4 is a front view of the elastic guide film in the embodiment of FIG.

FIG. 5 is an explanatory diagram showing a configuration of a main part of a conventional color electrophotographic copying machine.

FIG. 6 is an explanatory diagram of an example in which an elastic guide film is arranged in a paper feeding unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 photoconductor drum, 2 transfer drum, 3 suction opposing roll, 10 registration roll device, 13
Elastic guide film, 14 guide plate, 20
・ 30 elastic guide film, 21 ・ 33 guide plate, 24 solenoid, 26 CPU, 2
7 Paper size detection sensor, 31 slits.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiko Tatsuzaki 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina Business Office (72) Inventor Takuji Miyazawa 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina Co., Ltd. In the office

Claims (3)

[Claims] 1. A transfer drum is arranged corresponding to a photoconductor drum on which a color toner image is formed, and a paper is electrostatically carried on the surface of the transfer drum, so that the color toner image formed on the photoconductor drum is displayed. A mechanism for stacking and transferring is formed, and at a position where the paper is suction-held to the transfer drum,
In an image forming apparatus using means for arranging a suction facing roll and a charging means, and supporting the paper while pressing it against the surface of the transfer drum by the suction facing roll, in correspondence with the position where the paper is pressed against the transfer drum. In addition to disposing the elastic guide film, the elastic guide film is provided with means for controlling a pressing force on the paper, and the pressing force on the paper by the elastic guide film is adjusted according to the information of the paper size. Paper guide device for image forming apparatus. 2. A base portion of the elastic guide film is supported by a guide plate, the guide plate is swingably provided via a support shaft, drive means is provided for the guide plate, The sheet guide device of the image forming apparatus according to claim 1, wherein a drive unit for the guide plate is operated. 3. The guide plate is provided at a fixed position,
The elastic guide film supported by the guide plate is provided with a slit at a position corresponding to the width of the paper, and a mechanism capable of exerting a pressing force by the elastic guide film according to the size of the paper is configured. The sheet guide device of the image forming apparatus according to claim 1.