JPH101239A - Sheet conveyance device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct skewing of a sheet even when sheet size, paper surface quality or the like changes, by adjusting pressure-contact force against a belt surface according to the degree of skewing of sheet for optimization of the degree of slippage and constraint of the sheet against a belt surface. SOLUTION: This device is provided with an endless belt 6 which is tensed by two rollers and rotated by the driving force of a driving roller, fans 8a, 8b for pressuring a sheet present on the external surface of the endless belt 6 against the external surface by blowing air over the external surface, sensors 4a, 4b for detecting that the sheet is conveyed with the sheet front edge kept not orthogonal to the sheet conveying direction, and a control means for controlling the blowing air amount of the fans 8a, 8b according to the detected results by the sensors 4a, 4b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for conveying sheets such as manuscript paper and recording paper. In particular, the present invention relates to an apparatus having a function of correcting a skew state of a sheet.

[0002]

2. Description of the Related Art In an apparatus for feeding manuscript paper onto a manuscript reading table at a predetermined timing, the manuscript paper is temporarily stopped at a position immediately before paper feeding and made to wait, and then the manuscript paper is synchronized with the above timing. Paper is being fed. Similarly, in an apparatus that feeds a recording sheet to the image recording unit at a predetermined timing, the recording sheet is temporarily stopped at a position immediately before the sheet is fed and then put on standby, and then fed in synchronization with the timing. ing.

The above-mentioned temporary stop / standby and sheet feeding synchronized with the predetermined timing are performed, for example, as shown in FIG. Initially, the timing roller pair 10 is stopped. First, the paper (document paper or recording paper) P is fed from the right side to the left side in the drawing by the feed roller pair 100, and the leading edge of the paper P comes into contact with the nip of the timing roller pair 10. Subsequently, the rear end side of the sheet P is fed by the feed roller pair 100. Then, since the timing roller pair 10 is stopped as described above, the sheet P is curved as shown in the figure.

In this state, the rotation of the feed roller pair 100 is temporarily stopped. Next, at the predetermined timing,
The timing roller pair 10 and the feed roller pair 100 are simultaneously rotated in the same direction. Thereby, the skew of the sheet P is corrected, and the sheet P is fed to the left of the timing roller pair 10, that is, on the document reading table or the image recording unit. Skew means that the traveling direction of the paper P is due to poor side regulation of the paper P or the like.
It means a slight deviation from the original traveling direction. The force for pushing the sheet P into the nip of the pair of timing rollers 10 is given by the above-described bending of the sheet P.

Japanese Patent Laid-Open Publication No. Hei 7-33281 discloses FIG.
As shown in FIG. 1B, an apparatus is disclosed in which a recording sheet P is conveyed while being suctioned by air through a large number of holes 200a of a conveying belt 200 and adsorbed on a belt surface.

In this apparatus, the leading edge of the sheet P is a stopper.
Until the sheet P comes into contact with the sheet 201, the sheet P is conveyed while being restrained by the conveying belt 200 by the suction force of air. Next, when the leading edge of the sheet P comes into contact with the stopper 201, the suction of the air is stopped, and the rotation driving of the transport belt 200 is continued. That is, a conveying force is applied to the sheet P without restraining the sheet P by the conveying belt 200. As a result, the sheet P stopped by the stopper 201 slips on the transport belt 200, and the skew of the sheet P is corrected. When the skew of the sheet P is corrected in this way, the stopper 201 is retracted, and the suction of the air is restarted. Thus, the sheet P is conveyed to the left in the figure while being constrained by the conveying belt 200 by the suction force of air, and reaches an image recording unit (not shown).

[0007]

In the method shown in FIG. 10A, the leading end of the sheet P is brought into contact with the nip of the timing roller pair 10 by a force caused by the bending (loop) of the sheet P, and The skew is corrected according to the nip. For this reason, in the case of a paper having a weak force such as a paper having a weak stiffness or a paper having a damage such as a curl, a wrinkle, or a bend, there is a possibility that the skew cannot be sufficiently corrected. In addition, even if the paper is strongly stiff, if the degree of skew is large, the correction may be insufficient.

In the system disclosed in Japanese Patent Application Laid-Open No. 7-33281, since the paper P is sucked from the belt surface side through the large number of holes 200a, the pressure contact force has a nonuniform location, and is locally strong. The paper P is pressed against the belt surface by force.
Also, since the surface to which the pressing force (suction force) is applied is the same as the slip surface at the time of skew correction, the paper P is appropriately slipped while the pressing force is applied to restrain the paper P on the belt surface. It is difficult to let. Therefore, when correcting the skew, the suction of the air is stopped and the restraint of the paper P is completely released. However, if so, the size of the paper P, the paper quality (friction) of the surface of the paper P, etc. The degree of slip on the belt surface varies depending on the type of document. Therefore, in the case of so-called mixed document feeding, in which document sheets of different sizes are continuously fed, it may be difficult to satisfactorily correct skew. There is.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transport device capable of appropriately slipping a sheet P while the sheet P is appropriately restrained by applying a pressing force. Another object of the present invention is to make it possible to correct the skew of the sheet P by appropriately slipping the sheet P as described above. Further, an object of the present invention is to adjust the pressing force according to the degree of skew of the sheet P, thereby optimizing the degree of slip of the sheet P and the degree of restraint of the sheet P, and the size and the size of the sheet P An object of the present invention is to make it possible to correct the skew of the sheet P even when the surface paper quality or the like changes. Another object of the present invention is to make it possible to sufficiently correct the skew of the sheet P by making the pressing force different in the direction perpendicular to the conveyance of the sheet P.

[0010]

According to a first aspect of the present invention, there is provided an endless belt stretched by at least two rollers including a driving roller and rotated by a driving force of the driving roller, and an outer surface of the endless belt. And an air blowing means for pressing a sheet on the outer surface against the outer surface by blowing air toward the sheet conveying device. According to the first aspect of the present invention, since a force for pressing the sheet against the endless belt surface is given by blowing air, the sheet can be slipped appropriately with respect to the belt surface in a state where the sheet is appropriately restrained on the belt surface. Become.

According to a second aspect of the present invention, in the first aspect of the present invention, the sheet is further provided at a position downstream of the endless belt in the sheet conveying direction. Sometimes, the sheet conveying device includes a pair of timing rollers that pulls the sheet into the nip and feeds the sheet in the same direction, and a control unit that stops the blowing operation of the air blowing unit when the leading end of the sheet comes into contact with the timing roller. According to the second aspect of the present invention, the sheet is brought into contact with the timing roller in a state where the pressure contact of the sheet is released to stop and slip, so that the skew can be corrected.

According to a third aspect of the present invention, there is provided an endless belt stretched by at least two rollers including a driving roller and rotated by a driving force of the driving roller, and blowing air toward an outer surface of the endless belt. Air blowing means for pressing the sheet on the outer surface against the outer surface by attaching the sheet, and obliquely detecting that the sheet is being conveyed in a state where the leading edge of the sheet is not orthogonal to the sheet conveying direction. The sheet conveying device includes: a line detecting unit; and a control unit that controls an air blowing amount of the air blowing unit in accordance with a detection result by the skew detecting unit. According to the third aspect of the present invention, the pressing force is adjusted in accordance with the degree of skew of the sheet to optimize the degree of slip of the sheet and the degree of restraint of the sheet. Even if it changes, skew of the sheet can be corrected.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the plurality of air blowing means are arranged in a direction orthogonal to a sheet conveying direction so as to face an outer surface of the endless belt. 4 is a sheet conveyance device configured to have a fan.

According to a fifth aspect of the present invention, there is provided the sheet conveying apparatus according to the fourth aspect, wherein the control means is configured to control the air blowing amount of the plurality of fans.

[0015]

Embodiments of the present invention will be described below. FIG. 1 is a top view (upper part) and a side view (lower part) schematically showing the mechanism of the sheet conveying apparatus according to the present embodiment. 2 to 6 are explanatory diagrams showing the operation process of the apparatus shown in FIG. 1, and FIG. 8 is a flowchart showing the operation process.

The sheet transport apparatus is configured to feed a document sheet fed by a feed roller 1 as indicated by a leftward arrow in FIG.
The paper is conveyed in the same direction by the endless belt 6 while being pressed against the belt surface of the endless belt 6 by the wind force of 8a and 8b, and the leading end of the original paper is brought into contact with the nip (between the rollers) of the timing roller pair 10. The skew of the original paper is corrected by stopping the advance of the original paper and subsequently slipping the original paper on the endless belt 6 that is being rotationally driven. This is a device for feeding onto a platen glass (located to the left of the timing roller pair 10).

First, a document tray (not shown) (paper feed roller 1)
, A large number of original sheets are placed with the image surface facing downward. These manuscript papers are lifted by a lift (not shown), and when the uppermost manuscript paper reaches a height in contact with the paper feed roller 1 (see the lower diagram in FIG. 2), the paper feed motor M1
Is driven (FIG. 8, S11). This allows the feed roller 1
Is started to pull out a plurality of original sheets of the upper layer portion, and the forward driving of the upper separating roller 2 and the reverse driving of the lower separating roller 3 are started, so that the uppermost layer of the plurality of original sheets is started. One original sheet P is unwound. The separated manuscript paper P is sent to the endless belt 6 side as shown in FIG.

When the leading edge of the original sheet P separated by the upper and lower separating rollers 2 and 3 is detected by the paper feed sensor 4a or 4b (S13; YES in FIG. 8), the pickup solenoid SL3 is turned on and the assisting roller is turned on. 5 starts rotation (Fig.
Five). The assisting roller 5 is initially at a position where it is pressed against the belt surface of the endless belt 6. At the same time, the rotational drive of the endless belt 6 and the fans 8a and 8b is started (FIG. 8).
S15). As a result, the manuscript paper P is drawn into the nip between the assisting roller 5 and the endless belt 6 and is restrained.
While being pressed against the belt surface of the endless belt 6 by the blowing air of the fans 8a and 8b, the belt is conveyed to the left in the drawing by the endless belt 6.

The paper feed sensors 4a and 4b are provided at the same position in the conveying direction of the document paper P and at the right and left symmetrical positions. For this reason, for example, there is no skew when the leading ends of the manuscript paper P sent out from the separating rollers 2 and 3 are simultaneously detected by the sensors 4a and 4b, and when the leading end of the manuscript paper P is detected first by the sensor 4a, the left side of the manuscript paper P is detected. (The front side in the upper diagram) is the preceding skewed state. If the sensor 4b detects first, the right (the rear side in the upper diagram) portion of the manuscript paper P is the preceding skewed state. Thus, it is possible to determine the presence or absence of the skew state and the type of the skew state. It is also possible to calculate the degree of skew based on the detection time difference between the sensors 4a and 4b.
FIG. 3 shows a case where the leading end of the document paper P is detected first by the sensor 4a, that is, a case where the left portion of the document paper P is in a skewed state in which the preceding portion is detected.

When the assisting roller 5 is not used, that is, when the original paper P being conveyed is pressed against the belt surface only by the wind blast of the fans 8a and 8b and restrained, the feeding of the fans 8a and 8b is performed. By adjusting the air volume based on the detection results of the sensors 4a and 4b, it is possible to prepare for skew correction. For example, as shown in FIG. 3, in the case of the skew state in which the left portion of the document paper P is ahead, the right fan 8b
To increase the conveyance efficiency by strongly pressing and restraining the right side of the manuscript paper P against the belt surface, and to reduce the air flow of the left fan 8a to slip the left side of the manuscript paper P. By making it easier, it is possible to prepare for skew correction. In the sheet conveying apparatus, a fan 8a, the air blowing amount of 8b, strong (0.55m ³ / min) · weak (0.35 m ³
/ Min).

In the above description, the time detected by the sensor 4a or the sensor 4b is adopted as the reference time for starting the rotation of the fans 8a and 8b. Instead, the time is detected by the sensor 9 provided on the downstream side of the endless belt 6. The detection time may be employed. In that case, it is desirable to use the assisting roller 5. That is, when the original paper P is transported,
Is preferably restrained to the belt surface by the assisting roller 5. Note that the time required for starting the fans 8a and 8b can be ignored. Further, the fans 8a and 8b can be constantly rotated, and the rotation speed can be adjusted as needed. This adjustment may be performed, for example, as described above.

Next, it takes a sufficient time for the document paper P to be unwound from the document tray (450 msec in this sheet conveying apparatus).
When c) has elapsed (FIG. 8, S17; YES), the loosening release solenoid SL1 is turned on (FIG. 8, S19), and as shown in FIG.
The lower separating roller 3 is retracted to the lower position as shown by the arrow. At the same time, the paper feed motor M1 is turned off (S19 in FIG. 8), and the paper feed roller 1 and the upper and lower separating rollers 2, 3 are stopped.

Next, when the leading end of the document paper P conveyed by the endless belt 6 is detected by the sensor 9 on the downstream side of the endless belt 6 (S21; YES in FIG. 8), the pressure release solenoid SL2 is turned on. Then (S23 in FIG. 8), as shown in FIG. 4, the assisting roller 5 is retracted to the rear (to the right in the lower diagram) upper position as shown by the arrow. Thereby, the restraint by the assisting roller 5 is released, and the original paper P is free on the endless belt 6. In other words, the posture can be corrected (skew correction).

Even after the pressing of the assisting roller 5 is released as described above, the rotational drive of the endless belt 6 is continued. For this reason, the document paper P is conveyed to the left in the figure until the leading end thereof contacts the nip of the timing roller pair 10. In addition,
At this time, the manuscript paper P is slidably pressed against the belt surface by the wind blown from the fans 8a and 8b.

Next, when the leading end of the original paper P comes into contact with the nip of the pair of timing rollers 10, the original paper P is free on the endless belt 6 and fed from the fans 8a and 8b as described above. Since the belt is pressed against the belt surface by wind force in a slidable manner, it receives a reaction force from the nip of the timing roller pair 10 and, as shown in FIG. ) Slips, and the skew is corrected.

When a sufficient time elapses for such skew correction (S25; YES in FIG. 8), the rotation of the timing roller pair 10 is started (S27 in FIG. 8). Thereby, the manuscript paper P is
It is drawn into the nip of the timing roller pair 10, sent out of the nip, and sent to a platen glass (document reading section) (not shown) as shown in FIG. The “time sufficient for correcting the skew” can be determined by comparing the degree of skew of the original paper detected by the sensors 4a and 4b with the table data of the actually measured values. Further, the completion of the correction can be determined based on the detection results of the sensors provided at the two locations.

When the original paper P is sent out from the timing roller pair 10 and its leading end is detected by the discharge sensor 12 provided downstream of the timing roller pair 10 (FIG. 8).
S29; YES), while the rotation of the endless belt 6 is stopped,
The rotation of the fans 8a and 8b is stopped (FIG. 8, S31).

Further, when the trailing edge of the original paper P passes the position of the paper feed sensors 4a and 4b (FIG. 8, S33; YES), the pickup solenoid SL3 is turned off, and the rotation of the assisting roller 5 is stopped. The separation release solenoid SL1 is turned off, and the lower separation roller 3 is returned to the original position (Fig. 8, S3
Five).

When the trailing end of the document paper P passes through the discharge sensor 12 (FIG. 8, S37; YES), the pressure release solenoid SL2 is turned off, and the assisting roller 5 is returned to the original position, and
The rotation of the timing roller pair 10 is stopped (FIG. 8, S3
9). Thus, the operation of the present sheet conveying apparatus is performed.

In the above description, the case where the single endless belt 6 is provided in parallel with the sheet conveying direction has been described.
As shown in FIG. 9, a plurality (three in FIG. 9) of endless belts
6a, 6b, and 6c are provided in parallel with each other at an angle to the sheet conveyance direction, and the sheets are conveyed so as to be urged in the direction of inclination of the endless belts 6a, 6b, and 6c, so that the left of each sheet is The edge may be regulated by the left regulation guide G2. This configuration is particularly suitable for a so-called mixed original in which originals of various sizes are mixed. That is, it is suitable for correcting the skew of the mixed original and for restricting the left of the mixed original that is likely to be disturbed. To achieve this purpose significantly, the left regulation guide G2 just before the timing roller pair 10 is used.
The left regulation guide G1 in front of the endless belts 6a, 6b, 6c is provided with a step as shown in the drawing, so that the document paper of various sizes can be uniformly regulated to the left. Has been.

Each endless belt 6a, 6b, 6c shown in FIG.
Is configured to be driven simultaneously by the driving force of the motor M30 via a gear mechanism, but is configured to selectively drive only the endless belt 6a or only the endless belts 6a and 6b. Is also good.

In FIG. 9, each endless belt 6a, 6b,
Fans 80a, 80b, 80c provided above 6c, respectively,
By arranging them so that they can be rotated independently, or by adjusting the rotation speed independently, it is possible to correct the skew of the original paper in the same manner as when the two fans 8a and 8b are driven strongly. Can be optimized. In addition, it is possible to satisfactorily regulate the left position of the manuscript paper.

In the configuration shown in FIG. 9, the assisting spheres 50a, 50b, and 50b are replaced with the assisting roller 5 in the configuration of FIG.
50c is used. This is to make it possible to favorably control the above-described left position of the manuscript paper by setting the assisting direction to free.

[0034]

According to the first aspect of the present invention, the sheet can be slipped appropriately as required for skew correction or the like in a state where the sheet is constrained on the belt surface so that the sheet is conveyed normally. According to the second aspect of the present invention, the sheet can be slipped by being brought into contact with the timing roller and stopped while the pressure contact of the sheet is released, so that the skew of the sheet can be sufficiently corrected. According to the third aspect of the present invention, the degree of slip and the degree of restraint can be optimized by adjusting the pressing force according to the degree of skew of the sheet. Can be corrected. According to the fourth and fifth aspects of the present invention, since the pressing force can be adjusted in a direction orthogonal to the sheet conveying direction, the skew of the sheet can be sufficiently corrected.

[Brief description of the drawings]

FIG. 1 is a top view (upper view) and a side view (lower view) schematically illustrating a mechanism of a sheet conveying apparatus according to an embodiment of the present invention.

FIGS. 2A and 2B are a top view (upper diagram) and a side view (lower diagram) illustrating a process of feeding and separating original paper P in the sheet conveying apparatus of FIG.

FIG. 3 is a top view (upper diagram) illustrating a process of conveying the original paper P while restraining the same in the sheet conveying apparatus of FIG. 1;
And side view (lower figure).

4A and 4B are a top view (upper diagram) and a side view (lower diagram) illustrating a first half process of correcting skew of the document paper P in the sheet conveying device of FIG.

5A and 5B are a top view (upper diagram) and a side view (lower diagram) illustrating the latter half of the process of correcting the skew of the document paper P in the sheet conveying apparatus of FIG.

6A and 6B are a top view (upper view) and a side view (lower view) illustrating a process after sending out the original paper P in the sheet conveying apparatus of FIG.

FIG. 7 is a block diagram illustrating input / output signals of a control circuit of the sheet conveying apparatus of FIG. 1;

8 is a flowchart showing a procedure of processing executed by the CPU of FIG. 7 to realize the processes shown in FIGS. 2 to 6 in the sheet conveying apparatus of FIG. 1;

FIG. 9 is a top view showing a sheet conveying apparatus according to another embodiment of the present invention.

FIG. 10 is an explanatory diagram showing the principle of a conventional sheet conveying device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 paper feed roller 2 upper separating roller 3 lower separating roller 5 assisting roller 6 endless belt 8 (8a, 8b) fan 10 timing roller pair SL1 separation releasing solenoid SL2 pressure release solenoid

Claims (5)

[Claims] An endless belt stretched by at least two rollers including a driving roller and rotated by a driving force of the driving roller; and an outer end formed by blowing air toward an outer surface of the endless belt. Air blowing means for pressing a sheet on the surface against the outer surface; 2. The image forming apparatus according to claim 1, further comprising: a sheet provided downstream of the endless belt in a sheet conveying direction, stopping a sheet coming in contact with the sheet when it is not rotating, and drawing the sheet into a nip when it is rotating. A sheet conveying device comprising: a pair of timing rollers for feeding in the same direction; and control means for stopping a blowing operation of the air blowing means at a timing when a leading end of a sheet comes into contact with the timing rollers. 3. An endless belt stretched by at least two rollers including a driving roller and rotated by a driving force of the driving roller; and an outer end formed by blowing air toward an outer surface of the endless belt. Air blowing means for pressing the sheet on the surface against the outer surface, skew detecting means for detecting that the sheet is being conveyed in a state where the leading edge of the sheet is not orthogonal to the sheet conveying direction, Control means for controlling the amount of air blown by the air blowing means in accordance with the result of detection by the skew detecting means. 4. The sheet conveying apparatus according to claim 3, wherein the air blowing unit has a plurality of fans arranged in a direction orthogonal to a sheet conveying direction so as to face an outer surface of the endless belt. . 5. The sheet conveying device according to claim 4, wherein the control unit controls the air blowing amount of each of the plurality of fans.