JPH11314805A - Sheet carrier device and image forming device provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a proper image and perform the positioning of a sheet tip part without increasing frictional force to a carrier guide part or the like. SOLUTION: Slack is formed at a sheet tip part by abutting positioning means 33a, 33b on a tip part of a sheet P which is selectively carried from a sheet carrier path and the positioning in a carrier width direction of the sheet tip part is performed. After slack is formed by abutting the sheet P on the positioning means 33a, 33b, a carrier means 32 (41) is stopped and slack formation amount of the sheet tip part at the time of the positioning is changed according to the shape of the sheet carrier path by changing time when the carrier means 32 (41) is stopped after the sheet P is abutted on the positioning means 33a, 33b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus and an image forming apparatus provided with the same, and more particularly, to a sheet conveying apparatus provided for a plurality of sheet stacking means. The present invention relates to a sheet conveying apparatus that slackly aligns a leading end of a sheet in a conveying width direction.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus includes a plurality of sheet stacking means and a sheet conveying apparatus for conveying sheets stacked on the sheet stacking means to an image forming section. As this type of sheet conveying device, a device that sandwiches and conveys a sheet between a rotating cylindrical roller pair, a cylindrical roller and a roller, a cylindrical roller and a pad, and the like is widely used. In addition, these devices are arranged in a plurality of transport units and transport the sheets sequentially. This is because the movement of the sheet can be easily controlled by changing the rotation degree and ON / OFF timing of the drive roller.

[0005] On the other hand, adjacent sheet conveying sections are arranged at positions where the shortest sheet conveying length can be simultaneously held even in the most distant state. In addition, the sheet transport units are not generally arranged in a straight line with respect to the transport direction due to the miniaturization of the apparatus and the configuration of each process, and the transport direction of the sheet is changed in each part. Until the sheet is held between the two sheet conveying units,
The sheet is conveyed along a sheet conveying guide section provided between the two sheet conveying sections.

Incidentally, the conventional sheet conveying apparatus is provided with a sheet positioning means for forming an image. Here, as a positioning method of the positioning means, after abutting the leading end of the sheet conveyed by the sheet conveying means against a stopped cylindrical roller pair or a shutter member having a flat part, the sheet is further conveyed by the sheet conveying means. A method of forming a slack at the leading end of a sheet by feeding the sheet is widely used.

By forming the slack in this manner, even if the sheet is conveyed in a skew state, the position of the leading end of the sheet in the conveying width direction is aligned, and the accurate position of the sheet for image formation is obtained. Matching can be performed.

FIG. 10 is a diagram showing the overall configuration of an image forming apparatus provided with such a conventional sheet conveying device.
Reference numeral 00 denotes a sheet conveying device. In the sheet conveying apparatus 100, for example, the upper sheet cassette 1
The sheets P stacked on the sheet 50 are transported by the transport rollers 13 of the sheet first transport unit 131 on the upstream side in the transport direction of the sheets P.
1a rotates in the direction a, so that the transport rollers 13
1a and the sheet P sandwiched between the separation sheet 131b
Is transported in the b direction.

[0007] The sheet P conveyed by the first sheet conveying section 131 is fed to the first sheet conveying guide section 121.
The sheet is conveyed to the downstream side second conveyance section 132 along the upper guide 121a, and thereafter conveyed by a pair of rollers 132a and 132b rotating in the c and d directions.

Next, the sheet P conveyed by the second sheet conveying section 132 is moved along the upper guide 122a of the second sheet conveying guide section 122 and the upper guide 123a of the third sheet conveying guide section 123 on the downstream side. Downstream sheet 3
It is transported to the transport unit 133.

While the sheet P is being conveyed to the third sheet conveying section 133, the leading end position of the sheet P is detected by a detection lever 122c provided in front of the third sheet conveying section 133. Then, after the leading end position is detected in this manner, the sheet P is transferred to the upper roller 1 of the third sheet transport section 133.
33b, and after that, the third sheet conveying section 133
Is transported to a contact portion between the lower roller 133a and the upper roller 133b.

Here, at this time, the third sheet transport section 133
The lower roller 133a and the upper roller 133b are in a state in which the rotation is stopped, whereby the leading end of the sheet P stops at the contact portion between the lower roller 133a and the upper roller 133b.

However, as described above, the sheet third transport unit 13
Even when the conveyance of the sheet P is stopped, the upstream sheet second conveyance section 132 continues to convey the sheet P for a predetermined time after the leading end position is detected by the detection lever 122c. Form a sag at the tip.

By forming the slack in this way, even if the sheet is conveyed in a skew state, a force acts in a direction to reduce the slack, thereby aligning the position of the leading end of the sheet in the conveying width direction. Thus, accurate sheet alignment for image formation can be performed.

Next, after the position of the leading end of the sheet P is adjusted as described above, the lower roller 133a and the upper roller 133b of the third sheet conveying section 133 start to rotate.
As a result, the sheet P is conveyed to the fourth sheet conveying section 134 and the sheet conveying sections 13 on both the upstream side and the downstream side are transported.
Until the sheet is held between the sheets 4A and 134B, the sheet is conveyed to the downstream sheet conveying section along the fourth sheet guide section 124. This sheet conveyance operation is the same for the lower sheet cassette 151.

On the other hand, in FIG. 1, reference numeral 152 denotes a paper feed tray. When the sheets P stacked on the paper feed tray 152 are transported, the transport rollers 141a of the fifth sheet transport section 141 rotate in the i direction. Accordingly, the sheet P nipped between the transport roller 141a and the separation sheet 141b is transported in the j direction by the transport roller 141a.

The sheet P conveyed in the j direction from the fifth sheet conveying section 41 is conveyed to the downstream third sheet conveying section 133 along the upper guide 123a of the downstream third sheet conveying guide section 123. Go being.

Here, the sheet P conveyed by the sheet fifth conveyer 141 also has a sheet third conveyer 133 similar to the sheet conveyed by the sheet first conveyer 131.
, A slack is formed at the leading end of the sheet P, and the position of the leading end of the sheet P in the conveying width direction is aligned, so that accurate sheet positioning for image formation can be performed.

The position of the leading end of the sheet for forming an image is preferably adjusted in the sheet conveying section closest to the image forming section, and is preferably adjusted in the junction of many conveying paths. .

[0018]

By the way, in such a conventional sheet conveying apparatus, when forming a slack at the leading end of the sheet, it is better to increase the amount of slack at the leading end of the sheet. Can be suppressed,
If the amount of slack at the leading end of the sheet is increased, the sliding force of the sheet due to the slack of the sheet increases, and paper dust is generated with the increased sliding force, and the transport resistance increases.
The adverse effect of generating noise also occurs.

On the other hand, when the sheets P stacked on the sheet tray 152 described above are conveyed, that is, when the sheets are conveyed substantially linearly, and when the sheets P stacked on the sheet cassettes 150 and 151 are conveyed. In the case, that is, when the slack amount at the leading end of the sheet is the same when the sheet is conveyed in a curved manner, a larger sheet bending force is required when the sheet is conveyed substantially linearly.

Here, when the slack amount at the leading end of the sheet is increased so as to suppress the skew state of the sheet, the bending force of the sheet when the sheet is conveyed substantially linearly increases, and a force for pushing back the sheet is generated. . When the sheet push-back force is generated as described above, the sheet is pushed back by the sheet push-back force, so that the timing for forming an image does not match, and a problem that an image is not formed at an appropriate position on the sheet occurs. .

Accordingly, the present invention has been made in view of such a situation, and it is possible to form an appropriate image, and to increase a slidable force on a sheet guide portion without increasing a sliding force on a conveyance guide portion or the like. It is an object of the present invention to provide a sheet conveying apparatus capable of performing alignment and an image forming apparatus having the same.

[0022]

SUMMARY OF THE INVENTION According to the present invention, a sheet stacked on a plurality of sheet stacking means, and a sheet selectively conveyed from a sheet conveyance path provided in correspondence with each of the plurality of sheet stacking means is sagged. A sheet conveying apparatus that performs position adjustment of a sheet leading end in a conveying width direction by changing a slack forming amount of a sheet leading end at the time of the positioning according to the sheet conveying path. It is.

Also, the present invention provides a method for slackening a sheet stacked on a plurality of sheet stacking means and selectively conveyed from a sheet conveyance path provided for each of the plurality of sheet stacking means. In the sheet conveying device configured to perform the alignment in the conveying width direction, the sheet conveyed from the sheet conveying path abuts on the front end of the sheet to form a slack at the sheet front end, and the sheet front end in the conveying width direction is formed. A positioning unit for performing positioning, a conveying unit that discharges the sheets stacked on the sheet stacking unit to the sheet conveying path, and then conveys the sheet toward the positioning unit; After forming the slack in contact with the sheet, the conveying means is stopped, and the amount of slack formed at the leading end of the sheet during the alignment is adjusted. Control means for changing the time from when the sheet abuts on the positioning means to when the sheet is stopped so as to change according to the shape of the sheet conveying path. is there.

Further, according to the present invention, the control means preferably controls the sheet conveying path having a smaller curvature so that a sheet having a smaller curvature is smaller in the sheet conveying path than a sheet having a larger curvature. It is characterized in that the time from when the sheet comes into contact with the positioning means to when the conveying means is stopped is shortened.

Further, in the present invention, the control means may be arranged so that the substantially linear sheet conveying path has a smaller slack forming amount than a curved sheet conveying path as compared with a curved sheet conveying path. The time from when the sheet comes into contact with the positioning means to when the conveying means is stopped is shortened.

Further, the present invention is characterized in that the control means controls the transport means so as to reduce the slack amount of the leading end of the sheet after performing the alignment.

The present invention is characterized in that the control means drives the transport means again after the sheet contact operation of the positioning means is canceled so as to reduce the slack amount of the sheet leading end. Is what you do.

According to the present invention, a sheet stacked on a plurality of sheet stacking means and selectively conveyed from a sheet conveyance path provided for each of the plurality of sheet stacking means is slackened. In the sheet conveying device configured to perform the alignment in the conveying width direction, the sheet conveyed from the sheet conveying path abuts on the front end of the sheet to form a slack at the sheet front end, and the sheet front end in the conveying width direction is formed. A positioning unit for performing positioning, a conveying unit that discharges the sheets stacked on the sheet stacking unit to the sheet conveyance path, and then conveys the sheet toward the positioning unit; and detects a thickness of the sheet. After the sheet has formed a slack in contact with the positioning means, the sheet detecting means and the conveying means are stopped, and The sheet forming means adjusts the amount of slack formed at the leading end of the sheet according to the thickness of the sheet based on a detection signal from the thickness detecting means so that the sheet comes into contact with the positioning means. And control means for changing the time until the operation is stopped.

According to the present invention, when the thick sheet is conveyed so that the slack forming amount is smaller in the thick sheet than in the thin sheet, the control means may contact the positioning means with the thick sheet. The method according to the present invention is characterized in that the time from when the conveying means is stopped is shortened.

The present invention is characterized in that the control means drives the conveying means again after the sheet contact operation of the positioning means is canceled so as to reduce the slack amount of the sheet leading end. Is what you do.

According to the present invention, there is provided an image forming apparatus including an image forming section and a sheet conveying device, wherein the sheet conveying device is the sheet conveying device according to any one of claims 1 to 9. It is assumed that.

Further, as in the present invention, after the sheets stacked on the sheet stacking means by the conveying means are discharged to the sheet conveying paths provided respectively corresponding to the plurality of sheet stacking means, the sheets are selectively selected from the sheet conveying path. The leading end of the conveyed sheet is brought into contact with a positioning means to form a slack at the leading end of the sheet, and the leading end of the sheet is aligned in the conveying width direction. Then, after the sheet forms a slack in contact with the positioning means, the conveying means is stopped by the control means, and the time from when the sheet comes in contact with the positioning means to when the conveying means is stopped is changed. The amount of slack formation at the sheet tip during alignment is
It is changed according to the shape of the sheet conveying path.

[0033]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the shape of the components described in this embodiment,
The relative arrangement and the like are not intended to limit the scope of the present invention thereto unless otherwise specified.

First, a first embodiment of the present invention will be described.

FIG. 1 is an overall configuration diagram of an image forming apparatus provided with a sheet conveying apparatus according to the present embodiment, and FIG. 2 is an enlarged view of a main part of the image forming apparatus.

1 and 2, reference numeral 80 denotes an image forming apparatus; 81, an image forming apparatus main body (hereinafter, referred to as main body);
Denotes a sheet conveying device provided in the image forming apparatus 80. Reference numerals 86, 87 and 88 denote upper sheet cassettes, lower sheet cassettes as sheet stacking means for stacking sheets,
It is a paper feed tray.

Here, the sheet conveying device 1 includes a sheet first device having a conveying roller 31a and a separation sheet 31b.
Conveying unit 31, drive roller 32a and driven roller 32b
And a third sheet conveying unit 33 including a lower roller 33a and an upper roller 33b, a fourth sheet conveying unit 34, a conveying roller 41a and a separation sheet 41b, and a third sheet conveying unit. The sheet fifth transport unit 4, which is one of transport units that is substantially horizontal with the transport unit 33.
1. It has a sheet sixth transport section 51.

The first sheet transport section 31 and the sixth sheet
The transport unit 51 and the sheet second transport unit 32 each constitute a transport unit.

Further, the sheet conveying apparatus 1 includes a sheet first conveying guide section 21 having an upper guide 21a, a sheet second conveying guide section 22 having an upper guide 22a, and an upper guide 23a forming a sheet conveying path. And a fourth sheet guide unit 24 having a third sheet conveyance guide unit 23 and a fourth sheet guide unit 24.

In the embodiment of the present invention, the fourth sheet transport section 34 is provided with a photosensitive drum 3 serving as an image forming section.
4a and the transfer roller 34b, and the sheet P is formed by the photosensitive drum 34a and the transfer roller 3b.
4b, and is conveyed while forming an image on the photosensitive drum surface side.

On the other hand, in FIG.
The detection lever is provided in front of the conveyance unit 33 and detects the leading end position of the sheet P. The detection signal from the detection lever 22c is used to control the sheet conveyance operation of the sheet conveyance device 1 as shown in FIG. It is input to the control device 83 as a means.

Here, as described above, the sheet third transport section 33
When the detection signal is input from the detection lever 22c provided in front of the sheet P, the control device 83 determines that the leading end of the sheet P has reached the position where it comes into contact with the third sheet conveying section 33.
Then, after the detection signal is input, the sheet third transport unit 33 is stopped until a first predetermined time elapses. For example, when the sheet is fed from the upper sheet cassette 86, the sheet second transport unit 33 is stopped. 32 (if necessary, the first transport unit 3)
1), and when the sheet is fed from the sheet feeding tray 88, the fifth sheet conveying section 41 is continuously driven.

Thus, a slack is formed at the leading end of the sheet P as shown in FIG. By forming the slack in this way, even if the sheet is conveyed in a skew state, a force acts in a direction to reduce the slack, and the position of the leading end of the sheet in the conveying width direction is aligned. Of the sheet can be accurately adjusted.

By the way, this control device 83 is
In response to a selection signal from a selection button 84 for selecting paper feeding from the upper paper cassette 86, the lower paper cassette 87, and the paper tray 88, which is provided on an operation panel (not shown) provided on the upper surface of the The third sheet conveying section 33 is stopped and the second sheet conveying section 32 or the fifth sheet conveying section 4 is stopped.
The first predetermined time for continuously driving the motor 1 is changed.

For example, when the sheet feeding tray 88 is selected, the sheet conveying path formed by the third sheet guide portion 23 of the sheet feeding tray 88 is a substantially straight line having a small curvature, and thus a curved line having a large curvature. The first predetermined time is made shorter than that of the upper paper feed cassette 86 and the lower paper feed cassette 87 having the sheet conveyance path of FIG.

When the sheet feeding tray 88 is selected as described above, the first predetermined time is shortened, in other words, after the sheet P comes into contact with the third sheet conveying section 33, the fifth sheet conveying section Time to stop 41,
For example, by making the time shorter than the time required to stop the sheet second conveying unit 32, the amount of slack at the sheet leading end can be reduced, and an increase in the sliding force on the conveying guide unit or the like can be prevented. . As a result, it is possible to prevent paper dust and noise from being generated, and to perform stable sheet conveyance.

Further, by reducing the amount of slack at the leading end of the sheet, the bending force of the sheet can be reduced, and the generation of force for pushing back the sheet can be prevented. As a result, the sheet is not pushed back, and the timing for image formation can be adjusted more precisely.

On the other hand, when feeding paper from the upper paper feed cassette 86, for example, the control device 83 detects the detection lever 22c.
After the detection signal is input, the third sheet conveying section 33 is driven after a first predetermined time has elapsed, that is, after the leading end of the sheet P has been positioned.
Thereby, the lower roller 33a of the sheet third transport unit 33
And the upper roller 33b rotates in the f and g directions as shown in FIG. 5, and conveys the sheet P in the h direction.

The control device 83 operates the lower roller 33a and the upper roller 33
Even after the rotation of b is started, the rotation of the pair of rollers 32a and 32b of the second sheet conveying unit 32 is not started for the second predetermined time.

Then, as described above, the sheet third transport section 33
By not performing the sheet second conveying section 32 for the predetermined time while the sheet P is conveyed, the slack of the sheet P is reduced as shown in FIG. This makes it possible to reduce the sliding force on the conveyance guide and the like after the alignment. Note that the same effect can be obtained even if the rotation of the sheet fifth conveyance unit 41 is not started for the second predetermined time.

Next, the sheet conveying operation in the sheet conveying apparatus 1 configured as described above will be described.

First, in the case of cassette feeding, a case where the sheet P of the upper sheet feeding cassette 86 is conveyed will be described as an example.

First, as shown in FIG. 1, the sheets P stacked in the upper sheet cassette 86 are transferred to the transport rollers 31 of the sheet first transport unit 31 on the upstream side in the transport direction of the sheets P.
a rotates in the direction a, so that the transport rollers 31a
The sheet P sandwiched between the sheet P and the separation sheet 31b is transported in the direction b by the transport roller 31a.

Then, from the sheet first transport section 31, b
The sheet P conveyed in the direction is conveyed to the downstream sheet second conveying section 32 along the upper guide 21a of the sheet first conveying guide section 21 as shown in FIG.
A drive roller 32a that rotates in the c direction of the transport unit 32,
After being nipped by the driven roller 32b that is driven and rotated in the d direction, the sheet is transported in the e direction.

Next, the sheet P conveyed in the e direction from the second sheet conveying section 32 is moved to the second sheet conveying guide section 2.
The sheet is conveyed to the downstream sheet third conveying section 33 along the upper guide 22a of the second sheet and the upper sheet 23a of the downstream third sheet conveying guide section 23.

While the sheet P is being conveyed to the third sheet conveying section 33, the leading end position of the sheet P is detected by a detection lever 22c provided in front of the third sheet conveying section 33. Then, when the tip position is detected in this manner, the control device 83, based on the detection signal from the detection lever 22c,
Until the first predetermined time elapses, the sheet third transport unit 33
Is stopped, and the second sheet conveying section 32 (and the first sheet conveying section 31 if necessary) is continuously driven.

Thus, after the sheet P comes into contact with the upper roller 33b of the third sheet transport section 33, the sheet P
The sheet P is conveyed to a contact portion between the lower roller 33a and the upper roller 33b, and the leading end of the sheet P is eventually moved to the lower roller 33a and the upper roller 3 as shown in FIG.
It stops at the contact portion with 3b.

After this, the sheet P is continuously conveyed from the upstream sheet second conveying section 32 until the first predetermined time has elapsed, and as a result, as shown in FIG. Sag is formed, and accurate sheet alignment for image formation is performed.

After the position of the leading end of the sheet P is adjusted, the lower roller 3
3a and the upper roller 33b start rotating in the f and g directions, and the sheet P is conveyed in the h direction. In addition, the lower roller 33 a and the upper roller 33
Even after b starts rotating, the pair of rollers 32a and 32b of the second sheet conveying section 32 does not start rotating for a predetermined time, whereby the slack of the sheet P is reduced as shown in FIG.

Next, the sheet P conveyed in the h direction by the third sheet conveying section 33 is conveyed to the fourth sheet conveying section 34 shown in FIG. 1, and the sheet conveying on both the upstream side and the downstream side is performed. Until the sheet is sandwiched between the sections 34A and 34B, the sheet is conveyed to the downstream sheet conveying section along the fourth sheet guide section 24.

Next, the case of sheet feeding from the sheet feeding tray will be described.

In this case, as shown in FIG.
The sheet P stacked on the sheet No. 8 is pinched between the transport roller 41a and the separation sheet 41b by the rotation of the transport roller 41a of the sheet fifth transport section, which is substantially horizontal with the sheet third transport section, in the i direction. After the transfer, the transport roller 4
It is transported in the j direction by 1a. Then, the sheet P conveyed in the i direction from the fifth sheet conveying section 41 is conveyed to the downstream sheet third conveying section 33 along the upper guide 23a of the downstream sheet third conveying guide section 23. go.

Thereafter, in the sheet P conveyed from the sheet fifth conveyer 41, similarly to the sheet conveyed from the sheet first conveyer 31, in the sheet third conveyer 33, as shown in FIG. A slack is formed at the leading end of the sheet P, the positions of the leading end of the sheet in the conveying width direction are aligned, and accurate sheet positioning for image formation is performed.

Here, in the case where the sheet is conveyed from the fifth sheet conveying section 41 which is substantially horizontal to the third sheet conveying section 33,
Unlike the sheet conveyed from the sheet first conveyance unit 31, the sheet is hard to bend, and the conveyance in the sheet fifth conveyance unit 41 is directly affected by the bending force.
The slack amount at the leading end of the sheet P conveyed from the conveying unit 31 is smaller than the amount of slack.

That is, when the control device 83 detects that the paper feed tray 88 has been selected in response to the selection signal from the selection button 84, the control device 83 performs the first predetermined time compared to the case where the upper paper feed cassette 86 is selected. By shortening the time, in other words, by shortening the time for stopping the sheet fifth conveyance unit 41, the slack amount at the leading end of the sheet P is reduced.

When the sheet is fed from the lower sheet cassette 87, the sheet P conveyed by the sheet
Is different from the sheet conveyed from the sheet first conveyance unit 31, the sheet is not bent so much in the conveyance path,
Further, the influence of the back tension in the sixth sheet conveying section 51 is small in the third sheet conveying section 33.

For this reason, when the sheet feeding from the lower sheet feeding cassette 87 is selected, the control device 83 controls the sheet second conveying section 32 (necessary for the sheet feeding) at least as compared with the case where sheet feeding from the upper sheet feeding cassette 86 is performed. Then, the sheet sixth transport unit 51),
The time to stop is shortened. Thereby, the amount of slack at the leading end of the sheet P can be reduced.

In the above description, the case where the slack amount is changed based on the shape of the transport path has been described. However, the present invention is not limited to this. For example, the thicker the sheet, the greater the bending force of the sheet. Since a force for pushing back the sheet is generated, the amount of slack may be changed according to the thickness of the sheet.

Next, a second embodiment of the present invention will be described.

FIG. 8 is an enlarged view of a main portion of the image forming apparatus according to the present embodiment. In FIG. 8, reference numeral 61 denotes a position corresponding to the position of the third sheet conveying portion in the first embodiment. The sheet seventh transporting unit 61c disposed at the position of the confluence of the transporting path is a sheet thickness detecting means for detecting the thickness of the sheet.

Here, the sheet thickness detecting means 61c is
When the sheet P is nipped between the lower roller 61a and the upper roller 61b of the sheet seventh transport unit 61, the sheet thickness is detected by detecting the position change amount of the upper roller 61b which varies according to the sheet thickness, and The thickness information is input to the control device 83 as shown in FIG.

Then, the control device 83 determines the thickness of the sheet P based on the sheet thickness information, determines the amount of slack at the leading end of the sheet P, and, based on the amount of slack, the seventh sheet transport unit. The stop time of 61 is changed.

As a result, the amount of slack at the leading end of the sheet can be reduced in accordance with the thickness of the sheet, and an increase in the rubbing force on the conveyance guide and the like can be prevented. Further, by reducing the amount of slack at the leading end of the sheet, the bending force of the sheet can be reduced, and the generation of a force to push back the sheet can be prevented. As a result, the sheet is not pushed back, and the timing for image formation can be adjusted more precisely.

In FIG. 8, reference numeral 61d denotes a shutter member, and the sheet P conveyed by the seventh sheet conveying section 61 has a front end having a shutter member 6 having a flat portion.
Hits 1d. Here, this shutter member 61d
Has a function similar to that of the third sheet transport unit 33 of the first embodiment, and the leading end of the sheet P is a shutter member 61d.
After the sheet P has hit the sheet P,
Is transported, a slack is formed at the leading end of the sheet P.

The amount of slack formation can be changed by changing the stop time of the seventh sheet conveying section 61 in accordance with the thickness of the sheet P. The other sheet conveyance modes are the same as in the first embodiment.

In each of the above embodiments, the sheet P abuts on the third sheet transport section 33 (the lower roller 33a and the upper roller 33b) or the shutter member 61d based on the detection signal from the detection lever 22c. The case has been described in which it is determined that the sheet second conveyance unit 32, the fourth sheet conveyance unit 41, the seventh sheet conveyance unit 61, and the like are stopped, and the amount of slack formed at the leading end of the sheet is changed.

However, the present invention is not limited to this. For example, the drive times of the second sheet transport section 32, the fourth sheet transport section 41, the seventh sheet transport section 61, and the like are changed according to the shape of the sheet transport path. By doing so, the amount of slack formed at the leading end of the sheet may be changed.

[0078]

As described above, according to the present invention, after the slack is formed on the sheet, the time from when the sheet comes into contact with the positioning means to when the conveying means is stopped is changed to perform the positioning. By changing the amount of slack formation at the leading end of the sheet according to the shape of the sheet conveyance path or the sheet thickness, the timing for image formation can be adjusted more accurately, and stable conveyance can be performed.

After the position of the leading end of the sheet has been adjusted, the amount of slack at the leading end of the sheet is reduced, whereby
It is possible to prevent an increase in the rubbing force applied to the transport guide portion and the like, thereby making it possible to reduce the generation of paper dust, the increase in transport resistance, and the generation of noise.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus including a sheet conveying device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the image forming apparatus.

FIG. 3 is a block diagram of a control device of the image forming apparatus.

FIG. 4 is a diagram illustrating a state in which a slack is formed at a leading end of a sheet in the sheet conveying apparatus.

FIG. 5 is a view showing a state in which the slack of the sheet is reduced.

FIG. 6 is a diagram illustrating a state in which sheets stacked on a sheet feed tray of the image forming apparatus are transported downstream.

FIG. 7 is a diagram illustrating a state in which a slack is formed at a leading end of the sheets stacked on the sheet feeding tray.

FIG. 8 is an enlarged view of a main part of an image forming apparatus according to a second embodiment of the present invention.

FIG. 9 is a block diagram of a control device of the image forming apparatus.

FIG. 10 is a diagram illustrating an entire configuration of an image forming apparatus including a conventional sheet conveying device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sheet conveyance device 21 Sheet first conveyance guide part 22 Sheet second conveyance guide part 22c Detection lever 23 Sheet third conveyance guide part 24 Sheet fourth conveyance guide part 31 Sheet first conveyance part 32 Sheet second conveyance part 33 Sheet second 3 transport section 34 sheet 4th transport section 41 sheet 5th transport section 51 sheet 6th transport section 61 sheet 7th transport section 61c sheet thickness detecting means 83 control device 86 upper paper feed cassette 87 lower paper feed cassette 88 paper feed tray

Claims (10)

[Claims] 1. A sheet, which is stacked on a plurality of sheet stacking means and selectively conveyed from a sheet conveyance path provided for each of the plurality of sheet stacking means, slacks in a conveying width direction of a sheet leading end. In the sheet conveying device that performs the alignment in the above, the slack forming amount of the sheet leading end portion at the time of the alignment,
A sheet conveying apparatus characterized by changing according to the sheet conveying path. 2. A sheet, which is stacked on a plurality of sheet stacking means and is selectively conveyed from a sheet conveyance path provided corresponding to each of the plurality of sheet stacking means, slacks in a conveying width direction of a sheet leading end. In the sheet conveying device, the sheet is conveyed from the sheet conveying path to form a slack in the front end of the sheet by contacting the front end of the sheet, thereby adjusting the position of the front end of the sheet in the conveying width direction. Positioning means for performing, a conveying means for discharging the sheets stacked on the sheet stacking means to the sheet conveying path, and then conveying the sheets toward the positioning means, wherein the sheet abuts on the positioning means. After the slack is formed, the conveying means is stopped, and the amount of slack formed at the leading end of the sheet during the alignment is determined by the sheet. Control means for changing the time from when the sheet comes into contact with the positioning means to when the sheet is stopped so as to change according to the shape of the sheet conveying path. 3. The sheet conveying path having a smaller curvature in the sheet conveying path having a smaller curvature such that a sheet having a smaller curvature in the sheet conveying path has a smaller slack forming amount than a sheet having a larger curvature in the sheet conveying path. 3. The sheet conveying apparatus according to claim 2, wherein a time period from when the conveying unit comes into contact with the positioning unit to when the conveying unit is stopped is shortened. 4. The apparatus according to claim 1, wherein the control unit is configured to reduce the amount of slack formed in the substantially straight sheet conveyance path as compared with the curved sheet conveyance path. 3. The sheet conveying apparatus according to claim 2, wherein a time from when the sheet comes into contact with said positioning means to when said conveying means is stopped is shortened. 5. The control device according to claim 2, wherein the control unit controls the conveying unit so as to reduce a slack amount of the leading end of the sheet after performing the alignment.
The sheet conveying device according to any one of the above. 6. The control device according to claim 1, wherein the control unit drives the conveyance unit again after the sheet contact operation of the positioning unit is canceled so as to reduce the slack amount of the sheet leading end. 5. The sheet conveying device according to 5. 7. A sheet, which is stacked on a plurality of sheet stacking means and is selectively conveyed from a sheet conveyance path provided for each of the plurality of sheet stacking means, slacks in a conveying width direction of a sheet leading end. In the sheet conveying apparatus, the sheet is conveyed from the sheet conveying path to form a slack in the front end of the sheet by contacting the front end of the sheet, and the position of the front end of the sheet in the conveying width direction is adjusted. Positioning means for performing, sheet conveying means for discharging the sheets stacked on the sheet stacking means to the sheet conveying path, and then conveying the sheets toward the position adjusting means, thickness detection for detecting the thickness of the sheet Means, after the sheet abuts on the positioning means to form a slack, stops the transport means and performs the positioning. The conveying means is stopped after the sheet comes into contact with the positioning means based on a detection signal from the thickness detecting means so as to change the slack forming amount of the sheet leading end in accordance with the thickness of the sheet. And a control means for changing a time until the sheet is conveyed. 8. When the thick sheet is conveyed such that the slack formation amount is smaller in a thick sheet than in a thin sheet, the control means may control the conveyance after the sheet comes into contact with the positioning means. 7. The sheet conveying apparatus according to claim 6, wherein the time until the means is stopped is shortened. 9. The control device according to claim 1, wherein the control unit drives the conveyance unit again after the sheet contact operation of the positioning unit is canceled so as to reduce the slack amount of the sheet leading end. 8. The sheet conveying device according to 6 or 7. 10. An image forming apparatus provided with an image forming section and a sheet conveying device, wherein the sheet conveying device is the sheet conveying device according to any one of claims 1 to 9. Forming equipment.