JPH0672586A - Paper transport device - Google Patents

Abstract

(57) [Abstract] [Purpose] When the paper is sucked and conveyed by the conveyor belt, the paper is prevented from waving on the conveyor belt, thereby preventing paper jams and paper wrinkles and improving reliability. [Structure] A suction box 47 provided in the conveyor belt 41 is provided with substantially V-shaped suction ports 47a to 47c having a wide angle toward the conveyance direction. As a result, the suction position of the paper P is gradually expanded from the central portion of the paper in both lateral directions to prevent partial lifting of the paper.

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 and the like, and relates to improvement of a sheet conveying apparatus for sucking and conveying a sheet by using an endless conveying belt.

[0002]

2. Description of the Related Art In an electrophotographic apparatus or the like for conveying a sheet by using a conveying belt, a suction device is used to correct the curl of the sheet peeled from a photoreceptor after transfer. Is sucked from the back surface to the conveyor belt side while being conveyed. In the prior art, a suction device is provided at the front end and the rear end inside the conveyor belt to form a suction port that linearly extends in the width direction of the paper, that is, in the direction orthogonal to the conveyance direction. The sheet is sucked and conveyed from the back side through a ventilation hole formed in the belt.

[0003]

Conventionally, in a device for sucking and conveying a sheet on a conveying belt from the back side by a suction device, the suction port of the suction device is in a direction orthogonal to the sheet conveying direction. It was extended linearly.

For this reason, for example, the paper peeled off from the photosensitive drum after the completion of transfer is instantly attracted to the conveyor belt over the entire length in the width direction when landing on the conveyor belt, and the suction force varies depending on the position. A part of the paper floats up in the width direction, and the paper is often conveyed in a wavy state. If a sheet is inserted between a pair of rollers such as a fixing roller in this state, a paper jam will occur before the rollers, and the paper jam must be removed. Alternatively, there is a problem in that the paper is wrinkled while passing through the roller and the paper is wasted, resulting in a decrease in reliability.

Therefore, the present invention solves the above problems by preventing the corrugation of the paper when the paper is conveyed by the conveyor belt and when the suction operation for correcting the curl of the paper is performed. -Smoothly insert the paper between the
An object of the present invention is to provide a highly reliable paper transport device that prevents paper jams and paper wrinkles.

[0006]

In order to solve the above-mentioned problems, the present invention comprises an endless conveyor belt having a large number of ventilation holes for conveying a sheet to a predetermined position, and the conveyor belt. A drive unit for driving the conveyor belt and a substantially V angle provided in a space formed by the conveyor belt and the drive unit and having a wide angle toward the predetermined position direction on the sheet conveying surface side.
Suction means having a V-shaped suction port and sucking air through the ventilation hole of the conveyor belt is provided.

In order to solve the above-mentioned problems, the present invention drives an endless conveyor belt having a large number of ventilation holes for conveying a sheet to a predetermined position, and the conveyor belt being hung around the conveyor belt. Drive means for driving, and a space formed by the transport belt and the drive means, the center of which in the sheet transport direction protrudes from both sides thereof, and a wide angle is formed on the sheet transport surface side in the predetermined position direction. Suction means having a substantially V-shaped suction port for sucking air through the ventilation hole of the conveyor belt is provided.

Further, in order to solve the above-mentioned problems, the present invention comprises an endless conveyor belt having a large number of ventilation holes for conveying a sheet to a predetermined position, and the conveyor belt is stretched around the conveyor belt. The driving means for driving and the space formed by the conveyor belt and the driving means are provided in a shape such that the center of the sheet in the sheet conveying direction protrudes from both sides thereof, and the sheet has a wide angle toward the sheet conveying surface in the predetermined direction. A suction unit having a substantially V-shaped suction port for sucking air through the ventilation hole of the conveyor belt, and a sheet of the suction unit provided in a space composed of the conveyor belt, the driving unit, and the suction unit. A conveyance guide means having a diameter equal to the height of the central portion in the conveyance direction and a width equal to the width of the protruding portion of the suction means is provided.

[0009]

The present invention is configured as described above, and when the sheet is conveyed by the conveyor belt, the suction width is not sucked toward the conveyor belt instantaneously over the entire length in the width direction, and the suction width is adjusted to the center of the sheet as the sheet is conveyed. By gradually expanding from the part to both sides,
When the curl of the paper is corrected, the paper is prevented from waviness, and the paper jam or the paper wrinkle is prevented from occurring in the next operation step, and the reliability is improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows the image forming apparatus 100 as a whole, including an apparatus main body 1 having an image forming means 2, an automatic double-sided device 4, a large-capacity cassette device 5 as a paper accommodating means, and a document table on the upper surface of the apparatus main body 1. An automatic document feeder 6 for automatically feeding a document to the sheet feeding device 30 and a sheet feeding unit 7 for detachably supporting first to third sheet feeding cassette devices 7a to 7c which are sheet feeding means.

A photosensitive member 10, which is a drum-shaped image bearing member, is provided substantially in the center of the main body 1 of the apparatus. Around the photosensitive member 10, a charging device 11 is sequentially installed along the rotation direction thereof. The exposure unit 12a of the exposure device 12, the developing device 13,
The transfer peeling charger 14, the cleaning device 16, and the charge eliminating device 17 are provided to constitute the image forming means 2. Further, on the right side of the apparatus main body 1, a side cassette 18 having a manual feed tray 18a above to store the paper P and a large capacity cassette device 5 are attached, and a paper feeding unit 7 stores the paper P of an arbitrary size. The first to third sheet feeding cassette devices 7a to 7c are attached. Further, below the photoconductor 10 of the apparatus main body 1, a sheet stacking section 4a of the automatic double-sided apparatus 4 is provided.

From the paper feed cassette device or the like for supplying the paper P to the transfer position 10a, which is the paper conveyance start position facing the transfer / separation charger 14 on the photoconductor 10, the first to the third positions are provided. The sixth transport paths 33a to 33f are formed. A transport means is provided on each of the transport paths 33a to 33f, and includes a side cassette device 18, a large-capacity cassette device 5, first to third paper feed cassette devices 7a to 7c,
First to sixth sheets P that take out the respective sheets P from the sheet stacking unit 4a
Pickup rollers 34a to 34f, first to sixth separation and conveyance rollers 36a to 36f for separating and conveying the taken-out paper P, and first to third conveyance transmission rollers 3
7a to 37c are provided.

Further, the sheet P conveyed by any of the first to sixth separation / conveyance rollers 36a to 36f in the apparatus main body 1 is provided on the left side of the apparatus main body 1 via the photoconductor 10. A main transport path 22 leading to the paper tray 9 is formed.

A registration roller 24 is arranged on the upstream side of the photoconductor 10 in the main transport path 22, and a sheet P is transported downstream from the transfer position to a predetermined fixing position by an endless transport belt 41. Paper transport device 4
2. A pair of fixing rollers 27, which are provided at the fixing position and are composed of a heat roller 27a and a press roller 27b, a conveying roller 19, a paper discharging roller 28, and a paper discharging roller 28. To guide the paper P to either the side or the automatic duplexer 4 side.
29 is arranged.

Here, the sheet conveying device 42 will be described in detail.

Between the first and second driving rollers 43a and 43b, which are the driving means, is formed of a composite material containing elastic rubber.
Ventilation holes 44 having a diameter of about 3 [mm] are formed innumerably on the entire surface, and the first to third conveyor belts 41 having a thickness of about 2 [mm] are provided.
a, 41b, 41c are hung in parallel at equal intervals. Incidentally, the first and second drive rollers 43a, 43b.
The lengths of the conveyor belts 41a to 41c that are spanned between them are approximately 1/2 of the length [A.4] size in the vertical direction.
[Cm], and the distance from the outside of the first conveyor belt 41a to the outside of the third conveyor belt 41c is the vertical length [A.
3] 32 cm, which is slightly wider than the width of the size.

Reference numeral 46 denotes a suction device which is a suction means, and a suction box 47 is provided in the conveyor belt 41,
At positions on the upper surface facing the first to third conveyor belts 41a to 41c, there are formed substantially V-shaped first to third suction ports 47a to 47 having a wide angle toward the fixing roller 27.
c is opened. It should be noted that the transport belts 41a to 41c and the suction ports 47a to 47c are in close contact with each other so that the paper P on the transport belt 41 is efficiently sucked. Further, 48 is a suction fan, and 50 is a fixing guide for guiding the paper P from the conveying belt 41 to the fixing roller 27.

The automatic document feeder 6 includes a document tray 60.
From pickup roller 61a, judgment roller 61b,
The document D conveyed through the aligning roller 61c is
It is supplied onto the original table 30 by a conveyor belt 63 which is stretched between the belt rollers 62, and after the copying is completed, the conveyor belt 63.
The sheet is discharged to the sheet discharge section 68 side via the reversing roller 64a and the sheet discharge roller 64b.

Next, the operation will be described. At the start of copying, necessary image forming conditions such as the paper size, the number of copies, and the copy magnification are input from an operation panel (not shown), and the document D is directly placed on the document tray 60 of the automatic document feeder 6 or the document table 30. Is set, and a copy key (not shown) is turned on to start copying.

As a result, the image forming means 2, the automatic document feeder 6, the sheet feeding unit 7 and the like are driven, while the sheet transport device 42 on the main transport path 22 is driven by the first and second drives. The conveyor belt 41 is rotated in the arrow x direction by driving the rollers 43a and 43b, and the suction fan 4
Driving 8 causes an air flow in the direction of the arrow y in the suction box 47. In the fixing roller 27, heating of the heat roller 27a is started.

When the document D is fed from the automatic document feeder 6, the document D is placed on the document table 30 by the conveyor belt 63 via the pickup roller 61a, the separating roller 61b, the aligning roller 61c. Placed.

On the other hand, in the apparatus main body 1, the photoconductor 10
In accordance with the rotation, the image forming means 2 sequentially carries out the steps of charging, exposing and developing, a toner image is formed on the surface thereof, and reaches the transfer peeling charger 14.

In synchronization with this, the first to third sheet feeding cassette devices 7a to 7c, depending on the set sheet size,
The paper P supplied from either the side cassette 18, the manual feed tray 18a, or the large-capacity cassette device 5 is
The transfer position 10 between the photoconductor 10 and the transfer peeling charger 14 at the timing when the tip of the toner image on the photoconductor 10 is aligned.
Then, the toner image on the photoconductor 10 is transferred.

Next, the conveyance of the sheet P to the fixing roller 27 side by the conveyance belt 41 after the toner image transfer will be described in detail. After the transfer of the toner image is completed, the paper P is peeled off from the photoconductor 10 and the leading end of the paper P is placed on the conveyor belt 41 which is driven to rotate in the direction of arrow x. At the position of landing on the suction box 4
Of the suction ports 47a to 47c of No. 7, the second suction port 47b
Are only provided. Therefore, the sheet P is sucked only in the central portion by the second suction port 47b through the ventilation hole 44 formed in the second conveyor belt 41b, and is directed by the first to third conveyor belts 41a to 41c in the arrow x direction. Be transported to.

As the conveyance in the direction of the arrow x by the conveyance belt 41 progresses, the sheet P reaches above the first and third suction ports 47a and 47c on both sides of the second suction port 47b, and is sucked by the suction device 46. However, the sheet is gradually expanded from the central portion of the sheet P toward both sides, and the sheet is sucked and conveyed to the conveying belts 41a to 41c without waviness, and the fixing roller 27
Then, the image is fixed by being inserted between the fixing rollers 27.

After that, the sheets are stacked on the sheet discharge tray 9 by the sheet discharge roller 28 when the sheet is a single-sided copy, and when the sheet is a double-sided copy, the sheet is automatically double-sided by the gate 29 after completion of fixing. The sheet is conveyed to the apparatus 4 side and accumulated in the sheet accumulating section 4a,
Then, the back side is copied.

After the transfer is completed, the photoconductor 10 is made ready for the next copy through the cleaning device 16 and the static eliminator 17, and the above copying operation is repeated until the required number of copies is reached.

According to this structure, when the sheet P is conveyed by the conveying belt 41 while being sucked by the suction device 46 in order to correct the curl of the sheet P, the suction portion is the sheet P.
Since the sheet is gradually expanded from the central portion of the sheet to both sides as the sheet is conveyed, unlike the conventional case, a part of the sheet P floats during suction and the sheet P does not wavy. Therefore, paper jams and paper wrinkles do not occur during fixing, copy mistakes can be prevented, and the reliability and economy of the apparatus are improved.

Next, a second embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to 0.

In this embodiment, the shape of the suction box of the sheet conveying device in the first embodiment is different, but the others are the first.
Since it is the same as that of the first embodiment, the same parts as those of the first embodiment are designated by the same reference numerals and the description thereof is omitted.

The suction box 71 of the paper transporting device 70 for transporting the paper P from the transfer position to the fixing position of the main transport path 22 has a substantially V-shape on its upper surface, which has a wide angle toward the fixing roller 27. First to third suction ports 71a to 71
c is opened, and its center 72b is
Compared to a and 72c, the upper and lower sides are projected by about 3 [mm] each. On both sides 72a, 72c and the center 72b of the suction box 71, the first and third conveyor belts 73 are respectively provided.
a, 73c and the second conveyor belt 73b are stretched around.

Any of the conveyor belts 73a to 73c
Both of them are in close contact with the suction ports 71a to 71c, but in the case of the second conveyor belt 73b which is stretched around the center 72b of the suction box 71, the conveyor belts 73a, 73 on both sides are arranged.
In order to correct the deviation of the conveyance speed due to the difference in height from c, the diameter between the first and second drive rollers 74a and 74b and the suction box 71 is almost the same as the height of the center 72b of the suction box 71. With a suction box 71 center 72
First and second guide rollers 75a and 75b, which are guide means having a width substantially the same as the width b, and driven by the second conveyor belt 73b, are provided.

Each of the conveyor belts 73a to 73c is made of the same material and has the same structure as the conveyor belt 41 used in the first embodiment.

Reference numeral 76 is a suction fan.

Next, the operation will be described. After the toner image is transferred by the transfer peeling charger 14, the leading edge of the paper P peeled off from the photoconductor 10 is driven by both drive rollers 74.
a to 74b driven in the direction of arrow z by a and 74b
Is placed on the conveyor belts 73a to 73c, and is conveyed in the arrow z direction while only the central portion is sucked by the second suction port 71b. However, at this time, the second conveyor belt 73b
In this case, while the guide rollers 75a and 75b stretch the second conveyor belt 73b, the second conveyor belt 7
It is driven and rotated by 3b.

Then, as the conveyance belts 73a to 73c convey the paper P in the direction of the arrow z, the paper P reaches above the first and third suction ports 71a and 71c on both sides of the second suction port 71b, and the suction portion , The paper P is gradually enlarged from the central portion toward both sides.

During this time, the paper P is conveyed by the conveyor belts 73a to 73a.
Carried in a mountain-shaped curve along 3c,
The image is fixed by being inserted into the fixing roller 27 without causing waviness and waviness.

Thereafter, the paper is conveyed to the paper discharge tray 9 or the automatic duplexer 4 side as in the first embodiment.

According to this structure, when the first to third conveyor belts 73a to 73c convey the sheet P, the suction portion of the sheet P for correcting the curl of the sheet P to the side of the conveyor belts 73a to 73c is provided. Since the sheet is gradually expanded from the central portion of the sheet to both sides, there is no fear that the sheet P floats during suction and the sheet P is wavy as in the conventional case.

Further, since the paper P is curved in a mountain shape on the conveyor belts 73a to 73c and its waist is strengthened, the float which tends to occur on the paper at the time of suction is also extended by the strength of the waist. When the paper with weak stiffness such as recycled paper is used, it is possible to surely prevent the paper from wavy.

Therefore, at the time of fixing after the conveyance by the conveyance belts 73a to 73c is completed, paper jams and paper wrinkles do not occur, copy mistakes can be prevented, and the reliability and economy of the apparatus are improved.

Moreover, since the guide rollers 75a and 75b are provided inside the second conveyor belt 73b at the center of the suction box 71, the heights of the suction box 71 are different depending on the positions, but the first to the third. Conveyor belts 73a to 73
c can be driven at the same speed by the same drive rollers 43a and 43b.

The present invention is not limited to the above-described embodiment, and can be modified within the scope of the invention, and for example, an electrophotographic apparatus can be used as long as it is an apparatus that requires conveyance of paper. You don't have to. Further, the width, length, or number of the conveyor belts are not limited. Further, the size of the suction box is arbitrary, and the shape of the suction port may be a substantially continuous V-shape, and the second suction port 77b of the suction box 77 as in the first modification shown in FIG. Both ends, first and third
If the insides of the suction ports 77a and 77c are partially overlapped, the sheet P can be sucked more stably and the sheet P can be more reliably prevented from floating. Further, as in the second modified example shown in FIG. 12, the suction box 78 may be provided with the first and second V-shaped suction ports 80 and 81 in succession. It is possible to more stably convey the paper. The suction box is not a single structure,
As in the third modification shown in FIG. 3, the first to third housings 82 to
84 is connected by first and second ducts 86 and 87,
The first to third suction ports 82a to 84a, which are generally V-shaped as a whole, may be formed on the upper surfaces of the to third housings 82 to 84.

Further, when the center of the suction box is projected from both sides, it is sufficient that at least the sheet conveying surface side is projected, and the height of the projecting portion is not limited as long as it is a range in which the sheet is stiff.

[0046]

As described above, according to the present invention, the suction portion of the sheet toward the conveyor belt side by the suction means is gradually expanded from the central portion of the sheet to both sides as the sheet is conveyed. When the paper is sucked, part of the paper floats up and the curl can be corrected without waviness, and when inserted into the roller device after conveyance, there is no paper jam or paper wrinkle, and the paper is wasted. Can be prevented, maintenance can be reduced, and the reliability of the device can be improved.

Further, by making the central portion of the suction means project in comparison with both sides and curving the paper being conveyed into a mountain shape, the waist of the paper can be strengthened, and even when conveying a regenerated paper with a weak waist, The floating of the paper can be more effectively prevented, the paper jam and the paper wrinkle can be more reliably prevented, and the reliability of the apparatus can be further improved.

Further, although the central portion of the suction means is projected higher than the both sides, the guide means provided inside the central conveying belt allows the same driving means to move the conveying belts on both sides and the central portion. It can be driven at a high speed, and it is not necessary to provide a driving means individually, so that the driving means can be simplified.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a sheet conveying device according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken along the line AA ′ in FIG. 2 of the first embodiment of the present invention.
It is sectional drawing seen from.

FIG. 4 is a sectional view taken along line BB ′ in FIG. 2 of the first embodiment of the present invention.
It is sectional drawing seen from.

FIG. 5 is a plan view showing the suction box of the first embodiment of the present invention.

FIG. 6 is a perspective view showing a suction box according to a first embodiment of the present invention.

FIG. 7 is a plan view showing a sheet conveying device according to a second embodiment of the present invention.

FIG. 8 is a sectional view taken along line CC ′ of FIG. 7 of the second embodiment of the present invention.
It is a sectional view seen from

FIG. 9 is a side view showing a sheet conveying device according to a second embodiment of the present invention.

FIG. 10 is a perspective view showing a suction box according to a second embodiment of the present invention.

FIG. 11 is a plan view showing a suction box of a first modified example of the present invention.

FIG. 12 is a plan view showing a suction box of a second modified example of the present invention.

FIG. 13 is a perspective view showing a suction box of a third modified example of the present invention.

[Description of Reference Signs] 100 ... Image forming apparatus 10 ... Photoconductor 14 ... Transfer peeling charger 27 ... Fixing rollers 41a to 41c ... First to third conveyor belts 42 ... Paper conveyor 47 ... Suction box 47a ... 47c ... First to third suction ports

Claims (3)

[Claims] 1. An endless conveyor belt having a large number of ventilation holes for conveying a sheet to a predetermined position, driving means for driving the conveyor belt, and the conveyor belt and the conveyor belt. Suction means provided in a space formed by the drive means and having a substantially V-shaped suction port having a wide angle toward the predetermined position on the side of the sheet transport surface, and sucking air through the ventilation hole of the transport belt. A paper transporting device comprising: 2. An endless conveyor belt having a large number of ventilation holes for conveying a sheet to a predetermined position, a driving means for driving the conveyor belt, the conveyor belt and the conveyor belt. It has a shape in which the center in the sheet transport direction projects from both sides provided in a space defined by the drive means, and a substantially V-shaped suction port having a wide angle toward the predetermined position direction on the sheet transport surface side. A sheet conveying device comprising: suction means for sucking air through the ventilation holes of the conveying belt. 3. An endless conveyor belt having a large number of ventilation holes for conveying a sheet to a predetermined position, driving means for driving the conveyor belt by being stretched over the conveyor belt, the conveyor belt and the conveyor belt. The center of the sheet conveyance direction is provided in a space formed by the drive means and has a shape projecting from both sides thereof, and a substantially V-shaped suction port having a wide angle toward the predetermined direction is provided on the side of the sheet conveyance surface. A suction means for sucking air through the ventilation hole of the transport belt, and a diameter equivalent to the height of the central portion of the suction means in the sheet transport direction provided in the space composed of the transport belt, the driving means and the suction means. And a conveyor belt guide means having a width equal to the width of the protruding portion of the suction means.