JPH05119560A - Paper carrying device for image forming device - Google Patents

Abstract

PURPOSE:To constitute a paper carrying device which is arranged between a photosensitive drum and the fixing device of a guiding surface provided with a level difference part, and to control the size of the paper loop in a good state in an image forming device using a long-sized paper. CONSTITUTION:As to a paper carrying device 10 which is arranged between an image transfer part from a photosensitive drum 2 and a fixing device 5, a level difference part 12 is arranged between a carrying part 11 on an upperstream side and a carrying part 13 on a downstream side on the carrying surface, and the carrying part 13 on the downstream side is constituted of an upwardly curved surface. Carrying roller devices 20, 25 and 25a are respectively arranged in the paper carrying device 10, and the action of carrying the paper sucked by a sucking device is achieved. And also, two sensors are respectively arranged on the carrying surface, and a carrying speed in the fixing device 5 is adjusted while detecting the loop of the paper by the sensor so as to control the loop.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device for conveying a sheet carrying an unfixed toner image between an image carrier and a fixing device in an apparatus such as an electronic copying machine, and more particularly to a suction mechanism. The present invention relates to a device for facilitating the control of loop formation of a paper in a paper carrying device constituted by a carrying roller device.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electronic copying machine, a toner image is formed on an image bearing member such as a photosensitive drum by using an electrophotographic system, and the toner image is transferred onto a sheet of paper and then a fixing device. Through the use of such means as fixing and making a copy. In the general electronic copying machine, a sheet conveying device is arranged between the image transfer portion from the photosensitive drum and the fixing device, and the sheet conveying device is constituted by the conveying means and the suction means, and While sucking the back side, the conveying means sends the sheet toward the fixing device.

An example of the sheet conveying device is shown in FIG.
0, as shown in FIG. 0, the conveying roller device and the suction device are combined, and as shown in FIG.
For example, a device configured by combining a suction device and a conveyor belt is used. In the example shown in FIG. 10, a sheet conveying device 40 is arranged between the photosensitive drum 2 and the fixing device 5, and the sheet conveying device 40 is configured by combining a suction device 41 and a conveying roller device 42. ing. In the paper conveyance device 40, the fan 43 is arranged with respect to the suction device 41, and the paper on which the toner image is transferred from the photoconductor drum 2 by the transfer corotron 4 is sucked toward the surface of the roller, and the roller is moved. By driving, the operation of conveying the paper is performed.

In the example shown in FIG. 11, in the sheet conveying device 45, the conveying belt 46 is arranged with respect to the suction device 47, and air is sucked through the suction holes provided in the conveying belt 46. , The action of feeding the back side of the sheet carrying the unfixed toner image while pressing it against the conveying belt. Further, a peeling claw 30 is arranged on the photosensitive drum so as to correspond to a transfer portion of the toner image from the photosensitive drum, and means for peeling the sheet from the photosensitive drum is provided. The paper is guided toward the paper transport device. Further, in the sheet conveying apparatus shown in FIGS. 10 and 11, as shown in FIG. 11, the sensor S is arranged at a predetermined position of the apparatus and the sheet P is formed in a state in which the sheet loop Pc is formed. A mechanism is provided for detecting that the vehicle is guided along the transport device.

Forming a loop of the sheet in the sheet conveying device is performed between the two devices when there is a difference between the rotation speed of the photosensitive drum 2 and the sheet conveying speed in the fixing device. This is to prevent a state where the sheets are attracted to each other. For example, when the speed of the fixing device 5 is faster than the peripheral speed of the photoconductor drum, the paper is pulled directly from the part of the photoconductor drum by the fixing device, so that the paper is the surface of the photoconductor drum. And the toner image is disturbed. On the other hand, when the peripheral speed of the photoconductor drum is faster than that of the fixing device, the loop of the paper becomes large, and the slack portion of the paper protrudes to the upper side, so that the surface on which the unfixed toner image is carried becomes the paper conveyance path. There is a problem that the image is disturbed by sliding it on the upper member.

Therefore, in a general electronic copying machine or the like, a sensor for detecting a loop of a sheet is arranged between the photosensitive drum and the fixing device to constantly detect the state of the loop formed on the sheet. Then, a mechanism for controlling the conveyance speed in the fixing device is used in accordance with the loop of the sheet. As means for controlling the size of the loop of the paper,
For example, as disclosed in Japanese Patent Application Laid-Open No. 1-267237, means for controlling the speed of the fixing device by using the information obtained by detecting the loop of the sheet is used. In the above-mentioned conventional apparatus, a paper loop detecting means is arranged at a portion of a guide plate that connects the paper conveying device and the fixing device, and the paper loop is detected by the detecting means, and the paper loop is detected. The drive speed of the fixing device is controlled according to the size of the loop.

[0007]

However, in the paper transporting apparatus as shown in the above-mentioned conventional example, the loop of the paper is adjusted only at the portion of the guide plate, so that the control of the loop of the paper is performed. The length cannot be sufficiently obtained, and it becomes necessary to frequently control the speed of the fixing device. Therefore, it is conceivable to use a mechanism as disclosed in Japanese Patent Laid-Open No. 62-293272 as a mechanism capable of adjusting the loop of the sheet in the sheet conveying device. In the above-mentioned conventional example, the conveying speed of the fixing device is set to be higher than the conveying speed of the paper conveying device to configure the device.

In the above-mentioned conventional example, the sheet conveying surface of the sheet conveying device is formed in a substantially V shape, and the sheet is curved in a V shape along the conveying surface until the sheet is nipped by the fixing device. Will be moved in the open state. Then, after the sheet is nipped by the fixing device, the sheet is
The conveying action is imparted while being pulled by the fixing device. Further, in the image forming apparatus, the speed difference between the sheet conveying device and the fixing device is adjusted so that the sheet is not directly pulled by the fixing device until the trailing edge of the sheet is separated from the image transfer position of the photosensitive drum. Is set.

However, as described above, it is possible to satisfy the above conditions by setting the speed of each member when the maximum size is a relatively small size sheet such as A4 size. Is. However, for example, when copying is performed using a large size sheet such as A0 size, there is a problem that the loop absorbing means for the V-shaped sheet formed in the sheet conveying device cannot easily cope with it. .. Further, even when the means as disclosed in the above-mentioned Japanese Patent Laid-Open No. 1-267237 is used, the action of adjusting the size of the loop of the sheet is troublesome for long sheets.

Then, for example, when the operation of controlling the speed of the fixing device is frequently performed by using a means for adjusting the loop of the paper at any time, and when the speed of the fixing device is changed, the paper is changed. However, there is a problem that a shock is applied to the toner image, and the shock due to the change in the speed affects the transfer of the toner image from the photosensitive drum. In addition to this, in the case of a wide and large size paper, there is a problem that the paper corrugation phenomenon is apt to occur in the paper transport device, and the corrugated state also affects the transfer portion of the toner image. As a result, there is also a problem that the toner image transferred onto the paper is disturbed.

In addition to the problems described above, in the peeling claw arranged on the photosensitive drum, the tip of the claw is in direct contact with the photosensitive drum, and therefore the tip of the claw is easily soiled. There is a problem. Therefore, in order to clean the tips of the claws, a brush roller is used as disclosed in Japanese Utility Model Laid-Open No. 1-38604. Further, in the claw cleaning device, after the sheet is peeled by the peeling claw, the peeling claw is swung downward, and the cleaning operation can be performed by the brush roller member. However, in the cleaning device using the brush roller member, the driving mechanism is composed of a belt hung, and the driving mechanism is complicated in order to obtain the driving force from the driving shaft of the sheet conveying device. There is a problem that becomes.

[0012]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional sheet conveying apparatus. In an apparatus for conveying a large size sheet such as a drawing, the conveying surface is composed of a step portion and a curved surface. Thus, it is an object of the present invention to provide a device that makes it possible to easily control the size of a loop formed on a sheet and to perform a good cleaning action on a peeling claw.

[0013]

According to the present invention, a toner image is formed on an image bearing member using an electrophotographic method,
The present invention relates to an image forming apparatus configured to guide a sheet on which the toner image has been transferred to a fixing device via a sheet conveying device to perform fixing. In the paper carrying device of the present invention, the paper carrying device is provided with suction means, and a step is formed between a part on the upstream side for receiving the paper from the photoconductor drum and a part for carrying the paper, and the part for carrying the paper. Then, the transport surface is configured as an upward curved surface, and a plurality of transport roller devices are arranged on the transport surface configured as the curved surface to configure a mechanism for transporting while suctioning a sheet carrying an unfixed toner image. There is. Further, in the present invention, the paper transport device includes:
It is possible to arrange a plurality of suction means in the width direction and drive the suction means in correspondence with the sheet size.

Further, in the paper carrying device of the present invention, a carrying roller device is arranged at the upstream end of the paper carrying device, and the carrying roller device is driven in conjunction with the carrying roller device arranged on the curved surface part. A detecting unit for detecting the loop state of the sheet is arranged on the conveying surface configured as an upward curved surface, and the conveying speed in the fixing device can be controlled by the information from the detecting unit. Further, with respect to the transport roller device provided at the upstream end of the paper transport device,
It is also possible to dispose a cleaning means for the peeling claw, configure the cleaning means by a brush roller, and provide a mechanism for driving the brush roller in the direction opposite to the conveying roller device.

With the above-described structure, in the paper transporting device of the present invention, the guide surface of the paper transporting device is constituted by the step portion and the curved surface, and the loop can be easily formed on the paper. It is possible to prevent impact on the paper when controlling the loop. Further, by forming a loop of the paper on the conveying surface with a margin, and by making it possible to easily detect the loop of the paper, the action of controlling the loop of the paper can be easily performed. .. Furthermore, by using a means for operating the suction mechanism provided in the paper transporting device in accordance with the width of the paper, the action of sucking the paper can be performed in a good state corresponding to the paper. In addition to the above configuration, the cleaning mechanism for the peeling claw can be arranged at a position where the drive mechanism is interlocked with the upstream transport roller device, so that the drive mechanism can be simplified.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet conveying device of an image forming apparatus of the present invention will be described with reference to the illustrated example. In the example shown in FIG. 1, in the image forming apparatus 1, a configuration of a sheet transporting device 10 for transporting a sheet, which is disposed between a transfer unit for transferring an image from the photosensitive drum 2 and the fixing device 5, is shown. ing. In the image forming apparatus 1, the paper fed from the paper feed tray or the like is guided to the photoconductor drum 2 through the entrance guide 3, and the toner image formed on the photoconductor drum is discharged by the transfer / separation corotron 4. Transfer to paper. Further, a mechanism is provided in which the sheet is peeled from the photoconductor drum 2 by the peeling claw 30, is conveyed by the sheet conveying device 10, and is guided to the fixing device 5 via the introduction section guide 8. .. In the fixing device 5, as in the case of a general fixing device, the heating roller 6 and the pressure roller 7 are arranged so as to face each other, and heat and pressure are applied to the sheet carrying the toner image, and the toner is applied. Is melted and pressed against paper to make a copy.

In the sheet conveying device 10 arranged between the photosensitive drum and the fixing device, as shown in FIG. 2, the upstream side conveying portion 11 for receiving the sheet from the photosensitive drum and the upstream side thereof. The downstream side transport unit 13 is connected to the side transport unit 11 via the step portion 12. A transport roller 20 is arranged at the tip of the upstream transport unit 11,
It receives and conveys the paper that is peeled from the photoconductor drum. Conveying roller devices 25 and 25a are also arranged in the downstream side conveying unit 13 on the downstream side, respectively, and the conveying roller devices convey the sheet toward the fixing device. Also,
A sensor S is arranged on the downstream side transport unit 13 to detect the state of the loop formed on the sheet.

The downstream side transport section 13 is constructed as an upward curved surface, and the transport surface from the lower part of the stepped portion 12 to the insertion section guide 8 is constructed as a curved guide plate, and the guide plate is The paper is conveyed along the curved state. Further, a suction device 17 is arranged below the guide plate of the sheet conveying device, and a fan provided in the suction device 17 sucks air from a suction hole provided in the guide plate to carry an unfixed toner image. The sheet to be conveyed is pressed against the guide plate and the conveyance roller device so that the conveyance action by the roller can be performed in a good state. Further, in the sheet conveying device of the present invention, since the step portion is formed on the guide surface of the sheet, when the loop of the sheet is formed, the sheet is guided through the step portion 12 in a state of being drastically dropped. Therefore, the suction action of the sheet in the downstream side transport unit 13 can be exhibited well.

In the sheet transporting device constructed as described above, as shown in FIG. 3, the sheet of paper P is separated from the guide surface of the downstream transporting section 13 so that the sheet P is located between the photosensitive drum and the fixing device. When the sheet is in a tense state, as described above, the sheets are attracted by the two members, which causes a disorder in the toner image. Therefore, as described above, when the sheet is in a tensioned state, the sensors S1 and S2 arranged on the downstream side transport unit 13 output information on the state of the sheet and lower the transport speed to the fixing device. Control. Then, as shown in FIG. 4, control is performed so that a loop is formed on the sheet, and the state in which the sheet is conveyed by the two conveying roller devices 25 and 25a is set.

Therefore, the sheet conveyed along the guide surface of the sheet conveying device receives the sheet from the photosensitive drum at the upstream side conveying section 11 and is conveyed by the conveying roller device as in the case of the conventional sheet conveying device. The action of carrying can be performed normally. Then, at the step portion 12 extending from the upstream side transport unit 11 to the downstream side transport unit 13, a sheet loop Pc is formed along the guide surface of the downstream side transport unit 13 in a state of being largely curved downward. While carrying roller device 2
It is conveyed toward the fixing device by 5, 25a. further,
After the sheet is nipped by the fixing device, the conveyance speed of the fixing device is controlled using the detection information from the sensor. At that time, in a state where the sheet is detected by the sensor S, the fixing device can be driven at a high speed to perform a control for eliminating the loop of the sheet.

In the above-described paper transporting apparatus of the present invention, it is possible to dispose a transporting roller apparatus as shown in FIG. 5 and use a guide plate as shown in FIG. As shown in FIG. 5 and FIG. 6, in the sheet conveying device 10, the conveying roller device 2 is attached to the guide plate 15.
Aperture group 1 for the rollers 0, 25, 25a
6, 16a and 16b are respectively formed so that the rollers are projected from the groups of openings. Further, the group of openings 16 ... Also functions as an air suction hole. By sucking air from the group of openings, there is a function of pressing the sheet toward each roller constituting the transport roller device. To do.

In the carrying roller device provided in the paper carrying device of the present invention, as shown in FIG. 5, the upstream carrying roller device 20 includes a large number of rollers 22 ...
It uses the one that is attached in a skewered shape. further,
As will be described later, the drive shaft 21 supports a brush roller member 31 for cleaning the peeling claws, but the brush roller member 31 is only supported by the shaft, and The drive mechanism is used to rotate in the opposite direction. In the transport roller devices 25 and 25 a arranged for the downstream transport unit 13 separately from the transport roller device 20, as shown by the transport roller device 25, a large number of rollers 27 are skewered with respect to the drive shaft 26. Fixed in a shape. Further, the transport roller device 25,
In 25a, the respective rollers are arranged in a zigzag manner so that the conveying action on the paper can be exhibited well.

A drive mechanism is arranged on the side of the sheet conveying device with respect to the conveying roller device. In order to drive the transport roller devices, non-driving pulleys 28, 28a, 28b are provided on the drive shafts of the respective transport roller devices, and a conductive member 29 such as a timing belt is provided to these pulleys. , 29a is wrapped around. Then, by using the driving means, the roller members of the sheet conveying device are driven in an interlocked state so that the sheet is conveyed.

In contrast to the carrying roller device arranged as described above, in the paper carrying device 10 of the present invention, a plurality of fans as suction means are arranged in the width direction of the paper carrying path. The fans 18, 18a, ... Are arranged in the width direction of the paper transporting device at a predetermined interval so that each fan can be driven separately, and information such as paper size is used. It is possible to drive only the fan required for transportation. Therefore, for small size paper, the fan on the reference line side of conveyance is driven, but for large size paper, a mode is set to drive all fans, and the suction action on the paper is effective. Can be demonstrated. If the image forming apparatus is a center registration type apparatus, it is possible to drive the fan corresponding to the portion where the sheet is conveyed.

Therefore, when the above-described sheet conveying device is provided for a large-sized electronic copying machine for drawing, the function of controlling the loop of the sheet and the suction device are applied to large-sized sheets. It is possible to exert the suction action of the paper. Further, the sensor or the like arranged on the sheet conveying path can be arranged at a position most suitable for detecting the state of the sheet. Then, for a large size sheet, it is possible to prevent the fixing device from pulling the sheet excessively and set the image supporting state of the sheet to a good state.

(Peeling Claw Cleaning Device) In the image forming apparatus of the present invention configured as described above, the sheet conveying device 1
0 for the transport roller device 20 arranged in the upstream part of
A peeling claw cleaning device is provided. The peeling claw 30 is used for peeling the paper from the photoconductor drum 2. When peeling the paper from the photoconductor drum, the peeling claw 30 is swung to the position shown by the solid line in FIG. The action is over,
After the paper has passed, it is lowered to the position shown by the phantom line in the figure. A brush roller member 31 is arranged at a position where the peeling claw is lowered, and a tip end portion of the peeling claw 30 is in contact with the brush roller member 31 to allow the brush roller member 3 to move.
When 1 is rotated, a cleaning action is performed. As the brush roller member 31, a member configured as shown in FIGS. 8 and 9 is used.

As shown in FIG. 8, the brush roller member 31 has a roller brush 35 attached to a support member 36, and a gear 37 is provided on one side of the support member 36. Then, the supporting member 3 of the roller brush 35.
As shown in FIG. 9, 6 is supported on the drive shaft 21 of the upstream side conveyance roller device 20, and the support means for the drive shaft holds the support member in a freely rotating state. .. In order to drive the peeling claw 31 in the direction opposite to the drive shaft of the transport roller device, in the present invention, a drive shaft 38 different from the drive shaft 21 is arranged, and the drive shaft 38 is used as the drive shaft of the transport roller device. Drive in the same direction as 21,
A mechanism for reversing the brush roller member is used by engaging the gear 39 with the gear of the brush roller member.

Therefore, by using the brush roller member and the drive mechanism for the brush roller member as described above, in the paper conveying apparatus of the present invention, the peeling claw 30 is used to peel the paper from the photosensitive drum. After the action, when the sheet finishes passing through the peeling section, the peeling claw 30 is lowered from the peeling position, and the tip of the claw is pressed by the brush roller member 31. Then, the peeling claw can be cleaned by driving the brush roller member 31 by the operation of driving the transport roller device of the paper transport device. In the embodiment of the present invention, a brush member having an arbitrary configuration can be used as the brush roller member, and such brush roller members are a plurality of peeling claws arranged with respect to the photosensitive drum. In order to correspond to the above, a large number can be arranged and used in the width direction of the paper transport path.

[0029]

As described above, the sheet conveying device of the image forming apparatus of the present invention has the guide surface of the sheet conveying device formed by the step portion and the curved surface to easily form the loop on the sheet. Therefore, it is possible to prevent the paper from being impacted when controlling the paper loop. Further, by forming a loop of the paper on the conveying surface with a margin, and by making it possible to easily detect the loop of the paper, the action of controlling the loop of the paper can be easily performed. ..

Therefore, the paper transporting apparatus of the present invention can be applied to a large-sized electronic copying machine or the like which uses a large-sized paper without forming wrinkles in the length direction and the width direction of the paper. It is possible to satisfactorily exert the conveying action for. Furthermore, the suction mechanism provided in the paper transport device
By using the means that operates in correspondence with the width of the paper, the action of sucking the paper can be performed in a good state corresponding to the paper. In addition to the above configuration, in the cleaning mechanism for the peeling claw, by disposing the drive mechanism with respect to the transport roller device, the drive mechanism can be simplified.

[Brief description of drawings]

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

FIG. 2 is a side view of the sheet conveying device of the present invention.

FIG. 3 is an explanatory diagram of a state where a paper loop is eliminated.

FIG. 4 is an explanatory diagram of a state in which a paper loop is favorably formed.

FIG. 5 is an explanatory diagram showing a configuration of a sheet conveying device.

FIG. 6 is a plan view of a guide plate that constitutes the paper transport device.

FIG. 7 is a side view showing a relationship between a peeling claw and a brush roller member.

FIG. 8 is a sectional view of the brush roller member of the present invention.

FIG. 9 is an explanatory diagram of a drive device for a brush roller member.

FIG. 10 is an explanatory diagram showing a configuration of a conventional paper transport device.

FIG. 11 is an explanatory diagram showing the configuration of another conventional paper transport device.

[Explanation of symbols]

1 image forming apparatus, 2 photoconductor drums, 5
Fixing device, 10 paper transport device, 11 upstream transport part, 12 step part, 13 downstream transport part, 1
5 guide plates, 17 suction devices, 18 ・ 18a ...
... Juan, 20/25 / 25a transport roller device, 29 conductive belt, 30 peeling claw, 31
Brush roller member, 35 roller brush, 40
45 paper transport device, 42 transport roller device, 4
6 Conveyor belt.

Claims (4)

[Claims] 1. An apparatus for forming a toner image on an image bearing member by using an electrophotographic method, guiding a sheet on which the toner image is transferred to a fixing device through a sheet conveying device, and performing fixing, wherein the sheet conveying The apparatus is provided with suction means, and a step is formed between the upstream side portion for receiving the paper from the photosensitive drum and the portion for transporting the paper, and the transporting surface is configured as an upward curved surface in the portion for transporting the paper. A sheet conveying device of an image forming apparatus, wherein a plurality of conveying roller devices are arranged on the conveying surface configured as the curved surface to convey a sheet carrying an unfixed toner image while sucking the sheet. 2. The image forming apparatus according to claim 1, wherein the sheet conveying device is provided with a plurality of suction means arranged in a width direction thereof, and the suction means is driven corresponding to a sheet size. Paper transport device. 3. A conveying surface configured as an upward curved surface by disposing a conveying roller device at an upstream end of the sheet conveying device and driving the conveying roller device together with the conveying roller device arranged on a curved surface portion. The image forming apparatus according to claim 1, further comprising: a detecting unit for detecting a loop state of the sheet, and controlling the conveyance speed in the fixing device using information from the detecting unit. Paper transport device of the device. 4. A cleaning means for the peeling claw is arranged with respect to the conveying roller device provided at the upstream end of the paper conveying device, and the cleaning means is constituted by a brush roller, which is opposite to the conveying roller device. The sheet conveying device of the image forming apparatus according to claim 3, wherein a mechanism for driving the brush roller is provided in a direction.