JP5070078B2 - Sheet feeding apparatus and method, and image reading apparatus - Google Patents

Description

  The present invention relates to a sheet feeding apparatus and method and an image reading apparatus, and more particularly to a sheet feeding apparatus and method and an image reading apparatus capable of separating and feeding a sheet bundle one by one.

  Some copiers, scanners, printers, and the like include a sheet feeding device that separates sheet bundles one by one and feeds them into the apparatus. A sheet feeding apparatus generally includes a sheet feeding roller, a feeding roller, and a separation roller, and these are controlled by ON / OFF of a clutch. The driving force to the paper feed roller, feed roller, and separation roller is supplied from the transport motor via gears, belts, etc., and all the rollers are configured to rotate at the same rotation ratio in any state. Yes.

  However, when the sheet reading speed and the reading resolution are changed by changing the rotation speed of the conveyance motor, the rotation speeds of the paper feed roller, the feed roller, and the separation roller change at the same rotation ratio. As a result, the separation force and conveyance force determined by the dynamic friction coefficient between the sheets and the friction coefficient between the rollers also fluctuate, and separation and conveyance are performed in an unstable state, causing problems such as double feeding of sheets.

  In addition, when the state of the sheet to be fed, paper quality, etc. change, each roller operates at a constant rotation ratio via a gear or belt. For example, only the rotation speed of the separation roller is changed to change the sheet. It is impossible to optimize the separation power. Inability to deal with such external factors also caused double feeding.

In order to solve the above-described problems, the sheet feeding roller, the feeding roller, and the separation roller are driven by independent driving means, respectively, so that it is possible to set appropriate separation and conveyance conditions according to various sheets and conveyance states. A material feeding device has been proposed (see, for example, Patent Document 1).
Special registration No. 3398043

  In the above-described conventional sheet material feeding apparatus, as shown in FIG. 9A, when the sheet F2 is returned to the front of the separating and conveying unit composed of the feeding roller 6 and the separating roller 7, the sheet feeding roller 4 is also sent in the sheet conveyance direction. For this reason, the leading end of the sheet F2 may be bent in front of the separation conveyance unit. In order to solve this problem, there is a method in which the rotation of the paper feed roller 4 is stopped after the sheet F1 separated and conveyed by the separation conveyance unit is conveyed to a predetermined position.

  However, as shown in FIG. 9B, when the length of the sheet F1 in the transport direction is short, the subsequent sheet F2 is transported in the transport direction from the time when the paper feed roller 4 stops contacting the sheet F1. Then, the sheet F2 is bent in front of the separation conveyance unit. Due to the structure of the separation / conveyance unit, the vertical gap near the upstream side of the separation / conveyance unit is large, so that the amount of deflection generated in the sheet F2 is also large. Further, due to the arrangement of the paper feed roller 4, the feed roller 6, and the separation roller 7, the relationship of the conveyance force, and the inclination of the sheet F2 when the sheets are stacked, the amount of deflection and the place where the deflection occurs is uneven, and the sheet is not Is skewing or causing breakage.

  The present invention has been made in view of the above problems, and can reduce the deflection of the sheet that occurs during separation and conveyance, and can prevent the conveyance failure of the sheet that has been bent and improve the separation and conveyance performance. It is an object of the present invention to provide a sheet feeding apparatus and method, and an image reading apparatus.

  In order to achieve the above object, a sheet feeding apparatus according to claim 1 includes a feeding rotating body that rotates in a sheet conveying direction to feed a sheet, and a sheet fed by the feeding rotating body. A separating rotator that sandwiches a sheet between the conveying rotator to be conveyed and the conveying rotator and rotates in a direction opposite to the conveying direction, and the downstream of the conveying rotator and the separating rotator in the conveying direction. A deflection determining means for determining a deflection of a sheet fed by the feeding rotating body, in a sheet feeding device provided with a pair of sheet clamping rotating bodies that sandwich the sheet and convey the sheet in the conveying direction; When it is determined that there is a deflection by the deflection determination unit, a preceding conveyance rotation unit that rotates the conveyance rotation body by a predetermined amount in the conveyance direction in advance of the feeding rotation body, and the preceding conveyance rotation unit After rotating a predetermined amount feed rotary member in the transport direction, characterized in that it comprises a control means for rotating said feed rotary member in the transport direction.

  In order to achieve the above object, the sheet feeding method of the sheet feeding apparatus according to claim 7 is a feeding rotating body that rotates in the sheet conveying direction and feeds the sheet, and a feeding rotating body that feeds the sheet. More than the conveyance rotation body which conveys the sent sheet, the separation rotation body which sandwiches the sheet between the conveyance rotation body and rotates in the direction opposite to the conveyance direction, and the conveyance rotation body and the separation rotation body In a feeding method of a sheet feeding device, which is disposed downstream of the transport direction and includes a pair of sheet sandwiching rotating bodies that sandwich the sheet and transport the sheet in the transport direction, a sheet fed by the feed rotating body Deflection determining step for determining deflection, and preceding transport rotation for rotating the transport rotator by a predetermined amount in the transport direction in advance of the feeding rotator when it is determined that there is deflection in the deflection determination step. Process and the above After the transport rotary member by the transport rotation step by a predetermined rotation amount in the transport direction, characterized in that it comprises a control step of rotating said feed rotary member in the transport direction.

  According to the present invention, it is possible to improve the separation and conveyance performance by reducing the deflection of the sheet generated during the separation and conveyance and preventing the conveyance failure due to the sheet having the deflection.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a structural diagram illustrating a schematic structure of an image reading apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram illustrating a schematic structure of a main part of the image reading apparatus in FIG.

  Reference numeral 1 denotes a sheet table on which the sheet bundle F is stacked. Reference numeral 2 denotes a sheet table driving motor that moves the sheet table 1 up and down. Reference numeral 3 denotes a sheet detection sensor as a sheet detection unit that detects the sheet bundle F stacked on the sheet table 1.

  Reference numeral 4 denotes a sheet feeding roller as a feeding rotating body that rotates in the conveying direction to feed the sheet bundle F stacked on the sheet table 1 one by one. Reference numeral 5 denotes a paper feed motor as drive means, which drives the paper feed roller 4. Reference numeral 6 denotes a feed roller as a transport rotating body that rotates to transport the sheet fed by the paper feed roller 4 in the transport direction. Reference numeral 8 denotes a feed motor as drive means, which drives the feed roller 6. A separation roller 7 serves as a separation rotating body that separates a plurality of sheets one by one when the sheet is fed by the sheet feeding roller 4. Reference numeral 9 denotes a separation motor as driving means, which drives the separation roller 7. The feed roller 6 and the separation roller 7 constitute a separation conveyance unit (separation conveyance unit) in the image reading apparatus. The feed roller 6 is reversely driven in the direction opposite to the conveyance direction so that the subsequent sheet that has entered along with the preceding sheet returns to the front of the separation conveyance unit.

  Reference numeral 10 denotes a conveyance motor as a conveyance driving means. The conveyance motor 10 can drive a registration roller and a conveyance roller, which will be described later, so as to convey the separated and conveyed sheet from the sheet reading position to the sheet discharge position, and can change the sheet conveyance speed related to the sheet reading speed and resolution. It is configured as follows. Reference numeral 11 denotes a paper thickness adjusting motor. The paper thickness adjusting motor 11 adjusts the distance between the feed roller 6 and the separation roller 7. In the initial state, the paper thickness adjusting motor 11 adjusts the distance between the feed roller 6 and the separation roller 7 to the position where it is most narrowed.

  14 and 15 are sheet reading sensors, which change the scanning interval based on the sheet conveyance speed and resolution. Further, the sheet reading sensors 14 and 15 operate at a reading timing synchronized with the respective motors of the sheet feeding motor 5, the feeding motor 8, and the separation motor 9, or at an asynchronous reading timing. A sheet discharge sensor 16 detects a sheet that has passed through the sheet reading sensors 14 and 15 and is discharged to the sheet discharge unit.

  Reference numerals 17 and 18 denote registration rollers that are disposed downstream of the separating and conveying unit in the sheet conveying direction and serve as a pair of sheet nipping and rotating bodies. In the stopped state, the registration rollers 17 and 18 correct the skew of the sheet by restricting the sheet from moving first, while in the driving state, the registration rollers 17 and 18 convey the sheet to the sheet reading position of the sheet reading sensors 14 and 15. . Reference numeral 19 denotes a registration clutch which switches transmission / disconnection of the driving force of the conveyance motor 10 to the registration rollers 17 and 18. 20, 21, 22, and 23 are sheet conveying rollers that convey the sheet.

  Reference numeral 40 denotes an upper guide plate, and 41 denotes a lower guide plate. The sheet is conveyed between these two guide plates. S1 is a pre-feed sensor, S2 is a post-feed sensor, S3 is a pre-registration sensor, and S4 is a post-registration sensor. Based on the output of each sensor, a control unit (not shown) performs drive control of the motors of the respective units.

  In the present embodiment, the post-feed sensor S2 is used as a sheet detection unit and as a sheet length detection unit for detecting a length in the sheet conveyance direction (hereinafter simply referred to as “sheet length”). The control unit measures the length in the sheet conveyance direction based on the detection result of the post-feed sensor S2 and the sheet conveyance speed. Since the sheet conveyance speed does not become constant until the sheet is nipped by the registration rollers 17 and 18 from the separation conveyance unit, a post-feed sensor S2 and a post-registration sensor S4 are used to measure the sheet length more accurately. May be used together to measure the length of the sheet in the conveyance direction.

  Next, a sheet image reading operation in the image reading apparatus will be described.

  First, the user stacks the sheet bundle F on the sheet table 1. When a start switch (start SW) of an operation unit (not shown) is turned on, an ascending signal is sent from the control unit to the sheet table driving motor 2, and the sheet table driving motor 2 feeds the sheet table 1. Ascend to position. When the sheet bundle F raised together with the sheet table 1 is detected by the sheet detection sensor 3, the sheet feeding motor 5 is driven at a set speed, and the driving force of the sheet feeding motor 5 is transmitted to the sheet feeding roller 4 to be fed to the sheet feeding roller. 4 rotates.

  When the sheet F1 at the top of the sheet bundle F is conveyed to the separation conveyance unit by the rotation of the sheet feeding roller 4, the sheet F1 is detected by the pre-sheet feeding sensor S1. The sheet feeding roller 4 is rotated for a predetermined time after the sheet F1 is detected by the pre-sheet feeding sensor S1, whereby the sheet F1 is conveyed. The feed roller 6 is rotated by the feed motor 8 and the separation roller 7 is rotated by the separation motor 9 at the timing when the leading edge of the sheet F1 hits the separation sheet feeding unit. At the same time as the separation roller 7 starts to rotate, the paper thickness adjusting motor 11 is driven to increase the distance between the feed roller 6 and the separation roller 7. Eventually, the gap between the feed roller 6 and the separation roller 7 increases, and the sheet F1 begins to pass between these two rollers.

  The sheet F1 is detected by the post-feed sensor S2 when it passes through the separation conveyance unit. The paper thickness adjusting motor 11 is stopped by the signal from the post-feed sensor S2. If a sheet cannot be detected by the post-feed sensor S2 by the time when the sheet feeding motor 5 is driven and rotated by a predetermined amount, it is determined that a feeding error has occurred and the sheet feeding is stopped. The predetermined amount is preferably set to an amount corresponding to the length from the position of the feeding roller 4 to the position of the registration rollers 17 and 18, for example. Note that the predetermined amount may be changed as appropriate when the configurations of the sheet feeding device and the image reading device are different.

  Next, when the sheet F1 conveyed through the separation conveyance unit is detected by the pre-registration sensor S3, the separation motor 9 is temporarily stopped and only the feed motor 8 is driven. After passing through the pre-registration sensor S3, the sheet F1 hits the resist rollers 17 and 18 that are stopped. Then, the sheet F1 can be bent, and the entire tip portion thereof is along the nip portion of the registration rollers 17 and 18. Thereafter, the registration clutch 19 is turned on to correct the skew of the sheet F1.

  The sheet F1 abutted against the nip portion of the registration rollers 17 and 18 is conveyed by the registration rollers 17 and 18 after the registration clutch 19 is turned on after a predetermined time detected by the pre-registration sensor S3. Then, the rotation of the paper feed roller 4 and the feed roller 6 is stopped by stopping the driving of the paper feed motor 5 and the feed motor 8, and the separation roller 7 starts to rotate by resuming the drive of the separation motor 9. After the registration sensor S4 detects the sheet F1, the control unit controls each part until the sheet reading sensor 16 detects the sheet F1 at the same time when the sheet reading sensors 14 and 15 start the reading operation after a predetermined time. .

  Next, the operation of the separation / conveying unit when a plurality of sheets are continuously fed and conveyed will be described. Since the operation when the first sheet is fed and conveyed is as described above, the description thereof is omitted.

  FIGS. 3A and 3B are diagrams illustrating the operation of the separation conveyance unit when a plurality of sheets are continuously fed and conveyed. FIG. 3A illustrates a state in which the sheet F2 has entered with the sheet F1, and FIG. The state which the sheet | seat F2 which was done is returned in front of the separation conveyance part is shown. 4A is a diagram illustrating a state in which the sheet F2 has reached the post-feed sensor S2, and FIG. 4B is a diagram illustrating a state in which the sheet F2 has started to be returned by the separation conveyance unit. FIG. 5 is a diagram illustrating a state where the sheet F2 is returned to the front of the post-feed sensor S2 by the separation conveyance unit.

  The trailing edge of the sheet F1 fed and conveyed first is detected by a post-feed sensor S2. Then, as shown in FIG. 3A, the paper thickness adjusting motor 11 is connected to the feed roller 6, the separation roller 7, while the rotation of the feed roller 6 in the transport direction is stopped and the separation roller 7 is rotating. Drive in the direction to narrow the interval. At the same time, the registration clutch 19 stops at a position where the rear end of the sheet F1 slightly before the nip portion of the registration rollers 17 and 18 after a lapse of a predetermined time after the post-feed sensor S2 detects the rear end of the sheet F1. The driving of the registration rollers 17 and 18 is stopped. Then, the subsequent sheet F2 is prevented from being fed by the registration rollers 17 and 18. As a result, as shown in FIG. 3B, the sheet F2 that has entered the separation conveyance unit with the preceding sheet F1 is narrowed in front of the separation conveyance unit at the same time as the interval between the feed roller 6 and the separation roller 7 is narrowed. Returned.

  When the trailing edge of the preceding sheet F1 is detected by the pre-registration sensor S3 as shown in FIG. 4A, and the leading edge of the succeeding sheet F2 has already reached the post-feed sensor S2, as shown in FIG. It is determined that the distance between the trailing edge of the sheet F1 and the leading edge of the sheet F2 is equal to or less than the threshold value. When the pre-registration sensor S3 detects the trailing edge of the sheet F1, the feed roller 6 is driven in the direction opposite to the conveyance direction. In this way, the post-feed sensor S2 and the pre-registration sensor S3 function as a paper gap detection unit.

  Then, as shown in FIG. 4B, the sheet thickness adjusting motor 11 starts to drive in the direction of narrowing the distance between the feed roller 6 and the separation roller 7 after the feed roller 6 starts to reversely rotate, so that the sheet F2 Is returned by the feed roller 6 and the separation roller 7 to the front of the separation conveyance unit. Note that the above threshold determination is an example, and for example, determination may be performed using another existing sensor, or determination may be performed by adding other sensors.

  Further, as shown in FIG. 5, after the sheet feeding sensor S2 detects the leading edge of the sheet F2, the feed roller 6 is driven reversely for a predetermined time, and the sheet F2 is returned to the front of the separation conveyance unit. As a result, even when the sheet F2 is brought in after the sheet feeding sensor S2, the sheet F2 can be returned to the state before the separation conveyance, and the separation conveyance operation for the second and subsequent sheets can be performed. When the subsequent sheet F2 is returned to the front of the separation conveyance unit, the sheet feeding roller 4 is stopped and the sheet is not fed, so that a sheet can be formed between the sheet feeding roller 4 and the feeding roller 6. The amount of deflection is only the amount of deflection generated by returning by the separation roller 7.

  The sheet feeding roller 4 rotates until the sheet F1 starts to be conveyed by the registration rollers 17 and 18 after a predetermined time detected by the pre-registration sensor S3. When the length of the sheet F1 in the conveying direction is shorter than the distance from the position where the sheet feeding roller 4 is in contact with the sheet on the sheet table 1 to the position where the sheet roller 1 is sandwiched between the nip portions of the registration rollers 17 and 18, the sheet feeding roller 4 operates as follows. That is, the sheet feeding roller 4 contacts the sheet F2 and feeds the sheet F2 in the transport direction from the point when it does not contact the sheet F1. As a result, the amount of deflection generated on the sheet F2 between the sheet feeding roller 4 and the feeding roller 6 is such that the length of the sheet F1 in the conveying direction is from the position where the sheet feeding roller 4 contacts the sheet. This is larger than the deflection amount when the distance to the nip portion is long. Accordingly, a second and subsequent sheet separation / conveying operation, which is executed to reduce conveyance defects such as skew during conveyance due to the deflection generated in the sheet F2, will be described with reference to the flowchart of FIG.

  FIG. 6 is a flowchart illustrating an example of the separation and conveyance operation of the second and subsequent sheets in continuous feeding in the image reading apparatus. Note that this processing is performed by controlling each unit in the image reading apparatus by executing a control program by a CPU as a control unit.

  First, the CPU measures the length of the sheet F1 in the conveyance direction based on the detection result by the post-feed sensor S2 (and the post-registration sensor S4). Then, the length of the sheet F1 in the conveying direction is compared with the distance from the position of the sheet feeding roller 4 in contact with the sheet to the nip portion of the registration rollers 17 and 18 (step S1). When it is determined that the length in the conveyance direction of the sheet F1 is long (or the same) as the distance from the position where the sheet feeding roller 4 contacts the sheet to the nip portion of the registration rollers 17 and 18 (in step S1). NO), the process proceeds to step S2.

  In step S2, the CPU determines whether or not the feed roller 6 is driven reversely and the sheet F2 is returned to the front of the separating and conveying unit after the post-feed sensor S2 detects the sheet F2. If the feed roller 6 is not driven reversely and the sheet F2 is not returned to the front of the separation / conveyance unit (NO in step S2), the paper feed motor 5 and the feed motor 8 are driven to rotate forward and the conveyance of the sheet F2 is started. (Step S10).

  When it is determined that the length of the sheet F1 in the conveyance direction is shorter than the distance from the position where the sheet feeding roller 4 contacts the sheet to the nip portion of the registration rollers 17 and 18 (YES in step S1), FIG. Deflection as shown in a) may occur in the sheet F2. Further, even when the feed roller 6 is driven reversely and the sheet F2 is returned to the front of the separation conveyance unit (YES in step S2), the deflection as shown in FIG. 7A may occur in the sheet F2. Therefore, when the sheet F2 is conveyed, the CPU drives the feed roller 6 to rotate forward (rotates in the conveyance direction) and simultaneously widens the interval between the feed roller 6 and the separation roller 7 by the paper thickness adjusting motor 11 (step). S3). Then, as shown in FIG. 7B, the gap between the feed roller 6 and the separation roller 7 is opened, and the sheet F2 begins to pass between these two rollers while eliminating the generated deflection.

  Next, after the feed roller 6 is driven to rotate forward, as shown in FIG. 8A, when the post-feed sensor S2 detects the sheet F2 (YES in step S4), the feed roller 4 is moved in the transport direction. And the sheet F2 is fed (step S6). On the other hand, considering the case where the sheet F2 is not conveyed by the feed roller 6 as shown in FIG. 8B, the length from the position where the sheet feed roller 4 contacts the sheet F2 to the position of the post-feed sensor S2, It is determined whether the feed roller 6 has been rotated (step S5). When the feed roller 6 is rotated by the length from the position where the paper feed roller 4 contacts the sheet F2 to the position of the post-feed sensor S2 (YES in step S5), the paper feed roller 4 is rotated in the transport direction. Then, the sheet F2 is fed (step S7). Even when the paper feed motor 5 is driven in the transport direction in the form shown in FIG. 9B, the distance between the feed roller 6 and the separation roller 7 is necessary to pass the sheet F2. Since the sheet F2 is partially opened, the sheet F2 passes between these two rollers while eliminating the generated deflection.

  When the post-feed sensor S2 detects the sheet F2 after rotating the paper feed roller 4 (YES in step S8), the subsequent processing performed on the first sheet F1 is performed. On the other hand, when the post-feed sensor S2 does not detect the sheet F2 (NO in step S8), it is determined whether the paper feed roller 4 has been rotated a predetermined number of times (step S9). If the post-feed sensor S2 does not detect the sheet F2 even if the feed roller 4 is rotated a predetermined number of times, it is determined that a feeding error has occurred and the feeding is stopped.

  According to the above-described embodiment, the deflection of the sheet fed by the feeding roller 4 is determined, and when it is determined that there is a deflection, the feeding roller 6 is moved in the transport direction by a predetermined amount before the feeding roller 4. A control unit (preceding transport rotation means) (not shown) executes the rotation control. Then, after the feed roller 6 is rotated by a predetermined amount in the transport direction, a control unit (control means) (not shown) executes control to rotate the feed roller 4 in the transport direction. Accordingly, it is possible to reduce the deflection of the sheet that occurs during the separation and conveyance, and to prevent the conveyance failure of the sheet that has been bent, thereby improving the separation and conveyance performance. The control performed by the control unit can be executed by using CPU software or a hardware circuit or a combination thereof.

  In the above embodiment, processing is performed by time control using a timer or the like (not shown). However, processing may be performed by controlling the number of drive pulses using a stepping motor that can be stepped to the motor described above. .

  The object of the present invention can also be achieved by executing the following processing. That is, a storage medium that records a program code of software that realizes the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU, MPU, etc.) of the system or apparatus is stored in the storage medium. This is the process of reading the code. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the program code and the storage medium storing the program code constitute the present invention.

  Moreover, the following can be used as a storage medium for supplying the program code. For example, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM or the like. Alternatively, the program code may be downloaded via a network.

  Further, the present invention includes a case where the function of the above-described embodiment is realized by executing the program code read by the computer. In addition, an OS (operating system) running on the computer performs part or all of the actual processing based on an instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Is also included.

  Furthermore, a case where the functions of the above-described embodiment are realized by the following processing is also included in the present invention. That is, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

  Further, the present invention includes a case where the functions of the above-described embodiments are realized by executing the program code read by the computer. In addition, there is a case where the OS running on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. In this case, the program is supplied by downloading directly from a storage medium storing the program or from another computer or database (not shown) connected to the Internet, a commercial network, a local area network, or the like.

1 is a structural diagram illustrating a schematic structure of an image reading apparatus according to an embodiment of the present invention. It is a schematic block diagram which shows schematic structure of the principal part of the image reading apparatus of FIG. 4A and 4B are diagrams illustrating an operation of a separation and conveyance unit when a plurality of sheets are continuously fed and conveyed. FIG. 5A illustrates a state in which a sheet F2 enters the sheet F1, and FIG. The state returned before the separation conveyance part is shown. 4A and 4B are diagrams illustrating an operation of a separation conveyance unit when a plurality of sheets are continuously fed and conveyed. FIG. 5A illustrates a state in which the sheet F2 reaches the sensor S2 after feeding, and FIG. The state returned to the separation conveyance part front is shown. FIG. 10 is a diagram illustrating a state in which a sheet F2 is returned to the front of a post-feed sensor S2 by a separation conveyance unit. 6 is a flowchart illustrating an example of a separating and conveying operation of the second and subsequent sheets in continuous feeding in the image reading apparatus. 4A and 4B are diagrams for explaining a separation and conveyance operation for the second and subsequent sheets, in which FIG. 5A shows a state immediately after the feed roller 6 is driven to rotate forward, and FIG. 4B shows a state in which the separation conveyance unit is open. . 4A and 4B are diagrams for explaining the separation and conveyance operation of the second and subsequent sheets, in which FIG. 5A shows a state in which the deflection of the generated sheet F2 is eliminated, and FIG. . FIG. 10 is a diagram illustrating a separation and conveyance operation in a conventional image reading apparatus, where (a) illustrates a state in which deflection occurs, and (b) illustrates a multi-feed state that occurs when a previously conveyed sheet is short.

Explanation of symbols

3 Sheet detection sensor 4 Paper feed roller 5 Paper feed motor 6 Feed roller 7 Separation roller 8 Feed motor 9 Separation motor 10 Transport motor 11 Paper thickness adjustment motors 14, 15 Sheet reading sensor S1 Pre-feed sensor S2 Post-feed sensor S3 Resist Front sensor S4 Post-registration sensor

Claims (7)

The sheet is sandwiched between the feeding rotating body that rotates in the sheet conveying direction and feeds the sheet, the conveying rotating body that conveys the sheet fed by the feeding rotating body, and the conveying rotating body. A separating rotating body that rotates in a direction opposite to the conveying direction, and a sheet holding rotating body that is disposed downstream of the conveying rotating body and the separating rotating body in the conveying direction, and sandwiches the sheet and conveys the sheet in the conveying direction. In a sheet feeding apparatus comprising a pair,
Deflection determining means for determining the deflection of a sheet fed by the feeding rotating body;
If the deflection determination means determines that there is a deflection, a preceding conveyance rotation means that rotates the conveyance rotation body by a predetermined amount in the conveyance direction prior to the feeding rotation body;
A sheet feeding apparatus comprising: control means for rotating the feeding rotating body in the transport direction after rotating the transport rotating body by a predetermined amount in the transport direction by the preceding transport rotating means. The deflection determining means includes a sheet length detecting means for detecting the length of the sheet,
The length of the preceding sheet is detected by the sheet length detecting means, and when the detected sheet length is equal to or less than a predetermined length, it is determined that the succeeding sheet has a deflection. The sheet feeding apparatus according to claim 1.   The deflection determination means includes a paper gap detection means for detecting a gap between a preceding sheet and a succeeding sheet, and when the gap between the sheets is equal to or less than a threshold, the conveyance rotating body is set in a direction opposite to the conveyance direction. 3. A return means for rotating and returning a succeeding sheet, and when the succeeding sheet is returned by the returning means, it is determined that the succeeding sheet is deflected. Sheet feeding device.   3. The sheet feeding apparatus according to claim 2, wherein the predetermined length is a length from a position of the feeding rotating body to a position of the sheet sandwiching rotating body pair.   2. The sheet feeding apparatus according to claim 1, wherein the predetermined amount is an amount corresponding to a length from a position of the feeding rotating body to a position of the sheet sandwiching rotating body pair.   If the sheet detecting unit further detects a sheet conveyed by the conveying rotating body and rotates the conveying rotating body by a predetermined amount in the conveying direction, and no sheet is detected by the sheet detecting unit, a feeding error occurs. The sheet feeding apparatus according to any one of claims 1 to 5, wherein the sheet feeding device is determined. The sheet is sandwiched between the feeding rotating body that rotates in the sheet conveying direction and feeds the sheet, the conveying rotating body that conveys the sheet fed by the feeding rotating body, and the conveying rotating body. A separating rotating body that rotates in a direction opposite to the conveying direction, and a sheet holding rotating body that is disposed downstream of the conveying rotating body and the separating rotating body in the conveying direction, and sandwiches the sheet and conveys the sheet in the conveying direction. In a sheet feeding method of a sheet feeding apparatus comprising a pair,
Deflection determining step for determining the deflection of a sheet fed by the feeding rotating body;
When it is determined that there is a deflection in the deflection determination step, a preceding conveyance rotation step for rotating the conveyance rotation body by a predetermined amount in the conveyance direction in advance of the feeding rotation body;
A sheet feeding method comprising: a control step of rotating the feeding rotating body in the conveying direction after rotating the conveying rotating body by a predetermined amount in the conveying direction in the preceding conveying rotating step.

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