JP3450603B2 - Sheet conveying device and sheet processing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device,
The present invention relates to a sheet conveying device provided in a sheet processing device such as a copying machine, a printer, and a facsimile. In the present specification, an apparatus having a sheet processing unit that performs a predetermined process (for example, reading an image, forming an image, etc.) on sheets fed one by one is referred to as a sheet processing apparatus. ing.

[0002]

2. Description of the Related Art In a sheet processing apparatus such as an image reading apparatus or a copying machine, a skewed sheet is corrected so that a fed sheet can be correctly processed by a sheet processing section (image reading section, image forming section, etc.). The skewed state (posture) of the sheet toward the sheet processing unit is corrected by using the means. There are various types of skew correcting means, but the digitized sheet processing apparatus uses an active skew correcting means for correcting skew while nipping and conveying a sheet. In many cases.

The skew feeding correcting means of the active system is composed of two left and right registration roller pairs installed at the same position in the sheet conveying direction. The two registration roller pairs on the left and right are driven by individual motors (step motors). Then, while the two registration roller pairs on the left and right sides are sandwiching and conveying the sheet, the conveyance speed of one of the registration roller pairs is changed (a speed difference is provided between the registration roller pairs), so that the sheet is skewed. To correct.

By the way, in the case of such an active type skew feeding correcting means, when the pair of left and right registration rollers corrects the skew feeding of the sheet, the other roller pair does not sandwich the sheet. However, this is a condition for correctly correcting the skew of the sheet. For this purpose, it is necessary that the trailing edge of the sheet has already passed through the nip of the transport roller pair upstream of the registration roller pair when the pair of left and right registration rollers start correcting the skew. This is because if the trailing edge of the sheet is sandwiched by the nip of the pair of transport rollers, it becomes difficult to rotate the skewed sheet by the pair of registration rollers until the sheet is in the correct posture.

However, in the case of a sheet of a size other than the specific size, the trailing edge of the sheet does not pass through the nip between the registration roller pair and the upstream conveyance roller pair even when the registration roller pair starts correcting skew. The sheet being skew-corrected is also in a state of being conveyed by the conveying roller pair (a state of being sandwiched by a nip). This is because the position of the transport roller pair is determined according to the sheet of a specific size.

Conventionally, as a countermeasure for this, when the sheet to be fed is a sheet having a size other than a specific size, when the registration roller pair corrects the skew of the sheet, the registration roller pair and the upstream conveyance roller pair are corrected. The sheet sandwiching state is released so that the pair of conveyance rollers does not sandwich the sheet being skew-corrected. Generally, in the conveying roller pair, the driven side roller can be brought into contact with and separated from the driving side roller whose position is fixed. Normally, the driven roller is biased by a spring and comes into contact with the driving roller with a predetermined pressure to hold the sheet.However, when the driven roller is separated from the driving roller by a solenoid or the like, the sheet holding state is released. To do.

[0007]

However, in the case of the above measures, the sheet holding state of the conveying roller pair must be already released at the time when the registration roller pair starts correcting the skew feeding. If there is a problem (delay occurs) in the response performance of the solenoid or the like that separates the driven side roller from the roller, the timing of releasing the sheet holding state of the conveying roller pair is shifted, and the effect of releasing the sheet holding state is diminished. That is, if the release timing of the sheet sandwiched state is shifted, a sheet in which skew feeding is not correctly corrected is sent to the sheet processing unit. This problem is more likely to occur as the sheet conveying speed is higher and the distance from the registration roller pair to the sheet processing unit is shorter.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sheet conveying apparatus capable of feeding a sheet in which skew feeding is correctly corrected to a sheet processing unit.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a downstream sheet conveying means for correcting a skewed state of a sheet upstream of a sheet processing section while nipping and conveying the sheet, and a sheet sandwiched by the downstream sheet conveying means. The present invention relates to a sheet conveying device including an upstream sheet conveying unit that conveys an upstream sheet.

According to the first aspect of the present invention, a downstream sheet conveying means capable of correcting skew of the sheet while nipping and conveying the sheet, and a sheet conveying direction of the downstream sheet conveying means. Before the sheet is conveyed by the upstream sheet conveying means, which is provided on the upstream side and nips and conveys the sheet to the downstream sheet conveying means, and before the skew correction is started for the sheet conveyed by the downstream sheet conveying means. First, after decelerating the sheet being conveyed at the speed V1 by the upstream side conveying means to the speed V3, the nipping of the sheet by the upstream side sheet conveying means is released, and then the conveying speed of the sheet is changed from V3 to V1. And a control unit for increasing the speed. The present invention according to claim 2 is characterized in that a skewed state detection means for detecting a skewed state of the sheet is arranged on the downstream side of the downstream side sheet transport means in the sheet transport direction. Located in the sheet transport device. In the present invention according to claim 3, the control unit is configured to perform a sheet conveyance speed during a period from the detection of the sheet by the skewed state detection unit to the start of correction of the skewed state by the downstream side sheet conveyance unit. 3. The sheet conveying apparatus according to claim 2, wherein after the speed V1 is reduced to the speed V3, the sheet holding state of the upstream side sheet conveying means is released, and then the speed is increased from the speed V3 to the speed V1. is there. According to a fourth aspect of the present invention, the time required to release the sheet sandwiched state of the upstream side sheet conveying means is S, and the distance between the sheet processing section and the skewed state detecting means is L.
1. When the distance required for the skew feeding correction by the downstream side sheet conveying means is L2 and the distance required for increasing the speed from V3 to V1 is m, the speed V3 is V3 <(L1-L
The sheet conveying apparatus according to claim 3, wherein the sheet conveying apparatus has a relationship of 2-m) / S. According to a fifth aspect of the present invention, there is provided a first sheet leading edge detecting means that is provided on the upstream side of the skew feeding state detecting means in the sheet conveying direction, and detects a sheet leading edge, and the control means includes the first sheet leading edge detecting means. In the period from the detection of the front end of the sheet by the sheet front end detection unit to the detection of the sheet by the skewed state detection unit, the conveyance speed of the sheet is set to the speed V2 of V1>V2> V3. The sheet conveying apparatus according to claim 3, wherein the sheet conveying apparatus is decelerated. The present invention according to claim 6 is characterized in that the first sheet leading edge detecting means is arranged upstream of the downstream sheet conveying means in the sheet conveying direction. It is in. The present invention according to claim 7 has a second sheet leading edge detecting means for detecting the leading edge of the sheet between the downstream side sheet conveying means and the skewed state detecting means, and the control means includes the second sheet leading edge detecting means. After the sheet leading edge detecting means detects the leading edge of the sheet and before the skewed state detecting means detects the sheet, the sheet conveying speed V1 is reduced to the speed V3, and then the upstream side sheet conveying means. 3. The sheet conveying apparatus according to claim 2, wherein the sheet nip state is released, and then the speed is increased from the speed V3 to the speed V1. The present invention according to claim 8 is
The time required to release the sheet sandwiched state of the upstream side sheet conveying means is S, the distance between the second sheet leading edge detecting means and the skewed state detecting means is L3, and the speed is increased from V3 to V1. The sheet conveying apparatus according to claim 7, wherein the speed V3 has a relationship of V3 <(L3-m) / S, where m is a distance required for the sheet conveyance. According to a ninth aspect of the present invention, there is provided a third sheet leading edge detecting means which is provided on the upstream side of the second sheet leading edge detecting means in the sheet conveying direction and detects a leading edge of the sheet, and the control means includes The conveyance speed of the preceding sheet is V1>V2> from the time the third sheet leading edge detecting means detects the leading edge of the sheet until the second sheet leading edge detecting means detects the sheet. 8. The sheet conveying apparatus according to claim 7, wherein the speed is reduced to V3 which is V3. The present invention according to claim 10 is characterized in that the third sheet leading edge detecting means is arranged upstream of the downstream sheet conveying means in the sheet conveying direction. It is in. The present invention according to claim 11 provides
The sheet conveying device according to claim 1, wherein the downstream side sheet conveying means is two independent roller pairs arranged on the same line in the sheet width direction orthogonal to the sheet conveying direction. The present invention according to claim 12 is
12. The sheet conveying apparatus according to claim 11, wherein the two independent roller pairs are driven by a stepping motor provided corresponding to each roller pair. The present invention according to claim 13 is characterized in that the upstream side sheet conveying means is a roller pair, and at least one of the rollers of the roller pair moves in a direction to release the nipping of the sheet by operating a solenoid. The sheet conveying apparatus according to claim 1. Claim 1
The present invention according to claim 4, wherein the skewed state detecting means uses two left and right transmissive photosensors arranged on the same line in the sheet width direction orthogonal to the sheet conveying direction. The sheet conveying apparatus according to item 2.
The present invention according to claim 15 is characterized in that a transmissive photosensor is used for the first, second, and third sheet leading edge detection means. It is in the described sheet conveying device. According to a sixteenth aspect of the present invention, there is provided the sheet conveying device according to any one of the first to fifteenth aspects, and a sheet processing unit that performs a predetermined process on the sheet conveyed from the sheet conveying device. It is a feature of the sheet processing apparatus.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 shows the overall configuration of an image reading apparatus (sheet processing apparatus) including a sheet conveying apparatus according to the present invention.

On the original placing table 15 on which a plurality of originals (sheets) C are placed, the abutting surface 15 for abutting the leading edge of the original C on the lower side of the gently inclined original placing surface 15a in the inclination direction.
b is formed.

A paper feed roller 1 is installed above the original placing table 15 on the abutting surface 15b side. This paper feed roller 1
Touches the uppermost document C stacked on the document table 15 with a predetermined pressing force. Then, when the paper feed roller 1 is rotated in the clockwise direction, the uppermost original is fed out in order.

The original document C fed by the paper feed roller 1
Are separated one by one by the separation roller pair 2, and only the uppermost original C is fed. The fed document C is transported by the transport roller pairs 3 to 8 and reaches the active type registration roller pair 9-1. While being conveyed by the pair of registration rollers 9-1, the skew of the document is corrected and the document passes through the image reading position B. At this time, the reading of the image is ended in the single-sided reading mode, and the reading of the image on the first side is ended in the double-sided reading mode. A platen glass 17 is installed at the reading position B.

The original C which has passed the reading position B has a pair of rollers 9-2 which also serves as a pair of active registration rollers.
Sent to path 19. At this time, flapper 4
3, 18a are in the positions shown by the dotted lines, and the flapper 18b is in the position shown by the solid lines. In the single-sided reading mode, the document C guided to the path 19 is conveyed by the pair of conveying rollers 20 and 28, and then is discharged by the pair of discharging rollers 37 to the discharging tray 2.
7 is discharged. At this time, the flapper 25 is in the position shown by the dotted line.

In the double-sided reading mode, the document C guided to the path 19 is sent to the reversing path 21 by the pair of transport rollers 20 and 28, and then to the path 22 by the pair of transport rollers 29 and 30. At this time, the flapper 25 is in the position shown by the solid line. The flapper 18b is located at the position shown by the dotted line. While passing through the reversing path 21, the document C is reversed so that the second surface is on the lower side. The document C sent to the path 22 is transported by the transport roller pairs 31 and 32 and reaches the active type registration roller pair 9-2. Then, while being conveyed by the pair of registration rollers 9-2, the skew of the document is corrected and the document passes through the reading position B. At this time, the reading of the image on the second surface is completed.

The document C that has passed the reading position B is sent to the path 23 by the roller pair 9-1, and is conveyed to the conveying roller pair 3
After being conveyed by Nos. 4 to 36, the sheet is ejected onto the sheet ejection tray 27 by the pair of ejection rollers 37. At this time, the flappers 18a and 25 are at the positions shown by the solid lines. When the trailing edge of the document C passes through the flapper 18a, the flapper 18a
Is switched to the position shown by the dotted line, and the flapper 18b is switched to the position shown by the solid line to prepare for the conveyance of the next document.

Here, the structure of the active type registration roller pair 9-1, 9-2 will be described with reference to FIG.

The registration roller pair 9-1 is composed of two right and left roller pairs 9-1 which are arranged at the same position in the document conveying direction.
a, 9-1b. Also, the registration roller pair 9-2
Is composed of two right and left roller pairs 9-2a and 9-2b arranged at the same position in the document transport direction.

Drive from individual step motors (not shown) is transmitted to each roller pair 9-1a, 9-1b and each roller pair 9-2a, 9-2b of the registration roller pair 9-2. ing. Left and right roller pairs 9-
1a, 9-1b and 9-2a, 9-2b usually rotate at the same speed to convey the document C.

The pair of rollers 9-1a and 9-1b function as an active type registration roller pair when the document C fed from the document mounting table 15 moves in the document transport direction (1). The rotation speed of one roller pair is increased or decreased to correct the skew of the document C. Further, the original C fed from the original placing table 15 (and the original C fed from the original placing table 38 described later) is in the original conveying direction (2).
When it moves in the direction of, it functions as a pair of conveyance rollers. At this time, the roller pairs 9-1a and 9-1b rotate at the same speed.

The leading edge of the document C transported from the document transport direction (1) is placed on the left and right sides 2 at the same position in the document transport direction immediately downstream of the roller pairs 9-1a and 9-1b.
Two skew state detection sensors (transmission type photo sensor) 10
a and 10b detect and output to CPU60 which controls operation | movement of the whole image reading apparatus. The CPU 60 calculates the inclination of the document C based on the information sent from the skew feeding state detection sensors 10a and 10b, and changes (accelerates or decelerates) the rotational speed of either roller pair.

The roller pairs 9-2a and 9-2b are used for the document C (and the document table 38 described later) fed from the document table 15.
When the document C fed from the document C moves in the document transport direction (2), it functions as an active type registration roller pair, and the rotation speed of either one of the roller pairs is accelerated or decelerated so that the document C Correct skew. When the document C fed from the document table 15 moves in the document transport direction (1), it functions as a pair of transport rollers. At this time, the roller pairs 9-2a and 9-2b rotate at the same speed.

The leading edge of the document C transported from the document transport direction (2) is placed at the right and left 2 at the same position in the document transport direction immediately downstream of the roller pairs 9-2a and 9-2b.
Two skew state detection sensors (transmission type photo sensor) 10
c and 10d detect and output to the CPU 60. CPU6
0 calculates the inclination of the document C based on the information sent from the skewed state detection sensors 10c and 10d, and changes (accelerates or decelerates) the rotation speed of any roller pair.

In the present image reading apparatus, a plurality of original images are read by repeating the above-mentioned operation. However, since the original C is conveyed while correcting the skew feeding, the minimum original interval (paper It becomes possible to perform the reading process continuously during (interval). Further, it is also possible to feed the originals at intervals such that a plurality of (for example, two) originals are continuously fed into the reverse path 21. In this case, since the document is fed every two sheets, the second surface of the second sheet passes the platen glass 17 and then the first surface of the third sheet passes the platen glass 17. To increase the productivity in the double-sided reading mode, the registration roller pair 9-1,
The interval 9-2 is shortened to reduce the distance between sheets and the sheet is conveyed.

In the image reading apparatus, the document placing table 1
Since the document C fed from 5 is a standard size document, the conveying roller pairs 4 to 8 and the like are arranged according to several document sizes which are predetermined. When the document C is placed on the document placing table 15, or when the document placing table 15 is placed.
When a document C is fed from the document C, the document size detection sensor (not shown) detects the document size, separates the roller pairs other than the roller pair suitable for the document size (releases the document clamping state), and corrects the skew feeding. Sometimes, the document C is conveyed only by the registration roller pair 9-1 or 9-2.

In this image reading apparatus, thick paper, thin paper,
When reading a document such as a folded sheet that is not conveyed properly, the document C is manually fed one by one from the document placing table 38 so that the document C moves along substantially linear paths 42, 22, and 44.

The original C placed on the original placing table 38 is sent out by a paper feed roller 39, and a pair of conveying rollers 40,
It is conveyed by 41, 31, and 32 and reaches the registration roller pair 9-2. And the registration roller pair 9-2
While being conveyed, the skew of the document is corrected and the document passes through the reading position B. The document C that has passed the reading position B is sent to the path 44 by the roller pair 9-1 and then discharged to the outside by the discharge roller pair 45. At this time, the flappers 18b and 18a are in the positions shown by the dotted lines, and the flapper 43 is in the position shown by the solid lines.

In the case of the present image reading apparatus, the document placing table 38
The original C that is manually fed from is often an irregular size. Therefore, the active registration roller pair 9-2
The document C whose skew correction has been started while being nipped and conveyed by may be simultaneously conveyed (nipped) to the conveyance roller pair 32 or 31. In such a case, the skew feeding correction is not performed correctly, and therefore the original holding state of the conveying roller pair 32 or 31 must be released.

In this image reading apparatus, FIG.
As shown in FIG. 5, the document nipping state of the conveying roller pairs 31 and 32 can be released. Conveyor roller pair 31, 3
2, the driving side roller (lower roller) is fixed in position, and the driven side roller (upper roller) can come into contact with and separate from the driving side roller. The driven roller is in contact with the driving roller with a predetermined pressure by a spring, but can be separated from the driving roller by solenoids 46 and 47. This state is the state of releasing the document sandwiched state.

An original size detection sensor 61 installed in the path 42 detects the size of the original C manually fed from the original placing table 38 and outputs it to the CPU 60. CPU
Reference numeral 60 denotes a pair of conveyance rollers that should release the document sandwiched state from the information (size) sent from the document size detection sensor 61 when the fed document C is straightened by the registration roller pair 9-2. Then, the solenoid of the conveying roller pair is turned on. FIG. 2B shows a state in which the solenoid 47 is turned on and the document nipping state of the conveyance roller pair 32 is released.

However, if the timing of turning on the solenoid deviates due to the delay in the response of the solenoid, the pair of conveying rollers 32 (or 32, 31) even after the registration roller pair 9-2 starts skew correction of the original c. Sometimes holds the document C, and in such a case, the document c passes the reading position B without correct skew correction.

Therefore, the CPU 60 of the image reading apparatus
Even if the solenoid-on timing is deviated due to the delay in the responsiveness of the solenoid, the transport roller pair 32 (or 32, 31) is surely provided at the time when the registration roller pair 9-2 starts skew correction. The control is performed so that the release of the original sandwiched state is completed, and the original C, which is correctly skew-corrected, is sent to the reading position B.

FIG. 3 shows an example of control operation performed by the CPU.

The CPU 60 uses the skewed state detection sensor 10
When c and 10d detect the leading edge of the document, before the registration roller pair 9-2a and 9-2b start skew correction,
After the document transport speed is reduced from V1 to V3, the document sandwiching state of the transport roller pair 32 is released (the solenoid 47 is turned on), and then the speed is increased from V3 to V1.
Here, the time required to release the document nipping state of the conveying roller pair 32 is S, the image reading position B, and the skewed state detection sensor 1.
The distance between 0c and 10d is L1, the registration roller pair 9
-2a, 9-2b, L2 is the distance required for skew correction, and m is the distance required for increasing the speed from V3 to V1, the speed V3 is V3 <(L1-L2-m) / S.
Have a relationship.

In this way, the document conveyance speed is changed from V1 to V
Since the document nipping state of the conveying roller pair 32 is released after decelerating to 3, the distance that the document is conveyed when the document nipping state is released becomes short, and even if the solenoid is delayed, the registration roller pair 9-2a, By the time 9-2b starts skew correction, the document holding state of the transport roller pair 32 can be reliably released. <Second Embodiment> FIG. 4 shows another control operation example (1) of the CPU 60.

In the case of the control operation example of FIG. 3, when the conveying speed becomes high and it takes time and distance to raise and lower the conveying speed, as shown by an imaginary line in FIG. The skew correction is started before reaching the speed V1 from V3. Considering the variation in speed increase, the skew correction accuracy becomes low, and thus the skew correction becomes difficult. In order to solve such a problem, here, as indicated by a solid line, the speed at which the document C enters the skewed state detection sensors 10c and 10d is reduced (speed V2), so that the skewed state detection sensor is detected. The distances 10c and 10d required for decelerating the conveyance speed (V1 to V3) after detecting the document C are shortened. When the document detection sensor (transmissive photosensor) 50 arranged upstream of the pair of registration rollers 9-2a and 9-2b detects the leading edge of the document, the CPU 60 causes the skewed state detection sensors 10c and 10d to detect the leading edge of the document. The document conveyance speed V1 is reduced to V2 until the detection of "1". <Third Embodiment> FIG. 5 shows another control example (2) of the CPU 60.

Here, the pair of registration rollers 9-2a, 9-2
A document detection sensor 51 is provided immediately downstream of -2b. C
When the document detection sensor 51 detects the leading edge of the document, the PU 60 reduces the document transportation speed V1 to V3 until the skew feeding state detection sensors 10c and 10d detect the leading edge of the document, and then the transport roller. The document sandwiched state of the pair 32 is released, and then the speed is increased from V3 to V1. Here, the time required to release the document nipping state of the conveying roller pair 32 is S, the document detection sensor 51 and the skewed state detection sensor 10
The distance between c and 10d is L3, the speed V3 to the speed V1
If the distance required to accelerate to
3 has a relationship of V3 <(L3-m) / S.

In the case of this control operation example, when the leading edge of the document reaches the skew detection sensors 10c and 10d, the document nipping state of the transport roller pair 32 is already released, and the document transport speed is also increased to V1. . Therefore, the conveyance speed from the time when the document passes through the skew detection sensors 10c and 10d to when the skew correction is completed can be kept constant (V3).
The registration roller pair 9-2a and 9-2b and the registration roller pair 9-1a, which are caused by raising and lowering the document conveyance speed,
A slight phase shift of each motor (step motor) does not occur between 9-1b, and skew correction can be performed with higher accuracy. <Fourth Embodiment> FIG. 6 shows another control operation example (3) of the CPU 60.

In the case of the control operation example of FIG. 5, when the conveyance speed becomes fast and it takes time and distance to raise and lower the conveyance speed, as shown by an imaginary line in FIG. Since the leading edge of the document passes through the skew detection sensors 10c and 10d before reaching the speed V1 from V3, the skew detection accuracy becomes low in consideration of variations in speedup, and thus skew correction becomes difficult. . In order to solve such a problem, here, as indicated by the solid line, the speed at which the document detection sensor 51 and the document enter is reduced (speed V
By doing so, the distance required for deceleration of the conveyance speed (V1 to V3) performed after the document detection sensor 51 detects the document C is shortened. When the document detection sensor (transmissive photosensor) 52 disposed upstream of the pair of registration rollers 9-2a and 9-2b detects the leading edge of the document, the CPU 60 waits until the document detection sensor 51 detects the leading edge of the document. During this period, the document transport speed V1 is reduced to V2.

[0041]

As described above, according to the sheet carrying apparatus of the present invention, the sheet carrying means releases the sheet holding state while the sheet carrying speed is reduced, so that the sheet holding method is performed. The distance that the sheet is conveyed becomes shorter when the state is released. Therefore, even if there is a delay in the response of the solenoid or the like for canceling the sheet sandwiching state of the sheet conveying means, the sheet sandwiching state of the sheet conveying means can be surely maintained before the skew correction of the sheet is started. It can be canceled and highly accurate skew correction can be performed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view showing the overall configuration of an image reading apparatus (sheet processing apparatus) including a sheet conveying apparatus of the present invention.

FIG. 2 is a perspective view showing a configuration of a sheet conveying device of the present invention.

FIG. 3 is a diagram (FIG. 3 (a)) showing a positional relationship between respective members of the sheet conveying apparatus of the present invention and a diagram (FIG. 3 (b)) showing a sequence.
).

FIG. 4 is a diagram showing the positional relationship of each member (FIG. 4 (a)) and a sequence showing FIG. 4 (b) in another structural example (1).
).

FIG. 5 is a diagram showing the positional relationship of each member (FIG. 5 (a)) and a sequence diagram (FIG. 5 (b)) in another configuration example (2).
).

FIG. 6 is a diagram showing the positional relationship of each member (FIG. 6 (a)) and a sequence diagram (FIG. 6 (b)) in another configuration example (3).
).

[Explanation of symbols]

9-2a, 9-2b Registration roller pair (downstream sheet conveying means) 10a, 10b Oblique state detection sensor (oblique state detecting means) 17 Platen glass (sheet processing unit) 32 Conveying roller pair (upstream sheet conveying means) ) 47 solenoid 50 original detection sensor (first sheet leading edge detection means) 51 original detection sensor (second sheet leading edge detection means) 52 original detection sensor (third sheet leading edge detection means) 60 CPU (control means) C original (Sheet)

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Claims (16)

(57) [Claims] 1. A downstream sheet conveying means capable of correcting skew of the sheet while nipping and conveying the sheet; and a downstream side sheet conveying means provided upstream of the downstream sheet conveying means in the sheet conveying direction. An upstream sheet conveying means for nipping and conveying the sheet to the downstream sheet conveying means, and the upstream conveying means before starting skew correction for the sheet conveyed by the downstream sheet conveying means A control unit that decelerates the sheet being conveyed at a speed V1 to a speed V3, releases the nipping of the sheet by the upstream sheet conveying unit, and then increases the sheet conveying speed from V3 to V1. A sheet conveying device comprising: 2. The sheet conveying apparatus according to claim 1, further comprising a skewed state detecting unit for detecting a skewed state of the sheet, which is arranged downstream of the downstream sheet conveying unit in the sheet conveying direction. 3. The sheet conveying speed V between the detection of the skewed state detecting unit and the start of correction of the skewed state by the downstream side sheet conveying unit.
3. The sheet conveying apparatus according to claim 2, wherein after decelerating 1 to the speed V3, the sheet sandwiching state of the upstream side sheet conveying means is released, and then the speed is increased from the speed V3 to the speed V1. 4. The time required to release the sheet sandwiched state of the upstream sheet conveying means is S, the distance between the sheet processing section and the skewed state detecting means is L1, and the downstream sheet conveying means is inclined. When the distance required for line correction is L2 and the distance required to increase the speed from V3 to V1 is m, the speed V3 has a relationship of V3 <(L1-L2-m) / S. The sheet conveying device according to claim 3. 5. A first sheet leading edge detecting means for detecting a sheet leading edge is provided on the upstream side of the skew feeding state detecting means in the sheet conveying direction, and the control means has the first sheet leading edge detecting means. Between the detection of the leading edge of the sheet by the means and the detection of the sheet by the skewed state detection means, the conveyance speed of the sheet is reduced to the speed V2 of V1>V2> V3. The sheet conveying apparatus according to claim 3, which is characterized in that. 6. The sheet conveying apparatus according to claim 5, wherein the first sheet leading edge detecting unit is arranged upstream of the downstream sheet conveying unit in the sheet conveying direction. 7. A second sheet leading edge detecting means for detecting the leading edge of the sheet between the downstream side sheet conveying means and the skewed state detecting means, wherein the control means detects the second sheet leading edge. The sheet conveying speed V1 is reduced to the speed V3 between the time when the means detects the leading edge of the sheet and the time when the skewed state detecting means detects the sheet, and then the sheet is clamped by the upstream side sheet conveying means. 3. The sheet conveying apparatus according to claim 2, wherein the speed is released, and then the speed is increased from V3 to V1. 8. The time required to release the sheet sandwiched state of the upstream side sheet conveying means is S, the distance between the second sheet leading edge detecting means and the skewed state detecting means is L3, and the speed is from V3 to speed. The distance required to accelerate to V1 is m
The sheet conveying apparatus according to claim 7, wherein the speed V3 has a relationship of V3 <(L3-m) / S. 9. A third sheet leading edge detecting means is provided upstream of the second sheet leading edge detecting means in the sheet conveying direction to detect the leading edge of the sheet, and the control means includes the third sheet leading edge detecting means. After the sheet leading edge detecting unit detects the leading edge of the sheet and before the second sheet leading edge detecting unit detects the sheet, the conveyance speed of the preceding sheet is V1>
8. The sheet conveying apparatus according to claim 7, wherein the speed is reduced to a speed V2 that is V2> V3. 10. The sheet conveying apparatus according to claim 9, wherein the third sheet leading edge detecting means is arranged upstream of the downstream sheet conveying means in the sheet conveying direction. 11. The sheet according to claim 1, wherein the downstream sheet conveying means is a pair of independent rollers arranged on the same line in a sheet width direction orthogonal to the sheet conveying direction. Transport device. 12. The sheet conveying apparatus according to claim 11, wherein the two independent roller pairs are driven by a stepping motor provided corresponding to each roller pair. 13. The upstream sheet conveying means is a pair of rollers, and at least one of the rollers of the pair of rollers moves in a direction to release the sheet from being pinched by a solenoid operation. 1. The sheet conveying device according to 1. 14. The skewed state detecting means includes two left and right transmissive photosensors arranged on the same line in the sheet width direction orthogonal to the sheet conveying direction. The sheet conveying device described. 15. The sheet conveying according to claim 5, wherein a transmissive photosensor is used for the first, second and third sheet leading edge detecting means. apparatus. 16. A sheet, comprising: the sheet conveying device according to claim 1; and a sheet processing unit that performs a predetermined process on the sheet conveyed from the sheet conveying device. Processing equipment.