JP2012214294A - Sheet conveying device for separating multi-fed sheets, and image reading apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveying device that can automatically separate multi-fed sheets again and improve efficiency of sheet conveyance operation.SOLUTION: The sheet conveying device, in which sheets from a sheet bundle placed on a sheet tray are separated and fed on a one-by-one basis and a fed sheet is nipped and conveyed, is provided with a pair of conveying rollers having rotational axes extending in respective different directions. One of the pair of conveying rollers is disposed to convey a sheet in a sheet conveying direction, while the other of the pair of conveying rollers is disposed to obliquely convey the sheet with respect to the sheet conveying direction.

Description

  The present invention relates to a sheet conveying apparatus and an image reading apparatus, and more particularly to a separation technique for double feeding of sheets generated by a conveying mechanism that separates and conveys sheets one by one from a sheet bundle placed on a sheet tray.

  In an image reading apparatus provided with a conventional sheet conveying device, when double feeding is performed in a state where two or more sheets are overlapped, jamming (clogging) or image reading failure may occur. . In either case, the user needs to remove the sheet or reset the sheet, and the apparatus must be stopped during that time. In view of this, there has been proposed a sheet conveying apparatus that, when double feeding is detected, reversely conveys the double fed sheets by a predetermined distance in the direction of the sheet tray and separates them again using the separation mechanism (see, for example, Patent Document 1). ).

US Pat. No. 5,384,631

  However, in the above conventional sheet conveying apparatus, double feeding occurs due to the strong adhesion between the sheets, and therefore it is not always possible to reliably separate even if the same separation mechanism is used again.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet conveying apparatus and an image reading apparatus that can easily separate sheets that have been multifed and improve the efficiency of sheet conveyance.

  In order to achieve the above object, a sheet conveying apparatus according to a first aspect includes a sheet feeding unit that separates and feeds sheets one by one from a sheet bundle placed on a sheet tray, and a sheet feeding unit that feeds the sheet. A first conveying unit that includes a pair of conveying rollers that sandwich and convey the paper sheet and that have different rotation axis directions, and a second conveying unit that further conveys the sheet conveyed by the first conveying unit. And one of the pair of transport rollers is arranged to transport the paper sheet in the sheet transport direction of the second transport means, and the other of the pair of transport rollers is the paper sheet Is arranged so as to be transported obliquely with respect to the sheet transport direction of the second transport means.

  In order to achieve the above object, an image reading apparatus according to claim 10 separates sheets one by one from a sheet tray on which a sheet bundle is placed and the sheet bundle placed on the sheet tray. A sheet feeding unit that feeds the sheet, a sheet that is fed from the sheet feeding unit, and transports the sheet by nipping, and a pair of conveyance rollers having different rotation shaft directions, and the first conveyance unit And a reading unit that reads an image of the sheet conveyed by the second conveying unit, and one of the pair of conveying rollers includes the sheet feeding unit. The sheet is arranged so as to convey the sheet in the sheet conveying direction of the second conveying means, and the other of the pair of conveying rollers is configured so that the sheet is fed obliquely with respect to the sheet conveying direction of the second conveying means Arranged to transport And wherein the are.

  According to the present invention, one of a pair of conveying rollers having different rotation axis directions is disposed so as to be conveyed in the sheet conveying direction, and the other is disposed so as to be conveyed obliquely with respect to the sheet conveying direction. Thereby, it is possible to easily separate the multi-feed sheets, and it is possible to improve the efficiency of sheet conveyance.

1 is a schematic diagram of an image reading apparatus including a sheet conveying apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic block diagram of a control system of the ADF, reader unit, and image controller unit of FIG. 1. FIG. 3A is a schematic view of the drawing roller portion of FIG. 1, FIG. 3A is a schematic view seen from the direction of arrow A in FIG. 1, and FIG. 3B is a schematic view seen from the direction of arrow B in FIG. 4A to 4D are views for explaining the behavior of the sheet in the drawing roller portion. 6 is a flowchart of sheet separation processing of a drawing roller unit by a CPU according to the first embodiment. FIGS. 6A to 6C are diagrams for explaining a method for determining a double-fed sheet. It is a figure which shows the different degree of the change of the sheet detection width | variety of the sheet | seat detected by a sheet | seat width detection part. FIGS. 8A to 8D are diagrams for explaining the pushing operation of the sheet to the registration roller by the drawing roller portion. FIG. 6 is a partial perspective view of an ADF in an image reading apparatus provided with a sheet conveying apparatus according to a second embodiment of the present invention as viewed from above. 10A to 10C are views for explaining the behavior of the sheet in the drawing roller portion.

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

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

  1, the image reading apparatus includes an automatic document feeder (hereinafter referred to as “ADF”) 100 and an image reader (hereinafter referred to as “reader”) 200. The ADF 100 includes a sheet tray 30 on which a sheet bundle S composed of one or more sheets is placed. The sheets of the sheet bundle S are restricted from entering the ADF by the separation pad 21 before the sheet feeding operation is started. When the sheet feeding operation is started, the sheet (sheet fed sheet) is drawn into the ADF by driving the sheet feeding roller 1 pressed on the sheet bundle S, and only the uppermost sheet is separated by the separation pad 21 and the separation roller 2. Is fed onto the conveyance path.

  Actually, only the uppermost sheet may not always be separated by the separation pad 21 and the separation roller 2 due to the difference in the sheet type of the sheet and the frictional force of the surface. In this embodiment, it is assumed that a sheet fed in a state where two sheets are overlapped without being separated into one sheet at this time is a double-fed sheet.

  A separation sensor 10 is disposed downstream from the position of the separation pad 21 and the separation roller 2 along the sheet conveyance direction. The separation sensor 10 is used to detect the sheet interval after separation based on the sensor output. A sheet width in which a plurality of sheet detection sensors are arranged on the downstream side from the position of the separation sensor 10 along a direction (for example, a direction orthogonal) intersecting a sheet conveyance direction (hereinafter, simply referred to as “conveyance direction”). A detector 11 is arranged. In the sheet width detection unit 11, the width of the fed sheet is detected based on whether or not the plurality of sheet detection sensors are detected at a predetermined timing until the fed sheet hits the registration roller 4. The sheet width detection unit 11 may be configured by an array sensor such as a CCD or CIS.

  The sheet that has passed through the sheet width detection unit 11 is conveyed by the drawing roller unit (first conveyance unit) 3 and is abutted against the registration roller 4. Since the rotational driving of the registration roller 4 is stopped when the sheet arrives, the leading edge of the sheet cannot be advanced. In this state, the pulling roller unit 3 pushes the sheet toward the registration roller 4 to form a deflection on the sheet. Even when the leading edge of the sheet is inclined with respect to the conveying direction in the conveying process so far, the skew is eliminated by the deflection of the sheet by the registration rollers 4. Thereafter, the registration roller 4 is driven to rotate, so that the sheet is fed to the first conveying roller 5 and the roller 7, and further fed onto the flow reading glass 201 by these rollers. The reader unit 200 reads the surface image of the sheet through the platen glass 201.

  Thereafter, the sheet is conveyed by a second conveyance roller (second conveyance unit) 6 and passes between the roller 16 and the back surface reading glass 18. Then, the sheet is discharged to the sheet discharge tray 31 via the discharge flapper 20 and the discharge roller 8.

  The back surface image reading unit 17 is a unit that optically reads the image information of the sheet and outputs a photoelectrically converted image signal to the subsequent stage, and is located on the back side of the back surface reading glass 18 facing the roller 16. The back image reading unit 17 reads the back image of the sheet while the sheet passes through the gap between the roller 16 and the back surface reading glass 18.

  The sheet detection sensors 12, 13, and 14 detect whether or not there is a sheet at the sensor position. Although not shown, a conveyance guide is provided along the sheet conveyance path, thereby restricting the sheet from going outside a predetermined range in a direction orthogonal to the conveyance direction (hereinafter also referred to as “main scanning direction”). ing.

  The reader unit 200 is also a unit that optically reads sheet image information and outputs a photoelectrically converted image signal to the subsequent stage. The reader unit 200 includes a platen glass 201, a platen glass 202, a scanner unit 209, a second mirror 205, a third mirror 206, a lens 207, and a CCD (Charge Coupled Device) 208. The scanner unit 209 includes an illumination lamp 203 and a first mirror 204.

  When reading the image on the sheet surface, the scanner unit 209 is moved under the platen glass 201 in advance. In this state, the illumination lamp 203 is turned on, and the reflected light from the surface of the sheet passing on the flow-reading glass surface is guided to the lens 207 via the first to third mirrors 204, 205, 206, and on the CCD 208. Make an image. Through this process, the sheet surface image is photoelectrically converted by the CCD 208 to become a digital image signal.

  FIG. 2 is a schematic block diagram of a control system of the ADF 100, the reader unit 200, and the image controller unit 300 in FIG.

  In the reader unit 200, a central processing unit (hereinafter referred to as “CPU”) 251 controls the ADF 100 and the reader unit 200. The CPU 251 is connected to a ROM 252 which is a program storage memory and a RAM 253 which is a work area memory. The ROM 252 stores control programs for the reader unit 200 and the ADF 100, and the RAM 253 stores input data used for control and work data.

  The CPU 251 is connected to a motor driver unit 256 that is a driver circuit for driving an optical motor that moves the scanner unit 209 and a surface image reading unit 260. The surface image reading unit 260 includes the illumination lamp 203 and the CCD 208 described above, and a signal control unit 259 for converting the output of the CCD 208 into a digital image signal. The CPU 251 controls the motor driver unit 256 and the surface image reading unit 260 to perform image reading on the document surface.

  The sheet interval correction processing unit 254 performs parameter correction of the signal control unit 259 according to the sheet interval of the fed sheet (interval between the trailing edge of the preceding sheet and the trailing sheet and the leading edge). In this embodiment, the interval between sheets is treated as a time parameter, but may be a distance parameter. The image processing unit 255 processes the image signals read by the front surface image reading unit 260 and the back surface image reading unit 17, generates a timing signal, and transfers the timing signal to the image controller unit 300. The image buffer 261 is controlled by the image processing unit 255 and temporarily stores an image signal read by the front surface image reading unit 260 or the back surface image reading unit 17.

  An input / output port of the CPU 251 is connected to the ADF 100. A motor group 103, a solenoid group 101, and a clutch group 102 for driving various transport rollers are connected to the output port. On the other hand, various sensor groups 104 for generating a sheet conveyance timing signal and a sheet width detection unit 11 for detecting a sheet size in the conveyance process are connected to the input port.

  The CPU 251 controls the sheet conveying operation in the ADF 100 by executing a control program stored in the ROM 252. The back image reading unit 17 includes an illumination lamp 307 for reading the back image, a CIS (contact image sensor) 308, and a signal control unit 107. The back image reading unit 17 is connected to the CPU 251, reads the back image of the sheet in accordance with a control signal from the CPU 251, and transfers it to the image processing unit 255.

  The image signal stored in the image buffer 261 is read to the image processing unit 255 in synchronization with the timing signal, and sequentially transferred to the image controller unit 300 through the controller IF unit 350.

  In addition to the reader unit 200, the image controller unit 300 includes a CPU 301 for image control, a ROM 302, and a RAM 303. The image signal sent from the image processing unit 255 to the image controller unit 300 is subjected to input / output control by the image input / output unit 304, and is stored in the image memory 305 as image data in the order of sending.

  The image processing unit 310 performs various types of image processing on the image signal input from the image input / output unit 304 or the image data stored in the image memory 305. The operation unit 309 can notify the user of the state of the apparatus through a screen display, and inputs a user operation instruction to the apparatus. In response to an instruction input to the operation unit 309, the CPU 301 reads out image data from the image memory 305, and transfers the image and information to another device or personal computer through a telephone line or network connected to the external interface 312. Execute the process.

  In the present embodiment, a CCD is used for the front surface image reading unit in the reader unit 200, and a CIS is used for the back surface image reading unit in the ADF 100. Also good.

  Next, the drawing roller unit 3 will be described in detail.

  3A and 3B are diagrams showing a schematic configuration of the drawing roller portion 3 in FIG. 1, FIG. 3A is a schematic view seen from the direction of arrow A in FIG. 1, and FIG. These are the schematic views seen from the direction of arrow B in FIG.

  The drawing roller unit 3 is composed of a pair of conveying rollers of a pair of upper and lower upper rollers 3a and 3b. The upper roller 3a and the lower roller 3b convey the sheet P in the conveying direction by sandwiching and rotating the sheet P between them. The upper roller 3a and the lower roller 3b are rotationally driven by individual motors (included in the motor group 103 in FIG. 2).

  The rotation axes of the upper roller 3a and the lower roller 3 extend in different directions instead of the same direction. Specifically, the lower roller 3b has a rotation axis in the same direction as the paper feed roller 1, the separation roller 2, and the registration roller 4 (a direction orthogonal to the sheet conveyance direction), and the sheet P is straight in the downstream direction. It is a conveyance roller to be conveyed. On the other hand, the upper roller 3a is a skew feeding roller that is inclined in the horizontal direction with respect to the direction orthogonal to the conveying direction. In the present embodiment, the inclination angle of the upper roller 3a with respect to the lower roller 3b is 20 degrees. The inclination angle is changed according to the material and size of the roller, the frictional force, and the like, and is not limited to 20 degrees. Further, the relationship between the direction of the rotation axis of the upper roller 3a and the direction of the rotation axis of the lower roller 3b may be opposite to the above.

  Further, the conveying force applied to the sheet by the upper roller 3a is different from the conveying force applied to the sheet by the lower roller 3b. The reason will be described later.

  Furthermore, the upper roller 3a and the lower roller 3b have a structure capable of switching the contact / separation state. This is because, in a state where there is no sheet between the rollers, when a roller having a different axial direction is brought into direct contact and rotated, damage to the roller such as scraping or deformation is assumed. The contact / separation switching between the upper roller 3a and the lower roller 3b is performed by driving a specific solenoid of the solenoid group 101 described above in accordance with a control signal from the CPU 251. That is, this specific solenoid functions as a switching unit that switches the contact / separation state between the upper roller 3a and the lower roller 3b. Any structure or method may be used for switching between contact and separation between the upper roller 3a and the lower roller 3b.

  Next, the behavior of the sheet P in the drawing roller unit 3 will be described with reference to FIGS. 4 (a) to 4 (d). In the drawing, only the oblique feeding roller (upper roller 3a) is shown as the drawing roller unit 3, but as described above, the unillustrated conveying roller (lower roller 3b) is arranged at the position facing the roller. It is assumed that Further, in the vicinity of the drawing roller unit 3, a sheet width detection unit 11 that detects the width of the sheet in a direction intersecting the sheet conveyance direction of the registration roller 4 (lower roller 3 b) is disposed.

  FIG. 4A is a diagram illustrating a state before the sheet P reaches the drawing roller unit 3. In the state shown in the drawing, it is not apparent whether the sheet P is a normally separated single sheet or a double feed in which two sheets are overlapped. When the sheet P reaches the drawing roller unit 3, the drive control is performed so that the upper roller 3a and the lower roller 3b are switched from the separated state to the contact state.

  Here, the conveyance force with respect to the sheet | seat of the upper side roller 3a and the lower side roller 3b is demonstrated. The transport force can be obtained by using, as parameters, the driving force of each motor for each of the upper roller 3a and the lower roller 3b, the frictional force of the roller itself, the angular difference between the rotation axes of the two transport rollers, and the like.

  First, a case where the number of conveyed sheets P is one will be described.

  FIG. 4B is a diagram illustrating an example of a state when the conveyance force is set in advance so that the upper roller 3a> the lower roller 3b. In this case, since the conveying force of the upper roller 3a is superior, the sheet P is skewed and conveyed obliquely. On the other hand, FIG. 4C is a diagram showing a state in which the conveying force is set in advance so that the upper roller 3a <the lower roller 3b. In this case, the sheet P advances straight because the conveying force of the lower roller 3b is superior.

  Next, a case where the conveyed sheet P is a double feed will be described.

  When the upper roller 3a and the lower roller 3b are switched to the contact state with respect to the double fed sheet, the upper sheet P of the double fed sheet receives an oblique force by the upper roller 3a. On the other hand, the lower sheet Pa receives a force straight with respect to the conveying direction by the lower roller 3b. As a result, the sheet on the upper surface side and the sheet on the lower surface side in the double-fed sheet are twisted, and the sheet Pa overlapping the sheet P is separated as shown in FIG. In this case, it is known that the separation behavior does not change so much regardless of which conveying force is large between the upper roller 3a and the lower roller 3b. Note that the skew of the sheet skewed by the conveying force of the upper roller 3 a is corrected by the registration roller 4. Further, the sheet that has been skewed and is conveyed by the registration roller 4 has a configuration in which the sheet position in the width direction orthogonal to the conveyance direction is adjusted by the shift of the registration roller 4 in the axial direction. May be.

  FIG. 5 is a flowchart of the sheet separation process of the drawing roller unit 3 by the CPU 251 in the present embodiment.

  First, the CPU 251 controls to start a sheet pick-up operation on the ADF in response to an instruction to start a reading operation from the image controller unit 300 (step S800). Specifically, the sheet feeding roller 1 is turned on to drive / lower it to contact the upper surface of the sheet bundle S, and the sheet P is fed to the separation roller 2. At the same time, the separation roller 2 tries to separate the uppermost sheet P and conveys the separated sheet P into the apparatus.

  Next, the CPU 251 starts detection of the sheet width by the sheet width detection unit 11 after a predetermined time has elapsed from the start of the pickup operation (step S801).

  Thereafter, the CPU 251 waits until the sheet P reaches the drawing roller unit 3 (step S802), and immediately before the sheet P reaches the drawing roller unit 3, the drawing roller unit 3 that has been in the separated state is brought into a contact state. It is switched and rotated (step S803). Then, the CPU 251 drives and controls the upper roller 3a and the lower roller 3b, and pulls out (separates) the sheet P as shown in FIG. 4D (step S803).

  Next, the CPU 251 ends the pickup operation almost in synchronization with step S803, and facilitates the sheet extraction operation by the extraction roller unit 3 (step S804). Specifically, the drive of the paper feed roller 1 is stopped and lifted / stopped to be separated from the sheet bundle S, and the drive of the separation roller 2 is stopped to facilitate the pulling operation by the pulling roller unit 3. .

  Next, the CPU 251 determines whether or not the sheet P being conveyed is being double-fed based on the change in the sheet detection width by the sheet width detection unit 11 (step S805).

  Here, determination of double feeding of sheets will be described with reference to FIGS. 6A to 6C and FIG.

  In the present embodiment, the multi-feed determination is performed based on the sheet detection width of the sheet width detection unit 11.

  FIG. 6A is a diagram illustrating an example of a state before the sheet P reaches the drawing roller unit 3.

  In the illustrated example, the sheet detection width L0 when the sheet width detection unit 11 detects the sheet P is the same as the sheet width of the sheet P.

  FIG. 6B shows that under the condition that the conveying force is the upper roller 3a> the lower roller 3b, one sheet P reaches the drawing roller unit 3, and the conveying force is the upper roller 3a> the lower roller 3b. It is the figure which has become a skew state by being.

  The sheet detection width of the sheet P by the sheet width detection unit 11 in the illustrated example is L1. In the illustrated example, since the sheet P is skewed, L1> L0. Note that, under the condition that the conveying force is the upper roller 3a <the lower roller 3b, when one sheet P reaches the drawing roller unit 3, the sheet P goes straight as it is. Therefore, the sheet detection width of the sheet P by the sheet width detection unit 11 is L0 as in FIG.

  FIG. 6C is a diagram illustrating a state where the double-fed sheets have reached the drawing roller unit 3 and separation has started.

  The sheet detection width of the sheet P by the sheet width detection unit 11 in the illustrated example is L2. The apparent sheet widths L1 and L2 detected by the sheet width detection unit 11 change in the course of sheet conveyance / separation. FIG. 7 is a graph showing different degrees of change in the sheet width detected by the sheet width detection unit 11 after the sheet reaches the drawing roller unit 3. The vertical axis of the graph shown in FIG. 7 is the sheet detection width, and the horizontal axis is the elapsed time t. t0 is the timing at which the sheet width detection unit detects the sheet width at the leading edge of the sheet, and t1 is the timing at which the sheet reaches the drawing roller unit 3.

  In FIG. 7, the sheet detection width L <b> 1 for one sheet is constant from when the leading edge of the sheet starts to be detected by the sheet width detection unit 11 until the sheet reaches the drawing roller unit 3. Under the condition that the conveying force shown in FIG. 6B is set such that the upper roller 3a> the lower roller 3b, the skew increases as the sheet advances after the sheet reaches the drawing roller unit 3. Accordingly, the sheet detection width L1 at the time of sheeting gradually increases. The increase in L1 stops when the skew of the sheet P becomes the same as the inclination of the upper roller 3a. On the other hand, since the upper sheet P is skewed at the time of double feeding, the lower sheet Pa is conveyed as it is, so that the change amount of the sheet detection width L2, that is, the inclination of the graph becomes larger than the inclination of L1. . Note that the value of L2 is maximized when the skew of the sheet P becomes the same as the inclination of the upper roller 3a.

  Accordingly, by referring to the change in the sheet detection width after the sheet P reaches the drawing roller unit 3 over time, if the degree of change exceeds, for example, the predetermined threshold value T shown in the drawing, the sheet is conveyed. It can be determined that the sheet that has been double fed.

  In this embodiment, the multifeed determination is performed based on the change in the sheet detection width by the sheet width detection sensor. However, the multifeed determination method is not limited to this, and a dedicated sensor may be provided separately.

  When the determination result in step S806 of FIG. 5 is double feeding, the CPU 251 stops or decelerates driving of the lower roller 3b of the drawing roller unit 3 and switches to conveyance that mainly drives the upper roller 3a (step S807). . As a result, only the upper sheet of the sheet to be separated is conveyed first. Thereafter, the CPU 251 waits for the upper sheet to reach the registration roller 4 (step S808). Next, when the upper sheet reaches the registration roller 4 and is abutted against the registration roller 4 and the skew of the upper sheet is corrected, the CPU 251 drives the registration roller 4 to move the upper roller 3a to the lower roller 3b. And the drive of the upper roller 3a is stopped (step S809).

  Here, the operation of pushing the sheet into the registration roller 4 by the drawing roller unit 3 will be described with reference to FIGS.

  FIG. 8A is a diagram illustrating a state where the sheet P is skewed before reaching the registration roller 4. 8A to 8D, the upper side is a view of the registration roller 4, the drawing roller unit 3, and the sheet P viewed from directly above, and the lower side is a view of them viewed from the side. .

  In FIGS. 8A to 8D, the rollers drawn with diagonal lines indicate that they are in a driving state.

  In the state shown in FIG. 8B, the leading edge of the sheet P has reached the registration roller 4, but the sheet P cannot be advanced because the registration roller 4 is in a stopped state. On the other hand, since the sheet P is pushed from behind by the drawing roller unit 3, the deflection of the sheet P has started to be formed.

  FIG. 8C is a diagram illustrating a state in which the pushing by the drawing roller unit 3 is finished and the formation of the loop of the sheet P is finished. At this stage, the skew of the front end of the sheet is removed in a state of being abutted against the registration roller 4 due to the stress of the sheet and the regulation of the conveyance guide (not shown). Then, when the registration roller 4 is driven to rotate at a predetermined timing, the sheet is conveyed to the previous image reading position in a skewed state as shown in FIG. 8D.

  Returning to FIG. 5, in step S <b> 810, the CPU 251 waits for separation of the sheet P to be conveyed downstream by the registration roller 4. Completion of separation is determined by elapse of time from the start of driving of the registration roller 4 until the trailing edge of the upper sheet passes the registration roller. Upon confirming the completion of the sheet separation, the CPU 251 stops the driving of the registration roller 4, releases the separation of the upper roller 3a of the drawing roller unit 3, restarts the driving of both the upper and lower rollers (step S811), and double feeds The lower sheet is conveyed toward the registration roller 4, and the process proceeds to step S812. The processing after step S812 is the same as the case where the sheet is not double-fed in step S806.

  If the determination result in step S806 is not double feeding, the CPU 251 continues the sheet conveyance as it is and causes the sheet to reach the registration roller 4. After confirming the arrival at the registration roller 4 (step S812), the CPU 251 stops the driving of the drawing roller unit 3 at a predetermined timing, and returns the upper roller 3a and the lower roller 3b to the separated state (step). S813). Finally, the CPU 251 stops the sheet width detection unit 11 (step S814), ends the double width detection process based on the sheet width detection and the temporal change of the width detection signal, and ends a series of sheet pulling processes. .

  In the sheet conveying apparatus of the present embodiment, the conveying force of the lower roller 3b that is the same conveying direction as the sheet conveying direction of the registration roller 4 is smaller than the conveying force of the upper roller 3a. The conveyance force of 3a <the conveyance force of the lower roller 3b may be sufficient.

  As described above, according to the above-described embodiment, in order to separate the multi-feed sheets, one of the pair of conveying rollers having different rotation shaft directions is arranged to convey the sheet in the conveying direction, and the other is the sheet. Are arranged so as to be inclined with respect to the conveying direction. Thereby, the re-separation of the double-fed sheets can be easily performed, and the efficiency of sheet conveyance can be improved. In addition, since it is not necessary to stop the apparatus, the sheet conveyance efficiency can be improved.

  In the above embodiment, since the registration roller 4 is disposed downstream from the position of the drawing roller unit 3 in the transport direction, the registration roller 4 is reached in steps S808 and S812 of FIG. Judgment is made. However, what is arranged on the downstream side of the drawing roller portion is not limited to the registration roller, and may be another roller.

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

  FIG. 9 is a partial perspective view of the ADF 1100 viewed from above in the image reading apparatus provided with the sheet conveying apparatus according to the second embodiment of the present invention.

  As shown in FIG. 9, the ADF 1100 has a sheet tray 1030 on which a sheet bundle S composed of one or more sheets is placed. The sheet tray 1030 is configured such that the front side of the tray (lower side in the figure) protrudes obliquely forward of the apparatus, that is, the sheet guide member 1040 on the front side of the tray is in the conveyance direction (left-right direction in the figure). It is installed at an angle. With such an arrangement, when a user standing in front of the apparatus (the lower side in the drawing) places the sheet bundle S on the sheet tray 1030, the user stretches his / her hand to place the sheet bundle S. You do n’t have to. That is, the sheet bundle can be placed in a more ergonomically natural form.

  On the other hand, a space is provided on the back side (upper side in the drawing) of the sheet tray 1030 along the same direction as the transport direction. This is because the trailing edge of the sheet can move freely when the sheet drawn obliquely with respect to the transport direction from the sheet bundle S placed on the front side of the sheet tray 1030 changes direction along the transport direction. It is for doing so.

  The pull-in angle of the separation roller 1002 is set so that the axial direction of the separation roller 1002 is orthogonal to the inclination of the portion where the sheet guide member 1040 is in contact with the sheet bundle side. Since the sectional view of the ADF 1100 is substantially the same as FIG. 1 described in the first embodiment, it is omitted. However, in addition to the sheet tray 30 in FIG. 1, the paper feed roller 1, the separation pad 21, the separation roller 2, and the separation sensor 10 are disposed obliquely according to the angle of the sheet tray 1030 with respect to the conveyance direction.

  The conveying roller pair of the drawing roller unit 1003 is arranged such that one upper roller conveys the sheet in the sheet conveying direction, and the other lower roller is arranged in the same direction as the drawing direction of the sheet bundle S on the sheet tray. is doing. That is, the lower roller is disposed so as to convey the sheet obliquely with respect to the sheet conveyance direction.

  Regarding the conveyance force of the conveyance roller pair of the drawing roller unit 1003, the upper roller that conveys the sheet in the direction along the conveyance direction is configured to be larger than the lower roller.

  Note that the control block diagram and description of the image reading apparatus in the present embodiment are the same as those in the first embodiment, and are therefore omitted.

  Next, the behavior of the sheet P at the drawing roller unit 1003 will be described with reference to FIGS. Although not shown in the figure, as described above, the lower roller is arranged so as to be in the direction of drawing the sheet from the sheet tray 1030. The sheet width detection unit 1011 is disposed so as to be orthogonal to the sheet guide unit 1040, and the configuration thereof is the same as the configuration of the sheet width detection unit 11 in the first embodiment.

  FIG. 10A shows a state before the sheet P reaches the drawing roller unit 1003. Similar to the first embodiment, in this state, it is not apparent whether the sheet P is a single sheet or multiple sheets are fed. In addition, the point that the drawing roller unit 1003 is in a separated state at this point is the same as that in the first embodiment.

  FIG. 10B shows a case where the number of sheets P is one. Although the drawing roller unit 1003 is switched to the contact state, the sheet P is changed in the direction along the sheet conveying direction because the conveying force of the upper roller is large.

  FIG. 10C shows a case where the sheet P is double-fed. Similarly, after the sheet P arrives, the drawing roller unit 1003 is switched to the contact state. In this case, the upper sheet of the double fed sheets receives a force in the direction along the conveying direction by receiving a force from the upper roller. On the other hand, the lower sheet receives a force from the lower roller and receives a force in the sheet feeding direction. As a result, the upper and lower surfaces of the double-fed sheets are twisted to separate the double-fed sheets. Done.

  The control in the drawing roller unit 1003 of the present embodiment is also the same as the control procedure in the first embodiment, and is therefore omitted.

  As described above, even in the sheet conveying apparatus in which the sheet tray is protruded toward the front side so that the user can easily place the sheet, the drawing roller unit 1003 includes a pair of rollers having different conveying directions. To do. As a result, the sheet conveyance direction can be switched to the direction along the conveyance direction of the downstream conveyance roller (for example, the registration roller 4), and the sheet can be reliably re-separated even when double feeding is performed during sheet feeding.

  In the first and second embodiments, the image reading apparatus including the sheet conveying apparatus has been described. However, the present invention is not limited to this, and an image forming apparatus in which an image forming unit (printer unit) is added to the above configuration may be used. The present invention can be applied.

3 Pull-out roller section 3a Upper roller 3b Lower roller 4 Registration roller 11 Sheet width detection section 100 ADF
200 Reader unit 251 CPU
300 Image controller

Claims (10)

A sheet feeding means for separating and feeding sheets one by one from a sheet bundle placed on a sheet tray;
A first conveying unit that sandwiches and conveys a sheet fed from the sheet feeding unit, and includes a pair of conveying rollers having different rotation axis directions;
Second conveying means for further conveying the sheet conveyed by the first conveying means,
One of the pair of transport rollers is arranged to transport the paper sheet in the transport direction of the sheet of the second transport unit, and the other of the pair of transport rollers transports the paper sheet to the second transport A sheet conveying apparatus, wherein the sheet conveying apparatus is disposed so as to be inclined with respect to a sheet conveying direction of the means. Double feed determination means for determining whether or not the sheet conveyed by the first conveyance means is double-feeded;
Control means for controlling to stop or decelerate rotation of one of the pair of conveying rollers holding the double fed sheet when it is determined by the double feeding judging means that the sheet is double fed. The sheet conveying apparatus according to claim 1, further comprising: A sheet width detecting unit that is disposed in the vicinity of the first conveying unit and detects a width of the sheet in a direction intersecting a conveying direction by the first conveying unit;
The multi-feed determining unit determines whether or not the sheet is multi-feed based on a change in the sheet width detected by the sheet width detecting unit while the sheet is being conveyed by the first conveying unit. The sheet conveying apparatus according to claim 2, wherein   4. The sheet conveying apparatus according to claim 3, wherein the sheet width detecting unit includes a plurality of sensors arranged in a direction crossing a sheet conveying direction of the second conveying unit.   2. The sheet conveying apparatus according to claim 1, further comprising switching means for switching the conveying roller pair between a contact state in which one and the other are brought into contact with each other and a separated state in which the pair is separated.   The sheet conveying apparatus according to claim 5, wherein the switching unit switches the pair of conveying rollers that have been in a separated state to a contact state in synchronization with the arrival of the sheet.   The sheet conveying apparatus according to claim 1, wherein the conveying force by one of the conveying roller pair is different from the conveying force by the other of the conveying roller pair.   A guide member for guiding the placement of the sheet bundle on the sheet tray is provided, and the portion of the guide member that is in contact with the side of the sheet bundle is installed at an angle with respect to the sheet conveyance direction. The sheet conveying apparatus according to claim 7.   The conveying direction of one sheet of the conveying roller pair is the same as the conveying direction of the sheet of the second conveying means, and the conveying force by one of the conveying roller pair is greater than the conveying force by the other of the conveying roller pair. The sheet conveying apparatus according to claim 8, wherein the sheet conveying apparatus is large. A sheet tray on which a sheet bundle is placed;
A sheet feeding means for separating and feeding sheets one by one from the sheet bundle placed on the sheet tray;
A first conveying unit that sandwiches and conveys a sheet fed from the sheet feeding unit, and includes a pair of conveying rollers having different rotation axis directions;
Second conveying means for further conveying the sheet conveyed by the first conveying means;
Reading means for reading an image of the sheet conveyed by the second conveying means,
One of the pair of transport rollers is arranged to transport the paper sheet in the transport direction of the sheet of the second transport unit, and the other of the pair of transport rollers transports the paper sheet to the second transport An image reading apparatus, wherein the image reading apparatus is disposed so as to be transported obliquely with respect to the sheet transport direction of the means.

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