JP6839747B2 - Sheet feeder and image reader - Google Patents

Description

The present invention is used in an automatic banknote deposit / withdrawal machine installed in a bank or the like, an automatic sheet processing device for handling sheets such as an OCR (optical character reader) used in a school, a hospital, or the like. The present invention relates to a sheet monitoring method and a transfer mechanism for monitoring a transfer state, for example, whether or not an abnormality has occurred in skew, double feed, and the interval between sheets.

In recent years, the image forming apparatus has come to have a plurality of functions that can be provided, and has become multifunctional. Its 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 seat feeding device (ADF) capable of automatically feeding seats in sequence is also installed.

Here, in order to properly execute the above functions, it is indispensable to transport the sheets to be image-formed in the paper transport path without tilting them diagonally.

Normally, the sheet of the sheet processing device is conveyed by sandwiching the sheet between the drive roller and the driven roller urged by a spring or the like on the drive roller side, or the sheet is conveyed between the endless transfer belts. A method is used in which the belt is narrowly held and transported.

One of the biggest problems in such a sheet processing apparatus is sheet clogging. For example, when the sheet is inserted diagonally with respect to the sheet insertion slot, or when the sheet is transported diagonally due to an imbalance in the pressing force of the belt or roller of the transport means behind the seat insertion slot, the problem of sheet clogging occurs. Likely to happen.

Also, if the sheet is transported in a slanted state (oblique state), the image may be read in a slanted state, or if the sheet is severely tilted, the paper may be jammed in the transport path, causing damage to the sheet. May become. Regarding the problem of transport performance, the same problem can occur regardless of the type of sheet to be transported.

As a conventional means for detecting the conveyed state of a sheet, there is a device for detecting skew or shift of sheets by an image sensor, such as the apparatus described in Patent Document 1. By reading the entire width of the sheet transported by the image sensor provided on the transport path, binarizing the output of the image sensor, creating a data pattern by tracing in the longitudinal direction, and examining the created data pattern, which sheet is Analyze whether it was transported in such a state.

Further, as in the device described in Patent Document 2, the transmissive light emitting element and the light receiving element are arranged side by side in the direction intersecting the direction in which the sheet is conveyed, and the light emitted from the light emitting element is emitted by the light guide. It is configured to cross the transport path multiple times and enter the light receiving element. Since the light incident on the light receiving element is blocked during the period when the conveyed sheet blocks the optical path between the light emitting element and the light receiving element, it is possible to analyze the degree of inclination of the sheet by measuring the light blocking time. Become.

Japanese Unexamined Patent Publication No. 6-18365 Japanese Unexamined Patent Publication No. 2000-285278

However, in the technique described in Patent Document 1, although the skew state of the conveyed sheet can be determined from the image data read by the image sensor and shift or skew can be detected, the image data read by the image sensor can be detected. Since it is necessary to make a judgment after AD conversion and conversion into image data, there is a problem that the processing load of the control unit becomes large.

Further, since the conveyed state of the sheet is determined from the read image data, there is a problem that the detection of the skewed state of the sheets and the paper jam is delayed, which leads to the damage of the sheet.

Further, it is necessary to install the image sensor only for detecting the conveyed state of the sheet, which leads to an increase in the area of the installation location and an increase in cost.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to realize a sheet transfer device capable of more reliably preventing the occurrence of a paper jam in a sheet with an inexpensive configuration.

The sheet feeding device according to the present invention has a separate feeding means that separates and feeds sheets one by one from a sheet mounting table , and a sheet feeding direction for the sheets fed by the separate feeding means. The separate feeding means is provided with a skew detecting means for detecting the skew of the sheet by detecting the position of the edge of the sheet with a plurality of sensors arranged at different positions in the directions orthogonal to the sheet. Can be executed by switching between separate feeding in which the sheets are fed while being separated and non-separable feeding in which the sheets are fed without being separated, and the skew detection means is the separate feeding. In some cases, the skew of the sheet is detected by using the first threshold value for determining the skew of the sheet at the time of the separated feeding, and in the case of the non-separated feeding, the sheet at the time of the separated feeding is detected. It is characterized in that the skew of the sheet is detected by using a second threshold value different from the first threshold value for determining the skew of the sheet.

According to the present invention, it is possible to realize an inexpensive configuration of a sheet transfer device capable of more reliably preventing the occurrence of a paper jam in a sheet.

The front sectional view which shows the schematic structure of the image reading apparatus of embodiment of this invention. FIG. 3 is a schematic cross-sectional view showing a main part of the image reader shown in FIG. FIG. 5 is a side view schematically showing a main part of a sheet separation mechanism of a sheet feeding device 101. Top view schematically showing a main view of a sheet separation mechanism of a sheet feeding device 101. Top view schematically showing the main part of the separation mechanism and the arrangement area of the transport state detecting means. The block diagram which shows the electrical structure of a transport device. The figure which showed the item which makes an abnormality judgment by the sheet transport defect judgment means. Top view schematically showing how the sheet rotates when the staple document is fed. Top view schematically showing how the sheet rotates when a wide staple document is fed. Top view showing how the original is hung on S1R or S1L. Top view schematically showing how the sheet is jammed by the separation roller pair 42. The flowchart of the sheet transport state detection processing in embodiment of this invention. Top view schematically showing the main part of the separation mechanism of another form of the present invention. Top view schematically showing the main part of the separation mechanism of another form of the present invention. Top view schematically showing the main part of the separation mechanism of another form of the present invention. Top view schematically showing the main part of the separation mechanism of another form of the present invention. The figure which shows the positional relationship of the separated feeding area and an abnormality detection area in another embodiment.

The embodiment of the present invention is characterized by a mechanism for detecting an abnormality during feeding of sheets, and in particular, is characterized in detecting an abnormality when the sheets are separated one by one from the sheet mounting table and fed. There is.

Specifically, in the embodiment of the present invention, a separate feeding means for separating and feeding the sheets one by one from the sheet mounting table and an abnormality detecting means for detecting an abnormality during the separate feeding are provided. The feature is that the separated feeding area by the separated feeding means and the abnormality detecting area by the abnormality detecting means overlap at least partially.

Here, it is preferable that the separated feeding regions partially overlap the abnormality detection region on the upstream side in the sheet feeding direction. This makes it possible to immediately detect an abnormal state of the sheet in the separated feeding area. Further, the abnormality detection region may be formed in an area substantially larger than the separate feeding region. This is because it is possible to accurately detect the state change of the sheet that moves from the separated feeding region. Further, the abnormality detection region is preferably formed as a region extending outward from both ends of the separate feeding region in a direction orthogonal to the sheet feeding direction. This will be described in detail later. For example, when a plurality of sensors are arranged and formed in the abnormality detection area, the plurality of sensors can be arranged outside the separate feeding area, so that the plurality of sensors are arranged. This is because it is possible to effectively prevent interference between the separate feeding configuration and the separate feeding configuration. In addition, by detecting anomalies outside the separate feeding area and near the separate feeding area, it is possible to immediately grasp the movement of the seat during separate feeding, and it is possible to improve the abnormality detection accuracy. It will be possible. That is, it is possible to improve the abnormality detection accuracy by forming the abnormality detection area by a plurality of sensors so that the separated feeding area is included in the abnormality detection area.

The abnormality detection area is an area for detecting a state change in which a state such as an angle (tilt) in the seat surface direction in the sheet feeding direction and a seat feeding posture changes, and is, for example, a plurality of sensor groups. That is, it can be formed by substantially enclosing the separate feed region or its surroundings by arranging a plurality of sensors. Further, for example, if an optical sensor is used as a plurality of sensors, it is possible to prevent physical interference with the separate feeding configuration and accurately grasp the state change of the sheet in a non-contact manner.

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

Further, the separate feeding region is, for example, a region including a portion where the separate feeding means using a separation pad, a separation roller, or the like is in contact with the sheet. When the separate feeding means physically comes into contact with the seat, the feeding posture of the seat may change, and by detecting this change in the abnormality detection area, a quick response is possible.

The separated feeding area includes at least a separated area for separating the sheet as a portion that physically contacts the sheet. Since the separation region 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 this separation process.

In the embodiment of the present invention, when the traveling direction (posture in the feeding direction) of such a sheet changes, the abnormality detection region is separated and fed in order to quickly detect the state in the vicinity of the separated feeding means. It is preferable to form the feeding region as a region extending from the portion where the separated feeding means is in contact with the sheet to the downstream side in the sheet feeding direction.

In the embodiment of the present invention, when the separate feeding region is configured to include at least a roller structure, for example, a plurality of rollers (split rollers) are mounted on the roller shaft, and the gap between the rollers is effectively enabled. By utilizing it, it becomes 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, it is possible to form an abnormality detection region corresponding to the gap between the rollers. As a result, it is possible to substantially form the abnormality detection region even within the separate feeding region. Further, one abnormality detection area may be provided so as to surround one roller. For example, when two rollers are attached to one rotation shaft to feed the seat, an abnormality detection area may be provided so as to individually surround each roller. Further, as another form, when a comb-teeth-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 is adopted instead of the split roller, each of the gaps in the groove portion is used. Correspondingly, by providing each of the detection areas of the optical sensors 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 separate feeding area. It becomes. Further, if the abnormality detection region is formed in the separate feed region and the abnormality detection region is extended to the outside of the separate feed region in this way, more effective abnormality detection can be realized. .. In particular, the present invention makes it possible to realize effective abnormality detection in heterogeneous mixed loading type sheet feeding in which sheets having different width dimensions are mixedly loaded and fed.

Hereinafter, one embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view for explaining an image reading device including a sheet transporting device (document feeding device) according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a main part of the image reading device shown in FIG. It is a figure which shows.

As shown in FIGS. 1 and 2, the image reading device 200 of the present embodiment includes a document table 1 in which a plurality of sheets F are loaded and driven up and down by a document table drive motor 2. On both sides of the platen 1 in the width direction of the sheet F, regulation plates 51 are provided in contact with both sides of the sheet bundle loaded on the platen 1 in the width direction to regulate the skewing of the sheet F. The document detection sensor 3 detects the sheet F loaded on the document stand 1. The pickup roller 4 feeds out the sheet loaded on the platen 1 from the platen 1. The pickup motor 5 rotationally drives the pickup roller 4.

The feeding roller 6 is rotationally driven by the feeding motor 8 in the direction of transporting the seat F to the downstream side. The separation roller 7 receives a rotational force for transporting the seat 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 there is one sheet between the feeding roller 6 and the separating roller 7, the feeding roller is more than the upper limit of the rotational torque in the direction of pushing the sheet back to the upstream side, which is transmitted to the separating roller 7 by the torque limiter. The rotational torque in the direction of feeding the seat to the downstream side according to No. 6 exceeds. As a result, the separation roller 7 rotates following the feeding roller 6.

On the other hand, when a plurality of sheets are present between the feeding roller 6 and the separating roller 7, the separating roller 7 holds the sheets in the direction of pushing back to the upstream side to prevent the sheets other than the top sheet from entering.

In this way, when a plurality of sheets are stacked and fed to the nip portion 13 (FIG. 3) of the feeding roller 6 and the separating roller 7, the feeding roller 6 feeds the sheet to the downstream side and the separating roller. Due to the action of 7 pushing the sheet back to the upstream side, only the top sheet is fed to the downstream side. Except for the top sheet, it is returned to the upstream side, and the overlapping sheets are separated. Therefore, the feeding roller 6 and the separating roller 7 form a pair of separating rollers and 42.

In the present embodiment, the separation roller pair 42 is adopted as the separation feeding means, but instead of the separation roller pair 42, either the separation roller 7 or 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.

Further, the separation motor 9 may not be used, and the separation may be performed only by the force of the torque limiter. The separation motor 9 is held so that the shaft does not rotate. Especially for thin sheets, it may be possible to reduce jam caused by bending of the tip of the sheet by separating them by the returning force of the torque limiter.

The transport motor 10 drives a roller for transporting the sheet after separate feeding from the sheet reading position to the discharging position. Further, the transfer motor 10 drives the rollers so that the optimum speed for reading the sheet and the transfer speed of the sheet can be changed according to the settings such as the resolution of the sheet.

The image reading unit 43 includes reading sensors 14 and 15 that read the image of the sheet, and changes the scanning interval based on the reading speed and resolution of the sheet. The document ejection sensor 16 detects that the sheet has passed through the image reading unit 43 and has been ejected to the paper ejection tray 44.

The nip clearance adjusting motor 11 adjusts the gap between the feeding roller 6 and the separation roller 7, or the pressure contact force that the feeding roller 6 presses against the separation roller 7 via the sheet. As a result, the gap corresponding to the thickness of the sheet or the pressure contact force is adjusted, and the sheet can be separately fed.

The image reading unit 43 includes image reading sensors 14 and 15 for reading the image information of the 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 the image on the front surface of the sheet, and the image reading sensor 15 reads the image on the back surface of the sheet.

The document transport rollers pairs 20, 21, the document transport rollers pairs 22, 23, and the downstream roller pair transport the documents to the paper output tray 44. The upper guide plate 40 and the lower guide plate 41 guide the sheet conveyed by the separation roller pair 42, the resist roller pair 17, 18, the transfer roller pair 20, 21, the transfer roller pair 22, 23, and the downstream roller pair. To do.

The pre-resist sensor 32 and the post-resist sensor 33 are sensors that detect sheets to be conveyed along the transfer path, and sheet transfer is controlled based on the sheet detection timing by these sensors.

The transport state detecting means 60 is arranged in the vicinity of the feed roller 6 and the separation roller 7 immediately after the sheet F is inserted into the transport path, and detects the transport status of the sheet F. When the sheet transport defect determining means (not shown) determines that the sheet transport defect is determined based on the detection result of the transport state detecting means 60, the control unit 45 controls to stop the sheet transport operation.

When the separate feeding operation of all the sheets is completed and the sheets are waited to be placed on the platen 1, the platen 1 is lowered, moved to the bottom of the drive range, and stopped. Then, the sheet is placed on the platen 1 and waits until an instruction to start the separate feeding operation is given.

The pre-resist sensor 32 is arranged on the upstream side of the resist roller pairs 17 and 18 and detects the sheet to be conveyed. The post-resist sensor 33 is arranged on the downstream side of the resist roller pairs 17 and 18 and detects the sheet to be conveyed.

The control unit 45 controls the entire image reading device 200 including the sheet transporting device 101. For example, the motors are controlled based on the output signals from the sensors that detect the sheets to control the rotation of the rollers, and the sheets are conveyed. Further, it is controlled to read the image of the sheet to be conveyed.

FIG. 3 is a side view schematically showing a main part of the sheet separating mechanism of the sheet transporting device 101 in FIG. 1, and FIG. 4 is an upper view roughly showing a main view of the sheet separating mechanism of the sheet transporting device 101. is there. FIG. 3 shows the positional relationship between the transport state detecting means 60, the feed roller 6, the separation roller 7, and the nip portion 13 in which the feed roller 6 and the separation roller 7 are in contact with each other. FIG. 4 shows the positional relationship between the platen 1, the sheet bundle F, the sheet F1, the pickup roller 4, the feeding roller 6, the separation roller 7, the transport state detecting means 60, and the regulation plate 51.

In the separating means in the sheet transport mechanism configured in this way, the sheets are 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 separating roller 7 back to the upstream side. When fed to the nip portion of the roller 6 and the separation roller 7, only the top sheet is fed to the downstream side.

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

Among the sensors of the transport state detecting means 60, the sheet detection sensors S1L and S1R on the most upstream side are arranged near the nip portion between the feeding roller 6 and the separating roller 7, as shown in FIG. A side view of the periphery of the feeding roller 6 and the separating roller 7 is shown in FIG. The feeding roller 6 receives a constant pressure from the separating roller 7, and the rollers bend each other, and the region where the rollers are in contact with each other is the nip portion 13. When the sheet F is separated, the tip of the second sheet F from the upper side of the sheet F stays in the region of the nip portion 13, and only the uppermost sheet F1 is fed. If there are sheet detection sensors S1L and S1R on the downstream side of the tip of the second sheet F when the feeding of the sheet F1 is completed, the timing at which the tip of the sheet passes when the feeding of the sheet is started. Can be detected. On the other hand, in order to detect the abnormality of the sheet more quickly, 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 of them.

The sheet detection sensors S2L, S2R, S3L, and S3R are arranged in the area of the dotted line shown in FIG. 5 so that the feeding abnormality can be detected before the separated sheet hits the resist rollers 17 and 18. When the transport state detecting means 60 is arranged inside the resist rollers 17 and 18 in the sheet width direction, the sheet detection sensors S2L, S2R, S3L and S3R are arranged upstream of the resist rollers 17 and 18. When it is arranged outside the resist rollers 17 and 18, it may be arranged downstream from the resist rollers 17 and 18. This is because when the distance between the resist rollers 17 and 18 and the separation roller pair 42 is short, the tip of the sheet is the resist rollers 17 and 18 before the sheet is applied to the resist rollers 17 and 18 when the sheet is skewed. This is because it may precede the downstream side. In the arrangement area of FIG. 5, in consideration of the skew of the sheet, the area is wider toward the downstream side in the transport direction toward the outside in the width direction.

Next, a feeding abnormality determination method when the sheet detection sensors S1R, S1L, S2R, S2L, S3R, and S3L are used as the transport state detecting means 60 will be described.

FIG. 6 is a diagram schematically showing an electrical block configuration of the sheet transfer device of the present embodiment. In FIG. 6, the outputs of the sheet detection sensors S1L, S1R, S2L, S2R, S3L, and S3R are sent to the measuring unit 61, respectively. As will be described later, the measuring unit 61 calculates various transport information based on the output results of the sheet detection sensors S1L, S1R, S2L, S2R, S3L, and S3R. The information to be calculated is sheet non-feeding, skewing, rotation, transport distance, and speed fluctuation. These transfer information is sent to the comparator 62. The comparator 62 compares the sheet transport 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 transport defect determining means 64 determines that a transport abnormality has occurred, and sends an abnormality detection signal to the control unit 45. When the control unit 45 receives the abnormality detection signal, the control unit 45 stops the conveying means and stops the conveying of the sheet.

The timer counted by the measuring unit 61 may have a hardware configuration using a counter or the like, or a software configuration.

The above transport information will be described in detail below.

First, the timing of reaching the sheet detection sensors S1L, S1R, S2L, S2R, S3L, S3R and the pre-resist sensor 32 will be described. The sheet arrival timing is represented by the transport distance from the start of paper feeding to the arrival of the sheet tip at each sensor. The transport distance is expressed as tS1L, tS1R, tS2L, tS2R, tS3L, tS3R, tBR for each of the sheet detection sensors S1L, S1R, S2L, S2R, S3R, S3L and the pre-resist sensor 32, respectively. Since the feed motor 8 uses a stepping motor, the transport distance is the number of steps to be input to the motor. When the feed motor 8 is always driven at a constant speed, the transport distance may be expressed in time instead of the number of steps. When feeding is started and the feeding motor 8 is driven, the number of steps of the motor is counted, and the same values are stored in tS1L, tS1R, tS2L, tS2R, tS3L, tS3R, and tBR as the transport distances of the sheet detection sensor. This process continues only for sensors that have not yet detected the tip of the sheet since the start of paper feeding. This makes it possible to confirm the seat detection timing at each sensor position.

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

Each detection item will be specifically described with reference to FIG. In FIG. 6, the sheet detection sensors S1L, S1R, S2L, S2R, S3L, and S3R are arranged in the transport direction, so that S1L and S1R are in the first stage, S2L and S2R are in the second stage, and S3L and S3R are in the third stage. It is described as a sensor.

First, the non-feeding upstream of the separation will be described. The non-feeding upstream of the separation detects a state in which feeding is started after the sheet is loaded on the platen 1, but the sheet does not reach the separation roller pair 42 and the sheet cannot be fed. This detects that the sheet loaded on the platen 1 is removed and the paper cannot be fed after the paper feeding is started. The sheet detection sensor uses the first stage S1L and S1R. If the tip of the sheet does not reach either S1L or S1R even if only the threshold value TH0 is conveyed and fed after the start of paper feeding, it is determined that the sheet is not fed. If either tS1L ≦ TH0 or tS1R ≦ TH0 cannot be satisfied, the determination condition is non-feeding. If it is determined that the paper is not fed, the paper feeding is stopped, and the user is notified of a message or the like that there is no paper on the platen 1.

Next, skewing will be described. In skewing, it detects a state in which the sheet is fed while being tilted by a specified amount or more. When the image reading start timing is determined based on the post-resist sensor 33, if the sheet is conveyed while being skewed, the front end and the rear end of the sheet are cut off, and a portion that cannot be read occurs. In addition, the corners of the sheet may collide with the edge of the transport path to damage the sheet. To prevent these, skew is detected.

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

Further, of the seven types shown in FIG. 7, the remaining four types of skew amount are S1L and S2R, S2L and S3R, S2L and S1R, S3L and S2R as a combination of sensors in a direction inclined with respect to the seat width direction. The amount of skew is expressed as t12, t23, t21, and t32, respectively. In these combinations, since the sensors are separated from each other in the transport direction, the amount of skewing appears to be larger by that amount. As a determination condition, an offset value A of the transport distance is added in order to correct the distance between the sensors in the transport direction. Within the range of permissible detection timing difference due to this offset, the absolute values of the upper and lower limits are different. Therefore, the determination timing is set after the detection of either the left or right sensor, and the determination condition is changed for each sensor detected earlier.

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

The rotation detection of the sheet is particularly effective when the sheet stopped by the staples is conveyed. FIG. 8 shows the state of the staple sheet when it is fed. FIG. 8A is a view when the tip of the staple sheet reaches the nip portion 13 of the separation roller pair 42. At this stage, skewing has not yet occurred. When the feeding is continued, the result is as shown in FIG. 8 (b), in which the first staple sheet is slightly skewed and the second sheet rotates in the opposite direction to the first sheet. Here, a slight skew is detected by the timing difference of sheet detection between S1L and S1R. Further feeding, as shown in FIG. 8C, the first sheet rotates further, and it can be detected that the amount of skew increases in S2L and S2R.

Depending on the surface condition of the sheet and the size of the sheet, it may be difficult for the sheet to rotate. FIG. 9 is a view when a staple sheet wider than that of FIG. 8 is fed. In FIG. 9, as the staple sheet is fed, the sheet is wrinkled in the vicinity of the staple, but the rotation of the sheet is delayed in the vicinity of the sheet detection sensor as compared with FIG. When the tip of the staple sheet is at the point of S1L / S1R (Fig. 9 (a)), there is almost no skew, but when it reaches S2L / S2R, the skew progresses a little (Fig. 9 (b)), and further progresses. (Fig. 9 (c)). As described above, there are staple sheets whose skew starts immediately after the separation nip portion as shown in FIG. 8 and staple sheets whose skew increases after a little advance as shown in FIG. Therefore, it is effective to detect the amount of skew not only immediately after the nip portion but also in a plurality of sections in the transport direction to detect the rotation of the sheet.

Further, the sensor pair in the direction inclined with respect to the sheet width direction is also used because, for example, as shown in FIGS. 10 (a) and 10 (b), the sheet has already been detected by S1R or S1L at the start of paper feeding. In this case, since the sheet detection timing of these sensors is unknown, it is not possible to determine the abnormality. In this case, the detection section may be between S2L / S2R and S3L / S3R, but when S1R is detected, it is preferable to use the sensor on the upstream side as much as possible except for S1R. In this case, it is possible to detect the rotation of the seat at an earlier stage by using the space between S1L / S2R and S2L / S3R. Further, by increasing the number of detection sections, it is possible to detect more accurately.

In the rotation determination condition, TH2 and TH3 are used as threshold values depending on the detection section. TH2 is used in the detection section in which both the most upstream sheet detection sensors S1L and S1R are used, and TH3 is used in other areas. The relationship between the two is TH2> TH3, and the threshold value on the upstream side is increased. This is to widen the permissible range of rotation in the detection section on the upstream side and narrow the permissible 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 vs. 42, if there is no skewing of the sheet, the feeding roller when the sheet is hung on the sheet detection sensors S1L / S1R. It is stably delivered by 6. However, if the sheet is skewed before the start of paper feeding, the area where the sheet is sandwiched between the nip portions 13 is insufficient, and the tip may reach the sensor S1R or S1L while the feeding is still unstable. .. This is because the pickup roller 4 and the feeding roller 6 have a difference in peripheral speed, and the sheet feeding becomes unstable due to friction when the tip of the skewed sheet comes into contact with the transport path. If the feeding is continued in this state, the amount of skew tends to change until the tip stabilizes, so the threshold value is increased in the detection section on the upstream side. Further, when the tip of the sheet exceeds the nip portion 13 and the feeding is stabilized, the change in the amount of skewing other than an abnormal factor is small, so that the threshold value can be made smaller than that on the upstream side. By setting the optimum threshold value for each detection section in this way, abnormal rotation of the seat can be detected with high accuracy.

Next, the transport distance will be described. The sheet transport 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, and the seats on the left and right sides of the separation roller pair 42, respectively. Calculate the transport distance of the tip. On the left side, first, the transport distance required for the tip of the sheet to move from S1L to S2L is calculated by the difference in the sheet detection timing. Similarly, the above four types of transport distances are calculated from S2L to S3L, from S1R to S2R on the right side, and from S2R to S3R, and 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 rollers 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-resist sensor 32 is arranged on the downstream side of the sheet detection sensors S3L and S3R as shown in FIG. The transport distance in the section from the sheet detection sensors S3L and S3R to the pre-resist sensor 32 is calculated. The determination threshold is TH5.

Next, the speed fluctuation will be described. The speed fluctuation of the sheet is obtained by calculating the difference in the transport distance between the left and right detection sections of the separation roller pair 42 based on the four transport distances tL1, tL2, tR1, and tR2 that have already been calculated. This value is particularly effective in detecting anomalies in thin paper. Separate feeding of thin paper has the following problems. When the top sheet of thin paper is being fed, the second and subsequent sheets of paper are pushed in the transport direction by friction with the first sheet to be fed while the tips are stopped by the separation roller 7. This makes it easier for wrinkles to form near the tips of the second and subsequent sheets. When a number of thin papers are separated while contacting the separation roller 7, the lower part of the stack of loaded thin papers is pushed by the separation roller 7 each time the upper thin paper is fed, so that the wrinkles at the tip are formed. It will expand. When the thin paper becomes the top paper and is fed, the tip is caught by the separation roller 7 or the transport path and is transported. At this time, the moving speed of the tip of the thin paper is close to the feeding speed when it passes through the nip portion 13 of the separation roller pair 42, but it is immediately caught or clogged in the transport path itself. The movement speed is extremely reduced. At this time, as shown in FIG. 11B, since the center of the sheet is clogged so as to be caught, the change in the amount of skewing often does not occur so much. In this case, it is possible to prevent the sheet from spreading by detecting the speed fluctuation of the sheet. As a judgment condition, the absolute value of the permissible 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 detection sensors S1L, S1R, S2L, S2R, S3L, and S3R are reached will be described with reference to the flowchart shown in FIG. Here, the flow of 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 transport information in each detection section (S102). If the sensor has already detected the sheet before the sheet feeding is started, the detection timing is unknown by the sensor, so the transport information using the sensor is not calculated. In FIG. 7, the transport information including the sensor detecting the sheet is not calculated in the “used sensor” column, and the subsequent abnormality determination is not performed.

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

It is necessary to store the transport distance in each sensor in order to detect the transport abnormality. Therefore, the transport distance is updated only for the sensor in the paperless state (S106). The transport distance detected by each sensor stores the value of the paper feed step counter. Since the transport distance of the sensor with paper is not updated, the value of the paper feed step counter when the tip of the sheet is detected is held for each sensor.

Next, an item for comparing the values of the transport information is determined for abnormality determination (S107). Depending on the sensor and item used, it may not be possible to calculate until the sensor detects some sheets. If there is a paper detection condition in the "determination timing" of FIG. 7, the determination can be made only when the condition is satisfied. Further, since the item including the sensor that detected the sheet at the start of paper feeding in step S102 cannot be determined, it is excluded from the calculation target. Here, the items that can be determined are stored. For this stored item, a comparison value used for determining an abnormality is calculated for each transport information (S108). Here, each is calculated as shown in the “Comparison value” column of FIG. It is determined whether or not the calculated item is abnormal (S109). As a result of comparison, if all the items are normal (S109-Yes), it is confirmed whether the rear end of the sheet has passed through the pre-resist sensor 32 (S110). When the rear end of the sheet passes through the pre-resist sensor 32, the feeding of one sheet is completed (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 to be abnormal (S109-No), the paper feed motor is immediately stopped (S112) so that the sheet is not damaged. Subsequently, the user is notified of the occurrence of the abnormality (S113). The content of the error to be notified changes the message according to the detected item as described in the "Notification error" column of FIG. 7. Then, it ends abnormally (S114).

In step S109, when it is determined that any one of all the compared items is abnormal, the paper feed is abnormal, but a combination of a plurality of specific items may be a paper feed abnormality. For example, for an error notifying that it is skewed, only the item whose detection section is "third left and right" is used. Regarding the error to notify as a jam, an error occurs only when one of the total 6 items of rotation and speed fluctuation becomes abnormal, and the item of "3rd left and right to sensor before resist" in the transport distance becomes abnormal. And. In this determination method, by using the sheet detection sensor in the detection section on the downstream side to determine the skew, an error determination can be made when the amount of skew is stable. Further, regarding the determination of jam, since it can be detected that the abnormality continues in a plurality of regions from the upstream side to the downstream side, it is suitable for determining the abnormality of a wide range of paper types.

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

In the present embodiment, the sheet detection sensors S1L, S1R, S2L, S2R, S3L, and S3R are arranged in the vicinity of the separation roller pair 42, but the sheet detection sensors S1L, S1R, S2L, S2R, S3L, and S3R are arranged. 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 stopped by the staples may not be skewed in the vicinity of the separating roller 7. .. As an example, FIG. 9 is used as described above. If a sheet having a wide sheet width is often conveyed, the distance 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, since the region close to the stapled position can be detected, the rotation of the seat can be easily detected.

Further, 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. 13 (b). This makes it possible to detect rotation in a wider range, not just immediately after the separation nip.

Further, the sensors do not have to be only one pair on the left and right. As shown in FIG. 14, by arranging the pair on the left and right sides further on both sides, various seat widths can be supported.

In the present embodiment, three sheet detection sensors are arranged side by side in the transport direction, but the number may be two, or a larger number may be arranged as shown in FIG. Cost reduction can be achieved by using two. In addition, since the detectable area can be widened by arranging a large number of them, the detection accuracy can be further improved.

Further, in the present embodiment, the sheet detection sensors are arranged in a row in the transport direction, but they may be arranged at an angle inclined with respect to the transport direction as shown in FIG. In this case, it is possible to handle various seat widths with a smaller number of sensors.

Further, in the present embodiment, only TH1 is used as the threshold value for determining the abnormality of skewing. A different threshold value may be used for each detection section. Similarly, for rotation, the threshold values TH2 and TH3 are used for each detection section, but more threshold values may be set. Similarly, for the transport distance TH4 and the speed fluctuation TH6, the threshold value may be set individually for each detection section.

There is also a sheet feeding device having a non-separation mode in which the sheets are not separated. In the non-separation mode, the connection from the separation motor 9 is cut so that the separation roller 7 idles, and the separation roller 7 is driven by the rotation of the feeding roller 6, and the sheet is fed without being separated while being bound. (Mode in which the separating force is not transmitted to the seat). The connection from the separation motor 9 to the separation roller 7 may be disconnected by an electromagnetic clutch, or may be provided with a switching lever and manually switched by the user. This non-separable mode is used, for example, when it is desired to transport a half-folded sheet or a plurality of glued slips without separating them. As a method of picking up the sheet, there are a method of loading the sheet on the platen 1 and feeding it by the pickup roller 4, and a method of manually inserting the sheet into the feeding roller 6 without using the pickup roller 4.

In this non-separation mode, the load on the sheet by the separation roller 7 is smaller than that in the separation mode in which the sheets are separated, so that the sheet is less damaged. However, in the non-separation mode, sheets in poor condition are often transported, and a transport abnormality may occur around the separate feed region. Therefore, it is necessary to detect the transport abnormality. Therefore, since the load on the sheet is small in the non-separation mode, various threshold values for determining an abnormality may be reduced to stop the transportation more quickly. Further, in the non-separation mode, since the sheets are not separated, the rotation and speed fluctuation of the sheets are unlikely to occur. Sheets in poor condition or half-folded sheets may be loaded by hand, and when paper feeding starts, the hands may be released to feed the paper, so that the sheets are likely to be skewed. Therefore, in the non-separation mode, the threshold value of rotation and speed fluctuation may be reduced and the threshold value of skew may be increased.

Further, in the configuration in which the nip pressure of the separation roller pair 42 can be changed, the nip pressure may be weakened to facilitate the rotation of the sheet when a sign of the rotation of the sheet is detected. For example, when the skew of the seat is detected by S1R / S1L on the upstream side or the rotation is detected by S1R / S1L / S2R / S2L, the nip gap adjusting motor 11 is driven to weaken the nip pressure. Then, if the amount of rotation or skewing further increases on the downstream side, it is determined that there is an abnormality and the sheet transfer is stopped. If it is not determined to be abnormal, the nip pressure is returned to the original pressure. By this operation, the separation roller pair 42 can rotate the sheet quickly, and the detection accuracy can be improved.

Further, in the above embodiment, the sheet transport handling device for handling sheet-shaped paper such as OCR has been described, but the present invention is not limited to this, and the transport device and banknotes in the slip and mail processing device can be used. It can also be applied to securities other than banknotes such as deposit / withdrawal devices, checks and stock certificates, and voucher and mail processing devices.

Further, the present invention can be applied to a so-called horizontal sheet transport device in which sheets are stacked in the sheet setting direction, that is, with the sheet surface facing the sheet loading tray surface as in the above-described embodiment. It can also be applied to a so-called vertical sheet transport device in which the sheet bundle is placed on the sheet loading tray surface with the thickness direction as the horizontal direction. In the latter case, for example, in a check scanner that reads a check sheet with magnetic ink characters (MICR characters, etc.) by a magnetic reading means profitable in the transport path, a bundle of check sheets is read one by one from the sheet loading tray. When the separate feed is supplied to the transport path, the same effect as that of the above-described embodiment can be obtained by providing the abnormality detection region in the present invention so as to overlap the separate feed region. In the magnetic reading means, if the check sheet is tilted and read, the magnetic waveform fluctuates and there is a risk of misreading (misjudgment). Therefore, in order to improve the accuracy of magnetic reading, the tilt of the check sheet is more than that of magnetic reading. You may improve the work efficiency by taking measures such as stopping the feeding by detecting it before (previously), or improving the accuracy of the magnetic judgment by performing the magnetic judgment considering the inclination of the check sheet. Also contributes to.

Further, the sensor for detecting the sheet transport state may be a sensor capable of detecting the end portion in the sheet transport direction, for example, an optical transmission type sensor, an optical reflection type sensor, a contact type displacement detection sensor, a paper quality, or the like. A detectable media sensor, infrared sensor, or the like can be adopted.

(Other embodiments)
In the above embodiment, the region surrounded by the separate feed roller 6 and the separate roller 7, the abnormality detection region S1L, S1R, S2L, S2R, S3L, S3R, and the pre-resist sensor 32 is shown in FIG. , An example of arranging in the positional relationship as shown in FIG. 4 is shown. In this example, the overlapping region of the separate feeding region and the abnormality detection region is relatively small.

However, in the present invention, as shown in FIGS. 17 (a) and 17 (b), the separate feeding region and the abnormality detection region may be made to overlap more, or as shown in FIG. 17 (a), the abnormality detection region may be overlapped. May be arranged so as to completely include the separate feeding area. By arranging the abnormality detection area in this way, it is possible to detect an abnormality in the transportation at an earlier stage than when the sheet or the original is separately transported.

In FIG. 17A, the abnormality detection region is arranged so that the upstream end of the abnormality detection region includes the region on the upstream side of the separate feeding region. In this arrangement, for example, a pickup roller (not shown) located upstream in the feeding direction from the feeding roller 6 and the separating roller 7 which are the separating feeding regions is used to separate the originals into the separating feeding region (feeding roller 6 and the feeding roller 6 and the separation roller 7). When feeding paper toward the separation roller 7), an abnormality in the document can be detected at an earlier stage (that is, between the feeding roller 6 and the separation roller 7 and the pickup roller). Further, this arrangement is particularly effective when the pressing pressure on the document bundle by the pickup roller is weakened. For example, when the pressing pressure of the pickup roller is strong, the document bundle is sent to the separation feeding area more strongly, and after feeding the top one sheet of the document bundle, the tips of several upper sheets plunge into the separation feeding area. The probability of being there is high. In this case, if the upstream end of the abnormality detection region is arranged on the downstream side of the document tip, the movement of the document tip can be detected efficiently. On the contrary, when the pressing pressure of the pickup roller is weak, the force of feeding the uppermost sheets of the original bundle to the separate feeding area is weak, and after feeding the uppermost one of the original bundle, the tips of the upper several sheets are transferred. It is relatively common that the separate feeding area has not been reached. In this case, it is better to arrange the abnormality detection area on the upstream side of the separate feeding area.

Further, when the tip of the document does not reach the separate feeding area, the document is fed only by the pickup roller, so that the transporting force of the document is weakened. If a contact-type sensor is used as the sensor used in the abnormality detection region, the document transport is affected, but if an optical sensor is used, the document transport is not affected for abnormality detection. Therefore, when an optical sensor is used, the arrangement shown in FIG. 17A is particularly effective.

Depending on the shape near the feeding port on the upstream side of the separated feeding area and the arrangement of the pickup rollers, the overlap between the separated feeding area and the abnormality detection area may be reduced as shown in FIG. 17B. .. For example, in FIG. 3, in the vicinity of the feeding port on the upstream side of the separation roller 7, a slope-shaped guide portion is formed that is inclined toward the feeding port at a position relatively higher than the document placing surface. The slope separation of the guide portion substantially prevents a large number of document bundles from entering the separated nip portion 13 at the same time. In such a slope separation structure, when the original is skewed before feeding, the original receives a load from the slope, or the tip of the original plunges into the upper transport path when climbing the slope. The skew of the manuscript may be slightly corrected. In consideration of this point, since sufficient abnormality detection can be performed by starting the abnormality detection after the tip of the document reaches the separate feeding area, the abnormality detection area is moved to the downstream side of FIG. 17A. You may arrange it.

The arrangement of FIG. 17A is also valid in the non-separable mode. As described above, the non-separable mode is a mode in which a bundle of several sheets bound with staples or a half-folded sheet is fed without being separated. However, when the sheet bundle is fed to the feeding roller 6 and the separation roller 7 by the pickup roller, especially if the sheet bundle is thin paper with a weak waist, one of the sheet bundles is caused by friction between the sheet and the platen. The part is skewed and fed, and the shape of the original becomes abnormal in the scanned image. In order to prevent this, it is preferable to detect the skew of the sheet before the tip of the sheet rushes into the nip portion 13 by the feeding roller 6 and the separating roller 7, and in such a case, FIG. 17 ( The arrangement of a) becomes effective.

1 Document stand 2 Document stand drive motor S1R, S1L, S2R, S2L, S3R, S3L Sheet detection sensor F Document (sheet)
Top sheet of F1 sheet bundle 3 Sheet detection sensor (document base)
4 Pickup roller 5 Pickup motor 6 Feeding roller 7 Separation roller 8 Feeding motor 9 Separation motor 10 Conveyor motor 11 Nip gap adjustment motor 12 Storage unit 13 Nip part 14, 15 Image reading sensor 17, 18 Resist roller 19 Resist clutch 20, 21 Document transfer roller (sheet supply and transfer means)
22,24 Document transport roller (sheet discharge transport means)
26 Paper ejection driven roller 27 Conveyance roller 28 Paper ejection motor 32 Pre-resist sensor 33 Post-resist sensor 40 Upper guide plate 41 Lower guide plate 42 Separation roller vs. 43 Image reader 44 Paper ejection tray 45 Control unit 51 Control plate 60 Conveyance state detection Means 101 Sheet transport device 200 Image reader tS1L, tS1R, tS2L, tS2R, tS3L, tS3R Transport distance

Claims (6)

Separate feeding means that separates and feeds sheets one by one from the sheet mounting table,
With respect to the sheet fed by the separate feeding means, the sheet is tilted by detecting the position of the edge of the sheet with a plurality of sensors arranged at different positions in the direction orthogonal to the sheet transport direction. Equipped with an oblique detection means for detecting rows,
The separate feeding means can be executed by switching between separate feeding in which the sheets are fed while being separated and non-separable feeding in which the sheets are fed without being separated.
In the case of the separate feeding, the skew detecting means detects the skew of the sheet by using the first threshold value for determining the skew of the sheet at the time of the separate feeding, and the non-separated feeding. In the case of, the sheet feeding device is characterized in that the skewing of the sheet is detected by using a second threshold value different from the first threshold value for determining the skewing of the sheet at the time of the separated feeding. The sheet feeding device according to claim 1, wherein the second threshold value is smaller than the first threshold value. The sheet feeding device according to claim 1, wherein the second threshold value is larger than the first threshold value. The one according to any one of claims 1 to 3, wherein the skew detection region by the skew detection means at least partially overlaps the separate feed region by the separate feed means. Sheet feeder. The sheet feeding device according to claim 4, wherein the skew detection region is formed by being surrounded by the plurality of the sensors. The sheet feeding device according to any one of claims 1 to 5,
A reading means for reading an image of a sheet conveyed by the sheet feeding device, and
An image reading device comprising.

Images