JP2012162335A - Sheet feeding device, control method thereof, image reading device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an abnormal conveyance state of a type that a sheet bundle does not jump up even if a user forgets to return a multifeed detection means from a non-detection state to a detection state when a sheet abnormality detection means and the multifeed detection means are adopted as a means for detecting the abnormal conveyance state of the sheet bundle.SOLUTION: A document feeding device 101 feeds sheets one by one from a platen 1 to a conveying passage. A document abnormality detection sensor 35 detects the deformation of the sheet fed by the document feeding device 101. A multifeed detection sensor 32 is arranged at the downstream side of the document abnormality detection sensor 35 in the conveying direction, and detects a plurality of sheets which are fed in an overlapping state. An operation part 46 sets the document abnormality detection sensor 35 to be activated or deactivated. A control part 45 sets the multifeed detection sensor 32 to be also activated when the document abnormality detection sensor 35 is set to be activated.

Description

  The present invention relates to a sheet feeding device that feeds a sheet, a control method thereof, an image reading device that reads an image from a sheet fed by the sheet feeding device, and an image on a sheet fed by the sheet feeding device. The present invention relates to an image forming apparatus.

  A sheet feeding apparatus generally includes a separation mechanism that separates and feeds a plurality of sheets stacked on a sheet stacking table one by one. For this reason, even when sheets bound in a bundle by stapler, clip, gluing, etc. are stacked on the sheet stacking table, the sheet feeding device tries to separate and feed the sheets of the sheet bundle one by one. To do. At this time, a force is applied so that the uppermost sheet is pushed out in the conveyance direction, and the second and subsequent sheets are returned to the opposite side to the conveyance direction. As a result, the end of the remaining sheet is pulled by the uppermost sheet, so that a so-called document jump occurs, resulting in an abnormal conveyance state.

  According to Patent Document 1, a sheet abnormality detection unit that detects a jump of a document as an abnormal shape is proposed.

Japanese Patent No. 4118135

  However, in the case where the position of the sheet binding member that binds the sheet bundle is in the vicinity of the front end in the sheet conveyance direction and at the center in the direction orthogonal to the sheet conveyance direction, the sheet bundle does not jump up and is fed to the conveyance path. Will be sent. The sheet abnormality detection means described in Patent Document 1 cannot sufficiently detect such an abnormal conveyance state in which the sheet does not jump up. Further, the sheet abnormality detection means by the means for detecting the skew feeding of the sheet obliquely cannot be sufficiently detected.

  Therefore, it is desirable that such an abnormal conveyance state can be detected as an abnormal conveyance state by some method. If this cannot be detected, the sheet binding member interferes with the components provided in the conveyance path, and causes problems such as sheet conveyance failure, component destruction, and sheet breakage.

  Incidentally, the sheet feeding apparatus may include a double feed detection mechanism that detects double feed, which is a phenomenon in which a plurality of sheets are stacked and conveyed in the conveyance path. The double feed detection mechanism can detect a sheet bundle formed by binding a plurality of sheets into a bundle by stapler, clip, glue, etc. as double feed, so it is used as an abnormal conveyance state detection means together with the sheet abnormality detection means It seems to be possible.

  However, when a sheet feeding device having a double feed detection mechanism is used to feed a sheet in two folds or when a sheet is inserted into a carrier sheet for sheet protection, the double feed detection mechanism is not used. Must switch to detection state. This is because the double feed detection mechanism prohibits the conveyance of the folded sheet material or the sheet material inserted into the protective sheet. Therefore, the user switches the double feed detection mechanism to the non-detection state, but this operation is a manual switching operation by the user.

  As described above, since the user is involved in the switching operation between the detection state and the non-detection state of the double feed detection mechanism, a human error may occur. In particular, after the double feed detection mechanism is switched to the non-detection state, there is a possibility that the double feed detection mechanism is returned to the detection state and forgotten. If it is forgotten to return, both the sheet abnormality detection means and the double feed detection mechanism cannot detect the sheet bundle bound by the sheet binding member at the center near the leading end. As a result, the sheet binding member causes problems such as sheet conveyance failure, component destruction, and sheet damage.

  Note that the above-described problem does not occur only when the bound sheet bundle is fed, and similarly occurs in the case of, for example, a sheet take-in failure such as skew feeding where the sheets are fed obliquely. There is a fear.

  Therefore, in the present invention, when the sheet abnormality detection unit and the double feed detection unit are adopted as the unit for detecting the abnormal conveyance state of the sheet bundle, the user forgot to return the double feed detection unit from the non-detection state to the detection state. However, an object of the present invention is to detect an abnormal conveyance state such as a type in which the sheet bundle does not jump up.

The sheet feeding apparatus according to the present invention is:
A sheet stacking means for stacking a plurality of sheets;
Sheet feeding means for feeding the plurality of sheets stacked on the sheet stacking means one by one to a conveyance path;
Sheet abnormality detecting means for detecting deformation of the sheet fed by the sheet feeding means;
Double feed detection means that is disposed downstream of the sheet abnormality detection means in the transport direction and detects that a plurality of sheets are overlapped and fed,
First setting means for setting whether to enable or disable the sheet abnormality detection means;
When the sheet abnormality detection means is set to be effective by the first setting means, second setting means for setting the multifeed detection means to be effective;
And a sheet feeding control unit that stops the operation of the sheet feeding unit when the sheet abnormality detecting unit detects a deformation of the sheet or the double feeding detecting unit detects a double feeding.

  According to the present invention, when the sheet abnormality detection means is enabled, the multifeed detection means is automatically enabled, so that the user forgets to return the double feed detection means from the non-detection state to the detection state. However, it is possible to detect an abnormal conveyance state in which the sheet bundle does not jump up. As a result, it is possible to prevent the sheet from being damaged or jammed due to an abnormal conveyance state such as a type in which the sheet bundle does not jump up.

1 is a partial cross-sectional front view schematically showing a configuration of a document reading apparatus according to a first embodiment. 1B is a schematic diagram schematically showing a configuration of a main part of the document reading apparatus shown in FIG. 1A. FIG. It is a figure which shows an example of a control unit. It is a perspective view which shows a document abnormality detection sensor. It is a perspective view which shows a document abnormality detection sensor. FIG. 6 is a diagram illustrating an example in which a document abnormality detection sensor does not operate. It is a figure which shows an example of the operation screen which a control part displays on a touchscreen type operation part. It is a figure which shows an example of the operation screen which a control part displays on a touchscreen type operation part. It is a flowchart which shows the automatic validation of the double feed detection concerning embodiment. It is the flowchart which showed 2nd Embodiment. It is a figure which shows an example of the double feed detection range setting screen displayed on an operation part. It is a figure showing a plurality of multiple feed detection sensors. It is a figure which shows an example of the double feed detection range setting screen displayed on an operation part.

  In the present embodiment, a document feeding device that is a sheet feeding device and a document reading device that is an image reading device including the document feeding device will be described. The document feeder according to the present embodiment is also used as a recording material feeder that feeds a recording material on which an image is not formed instead of a document to an image forming unit of the image forming apparatus. Can do. The image forming unit is an example of an image forming unit that forms an image on a sheet fed by a sheet feeding device. In addition, the document feeding device may be provided in a post-processing device that binds a document or makes a hole, and may feed the document to the post-processing device. Further, the same effect can be obtained even if the arrangement positions of the light receiving part and the light emitting part are switched.

<First Embodiment>
FIG. 1A is a partial cross-sectional front view schematically showing the configuration of the document reading apparatus according to the first embodiment. FIG. 1B is a schematic diagram schematically showing a configuration of a main part of the document reading apparatus shown in FIG. 1A. In FIG. 1A and FIG. 1B, the document reading device 200 includes a document feeding device 101. The document table 1 functions as a sheet stacking unit on which a plurality of sheets (for example, a plurality of documents) are stacked. The document table 1 is configured to be movable up and down. The document table drive motor 2 moves the document table 1 up and down. A stack of documents stacked on the document table 1 is regulated by the regulation plate 50. The document feeder 101 functions as a sheet feeding unit that feeds a plurality of sheets stacked on the sheet stacking unit one by one to the conveyance path.

  The pickup roller 4 is a feeding unit that feeds the document F on the document table 1 from the document table 1 to the conveyance path. The pickup roller drive motor 5 rotates the pickup roller 4. The feed roller 6 is driven by a feed motor 8 so as to feed the document downstream in the transport direction. The separation roller 7 always receives a rotational force that pushes the document back to the upstream side in the conveyance direction from the separation motor 9 via a torque limiter (slip clutch) (not shown). When there is one document between the feeding roller 6 and the separation roller 7, the rotational force that the feeding roller 6 feeds the document downstream is the rotational force that the separation roller 7 pushes the document upstream. Above the upper limit of. As a result, the separation roller 7 rotates following the feeding roller 6. On the other hand, when there are a plurality of documents between the feeding roller 6 and the separation roller 7, the separation roller 7 rotates in a direction to push the document back to the upstream side, and pushes back other than the uppermost document.

  1A and 1B, the separation mechanism shown in FIGS. 1A and 1B has the function of feeding the document to the downstream side and the operation of pushing the document of the separation roller 7 back to the upstream side. Only the document is fed downstream, and the other documents are pushed back upstream. Therefore, the feeding roller 6 and the separation roller 7 constitute a pair of separation rollers 42. In the embodiment, the separation roller pair 42 is used, but instead of the separation roller pair 42, a separation belt roller pair in which either the separation roller or the feeding roller is a belt may be used. Further, since the present invention is not an invention depending on the specific configuration of the separation mechanism, other types of separation mechanisms may be employed.

  The transport motor 10 drives the transport rollers 20 and 21 and the transport rollers 22 and 23 in order to transport the separated and fed document from the document reading position to the discharge position on the transport path. In addition, the transport motor 10 drives each roller so that the document transport speed can be changed according to the optimum speed for reading the document, the resolution of the document, and the like. The nip clearance adjustment motor 11 adjusts the clearance between the feeding roller 6 and the separation roller 7 or the pressure contact force with which the feeding roller 6 comes into pressure contact with the separation roller 7 via the document.

  The image reading unit 43 includes document reading sensors 14 and 15 that read a document. The document discharge sensor 16 detects that the document is being discharged to the discharge stacking unit 44 through the image reading unit 43.

  The registration clutch 19 switches between transmission and interruption of the rotational driving force of the conveyance motor 10 with respect to the registration roller 18. By stopping the rotation of the registration rollers 17 and 18, the leading edge of the fed document is abutted against the nip portion of the registration rollers 17 and 18 to correct the skew of the document. The conveyance rollers 20 and 21 and the conveyance rollers 22 and 23 convey the document F to the discharge stacking unit 44. Two guide plates, an upper guide plate 40 and a lower guide plate 41, guide the document conveyed by the separation roller pair 42, the registration rollers 17 and 18, the conveyance rollers 20 and 21, and the conveyance rollers 22 and 23.

  FIG. 2 shows an example of the control unit. The control unit 45 uses various sensors to detect the position of the document on the conveyance path, double feed, and the like. The control unit 45 includes a CPU 71 that controls each unit in accordance with a program stored in the ROM 72. The CPU 71 stores, in the RAM 73, a flag indicating whether abnormal document detection is valid or invalid, a flag indicating whether double-feed detection is valid or invalid, detection results of each sensor, and the like, and uses them for various controls. The drive circuit 47 controls the document table drive motor 2, the pickup roller drive motor 5, the feed motor 8, the separation motor 9, and the carry motor 10 in accordance with a drive start signal and a stop signal from the CPU 71. The analog-digital converter (ADC) 48 converts the analog detection signals of the pre-feed sensor 31, the double feed detection sensor 32, the pre-registration sensor 33, the post-registration sensor 34, and the document abnormality detection sensor 35 into digital detection signals and sends them to the CPU 71. Output.

  The pre-feed sensor 31 detects the front end (downstream side end) and the rear end (upstream side end) of the fed document. The double feed detection sensor 32 is disposed downstream of the sheet abnormality detection unit in the conveyance direction, and functions as a double feed detection unit that detects that a plurality of sheets are overlapped and fed. That is, the double feed detection sensor 32 is a sensor that detects double feed of a fed document. As the double feed detection method, any method such as an ultrasonic method, an infrared transmitted light amount method, and a document thickness detection method may be adopted. The pre-registration sensor 33 is arranged on the upstream side of the registration rollers 17 and 18 and detects a document conveyed on the conveyance path. The post-registration sensor 34 is disposed on the downstream side of the registration rollers 17 and 18 and detects a document conveyed on the conveyance path. These sheet sensors can also be used when detecting the length of the document F in the transport direction or detecting the transported distance. For example, the length can be obtained by multiplying the time from the time when the pre-feed sensor 31 detects the leading edge of the document F to the time when the trailing edge is detected by the conveyance speed. Similarly, if the elapsed time from the time when the leading edge is detected is multiplied by the conveyance speed, the distance that the leading edge of the document is conveyed can be obtained. The CPU 71 executes various count processes using the counter 74. The CPU 71 accepts user input or outputs information from an operation unit 46 that includes a display device and an input device. As described above, the operation of the control unit 45 is executed mainly by the CPU 71.

  3 and 4, a light emitting unit 51 and a light receiving unit 52 constituting the document abnormality detection sensor 35 are shown. The document abnormality detection sensor 35 functions as a sheet abnormality detection unit that detects deformation of the sheet fed by the sheet feeding unit. 3 and 4, the binding position of the sheet binding member SP1 for binding the original bundle is different. According to FIG. 3, if the light emitted from the light emitting unit 51 cannot be detected by the light receiving unit 52 disposed on the opposite side of the light emitting unit 51, the control unit 45 indicates that the document has jumped up. judge. Therefore, the control unit 45 controls the motor to stop the conveyance of the document F. On the other hand, as shown in FIG. 4, if the light receiving unit 52 can detect the light emitted from the light emitting unit 51, the control unit 45 determines that the document has not jumped up.

  As described above, in FIG. 3, the binding position of the sheet binding member SP1 is the end portion of the leading end of the document, and therefore, jumping occurs. Therefore, the abnormal conveyance state can be detected by the original abnormality detection sensor 35.

  On the other hand, in FIG. 4, since the binding position of the sheet binding member SP1 is the central portion of the leading edge of the document, no jumping occurs. This is because the sheet binding member SP1 strongly binds the first document F1 even when there is an action of the separation roller 7 at the position where the pickup roller 4 and the feeding roller 6 face each other. This is because a rotational force cannot be applied to the document F1. Therefore, since the abnormal conveyance state cannot be detected by the document abnormality detection sensor 35, the abnormal conveyance state must be detected by the double feed detection sensor 32.

  In the above description of the present embodiment, the case where the jumping of the document is detected as the document abnormality detection is described, but the present invention is not limited to this. For example, the present invention can be applied to oblique feeding of sheets (or sheet bundles), that is, so-called skew detection. For example, the skew of the sheet can be detected by providing a plurality of optical sensors (such as sensors for detecting the presence or absence of a sheet) in the direction orthogonal to the sheet conveyance direction in the vicinity of the sheet feeding opening. As a specific example, an optical sensor on the center side is installed corresponding to the central portion in the sheet width direction, and a plurality of optical sensors are installed on both sides thereof. Thus, for example, even if the center sensor detects that there is a sheet, if one of the optical sensors on both sides detects that there is no sheet, it can be determined that the sheet is skewed. Alternatively, it is possible to detect the skew of the sheet by providing a plurality of movement amount detection units for detecting the movement amount of the fed sheet at a plurality of locations in the width direction of the sheet. In this case, for example, an encoder or the like can be applied to the movement amount detection unit, and the movement amount of the sheet can be measured based on the number of pulses output from the encoder. For example, a rotary encoder can be installed in the sheet conveyance path, and the amount of movement of the sheet can be detected by a rotation operation in the sheet conveyance direction. The encoder may be brought into direct contact with the sheet, but an encoder or the like may be attached to the shaft of a driven roller that is driven along with the movement of the sheet to form a movement amount detection unit.

  Such skewing of the sheet may occur even when a single sheet is fed, but may occur along with the flip-up depending on the sheet binding position with respect to the sheet bundle. Further, the skew of the sheet may occur when the sheet is caught on something while the sheet is being fed. Such skew detection of the sheet can be used in combination with the above-described detection of document jumping. However, in the skew detection method as well as the bounce detection method, there is a case where the skew of the sheet does not occur depending on the position of the sheet binding member and the binding condition, and abnormal conveyance by the binding member cannot be detected. In that case, when the sheet skew detection is enabled, the flip-up detection is automatically enabled (or vice versa), and the double feed detection setting is also automatically enabled at that time. It becomes possible to more effectively suppress sheet breakage, jam, and the like due to abnormal feeding.

  As shown in FIG. 5, when the document F <b> 1 bound by the sheet binding member SP passes through the double feed detection sensor 32 disposed after the feed roller 6 and the separation roller 7, the control unit 45 displays the double feed detection sensor 32. Based on this detection result, it is determined that double feeding is performed, and the conveyance of the document F1 is stopped. The conveyance stop of the document F1 is realized by the CPU 71 sending a stop signal to the drive circuit 47. This reduces the possibility of damaging a plurality of documents bound by the sheet binding member SP1. In addition, the sheet binding member SP1 can enter the image reading unit 43 at the subsequent stage. This is because the double feed detection sensor 32 is arranged upstream of the image reading unit 43 in the conveyance path. As described above, the CPU 71 and the drive circuit 47 of the control unit 45 feed the sheet feeding unit that stops the operation of the sheet feeding unit when the sheet abnormality detection unit detects the deformation of the sheet or the double feeding detection unit detects the double feeding. It functions as a control means.

  FIG. 6 shows an example of an operation screen displayed on the touch panel type operation unit 46 by the control unit 45. The operation unit 46 includes a display unit such as a liquid crystal display device and a pressure-sensitive or capacitive input unit. The operation screen 60 includes a check box 61 for designating whether abnormal document detection is enabled (ON) or disabled (OFF), and multifeed detection is enabled (ON) or disabled (OFF). There is a check box 62 for designating. The detail button 63 is a button for instructing detailed settings for double feed detection. When it is detected that the detail button 63 has been pressed, the control unit 45 displays a setting screen (dialog) for a double feed detection target area, which will be described later, on the operation unit 46. The check box 61, the CPU 71 of the control unit 45, and the operation unit 46 function as first setting means for setting whether to enable or disable the sheet abnormality detection means. The check box 61, the CPU 71 of the control unit 45, and the operation unit 46 function as a first selection instruction receiving unit that receives a selection instruction to enable or disable the sheet abnormality detection unit.

  FIG. 7 is a diagram showing an example of a setting dialog to which the present invention is applied. The control unit 45 displays a check in the check box 61 when detecting that the check box 61 is checked to enable abnormal document detection based on the detection signal from the operation unit 46. Further, the control unit 45 grays out the check box 62 and the detail button 63 so that the user cannot operate the check box 62 and the detail button 63. Further, the control unit 45 enables both abnormal document detection and double feed detection. Thereby, even if the user forgets to validate the double feed detection, it is possible to make the double feed detection function effectively. As described above, the check box 62, the CPU 71 of the control unit 45, and the operation unit 46 serve as second setting means for setting the double feed detection means to be effective when the sheet abnormality detection means is set to be effective by the first setting means. Function. The check box 62, the CPU 71 of the control unit 45, and the operation unit 46 function as a second selection instruction receiving unit that receives a selection instruction to enable or disable the double feed detection unit. Further, when the CPU 71 of the control unit 45 receives a selection instruction indicating that the first selection instruction receiving unit validates the sheet abnormality detection unit, the second selection is performed so that the second selection instruction receiving unit does not receive the selection instruction. It functions as an acceptance control means for controlling the instruction acceptance means. Further, the display device of the CPU 71 and the operation unit 46 functions as a display unit that displays that the second selection instruction receiving unit is in a state where the selection instruction cannot be received.

  In addition, since it is sufficient if the user cannot operate the check box 62 and the detail button 63, the grayout process is not necessarily essential. For example, when the control unit 45 detects that the check box 61 is checked, the control unit 45 displays check marks in both the check box 61 and the check box 62. Furthermore, as long as the check box 61 is checked, the control unit 45 performs control so that the user input to the check box 62 is ignored and the check box 62 is not unchecked. If the check box 61 is not checked, the control unit 45 controls the check box 62 to be checked or unchecked according to the input signal from the operation unit 46.

  FIG. 8 is a flowchart illustrating automatic validation of double feed detection according to the embodiment. In step S <b> 801, the control unit 45 determines whether the input signal from the operation unit 46 is a signal for instructing validation of abnormal document detection. If it is an abnormal document detection validation instruction, the process proceeds to S801, and if it is not an abnormal document detection validation instruction, the process proceeds to S809.

  In step S802, the control unit 45 validates abnormal document detection and validates double feed detection. Therefore, when detecting an abnormal document by detecting an abnormal document or detecting a double feed by detecting double feed, the control unit 45 outputs a stop signal to a motor involved in the transport so as to stop the transport of the document.

  In step S <b> 803, the control unit 45 displays a message or a mark indicating that the abnormal document detection has been enabled on the operation unit 46, and grays out controls related to double feed detection. Note that the control unit 45 may display a message or mark on the operation unit 46 indicating that the double feed detection is also enabled.

  In step S <b> 804, the control unit 45 determines whether the input signal from the operation unit 46 is a signal instructing invalidation of double feed detection. If it is a double feed detection invalidation instruction, the process proceeds to S804, and if it is not a double feed detection invalidation instruction, the process proceeds to S806.

  In S805, the control unit 45 rejects the double feed detection invalidation instruction and continues invalidating the double feed detection. At this time, the control unit 45 may display a message or mark on the operation unit 46 indicating that the double feed detection cannot be invalidated when the abnormal document detection is enabled.

  In step S <b> 806, the control unit 45 determines whether the input signal from the operation unit 46 is a signal that instructs invalidation of abnormal document detection. If it is an abnormal document detection invalidation instruction, the process proceeds to S807, and if it is not an abnormal document detection invalidation instruction, the process returns to S804.

  In step S <b> 807, the control unit 45 invalidates the abnormal document detection. When the abnormal document detection is invalidated, the control unit 45 executes document conveyance control without executing the abnormal document detection. Note that if the abnormal document detection is invalidated, the control unit 45 may invalidate the double feed detection. Here, it is assumed that the double feed detection is kept valid.

  In step S <b> 808, the control unit 45 displays a message or mark indicating that the abnormal document detection has been invalidated on the operation unit 46. When abnormal document detection is disabled, the control unit 45 can disable or enable double feed detection based on a user operation. That is, when the first setting unit sets the sheet abnormality detection unit to invalid, the control unit 45 sets whether to enable or disable the double feed detection unit according to a user operation.

  In step S809, the control unit 45 determines whether the input signal from the operation unit 46 is a signal for instructing invalidation of double feed detection. If it is a double feed detection invalidation instruction, the control unit 45 proceeds to S810, and if it is not a double feed detection invalidation instruction, the process ends. You may return to S801, without complete | finishing this process.

  In S810, the control unit 45 invalidates double feed detection. When a document is conveyed using a carrier sheet (document protection sheet), double feed detection is invalidated. In step S811, the control unit 45 displays a message or mark on the operation unit 46 indicating that double feed detection has been invalidated.

  In step S812, the control unit 45 determines whether the input signal from the operation unit 46 is a signal for instructing validation of double feed detection. If it is a double feed detection validation instruction, the control unit 45 proceeds to S813, and if it is not a double feed detection validation instruction, the process ends. You may return to S801, without complete | finishing this process. In step S813, the double feed detection is validated, and a message or mark indicating that the double feed detection is validated is displayed on the operation unit 46.

  As described above, in the present embodiment, when the abnormal document detection is set to be effective, the control unit 45 automatically switches the double feed detection to effective, so that the case shown in FIG. 4 can be accurately detected. Become. As a result, it is possible to suppress damage to the document and damage to the component devices arranged on the conveyance path. In the example illustrated in FIG. 7, the control related to the double feed detection is grayed out in order to make it easy for the user to understand that the double feed detection cannot be invalidated. However, double feed detection may be enabled as a process of the control unit 45 without grayout display.

  It should be noted that, after the abnormal document detection is effectively switched, instead of forcibly enabling double feed detection, the control unit 45 may display a message prompting the user to enable double feed detection on the operation unit 46. Good. This will be effective when there are a plurality of operation units 46 (for example, a display screen on the PC side and a display unit of the document reading apparatus 200). In this way, when abnormal document detection is enabled, prompting the user to also enable double feed detection can suppress sheet material breakage, jamming, etc. caused by user's forgotten operation or incorrect operation. Let's go.

Second Embodiment
In the second embodiment, when abnormal document detection is enabled, even if double feed detection is disabled, only the leading portion of the document is automatically detected for double feed. For example, the control unit 45 may validate double feed detection when the pre-feed sensor 31 detects the leading edge of the document, and invalidate double feeding detection when the post-registration sensor 34 detects the leading edge of the document. Alternatively, when the pre-feed sensor 31 detects the leading edge of the document, the control unit 45 validates the double feed detection, and when the elapsed time or the conveyance distance exceeds the threshold after the pre-feed sensor 31 detects the leading edge of the document. Double feed detection may be disabled. The elapsed time or the conveyance distance may be counted by the controller 45 itself or by the counter 74. As a result, the double feed detection is automatically performed only at the leading portion of the document, so that it may be possible to suppress the sheet material from being damaged or jammed due to the user's forgetting operation or erroneous operation.

  FIG. 9 is a flowchart showing the second embodiment. This flowchart shows the document transport operation more simply than the actual operation. The control unit 45 and the multi-feed detection sensor 32 function as a multi-feed detection unit that detects multi-feed using only the leading portion of the sheet in the transport direction as a target area for multi-feed detection.

  In step S <b> 901, the control unit 45 outputs a drive signal to a corresponding motor so as to drive the pickup roller 4, the feeding roller 6, and the separation roller 7.

  In step S <b> 902, the control unit 45 determines whether the leading edge of the document has reached the detection position of the post-registration sensor 34 in the conveyance path based on the detection signal of the post-registration sensor 34. If the document cannot be detected, the process proceeds to S903.

  In step S903, the control unit 45 determines whether there is an abnormal document based on a detection signal from the abnormal document detection sensor. As described above, when receiving the detection signal indicating that the light receiving unit 52 cannot detect the light from the light emitting unit 51, the control unit 45 determines that an abnormal document exists. If an abnormal document exists, the process proceeds to S908.

  In S908, the control unit 45 outputs a stop signal to the corresponding motor to stop the pickup roller 4, the feeding roller 6, and the separation roller 7. In step S909, the control unit 45 executes error processing and ends this processing. Examples of the error processing include a process in which the control unit 45 displays a message or mark indicating that an abnormal document has been detected on the operation unit 46.

  If no abnormal document is detected in S903, the process proceeds to S904. In step S <b> 904, the control unit 45 determines whether double feeding has occurred based on the detection signal from the double feeding detection sensor 32. If double feeding has occurred, the process proceeds to S908 described above. If double feeding has not occurred, the process returns to S902.

  If the control unit 45 detects a document in S902, the process proceeds to S905. In step S <b> 905, the control unit 45 outputs a stop signal to the corresponding motor to stop the pickup roller 4 and the feeding roller 6.

  In step S906, the control unit 45 determines whether the post-registration sensor 34 has detected a document. If no document is detected, the process proceeds to S910. In S910, the control unit 45 outputs a stop signal to the corresponding motor to stop the separation roller 7. Thus, when the post-registration sensor 34 no longer detects the document, it is determined that the trailing edge of the document has passed, and the control unit 45 stops the separation roller 7.

  On the other hand, if the post-registration sensor 34 detects a document in S906, the process proceeds to S907. In step S907, the control unit 45 determines whether an abnormal document exists based on a detection signal from the abnormal document detection sensor. If an abnormal document exists, the process proceeds to S908. If no abnormal document is detected in S907, the process returns to S906.

  According to the second embodiment, double feed detection is automatically enabled until the leading edge of the document reaches the post-registration sensor 34, that is, only the leading edge portion of the document. Therefore, even when the abnormal document detection does not work normally due to the sheet binding member SP1 at the leading edge of the document, the double feed detection by the double feed detection sensor 32 can be automatically enabled.

  In the second embodiment, the target range of double feed detection by the double feed detection sensor 32 in the document is defined by the transport position of the post-registration sensor 34. However, the target range of double feed detection includes the rotation speed of each roller indicating the transport distance of the document from the start of sheet feeding, the transport time, and the document transport amount sensor that is in contact with or not in contact with the leading edge of the document. May be used. When the conveyance distance or conveyance time is used, the counter 74 functions as a counting unit that counts the conveyance distance or conveyance time of the sheet when the sheet feeding unit starts feeding the sheet. Further, the CPU 71 of the control unit 45 functions as a determination unit that determines whether or not the count value of the counting unit exceeds a predetermined threshold, and in a period until the count value of the counting unit exceeds the predetermined threshold, It functions as double feed detection means for detecting double feed for a sheet.

  According to the second embodiment, abnormal document detection using the abnormal document detection sensor and the multi-feed detection sensor 32, even when a document with a sticky note or a receipt pasted in the middle of a document, which is often seen in accounting processing, is mixed. Function normally. For example, a protective member called a carrier sheet that protects a document that is easily torn may be used. The carrier sheet has a part that protects the document by sandwiching it and a part that cannot sandwich the document (non-overlapping part). The portion to be protected by sandwiching the document is usually provided on the rear end side of the carrier sheet in the transport direction. The portion where the document cannot be sandwiched is usually provided on the leading end side of the carrier sheet in the transport direction. Therefore, the control unit 45 performs double feed detection only with the non-overlapping portion provided at the leading portion of the carrier sheet. Therefore, even if the carrier sheet is conveyed, the conveyance is not stopped.

<Third Embodiment>
In the third embodiment, when the user sets the double feed detection range, the double feed detection is executed at the head portion of the document by limiting the double feed detection at the head portion of the document so that it cannot be invalidated. It is an embodiment.
FIG. 10 is a diagram illustrating an example of the double feed detection range setting screen 90 displayed on the operation unit 46. FIG. 11 is a diagram illustrating a plurality of double feed detection sensors 32a, 32b, and 32c.

  As shown in FIG. 11, three double feed detection sensors 32a, 32b, and 32c are provided along a direction orthogonal to the document conveyance direction. The three double feed detection sensors 32a, 32b, and 32c are an example of a plurality of sensors that are arranged along a direction orthogonal to the sheet conveyance direction and constitute a double feed detection unit.

  As shown in FIG. 10, on the double feed detection range setting screen 90, settable ranges 91a, 91b, 91c corresponding to the double feed detection sensors 32a, 32b, 32c are displayed. Of the settable range 91c, the detection target range 95 indicates a range where the double feed detection sensor 32c actually detects double feed. The non-detection range 96 indicates a range where the double feed detection sensor 32c does not actually detect double feed. That is, when the document passes through the detection target range 95, the control unit 45 executes double feed detection based on the detection signal from the double feed detection sensor 32. On the other hand, when the document passes through the non-detection range 96, the control unit 45 does not execute double feed detection. Note that the control unit 45 sets the detection target range 95 and the non-detection range 96 according to the input signal from the input unit of the operation unit 46. Since the input unit is a touch sensor, the user can freely specify the detection target range 95 and the non-detection range 96. As described above, the control unit 45, the operation unit 46, and the double feed detection range setting screen 90 determine in advance a range that is a detection target and a non-detection range of the multiple feed in the sheet conveyance direction for each of the plurality of sensors. It functions as a designation means for designating from within the specified range.

  By the way, in the example shown in FIG. 10, the non-detection range 96 can be set freely, so that the leading portion of the document can also be set to the non-detection range 96. Therefore, even if the abnormal document detection sensor is enabled, the double feed detection sensor may be disabled. Therefore, in the third embodiment, when the abnormal document detection is validated, the control unit 45 restricts at least the non-detection range 96 of double feed detection corresponding to the double feed detection sensor 32b arranged in the center of the conveyance path. I will do it.

  FIG. 12 is a diagram illustrating an example of the double feed detection range setting screen 90 displayed on the operation unit 46. In FIG. 12, the control unit 45 displays the range corresponding to the head portion of the document as the setting limit range 97 in the settable range 91 b corresponding to the double feed detection sensor 32 b. The setting restriction range 97 and the control unit 45 are configured to restrict the predetermined range of the plurality of sensors, which is relatively centered in the orthogonal direction, from the plurality of sensors. It functions as a designation restricting means that causes the leading end of the sheet to be detected as a double feed detection target area.

  As described above, when the abnormal document detection is validated, the control unit 45 displays the range corresponding to the head portion of the document as the setting limit range 97 that cannot be set by the user. Further, the control unit 45 automatically enables double feed detection for the setting limit range 97. As a result, the control unit 45 can accurately detect the document bundle bound by the sheet binding member SP1. This will also prevent damage to the sheet material and jamming.

Claims (10)

A sheet stacking means for stacking a plurality of sheets;
Sheet feeding means for feeding the plurality of sheets stacked on the sheet stacking means one by one to a conveyance path;
Sheet abnormality detecting means for detecting deformation of the sheet fed by the sheet feeding means;
Double feed detection means that is disposed downstream of the sheet abnormality detection means in the transport direction and detects that a plurality of sheets are overlapped and fed,
First setting means for setting whether to enable or disable the sheet abnormality detection means;
When the sheet abnormality detection means is set to be effective by the first setting means, second setting means for setting the multifeed detection means to be effective;
And a sheet feeding control unit that stops the operation of the sheet feeding unit when the sheet abnormality detecting unit detects a deformation of the sheet or the double feeding detecting unit detects a double feeding. Feeding device. First selection instruction receiving means for receiving a selection instruction for enabling or disabling the sheet abnormality detection means;
Second selection instruction receiving means for receiving a selection instruction for enabling or disabling the double feed detection means;
When the first selection instruction accepting unit accepts a selection instruction indicating that the sheet abnormality detection unit is valid, the second selection instruction accepting unit is controlled so that the second selection instruction accepting unit does not accept the selection instruction. The sheet feeding apparatus according to claim 1, further comprising: a reception control unit that performs the reception control.   The sheet feeding apparatus according to claim 2, further comprising a display unit configured to display that the second selection instruction receiving unit is in a state where the selection instruction cannot be received.   When the first setting unit sets the sheet abnormality detection unit to invalid, the second setting unit sets whether to enable or disable the double feed detection unit according to a user operation. The sheet feeding apparatus according to any one of claims 1 to 3.   5. The sheet feeding apparatus according to claim 1, wherein the multi-feed detection unit detects multi-feed using only a leading portion of a sheet in a transport direction as a target area for multi-feed detection. 6. . When feeding of the sheet is started by the sheet feeding means, a counting means for counting the transport distance or transport time of the sheet;
Determination means for determining whether the count value of the counting means exceeds a predetermined threshold,
The sheet feeding apparatus according to claim 5, wherein the double feeding detection unit detects double feeding of the sheet during a period until the count value of the counting unit exceeds a predetermined threshold value. A plurality of sensors arranged along a direction orthogonal to the sheet conveying direction, and constituting the double feed detecting means;
A designation unit that designates a range that is a detection target of double feeding and a range that is not a detection target for each of the plurality of sensors from a predetermined range;
In the designating unit, by restricting the predetermined range of the plurality of sensors, the sensor disposed relatively centrally in the orthogonal direction, the leading end portion of the sheet is detected by double feed detection. The sheet feeding apparatus according to claim 5, further comprising: a designation limiting unit that causes the multifeed detection unit to detect double feed as a target area. A sheet stacking means for stacking a plurality of sheets;
Sheet feeding means for feeding the plurality of sheets stacked on the sheet stacking means one by one to a conveyance path;
Sheet abnormality detecting means for detecting deformation of the sheet fed by the sheet feeding means;
A control method for a sheet feeding apparatus, which is disposed downstream of the sheet abnormality detection means in the transport direction and includes a double feed detection means for detecting that a plurality of sheets are overlapped and fed,
A first setting step for setting whether to enable or disable the sheet abnormality detection unit; and if the sheet abnormality detection unit is set to be effective in the first setting step, the multifeed detection unit is also set to be enabled A second setting step,
And a sheet feeding control step of stopping the operation of the sheet feeding unit when the sheet abnormality detecting unit detects deformation of the sheet or when the double feeding detecting unit detects double feeding. Control method of feeding device. An image reading device,
A sheet feeding device according to any one of claims 1 to 7,
An image reading apparatus comprising: a reading unit that reads an image of a sheet fed by the sheet feeding apparatus. An image forming apparatus,
A sheet feeding device according to any one of claims 1 to 7,
An image forming apparatus comprising: an image forming unit that forms an image on a sheet fed by the sheet feeding device.