JPH05216365A - Form paper carrying device for electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To prevent a form paper ejected from a fixing device from being wrinkled by carrying the paper while it is bent so that the central part thereof becomes the highest as for a from paper carrying device arranged at the upstream part of the fixing device in a side-register system image forming device. CONSTITUTION:The form paper carrying device 20 arranged between an image transfer part and the fixing device from a photosensitive drum is constituted of sucking and carrying members 21 and 21a, a belt device 26 and guide members 30, 30a and 30b arranged among the respective belt devices. As for the guide member, plural slits 32,... are provided on a guide plate 31 and movable guide members 33,... are provided so that they can appear and disappear from the slit 32. Besides, the movable guide member is made to project from the guide plate according to the size of the paper used for producing a copy. Then, the paper is carried while it is bent so that the central part thereof becomes the highest and introduced to the nip part of the heat roller system fixing device.

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 an electronic copying machine, for making a recording sheet by using an electrophotographic method, and a sheet conveying apparatus arranged between an image transfer section and a fixing apparatus. More particularly, the present invention relates to a sheet conveying device of an electronic copying machine, which is provided with a mechanism for bending the sheet so that the central portion of the sheet is raised when the sheet is guided toward a nip portion of a heat roller type fixing device.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electronic copying machine or a printer for making recording paper by using an electrophotographic method, a toner image is formed on an image bearing member such as a photosensitive drum, and the toner image is formed. Is transferred to a sheet and then fixed through a fixing device to form a recording sheet. As the fixing device, a heat roller type fixing device is generally used, and in this fixing device, a heating roller provided with a heating source such as a halogen lamp and a pressure roller not provided with a heating source are opposed to each other. And the predetermined nip pressure is set between both rollers. Then, in the fixing device, when the paper carrying the toner image is passed between the rollers, the toner is melted by heat and the melted toner is pressed against the paper to be fixed to obtain a copy. ing.

The fixing device is constructed, for example, as shown in FIG. Image forming apparatus 1 shown in FIG.
Then, a toner image forming mechanism using an electrophotographic system is provided around the photosensitive drum 2, and the charging corotron 3, the developing device 4, the transfer / peeling corotron 5 are provided as the mechanism.
In addition, the cleaning device 6 and the like are included. Then, after uniformly charging the photosensitive drum 2 by the discharge from the charging corotron 3, the image light is irradiated to form an electrostatic latent image, and the electrostatic latent image is developed. Toner is supplied from the device 4 to form a toner image.

The toner image formed as described above is transferred to the paper P by the discharge of the transfer corotron 5.
The sheet on which the toner image is transferred is conveyed by the sheet conveying device 10 toward the fixing device. Further, the toner remaining on the surface of the photoconductor drum 2 after the toner image is transferred to the sheet is cleaned by the cleaning device 6 and charged by the charging corotron to correspond to the writing of the next image and the formation of the toner image. .. The sheet on which the toner image has been transferred is conveyed by the sheet conveying device 10 and is introduced into the nip portion through the guide plate 11 arranged at the entrance of the fixing device 15 to perform the fixing action.

By the way, the paper carrying the toner image is
Immediately before the nip between the rollers of the fixing device, the leading edge of the paper becomes straight along a flat guide plate and is introduced between the rollers as it is to fix it. Is performed. However, in general, the paper used for copying has a non-uniform water content and the like, and is curled in the width direction of the paper because stress is applied by a carrying roller device or the like during transportation. There are many cases. Then, the curled paper enters into the nip portion first, and the non-curled portion is nipped later, which causes wrinkles and the like on the paper. There is. Further, in the nip portion of the fixing device, the nip shape between the two rollers is not set uniformly in the width direction of the paper, so that the leading end of the paper is not set linearly. There are many problems that wrinkles easily occur.

Therefore, in order to solve the above-mentioned problems, for example, as shown in JP-A-60-107668 and JP-A-57-198480, the leading end portion of the sheet has both rollers. It has been proposed to plunge into the nip between them at the same time. In the above-mentioned two conventional examples, a guide member provided with a suction means is arranged between the sheet conveying device and the fixing device to correct the curled state of the sheet, and the nipping is performed while the leading end of the sheet is flat. It is possible to rush into the part. By using such means, it is possible to prevent the paper from wrinkling even when the distribution of the water content of the paper is not uniform.

[0007]

However, as described above, even when a mechanism for flatly forming a sheet is provided in the introduction portion of the fixing device, the force of the suction means is relatively weak, In some cases, it may not be possible to effectively correct paper that has a significantly different distribution of water content. Further, with such a sheet, there remains a problem that wrinkles are likely to occur in the copy. Further, even when the paper has a large curl, the function of correcting the curl is not sufficiently exerted, and there is a disadvantage that the copy is wrinkled.

In the above-described conventional fixing device, wrinkles can be reduced on a relatively small size paper,
In the case of large size paper, remarkable wrinkles may occur. Therefore, for a large-sized sheet, for example, as shown in Japanese Utility Model Laid-Open No. 2-136272, the entrance guide plate is configured to be curved, and is curled so that the central portion of the sheet becomes high. It has been proposed to use a means for nipping the fixing device. In the apparatus of the conventional example, as shown in FIG. 7, the guide plate 12 arranged immediately in front of the fixing device 15 is formed in a curved shape, and a sheet guided along the guide plate 12 is formed. A mechanism for curling P in the width direction is used. Further, the nip shape of both rollers and the curved state of the paper can prevent wrinkles from occurring in the copy.

However, the above-mentioned conventional apparatus is applicable only to a center register type apparatus in which the central portion of the paper coincides with the central portion of the paper transport path in the paper transport apparatus. However, there is a problem that it is difficult to apply to the side registration type sheet conveying device. Further, as disclosed in Japanese Utility Model Application Laid-Open No. 2-136272, in an image forming apparatus using a large size sheet such as an electronic copying machine for drawings, a means for forming a curved guide plate is easy. Can be used for. However, in a general small-sized electronic copying machine or the like, the guide plate as shown in FIG. 7 is used because the size of the paper is different and the curl or the like generated on the paper is greatly different depending on the storage state of the paper. However, the problem remains that wrinkles on the recording paper cannot be easily solved.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem of wrinkles in a conventional electronic copying machine. In a sheet conveying apparatus, the sheet is conveyed in a curved state so that the central portion of the sheet becomes high. An object of the present invention is to provide a device capable of preventing wrinkles from being formed on a recording paper by nipping the paper in a state where the central portion of the paper comes into contact with the fixing roller first when the paper is introduced into the fixing device.

[0011]

SUMMARY OF THE INVENTION In the present invention, a toner image is formed on an image bearing member such as a photosensitive drum by using an electrophotographic method, and the paper on which the toner image is transferred is directed to a fixing device. The present invention relates to a sheet conveying device that uses suction conveying means for conveying. In the paper transporting device of the present invention, the paper transporting device is configured by combining a suction transporting member and a guide member, and a belt device having no suction means, and a plurality of movable guide members are respectively projected and retracted in the guide member. A push-up device is arranged to move the movable guide member up and down so that the central portion of the paper becomes the highest by using the paper size information input to the control device of the image forming apparatus. A mechanism for restricting the upward movement of the movable guide member is provided.

In addition to the above construction, in the paper carrying device of the present invention, the suction carrying member is arranged at the reference line side of the paper carrying path and at the other end portion corresponding to the most used paper size, and two suction carrying members are provided. It is possible to dispose a belt device having no suction means between them and dispose the guide member between the respective belt devices. Then, a plurality of movable guide members are provided so as to be retractable with respect to the guide member, and a guide member is also disposed outside the suction conveyance member at the other end so that the movable guide members bend the sheet. A mechanism for setting the shape can be provided.

Further, in the paper transporting device of the present invention, the push-up device is arranged with respect to the movable guide member provided on the guide member, and the drive mode corresponding to the paper size is set for the push-up device. The information on the obtained paper size is used to cause the push-up device to project and retract on the paper transport surface so that the paper transport device can perform the transport operation in a state where the paper is curved. Further, as a push-up device for driving the movable guide member of the present invention, a protrusion member is arranged corresponding to each movable guide member, and the corresponding movable guide member is projected and retracted in accordance with the information of the paper size, so that the paper A means for setting the curved shape of can be used.

With the above-described structure, in the paper carrying device of the present invention, when the paper is sucked and carried by the suction carrying member provided in the paper carrying device, the curved shape of the paper is set by the movable guide member. Even when the distribution of the water content of the paper is not uniform, the fixing operation can be performed in a good state. Also, even when the paper size is different, the curved shape corresponding to the paper can be set according to the information of the paper size, so that both side edges of the paper come before the nip part of the heat roller type fixing device. As a result, the sheet fixed by the fixing device can be prevented from wrinkling or the like.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet conveying device for an electronic copying machine according to the present invention will be described with reference to the illustrated example. The example shown in FIG.
In the image forming apparatus as shown in FIG. 6, instead of the paper transporting device 10 arranged between the image transfer portion from the photosensitive drum and the fixing device, a paper transporting device for transporting paper. 20 shows the configuration of 20. The sheet conveying device 20 shown in FIG. 1 has a suction conveying member 21 for conveying a sheet while sucking the sheet, as in the case of the conventional sheet conveying device.
The suction conveyance member 21 is a belt 2 having a large number of holes 23 provided in a chamber connected to a suction means.
2 is arranged, and a mechanism for conveying the paper is constructed while suctioning the paper using the hole 23 provided in the belt. The suction conveyance member 21 is arranged on the reference line side of the sheet conveyance device 20 that conveys a sheet, and the belt device 2 in which the guide member 30 and the suction means are not provided on the side of the suction conveyance member.
6 and the guide member 30a are arranged, the suction conveyance member 21a is arranged on the outer side (outer side of the reference line), and the guide member 31b is arranged on the outer side of the suction conveyance member 21a. ing.

In the sheet carrying device 20 having the above-mentioned structure, the suction carrying member 21a is the suction carrying member 2
The configuration is the same as that in the case of No. 1, and the two suction conveyance members 21 and 21a can be arranged corresponding to the paper size most frequently used in the image forming apparatus. Then, the suction means provided in the two suction / transport members performs the transport operation while suctioning the portions on both sides of the sheet. Further, the belt device 26 arranged in the middle of the two suction / conveyance members does not normally perform a conveyance action, but is a small size sheet or a special sheet such as an O sheet.
When the HP film or the like is conveyed, it is provided so as to exhibit the conveying action together with the suction conveying member. A mechanism for driving the plurality of belts by a pulley 25 provided on the drive shaft 24 is provided, and the belts convey the paper in the arrow X direction.

The guide members 30, 30a, 3 are made to correspond to the suction conveyance member and the belt device configured as described above.
0b are arranged to configure a guide mechanism for the paper. The plurality of guide members are flat plate members 31.
, A plurality of slits 32 are arranged in parallel, and movable guide members 33 are provided for each slit. The movable guide member 33 and the mechanism for vertical movement are configured as shown in FIG. 2, and the upstream portion of the substantially vertical plate-shaped movable guide member 33 in the sheet conveying direction is provided with a support shaft 34. And a push-up device 35 is disposed below the movable guide member 33. The push-up device 35
Has a protruding member 39 having a different height with respect to the drive shaft 38.

As described above, the push-up device 35 provided with a plurality of projecting members can be constructed as shown in FIG. 3, and is movable with respect to the drive shaft 38 in a plurality of guide members. The protruding members 39 are arranged at the positions corresponding to the guide members. In addition, the push-up device 3
In 5, the drive motor 3 has a drive shaft with a reduction mechanism incorporated therein.
6 is arranged and the rotary encoder 37 is combined with the drive shaft so that the rotation of the drive shaft can be controlled. When the paper size information is input from the control device of the image forming apparatus to the drive control means of the push-up device, the rotary encoder detects the rotation of the drive shaft and drives the motor 36 to drive the drive. The corresponding movable guide member is raised by the protruding member provided on the shaft.

As the drive means for the movable guide member provided on the drive shaft, not only the protruding member as shown in the drawing, but also a member such as a disk can be used. Then, the driving means of the movable guide member is configured, for example, in a shape capable of raising each movable guide member according to the paper size, and the movable guide member can be driven according to the information of the paper size. Can be configured to. Further, as the information for driving the push-up device, it is also possible to directly use the information in which the tray for feeding is selected in the image forming apparatus such as an electronic copying machine.

In the sheet conveying apparatus 20 of the present invention constructed by combining the guide member and the suction conveying member and the like, as shown in FIG. 4, when the sheet of the size most used in the image forming apparatus is conveyed. In addition, the conveyance operation is performed in a state where the portions on both sides of the paper Pa are sucked by the suction conveyance members 21 and 21a. In the example shown in FIG. 4,
The central portion of the sheet of paper Pa is the portion of the belt device 26, and the guide members 30, 30 are provided on both sides of the belt device 26.
The movable guide members 33 ... Provided on a are made to perform the ascending action. Then, in accordance with the size of the sheet, the pushing-up device 35 for the guide member sets a curved state in which the central portion of the sheet becomes the highest due to the rise of the guide member 33.

Further, in the case of a large size sheet, the action of conveying the sheet is performed in the state as shown in FIG. That is, in the case of a large-sized sheet Pb, the end portion on the reference line side of the sheet is in a state of being sucked by the suction / conveyance member 21, but the other side portion exceeds the suction / conveyance member 21a and the guide member 30b. It will be located in the part. Even in the state shown in FIG. 5, the suction-conveying action on the sheet is performed by the two suction-conveying members 21 and 21a. However, among the plurality of guide members 30, 30a and 30b, the central portion in the width direction of the sheet is the highest. As described above, the protruding height of each movable guide member 33 is controlled so that the curved shape of the sheet can be set. Therefore, as described above, by configuring the shape of the protruding member provided in the push-up device 35 in order to set the curved shape for the paper, it is possible to correspond to the case of FIG. 4 and the case of FIG. 5, respectively. ..

As described above, by setting the curved shape of the sheet in the sheet conveying device, even when the sheet size is different, the protruding height of the movable guide member is set according to the sheet size, and the fixing device is set. It is possible to set a state in which both sides of the sheet are nipped first when the sheet is nipped by. Then, even if the water content of the paper differs in the width direction or the curl state of the leading end of the paper is not constant, the paper can be curved while being conveyed by the paper conveying device. It is possible to prevent wrinkles and the like from occurring on the paper discharged from the fixing device.

The sheet conveying device of the present invention can be installed in a sheet conveying device provided with a suction conveying member, and the structure of the suction conveying member and the shape and width of the belt can be arbitrarily set. Can be configured. Further, the paper transporting device of the present invention can be applied to an image forming apparatus using a laser printer or other electrophotographic system, in addition to an electronic copying machine, and also as a fixing device of a heat roller system. It is also applicable to an apparatus in which one fixing roller is provided with a heating source. Further, in the paper transporting device of the present invention, it is also possible to configure it so as to be able to exert a suction force also on the belt device, and the suction transporting member and the mechanism of the transporting device such as the belt device can be arbitrarily set. Can be set.

[0024]

The sheet conveying device of the electronic copying machine of the present invention is
Using the paper transporting device configured as described above, when performing suction suction of the paper by the suction transporting member provided in the paper transporting device, it is possible to set the curved shape of the paper by the movable guide member, Even if the distribution of the water content of the paper is not uniform, the fixing operation can be performed in a good state. Also, even when the paper size is different, the curved shape corresponding to the paper can be set according to the information of the paper size, so that both side edges of the paper come before the nip part of the heat roller type fixing device. To rush into
It is possible to prevent wrinkles and the like from being generated on the sheet fixed by the fixing device. Further, by operating the mechanism for driving the movable guide member provided on the guide member in accordance with the paper size, it is possible to bend the paper of any size so that the central portion becomes the highest. The sheet introduced into the nip portion of the heat roller type fixing device can be nipped without wrinkling.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a sheet conveying device according to the present invention.

FIG. 2 is an explanatory diagram of a movable guide member provided on the guide member and a drive mechanism thereof.

FIG. 3 is an explanatory diagram showing a configuration of a push-up device.

FIG. 4 is an explanatory diagram of a sheet conveyance state by a sheet conveyance device.

FIG. 5 is an explanatory diagram of a conveyance state for a large size sheet.

FIG. 6 is a side view showing the configuration of a general image forming apparatus.

FIG. 7 is a perspective view showing a configuration of a conventional entrance guide plate.

[Explanation of symbols]

1 image forming apparatus, 2 photosensitive drum, 10
Paper transport device, 15 fixing device, 20 paper transport device, 21 / 21a suction transport member, 26 belt device, 30 guide member, 31 guide plate,
32 slits, 33 movable guide member, 35
Push-up device, 38 drive shaft, 39 protruding member.

Claims (1)

[Claims] 1. A suction conveyance means is used for forming a toner image on an image bearing member such as a photoconductor drum by using an electrophotographic method, and conveying the paper on which the toner image is transferred toward a fixing device. In the transport device, the paper transport device is configured by combining a suction transport member and a guide member, and a belt device having no suction means, and the guide member is provided with a plurality of movable guide members that can be retracted and retracted, respectively. In order to move the movable guide member up and down, a push-up device is arranged, and the movable guide member is arranged so that the central portion of the paper becomes the highest by using the information of the paper size input to the control device of the image forming apparatus. A paper transporting device for an electronic copying machine, which regulates the rising position of the paper.