JP2020015630A - Sheet feeder and image reading device - Google Patents

Abstract

To provide a sheet feeder in an inexpensive structure that surely prevents paper sheet jamming from occurring.SOLUTION: The sheet feeder includes: a separating feeding part that separates and feeds each sheet from a sheet loading table; and a skew detection part that detects skew of the sheet being transported by the separating feeding part. The separating feeding part can switch between the separating feeding that feeds a sheet while separating and the non-separating feeding that feeds without separating a sheet. When separating feeding, the skew detection part detects the skew of a sheet using a first threshold for determining the skew of the sheet during the separating feeding, and when feeding without separating, detects the skew of a sheet using a second threshold which is different from the first threshold for determining the skew of a sheet during separating feeding.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an automatic banknote depositing / dispensing machine installed in a bank or the like, and an automatic sheet processing apparatus that handles sheets such as an OCR (optical character reader) used in schools and hospitals. The present invention relates to a sheet monitoring method and a conveyance mechanism for monitoring a conveyance state, for example, whether there is an abnormality in a skew, a double feed, a gap between sheets, and the like.

  2. Description of the Related Art In recent years, image forming apparatuses have been provided with a plurality of functions that can be provided, and are becoming multifunctional. The functions include a copy function, a facsimile transmission function, a scan function, a print function, and the like, and there are various types. Further, with the diversification of the above functions, an automatic sheet feeding apparatus (ADF) capable of automatically sequentially feeding sheets has been mounted.

  Here, in order to properly execute the above function, it is indispensable that the sheets to be subjected to image formation are transported in the paper transport path without being inclined obliquely.

  Normally, the sheet is conveyed by the sheet processing apparatus by nipping and conveying the sheet between a driving roller and a driven roller urged by a spring or the like on the driving roller side, or by conveying the sheet between endless conveyance belts. And transporting the paper.

  One of the biggest problems in such a sheet processing apparatus is sheet jam. For example, when the sheet is obliquely inserted into the sheet insertion port, or when the sheet is conveyed obliquely due to imbalance of the pressing force of the belt or the roller of the conveyance means behind the sheet insertion port, a problem of sheet jamming occurs. Likely to happen.

  Also, if the sheet is conveyed in a skewed state (skewed state), the image will be read in an skewed state, or if the sheet is steeply skewed, the paper will be jammed in the conveyance path, causing the sheet to be damaged. It may be. Regarding the problem of transport performance, a similar problem may occur regardless of the type of sheet being transported.

  As a conventional means for detecting a sheet conveyance state, there is a means for detecting a skew or a shift of sheets using an image sensor, as in an apparatus described in Patent Document 1. The entire width of the sheet conveyed by the image sensor provided on the conveyance path is read, the output of the image sensor is binarized, a data pattern is created in the longitudinal direction, and the created data pattern is examined. It is analyzed whether it was transported in such a state.

  Further, as in the device described in Patent Document 2, a light-emitting element and a light-receiving element of a transmission type are arranged side by side in a direction crossing the direction in which a sheet is conveyed, and light emitted from the light-emitting element is transmitted by a light guide. It is configured to cross the transport path a plurality of times and enter the light receiving element. While the conveyed sheet blocks the light path between the light-emitting element and the light-receiving element, the light incident on the light-receiving element is shielded, so it is possible to analyze the degree of inclination of the sheet by measuring the light-shielding time. Become.

JP-A-6-183605 JP 2000-285278 A

  However, according to the technology described in Patent Document 1, although the skew state of a conveyed sheet can be determined from image data read by an image sensor and shift and skew can be detected, the image data read by the image sensor can be detected. Has to be determined after A / D conversion and conversion into image data, there is a problem that the processing load on the control unit is increased.

  Further, since the sheet conveyance state is determined from the read image data, the detection of the skew state of the sheets or the paper jam is delayed, which leads to a problem that the sheet is damaged.

  In addition, it is necessary to install an image sensor only to detect the sheet conveyance state, which causes a problem that the area of the installation location is increased and the cost is increased.

  The present invention has been made in view of the above-described problem, and an object of the present invention is to realize a sheet transporting device that can more reliably prevent a sheet jam from occurring with an inexpensive configuration.

  A sheet feeding apparatus according to the present invention separates and feeds a sheet one by one from a sheet mounting table and feeds the sheet, and detects skew of the sheet being fed by the separation and feeding means. Skew detecting means, and the separation and feeding means can be executed by switching between a separated feeding for feeding while separating the sheet and a non-separating feeding for feeding without separating the sheet. The skew detecting means detects the skew of the sheet using the first threshold value for determining the skew of the sheet at the time of the separated feeding in the case of the separated feeding; At the time of feeding, the skew of the sheet is detected by using a second threshold different from the first threshold for determining the skew of the sheet at the time of the separated feeding.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to implement | achieve the sheet | seat conveyance apparatus which can prevent generation | occurrence | production of a paper jam of a sheet | seat more reliably with a cheap structure.

FIG. 1 is a front sectional view showing a schematic configuration of an image reading apparatus according to an embodiment of the present invention. FIG. 2 is a schematic sectional view showing a main part of the image reading apparatus shown in FIG. 1. FIG. 2 is a side view schematically showing a main part of a sheet separation mechanism of the sheet feeding apparatus 101. FIG. 3 is a top view schematically illustrating a main view of a sheet separating mechanism of the sheet feeding apparatus 101. FIG. 4 is a top view schematically showing a main part of a separation mechanism and an arrangement area of a conveyance state detection unit. FIG. 2 is a block diagram showing an electrical configuration of the transfer device. FIG. 5 is a diagram illustrating items for which an abnormality is determined by a sheet conveyance failure determining unit. FIG. 5 is a top view schematically showing a state in which a sheet rotates when a staple document is fed. FIG. 9 is a top view schematically illustrating a state in which a sheet rotates when a wide staple document is fed. FIG. 5 is a top view showing a state where a document is hanging on S1R or S1L. FIG. 4 is a top view schematically illustrating a state in which a sheet is jammed by a separation roller pair. 9 is a flowchart of a sheet conveyance state detection process according to the embodiment of the present invention. FIG. 9 is a top view schematically showing a main part of a separation mechanism according to another embodiment of the present invention. FIG. 9 is a top view schematically showing a main part of a separation mechanism according to another embodiment of the present invention. FIG. 9 is a top view schematically showing a main part of a separation mechanism according to another embodiment of the present invention. FIG. 9 is a top view schematically showing a main part of a separation mechanism according to another embodiment of the present invention. The figure which shows the positional relationship of the separation feeding area | region in another embodiment, and the abnormality detection area | region.

  The embodiment of the present invention is characterized by a mechanism for detecting an abnormality at the time of sheet feeding, and in particular, is characterized by detecting an abnormality at the time of separating and feeding sheets one by one from a sheet mounting table. There is.

  In detail, in the embodiment of the present invention, a separation feeding unit that separates and feeds the sheets one by one from the sheet mounting table, and an abnormality detection unit that detects an abnormality at the time of separation and feeding, It is characterized in that the separation feeding area by the separation feeding means and the abnormality detection area by the abnormality detecting means at least partially overlap.

  Here, it is preferable that the separation feeding area partially overlaps on the upstream side in the sheet feeding direction in the abnormality detection area. This makes it possible to immediately detect an abnormal state of the sheet in the separation feeding area. Further, it is preferable that the abnormality detection area is formed to have a substantially larger area than the separation feeding area. This is because it is possible to accurately detect a change in the state of a sheet moving starting from the inside of the separation feeding area. Further, it is preferable that the abnormality detection region is formed as a region extending from both ends of the separation feeding region to the outside thereof in a direction orthogonal to the sheet feeding direction. This will be described in detail later. For example, when the abnormality detection area is formed by arranging a plurality of sensors, the plurality of sensors can be arranged outside the separation and feeding area. This is because it is possible to effectively prevent the configuration and the separate feeding configuration from interfering with each other. Further, by performing abnormality detection outside the separation feeding area and close to the separation feeding area, it is possible to immediately grasp the movement of the sheet at the time of separation feeding, thereby improving the abnormality detection accuracy. It becomes possible. In other words, by forming the abnormality detection area with a plurality of sensors so that the separation feeding area is included in the abnormality detection area, the abnormality detection accuracy can be improved.

  The abnormality detection area is an area for detecting a state change such as an angle (inclination) of a sheet surface direction in the sheet feeding direction or a sheet feeding posture, and includes, for example, a plurality of sensor groups. That is, it can be formed by substantially surrounding the separated feeding area or its periphery by the arrangement of a plurality of sensors. Further, for example, if an optical sensor is used as the plurality of sensors, it is possible to prevent physical interference with the configuration of the separation and feeding, and accurately grasp the state change of the sheet without contact.

  For example, the abnormality detection area may include a rectangular area formed by arranging a plurality of pairs of detection sensors facing each other in a direction orthogonal to the sheet feeding direction in the sheet feeding direction. This makes it possible to grasp the abnormal state of the sheet or a change in the state at a plurality of positions in the sheet feeding direction on the time axis.

  Further, the separation feeding area is an area including a portion where the separation feeding means using a separation pad, a separation roller, or the like is in contact with the sheet. The sheet feeding posture of the sheet may change due to the separation / feeding unit physically contacting the sheet. By detecting this change in the abnormality detection area, a quick response is possible.

  Note that the separation and feeding area includes at least a separation area for separating the sheet as a part that physically contacts the sheet. Since the separation area separates the sheets one by one from the sheet bundle by controlling the friction with the sheets, the traveling direction of the sheets may change during the separation process.

  In the embodiment of the present invention, when the advancing direction (posture in the feeding direction) of such a sheet changes, the state is detected as soon as possible near the separation / feeding means. It is preferable to form the sheet feeding area as an area extending from a portion where the separation feeding unit is in contact with the sheet to a downstream side in the sheet feeding direction.

  In the embodiment of the present invention, when the separation / feed area includes at least a roller structure, for example, a plurality of rollers (split rollers) are mounted on a roller shaft, and a gap between the rollers is effectively reduced. By utilizing this, it is possible to arrange a plurality of sensors forming an abnormality detection area. In particular, if the sensor is a non-contact type sensor such as an optical sensor for a sheet, it is possible to form an abnormality detection area corresponding to the gap between the rollers. This makes it possible to substantially form the abnormality detection region even in the separation feeding region. Further, one abnormality detection area may be provided so as to surround one roller. For example, when two rollers are mounted on one rotation shaft to feed a sheet, an abnormality detection area may be provided to individually surround each roller. Further, as another form, when a comb-shaped roller having a plurality of grooves provided in the axial direction of the roller shaft with respect to the outer periphery of the roller instead of the split roller is employed, each of the gaps of the groove portions is used. Correspondingly, by providing the detection areas of the optical sensors respectively and forming the abnormality detection area by the detection areas of the plurality of optical sensors, it is possible to substantially form the abnormality detection area in the separated feeding area Becomes Further, if the abnormality detection area is formed inside the separation feeding area and the abnormality detection area is extended to the outside of the separation feeding area, more effective abnormality detection can be realized. . In particular, the present invention can realize effective abnormality detection in heterogeneous sheet feeding in which sheets having different widths are mixed and fed.

  Hereinafter, an embodiment of the present invention will be described more specifically with reference to the accompanying drawings.

  FIG. 1 is a schematic cross-sectional view illustrating an image reading apparatus including a sheet conveying device (document feeding device) according to an embodiment of the present invention, and FIG. 2 is a schematic diagram illustrating a main part of the image reading device illustrated in FIG. FIG.

  As shown in FIGS. 1 and 2, the image reading apparatus 200 of the present embodiment includes a document table 1 on which a plurality of sheets F are stacked and driven up and down by a document table driving motor 2. On both sides of the platen 1 in the width direction of the sheet F, there are provided regulating plates 51 which are in contact with both side portions of the sheet bundle stacked on the platen 1 in the width direction and restrict the skew of the sheet F. The document detection sensor 3 detects a sheet F stacked on the document table 1. The pickup roller 4 sends out the sheets stacked on the document table 1 from the document table 1. The pickup motor 5 drives the pickup roller 4 to rotate.

  The feed roller 6 is rotationally driven by a feed motor 8 in a direction for transporting the sheet F to the downstream side. The separation roller 7 receives a rotational force for conveying the sheet F to the upstream side from the separation motor 9 via a torque limiter (not shown). The feed motor 8 uses a stepping motor, and the motor rotates according to the number of input steps.

  When one sheet is present between the feed roller 6 and the separation roller 7, the feed roller is driven by the upper limit of the rotational torque transmitted to the separation roller 7 by the torque limiter and pushing the sheet back to the upstream side. 6, the rotational torque in the direction of feeding the sheet downstream is increased. As a result, the separation roller 7 rotates following the feed roller 6.

  On the other hand, when there are a plurality of sheets between the feed roller 6 and the separation roller 7, the separation roller 7 holds the sheet in a direction of pushing back the sheet upstream, thereby preventing any entry other than the uppermost sheet.

  As described above, when a plurality of sheets are stacked and fed into the nip portion 13 (FIG. 3) between the feed roller 6 and the separation roller 7, the action of the feed roller 6 to feed the sheet downstream and the separation roller By the action of 7 pushing the sheet back to the upstream side, only the uppermost sheet is fed downstream. The sheets other than the top sheet are returned to the upstream side, and the overlapped sheets are separated. Therefore, the feed roller 6 and the separation roller 7 form a pair of separation rollers 42.

  In this embodiment, the separation roller pair 42 is employed as the separation and feeding means. However, instead of the separation roller pair 42, one of the separation roller 7 and the feeding roller 6 is used as a belt. A pair may be adopted. Alternatively, a separation pad may be used instead of the separation roller 7.

  Alternatively, the separation may be performed only by the torque limiter without using the separation motor 9. The separation motor 9 is held so that the shaft does not rotate. In particular, for a thin sheet, separating the sheet by the return force of the torque limiter may reduce the jam caused by the bent end of the sheet.

  The transport motor 10 drives a roller for transporting the separated and fed sheet from the sheet reading position to the discharge position. Further, the transport motor 10 drives the rollers so that the transport speed of the sheet can be changed according to the optimal speed for reading the sheet, the resolution of the sheet, and the like.

  The image reading section 43 includes reading sensors 14 and 15 for reading an image on a sheet, and changes a scanning interval based on a reading speed and a resolution of the sheet. The document discharge sensor 16 detects that the sheet has passed through the image reading unit 43 and has been discharged to the discharge tray 44.

  The nip gap adjusting motor 11 adjusts a gap between the feeding roller 6 and the separation roller 7 or a pressing force with which the feeding roller 6 is pressed against the separation roller 7 via a sheet. As a result, the gap or the pressing force adjusted to the thickness of the sheet is adjusted, and the sheet can be separated and fed.

  The image reading section 43 includes image reading sensors 14 and 15 for reading image information of a sheet, and is controlled to change the line scanning interval based on the setting of the sheet reading speed and the resolution. The image reading sensor 14 reads an image on the front side of the sheet, and the image reading sensor 15 reads an image on the back side of the sheet.

  The document transport roller pairs 20 and 21, the document transport roller pairs 22 and 23, and the downstream roller pair transport the document to the paper discharge tray 44. The upper guide plate 40 and the lower guide plate 41 guide the sheet conveyed by the separation roller pair 42, the registration roller pairs 17, 18, the conveyance roller pairs 20, 21, the conveyance roller pairs 22, 23, and the downstream roller pair. I do.

  The pre-registration sensor 32 and the post-registration sensor 33 are sensors for detecting a sheet conveyed on the conveyance path, and the conveyance of the sheet is controlled based on the sheet detection timing by these sensors.

  The conveyance state detecting means 60 is disposed near the feeding roller 6 and the separation roller 7 immediately after the sheet F is inserted into the conveyance path, and detects the conveyance state of the sheet F. When the sheet conveyance failure judging unit (not shown) judges that the conveyance is abnormal based on the detection result of the conveyance state detection unit 60, the control unit 45 controls to stop the sheet conveyance operation.

  When the separation and feeding operation of all the sheets is completed and the waiting for the sheets to be placed on the document table 1 is waited, the document table 1 is lowered, moved to the lowermost position of the driving range, and stopped. Then, the sheet is placed on the document table 1 and waits until an instruction to start the separating and feeding operation is given.

  The pre-registration sensor 32 is disposed upstream of the pair of registration rollers 17 and 18 and detects a conveyed sheet. The post-registration sensor 33 is disposed downstream of the pair of registration rollers 17 and 18 and detects a conveyed sheet.

  The control unit 45 controls the entire image reading device 200 including the sheet conveying device 101. For example, based on an output signal from a sensor that detects each of the sheets, the motor is controlled to control the rotation of each of the rollers and convey the sheet. Further, control is performed to read the image of the conveyed sheet.

  FIG. 3 is a side view schematically showing a main part of a sheet separating mechanism of the sheet conveying apparatus 101 in FIG. 1, and FIG. 4 is a top view schematically showing a main part of the sheet separating mechanism of the sheet conveying apparatus 101. is there. FIG. 3 shows the positional relationship of the conveyance state detecting means 60, the feeding roller 6, the separating roller 7, and the nip portion 13 where the feeding roller 6 and the separating roller 7 are in contact. FIG. 4 shows the positional relationship among the document table 1, the sheet bundle F, the sheet F1, the pickup roller 4, the feed roller 6, the separation roller 7, the conveyance state detecting means 60, and the regulating plate 51.

  In the separating means of the sheet transport mechanism configured as described above, the sheet is overlapped and fed by the action of the feeding roller 6 feeding the sheet to the downstream side and the action of pushing the sheet of the separation roller 7 back to the upstream side. When the sheet is fed to the nip between the roller 6 and the separation roller 7, only the uppermost sheet is fed downstream.

  As a conveyance state detecting unit 60 shown in FIGS. 1 and 2, as shown in FIGS. 3 and 4, a sheet that is a non-contact type optical sensor that detects the edge of the sheet in the conveyance direction around the separation roller pair 42. The detection sensors S1L, S1R, S2L, S2R, S3L, S3R are arranged. The sheet detection sensors S1L, S2L, S3L are arranged on the left side of the separation roller 7 at equal intervals in the sheet conveyance direction. Similarly, the sheet detection sensors S1R, S2R, and S3R are arranged on the right side of the separation roller 7 (opposite to the sheet detection sensor S1L and the like) at equal intervals in the sheet conveyance direction. Each of the sheet detection sensors S1R and S1L, each of the sheet detection sensors S2R and S2L, and each of the sheet detection sensors S3R and S3L are spaced apart on the same line in a direction orthogonal to the conveyance direction.

  Among the sensors of the conveyance state detection means 60, the sheet detection sensors S1L and S1R located at the most upstream side are arranged near the nip portion between the feeding roller 6 and the separation roller 7, as shown in FIG. FIG. 3 is a side view showing the periphery of the feeding roller 6 and the separation roller 7. The feeding roller 6 receives a certain pressure from the separation roller 7 and the rollers bend, and a contact area is the nip portion 13. When the sheet F is separated, the leading end of the second sheet F from the upper side of the sheet F remains in the area of the nip portion 13 and only the uppermost sheet F1 is fed. If the sheet detection sensors S1L and S1R are located downstream of the leading end of the second sheet F when the feeding of the sheet F1 ends, the timing at which the leading end of the sheet passes when the feeding of the sheet is started. Can be detected. On the other hand, in order to detect a sheet abnormality earlier, it is necessary to arrange the sheet detection sensors S1L and S1R on the upstream side as much as possible. Therefore, the sheet detection sensors S1L and S1R are arranged on the boundary line on the downstream side of the nip portion 13 so as to satisfy both.

  The sheet detection sensors S2L, S2R, S3L, and S3R are arranged in a region indicated by a dotted line in FIG. 5 so that a feeding error can be detected before the separated sheets reach the registration rollers 17 and 18. When the conveyance state detecting means 60 is disposed inside the registration rollers 17 and 18 in the sheet width direction, the sheet detection sensors S2L, S2R, S3L and S3R are disposed upstream of the registration rollers 17 and 18. When it is arranged outside the registration rollers 17, 18, it may be arranged downstream from the registration rollers 17, 18. This is because, when the distance between the registration rollers 17 and 18 and the separation roller pair 42 is short, when the sheet is skewed, the leading edge of the sheet is moved before the sheet is applied to the registration rollers 17 and 18. This is because there may be a case in which it precedes downstream. In the arrangement region of FIG. 5, in consideration of the skew of the sheet, the width is made wider toward the downstream side in the transport direction as it goes outward in the width direction.

  Next, a description will be given of a feeding abnormality determination method when the sheet detection sensors S1R, S1L, S2R, S2L, S3R, and S3L are used as the conveyance state detection unit 60.

  FIG. 6 is a diagram schematically illustrating an electric block configuration of the sheet conveying apparatus according to the present embodiment. In FIG. 6, each output of the sheet detection sensors S1L, S1R, S2L, S2R, S3L, S3R is sent to the measuring unit 61, respectively. The measuring section 61 calculates various types of transport information based on the output results of the sheet detection sensors S1L, S1R, S2L, S2R, S3L, and S3R as described later. The information to be calculated is non-feed, skew, rotation, transport distance, and speed fluctuation of the sheet. These pieces of transport information are sent to the comparator 62. The comparator 62 compares the sheet conveyance information measured by the measuring unit 61 with the reference value stored in the storage unit 12. As a result, when the normal condition cannot be satisfied, the sheet conveyance failure determination unit 64 determines that a conveyance abnormality has occurred, and sends an abnormality detection signal to the control unit 45. When receiving the abnormality detection signal, the control unit 45 stops the conveying unit and stops conveying the sheet.

  Note that the timer counted by the measuring unit 61 may be a hardware configuration using a counter or the like, or may be a software configuration.

  The transport information will be described in detail below.

  First, the arrival timing of the sheet to the sheet detection sensors S1L, S1R, S2L, S2R, S3L, S3R and the pre-registration sensor 32 will be described. The arrival timing of the sheet is represented by a conveyance distance from the start of sheet feeding to the leading edge of the sheet reaching each sensor. The transport distance is represented as tS1L, tS1R, tS2L, tS2R, tS3L, tS3R, tBR for the sheet detection sensors S1L, S1R, S2L, S2R, S3R, S3L and the pre-registration sensor 32, respectively. Since the feed motor 8 uses a stepping motor, the transport distance is the number of steps input to the motor. When the feed motor 8 is driven at a constant speed, the transport distance may be represented by time instead of the number of steps. When the sheet feeding is started and the feeding motor 8 is driven, the number of steps of the motor is counted, and the same value is stored as tS1L, tS1R, tS2L, tS2R, tS3L, tS3R, and tBR as the conveyance distance of the sheet detection sensor. This process is continued only for the sensors that have not yet detected the leading edge of the sheet after the start of sheet feeding. Thereby, the detection timing of the sheet at each sensor position can be confirmed.

  Various information of the sheet is calculated based on the transport distances of these sensors, and it is determined whether or not the sheet is abnormal. The items to be determined and the types of the detection sections are as shown in FIG. FIG. 7 shows a detection item to be determined, a detection section thereof, a sensor used for detection in each detection section, a comparison value calculated for the determination, a determination timing to be determined, a condition for determining a normal state, and a determination. Indicates the type of error to notify the user when the result is abnormal.

  Each detection item will be specifically described based on FIG. In FIG. 6, from the arrangement of the sheet detection sensors S1L, S1R, S2L, S2R, S3L, and S3R in the transport direction, S1L and S1R are at the first stage, S2L and S2R are at the second stage, and S3L and S3R are at the third stage. Described as a sensor.

  First, non-feeding upstream of the separation will be described. In the non-feeding upstream of the separation, the sheet feeding is started after the sheets are stacked on the document table 1, but the sheet does not reach the separation roller pair 42 and the sheet cannot be fed. This detects that the sheet stacked on the document table 1 has been removed after the start of sheet feeding, and cannot be fed. The sheet detection sensor uses S1L and S1R of the first stage. If the leading end of the sheet does not reach any of S1L and S1R even if the sheet is conveyed and fed by the threshold value TH0 after the start of sheet feeding, it is determined that the sheet is not fed. If the determination condition is such that tS1L ≦ TH0 or tS1R ≦ TH0 cannot be satisfied, the transmission is not performed. If it is determined that the paper is not fed, the paper supply is stopped, and a message indicating that there is no paper on the document table 1 is notified to the user.

  Next, skew will be described. In the skewing, a state in which the sheet is fed while being tilted by a predetermined amount or more is detected. When the image reading start timing is determined based on the post-registration sensor 33, if the sheet is conveyed while being skewed, the leading end and the trailing end of the sheet are cut off, and a portion that cannot be read occurs. Further, there is a possibility that the corner of the sheet collides with the end of the conveyance path and the sheet is damaged. To prevent these, skew is detected.

  One of the sheet detection sensors S1L, S2L, and S3L on the left side of the separation roller 7 and one of the sheet detection sensors S1R, S2R, and S3R on the right side. Calculate the skew amount. There are seven combinations shown in FIG. Of the seven ways, there are three combinations in the direction orthogonal to the transport direction, which are combinations of S1L and S1R, S2L and S2R, and S3L and S3R. The skew amounts are represented as t11, t22, and t33, respectively. The absolute value of the threshold value permitted as the skew amount of the sheet is set to TH1. The comparison value is calculated by calculating the difference between the detection timings so that the skew amount in the state where the right end of the sheet precedes the downstream side becomes a positive value. If the left end of the sheet is skewed ahead of the downstream side, the value is a negative value. The timing at which the determination can be made can be made at any time after the start of feeding. The skew amount becomes 0 until a sheet is detected by one sensor, and the skew amount increases or decreases after the sheet is detected. When two sheets are detected, the skew amount is determined.

  7, the remaining four skew amounts are S1L and S2R, S2L and S3R, S2L and S1R, S3L and S2R as combinations of sensors in a direction inclined with respect to the sheet width direction. And the skew amounts are represented as t12, t23, t21 and t32. In these combinations, since the distance between the sensors is large in the transport direction, the amount of skew is large as much. As a determination condition, an offset value A of the transport distance is added to correct the distance in the transport direction between the sensors. The absolute value of the upper limit and the lower limit of the range of the detection timing difference allowable by this offset are different. Therefore, the determination timing is after the detection of either the left or right sensor, and the determination condition is changed for each of the previously detected sensors.

  Next, rotation will be described. For the rotation of the sheet, a difference (rotation amount) of the skew amount for each detection section is calculated based on the seven skew amounts t11, t22, t33, t12, t23, t21, and t32 that have already been calculated. . There are four types of detection sections, between S1L / S1R and S2L / S2R, between S2L / S2R and S3L / S3R, between S1L / S2R and S2L / S3R, and between S2L / S1R and S3L / S2R. Each detection section is determined such that straight lines connecting the left and right sheet detection sensors are parallel.

  The detection of the rotation of the sheet is particularly effective when the stapled sheet is conveyed. FIG. 8 shows a state of the staple sheet when the staple sheet is fed. FIG. 8A is a diagram when the leading end of the staple sheet has reached the nip 13 of the separation roller pair 42. At this stage, no skew has yet occurred. When the feeding is further continued, as shown in FIG. 8B, the first staple sheet is slightly skewed and the second staple sheet rotates in the opposite direction to the first staple sheet. Here, a slight skew is detected in S1L and S1R based on the difference in sheet detection timing. When the sheet is further fed, as shown in FIG. 8C, the first sheet is further rotated, and it can be detected that the skew amount has increased in S2L and S2R.

  Depending on the condition of the sheet surface and the size of the sheet, the sheet may be difficult to rotate. FIG. 9 is a diagram when a staple sheet wider than that in FIG. 8 is fed. In FIG. 9, as the staple sheet is fed, wrinkles are formed in the vicinity of the staple, but the rotation of the sheet in the vicinity of the sheet detection sensor is later than in FIG. When the leading end of the staple sheet is at the point of S1L / S1R (FIG. 9 (a)), there is almost no skew, but when the staple sheet advances to S2L / S2R, the skew slightly advances (FIG. 9 (b)), and further proceeds. And the skew increases (FIG. 9C). As described above, there is a staple sheet in which the skew starts immediately after the separation nip portion as shown in FIG. 8, and a staple sheet in which the skew increases after a little advance as shown in FIG. Therefore, it is effective to detect the skew amount and detect the rotation of the sheet not only immediately after the nip portion but also in a plurality of sections in the transport direction.

  Also, the reason for using the sensor pair inclined in the sheet width direction is that, for example, as shown in FIGS. 10A and 10B, the sheet is already detected at S1R or S1L at the start of sheet feeding. In this case, since the sheet detection timing of these sensors is unknown, it is impossible to determine the abnormality. In this case, the detection section may be between S2L / S2R and S3L / S3R. However, when S1R has been detected, it is preferable to use a sensor on the upstream side as much as possible except for S1R. In this case, the rotation of the sheet can be detected at an earlier stage by using the interval between S1L / S2R and S2L / S3R. Further, by increasing the number of detection sections, detection can be performed with higher accuracy.

  In the rotation determination condition, TH2 and TH3 are used as thresholds depending on the detection section. TH2 is used in the detection section in which both the sheet detection sensors S1L and S1R on the most upstream side are used, and TH3 is used in the other sections, and the relationship between the two is set as TH2> TH3, and the threshold value on the upstream side is increased. This is to increase the allowable range of rotation in the detection section on the upstream side and narrow the allowable range on the downstream side. Since the sheet detection sensor is arranged further downstream from the downstream boundary of the nip portion 13 of the separation roller pair 42, if there is no skew of the sheet, the sheet feed sensor is used when the sheet is applied to the sheet detection sensors S1L and S1R. 6 enables stable feeding. However, when the sheet is skewed before the start of sheet feeding, the area where the sheet is sandwiched by the nip portion 13 is insufficient, and the leading end may reach the sensor S1R or S1L with the feeding still unstable. . This is because sheet feeding becomes unstable due to a difference in peripheral speed between the pick-up roller 4 and the feeding roller 6 and friction when the leading edge of the skewed sheet comes into contact with the conveyance path. If the feeding is continued in this state, the skew amount is apt to change before the leading edge is stabilized. Therefore, the threshold value is increased in the upstream detection section. Further, when the leading end of the sheet exceeds the nip portion 13 and the feeding is stabilized, a change in the skew amount due to factors other than abnormal factors is reduced, so that the threshold value can be smaller than that on the upstream side. By setting the optimum threshold value for each detection section in this way, abnormal rotation of the sheet can be detected with high accuracy.

  Next, the transport distance will be described. The sheet conveyance distance is calculated in five detection sections as shown in FIG. Four of the five detection sections use the sheet detection sensors S1L, S2L, S3L on the left side of the separation roller pair 42 and the sheet detection sensors S1R, S2R, S3R on the right side. Calculate the transport distance at the tip. On the left side, first, the transport distance required for the leading edge of the sheet to move from S1L to S2L is calculated from the difference in sheet detection timing. Similarly, four transport distances are calculated from S2L to S3L, the right side is also S1R to S2R, and the transport distance is S4R from S2R to S3R, and they are represented by tL1, tL2, tR1, and tR2, respectively. These transport distances are determined to be abnormal if the transport distance of the sheet is extremely small with respect to the rotation distance of the roller when the feed roller 6 is driven. TH4 is used as the threshold value.

  The fifth detection section of the transport distance can be detected when the pre-registration sensor 32 is disposed downstream of the sheet detection sensors S3L and S3R as shown in FIG. The conveyance distance in the section from the sheet detection sensors S3L and S3R to the pre-registration sensor 32 is calculated. The determination threshold is TH5.

  Next, the speed fluctuation will be described. The speed variation of the sheet is obtained by calculating the difference between the transport distances in the left and right detection sections of the separation roller pair 42 based on the four transport distances tL1, tL2, tR1, and tR2 already calculated. This value is particularly effective for abnormality detection of thin paper. There are the following problems in separating and feeding thin paper. When the uppermost sheet of thin paper is being fed, the second and subsequent sheets are pushed in the transport direction by friction with the first fed sheet while the leading end is stopped by the separation roller 7. This makes it easy to wrinkle near the front end of the second and subsequent sheets. If many thin papers are separated while contacting the separation roller 7, the lower part of the stacked bundle of thin papers is pushed by the separation roller 7 each time the upper thin paper is fed, so that the wrinkles at the leading end are reduced. Expand. When the thin paper is fed as the uppermost paper, the thin paper is conveyed while being caught by the separation roller 7 or the conveyance path. At this time, the moving speed of the leading end of the thin paper is fed at a speed close to the feeding speed after passing through the nip portion 13 of the separation roller pair 42, but is immediately caught or clogged in the conveying path itself. The moving speed decreases extremely. At this time, as shown in FIG. 11B, the center of the sheet is jammed so as to be caught, so that the skew amount often does not change much. In this case, it is possible to prevent the damage of the sheet from spreading by detecting the speed fluctuation of the sheet. As the determination condition, the absolute value of the allowable speed fluctuation is set to TH6.

  Next, in such a configuration, a process of measuring the inclination of the sheet at the time when the sheet has reached each of the sheet detection sensors S1L, S1R, S2L, S2R, S3L, and S3R will be described with reference to a flowchart shown in FIG. Here, a flow for feeding one sheet will be described, but in reality, this flow is continuously repeated to convey the sheets one after another (S101).

  First, it is confirmed whether the sheet detection sensor can detect the conveyance information in each detection section (S102). If the sensor has already detected the sheet before the sheet feeding is started, the detection timing of the sensor is unknown, so that the transport information using the sensor is not calculated. In FIG. 7, the transport information including the sensor that detects the sheet in the column of “use sensor” is not calculated, and the subsequent abnormality determination is not performed.

  Next, the sheet feeding step counter is cleared (S103). The paper feed step counter counts the steps for driving the paper feed motor that is the basis of the transport distance. By clearing this counter at the start of sheet feeding, the number of drive steps of the sheet feeding motor from the start of sheet feeding can be known. Then, after the count of the sheet feeding step counter is started (S104), the sheet feeding motor is driven (S105), and sheet feeding is started.

  In order to detect a transport abnormality, it is necessary to store the transport distance of each sensor. Therefore, only the sensor in the paper-out state updates the transport distance (S106). The transport distance detected by each sensor stores the value of the paper feed step counter. Since the conveyance distance of the sensor indicating that there is a sheet is not updated, the value of the sheet feeding step counter when the leading edge of the sheet is detected is held for each sensor.

  Next, an item to be compared with the value of the transport information for abnormality determination is determined (S107). Depending on the sensor or the item to be used, the calculation may not be possible until the sensor detects some sheets. If there is a paper detection condition at the “determination timing” in FIG. 7, the determination can be made only when the condition is satisfied. Also, in step S102, the item including the sensor that detected the sheet at the start of sheet feeding cannot be determined, and thus is excluded from the calculation target. Here, items that can be determined are stored. For this stored item, a comparison value used for abnormality determination is calculated for each piece of transport information (S108). Here, they are calculated as shown in the column of “comparison value” in FIG. It is determined whether the calculated item is abnormal (S109). As a result of the comparison, if all the items are normal (S109-Yes), it is checked whether the trailing edge of the sheet has passed the pre-registration sensor 32 (S110). When the trailing edge of the sheet passes through the pre-registration sensor 32, the feeding of one sheet is terminated (S111). If it cannot be completed yet (S110-No), S106, S107, S108, and S109 are repeated, and the sheet abnormality determination is repeated. If it is determined that the sheet is abnormal (S109-No), the sheet feeding motor is immediately stopped (S112) to prevent the sheet from being damaged. Subsequently, the occurrence of the abnormality is notified to the user (S113). The content of the error to be notified changes the message according to the detected item as described in the column of “notification error” in FIG. Then, the process ends abnormally (S114).

  In step S109, if any one of all the compared items is determined to be abnormal, the sheet is determined to be abnormal. However, the sheet may be determined to be abnormal by a combination of specific items. For example, for an error notifying the skew, only the item whose detection section is “the third row on the left and right” is used. For the error to be notified as a jam, an error occurs only when one of the six items of rotation and speed fluctuation becomes abnormal and the item of “3rd stage from left to right to pre-registration sensor” in the transport distance becomes abnormal. And In this determination method, an error can be determined when the amount of skew is stable by using the sheet detection sensor in the downstream detection section for skew determination. Further, in the determination of the jam, it is possible to detect that the abnormality continues in a plurality of areas from the upstream side to the downstream side.

  Further, the user may be allowed to select an item to be determined in step S109.

  In the present embodiment, the sheet detection sensors S1L, S1R, S2L, S2R, S3L, S3R are arranged near the separation roller pair 42, but the arrangement of the sheet detection sensors S1L, S1R, S2L, S2R, S3L, S3R. Is not limited to this arrangement.

  When the friction coefficient of the surface of the feeding roller 6 is high, or when the pressing force of the separating roller 7 on the feeding roller 6 is strong, the sheet stapled may not skew near the separating roller 7. . As an example, FIG. 9 has been described above. If a sheet having a wide sheet width is frequently conveyed, the interval between the left and right sensors of the separation roller may be increased as shown in FIG. In this case, as shown in FIG. 13A, an area close to the stapled position can be detected, so that the rotation of the sheet can be easily detected.

  Also, as the width of the sheet increases, the transport distance at the sensor position when the sheet rotates also increases. In order to detect in a wider range, the interval in the transport direction may be widened as shown in FIG. Thus, rotation can be detected not only immediately after the separation nip but also in a wider range.

  Furthermore, the sensors need not be only one pair of left and right. As shown in FIG. 14, by arranging the pair on the left and right sides further, it is possible to cope with various sheet widths.

  In the present embodiment, three sheet detection sensors are arranged in the transport direction. However, the number may be two or more may be arranged as shown in FIG. If two, the cost can be reduced. In addition, since a large number of detection areas can be widened, the detection accuracy can be further improved.

  Further, in the present embodiment, the sheet detection sensors are arranged in a line in the transport direction, but may be arranged at an angle inclined with respect to the transport direction as shown in FIG. In this case, various sheet widths can be handled with a smaller number of sensors.

  In the present embodiment, only TH1 is used as the threshold value for determining that the skew is abnormal. A different threshold value may be used for each detection section. Similarly, the rotation uses the threshold values TH2 and TH3 for each detection section, but more threshold values may be set. Similarly, the threshold value of the transport distance TH4 and the threshold value of the speed variation TH6 may be individually set for each detection section.

  There is also a sheet feeding apparatus having a non-separation mode in which sheets are not separated. In the non-separation mode, the connection from the separation motor 9 is cut off to cause the separation roller 7 to idle, and the rotation of the feeding roller 6 causes the separation roller 7 to follow, thereby feeding the sheet without separating it without binding. (A mode in which the separating force is not transmitted to the sheet). The connection from the separation motor 9 to the separation roller 7 may be disconnected by an electromagnetic clutch, or a switching lever may be provided to switch manually by the user. This non-separation mode is used, for example, when it is desired to convey a half-folded sheet or a plurality of pasted slips without separation. As a method of picking up the sheet, there are a method of stacking the sheet on the document table 1 and feeding the sheet by the pickup roller 4, and a method of inserting the sheet to the feeding roller 6 by the user manually without using the pickup roller 4.

  In the non-separation mode, the load on the sheet by the separation roller 7 is smaller than in the separation mode in which the sheet is separated, so that the breakage of the sheet is reduced. However, in the non-separation mode, a sheet in a poor state is often conveyed, and a conveyance abnormality may occur around the separation / feeding area. Therefore, in the non-separation mode, since the load on the sheet is small, various threshold values for determining an abnormality may be reduced, and the conveyance may be stopped more quickly. Further, in the non-separation mode, since the sheets are not separated, the rotation and the speed fluctuation of the sheets hardly occur. Sheets in poor condition or half-folded sheets are stacked by hand, and once the sheet feeding is started, the user may release the hand and feed the sheet. Therefore, the sheet is likely to be skewed. Therefore, in the non-separation mode, the threshold value of the rotation or the speed fluctuation may be reduced and the threshold value of the skew may be increased.

  In a configuration in which the nip pressure of the separation roller pair 42 can be changed, when a sign of sheet rotation is detected, the nip pressure may be reduced to make it easier for the sheet to rotate. For example, when skew of the sheet is detected by S1R / S1L on the upstream side or rotation is detected by S1R / S1L / S2R / S2L, the nip gap adjustment motor 11 is driven to reduce the nip pressure. If the amount of rotation or skew increases greatly further downstream, it is determined that an abnormality has occurred and the conveyance of the sheet is stopped. If not determined to be abnormal, the nip pressure is returned to the original pressure. By this operation, the rotation of the sheet is quickly generated by the separation roller pair 42, and the detection accuracy can be improved.

  Further, in the above-described embodiment, the sheet transporting and handling apparatus for handling sheet-like paper such as OCR has been described. However, the present invention is not limited to this. The present invention can be similarly applied to a handling device such as a banknote handling device, a security other than a banknote such as a check or a stock certificate, or a voucher or a postal matter.

  Further, the present invention can be applied to a so-called flat-type sheet conveyance device in which the sheet is set in the sheet setting direction, that is, as in the above-described embodiment, the sheets are stacked with the sheet surface facing the sheet stacking tray surface. The present invention can also be applied to a so-called vertical type sheet conveying device that places the sheet bundle on the sheet stacking tray surface with the thickness direction of the sheet bundle being the horizontal direction. In the latter case, for example, in a check scanner that reads check sheets to which magnetic ink characters (such as MICR characters) are attached by magnetic reading means provided in the transport path, a check sheet bundle is read from a sheet stacking tray one by one. By providing the abnormality detection area in the present invention so as to overlap with the separated feeding area in feeding the separated feeding to the conveyance path, the same effect as in the above-described embodiment can be obtained. In the magnetic reading means, if the check sheet is read with an inclination, the magnetic waveform may fluctuate and erroneous reading (erroneous determination) may occur. To improve the work efficiency by taking measures such as stopping the feeding by detecting it before (before), or improving the accuracy of the magnetic judgment by performing the magnetic judgment considering the inclination of the check sheet Also contributes.

  The sensor for detecting the sheet conveyance state may be any sensor that can detect the end in the sheet conveyance direction, such as an optical transmission type sensor, an optical reflection type sensor, a contact type displacement detection sensor, and paper quality. A detectable media sensor, an infrared sensor, or the like can be employed.

(Other embodiments)
In the above embodiment, FIG. 3 shows an area surrounded by the feeding roller 6 and the separating roller 7 as the separation feeding area, the S1L, S1R, S2L, S2R, S3L, S3R as the abnormality detection areas, and the pre-registration sensor 32. In the example shown in FIG. In this example, the overlapping area of the separation feeding area and the abnormality detection area is relatively small.

  However, in the present invention, as shown in FIGS. 17A and 17B, the separation feeding area and the abnormality detection area may be made to largely overlap, or as shown in FIG. May be arranged to completely include the separate feeding area. By arranging the abnormality detection area in this way, it is possible to detect a conveyance abnormality at an earlier stage than when a sheet or a document is separated and conveyed.

  In FIG. 17A, the abnormality detection area is arranged such that the upstream end of the abnormality detection area includes an area upstream of the separation and feeding area. In this arrangement, for example, the original is separated from the separation feeding area (the feeding roller 6 and the feeding roller 6) by using a pickup roller (not shown) upstream of the feeding roller 6 and the separation roller 7 in the feeding direction. When paper is fed toward the separation roller 7), an abnormality in the document can be detected at an earlier stage (that is, between the feed roller 6 and the separation roller 7 and the pickup roller). This arrangement is particularly effective when the pressure of the pickup roller against the bundle of documents is reduced. For example, when the pressing pressure of the pickup roller is strong, the original bundle is more strongly fed into the separation and feeding area, and after feeding the topmost sheet of the original bundle, the leading ends of several upper sheets rush into the separation and feeding area. Probability increases. In this case, the movement of the leading edge of the document can be detected efficiently if the upstream end of the abnormality detection area is located downstream of the leading edge of the document. On the other hand, when the pressing pressure of the pickup roller is weak, the force of the uppermost sheets of the document bundle to be fed into the separation feeding area is weak, and after feeding the topmost sheet of the document bundle, the leading ends of the uppermost sheets are It is relatively likely that the sheet has not reached the separation feeding area. In this case, it is better to arrange the abnormality detection area on the upstream side of the separation feeding area.

  Further, when the leading end of the document has not reached the separation feeding area, the document is fed only by the pickup roller, and the conveyance force of the document is reduced. If a contact-type sensor is used as a sensor used in the abnormality detection area, the conveyance of the document is affected. However, if an optical sensor is used, the conveyance of the document is not affected due to the abnormality detection. Therefore, when an optical sensor is used, the arrangement shown in FIG.

  In addition, depending on the shape near the feeding port on the upstream side of the separation feeding area and the arrangement of the pickup roller, the overlap between the separation feeding area and the abnormality detection area may be reduced as shown in FIG. . For example, in FIG. 3, in the vicinity of the feed port on the upstream side of the separation roller 7, a slope-shaped guide portion inclined toward the feed port relatively higher than the document placing surface is formed. The inclined separation of the guide portion substantially prevents a large number of original bundles from simultaneously entering the separation nip 13. In such a slope separation structure, when a document is skewed before feeding, the document receives a load from the slope, or when the document is climbing the slope, the leading edge of the document enters the upper conveyance path, The skew of the original may be slightly corrected. In consideration of this point, sufficient abnormality detection can be performed by starting abnormality detection after the leading edge of the document has reached the separation feeding area. Therefore, the abnormality detection area is moved to the downstream side as compared with FIG. It may be arranged.

  The arrangement shown in FIG. 17A is effective even in the non-separation mode. As described above, the non-separation mode is a mode in which, for example, several sheet bundles or half-folded sheets stapled with staples or the like are fed without being separated. However, when the sheet bundle is fed to the feed roller 6 and the separation roller 7 by the pickup roller, especially when the sheet bundle is a thin thin paper, the friction between the sheet and the document table causes The sheet is fed skewed, and the shape of the original becomes abnormal in the read image. In order to prevent this, it is preferable to detect the skew of the sheet before the leading end of the sheet enters the nip portion 13 formed by the feed roller 6 and the separation roller 7. In such a case, FIG. The arrangement of a) becomes effective.

1 Document Plate 2 Document Plate Drive Motors S1R, S1L, S2R, S2L, S3R, S3L Sheet Detection Sensor F Document (Sheet)
F1 Top sheet 3 of sheet bundle Sheet detection sensor (document table)
4 Pickup Roller 5 Pickup Motor 6 Feeding Roller 7 Separation Roller 8 Feeding Motor 9 Separation Motor 10 Transport Motor 11 Nip Gap Adjustment Motor 12 Storage Unit 13 Nip Unit 14, 15 Image Reading Sensor 17, 18 Registration Roller 19 Registration Clutch 20, 21 Document Conveying Roller (Sheet Feeding Conveying Means)
22, 24 Document conveyance roller (sheet discharge conveyance means)
26 Discharge driven roller 27 Conveyance roller 28 Discharge motor 32 Pre-registration sensor 33 Post-registration sensor 40 Upper guide plate 41 Lower guide plate 42 Separation roller pair 43 Image reading unit 44 Discharge tray 45 Control unit 51 Restriction plate 60 Conveyance state detection Means 101 Sheet transport device 200 Image reading device tS1L, tS1R, tS2L, tS2R, tS3L, tS3R Transport distance

Claims (6)

Separating and feeding means for separating and feeding sheets one by one from the sheet mounting table;
Skew detecting means for detecting skew of the sheet being fed by the separation feeding means,
The separating and feeding means can be executed by switching between a separated feeding for feeding while separating the sheet and a non-separating feeding for feeding without separating the sheet,
The skew detecting means detects the skew of the sheet using the first threshold value for determining the skew of the sheet at the time of the separation feeding and performs the non-separation feeding. Wherein the skew of the sheet is detected by using a second threshold different from the first threshold for determining the skew of the sheet at the time of the separated feeding.   The sheet feeding device according to claim 1, wherein the second threshold is smaller than the first threshold.   The sheet feeding device according to claim 1, wherein the second threshold is larger than the first threshold.   4. The skew detection area of the skew detection means at least partially overlaps with a separation feeding area of the separation feeding means. Sheet feeding device.   The sheet feeding device according to claim 4, wherein the skew detection area is formed by being surrounded by a plurality of sensor groups. A sheet feeding device according to any one of claims 1 to 5,
Reading means for reading an image of a sheet conveyed by the sheet feeding device;
An image reading apparatus comprising:

Images