JP2012206858A - Image processing apparatus and sheet conveyance method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique that improves productivity in image processing while suppressing the occurrence of serious jam.SOLUTION: An image processing apparatus includes: an image processing unit for processing an image using a sheet 5; a conveyance mechanism that has a conveyance path 43, and conveys the sheet along the conveyance path; at least one position detection unit 33 that detects a position (xl, yl) of an end of the sheet 5 that is conveyed on the conveyance path; at least one skew quantity detection unit 33 that detects a skew quantity θof the sheet, an end position of which is detected; a prediction unit that predicts first predicted a position (xe, ye) where the end LT of the sheet protrudes by a predetermined amount ΔWt from a predetermined width Wt in a direction X crossing a sheet conveyance direction based on the end position (xl, yl) detected by the position detection unit and the skew quantity θ detected by the skew quantity detection unit; and a stopping unit that stops the conveyance mechanism before the first predicted position.

Description

  The present invention relates to an image processing apparatus and a sheet conveying method, and more particularly to a technique for suppressing the occurrence of sheet jamming related to image formation in an image processing apparatus.

  Conventionally, as a technique for suppressing jamming of an image forming sheet in an image processing apparatus, for example, Japanese Patent Application Laid-Open No. 2003-228561 discloses an oblique angle obtained from a moving amount of a sheet in a conveyance direction and a change amount of an end position in the main scanning direction of image reading. An image reading apparatus that stops sheet conveyance based on a line amount is disclosed.

JP 2006-335525 A

  However, if the conveyance of the sheet is stopped after detecting that the sheet is actually tilted so as to be jammed, the conveyance of the sheet is delayed, and the sheet may bite into the conveyance roller and the jam may be difficult to be eliminated. On the other hand, in order to prevent the former problem, if the skew amount as a reference for stopping the sheet conveyance is set small, the sheet conveyance can be stopped before a serious jam occurs, but the jam does not actually occur. Even in such a case, the conveyance of the sheet is often stopped, and the image processing productivity may be lowered.

  The present invention provides a technique for improving image processing productivity while suppressing the occurrence of serious jams.

  An image forming apparatus disclosed in the present specification is an image processing apparatus including an image processing unit that performs image processing using a sheet, has a conveyance path, and conveys the sheet along the conveyance path. Detecting at least one position detecting unit for detecting a position of a leading end portion of the sheet conveyed on the conveying path, and a skew amount of the sheet from which the position of the leading end portion is detected; Based on at least one skew amount detection unit, the position of the leading end detected by the position detection unit, and the skew amount detected by the skew amount detection unit, in a direction orthogonal to the sheet conveyance direction. A prediction unit that predicts a first predicted position where the leading edge of the sheet protrudes from the predetermined width by a predetermined amount; and a stop unit that stops the conveyance mechanism before the first predicted position.

  Further, in the image processing apparatus, the at least one position detection unit and the at least one skew amount detection unit are each configured by one position detection unit and one skew amount detection unit, and the prediction unit includes: Based on the position and skew amount of the tip detected previously by the one position detector and skew amount detector and the position and skew amount of the tip detected this time, the first prediction The position may be predicted.

  The image processing unit may include an image reading unit that reads an image on the sheet to generate image data, the position detection unit, and the skew amount detection unit.

  The transport mechanism includes a transport roller on a downstream side in the sheet transport direction of the image processing unit, and the predetermined width is a distance between two walls provided on both sides in the width direction of the transport path, and the prediction unit Predicts the position in the predetermined width direction of the sheet leading end when the sheet reaches the conveying roller, and the stop portion protrudes from the predetermined width when the sheet reaches the conveying roller. If predicted, the transport mechanism may be stopped before the transport roller.

  In addition, the predetermined width is a distance between two walls provided on both sides in the width direction of the conveyance path, and the prediction unit predicts a skew amount when the sheet leading edge protrudes from the predetermined width, and the stop The unit may continue the conveyance of the sheet by the conveyance mechanism when the predicted skew amount is smaller than a predetermined value.

  Further, the predetermined width is a distance between two walls provided on both sides in the width direction of the transport path, and the predicting unit has a predetermined amount of the leading end of the sheet protruding from the predetermined width, and the skew amount is equal to or larger than the predetermined amount. The second predicted position may be predicted, and the stop unit may continue the conveyance of the sheet by the conveyance mechanism when the second predicted position is downstream of the sheet discharge port.

  The stopping unit may stop the conveyance mechanism after an image reading operation is performed when the leading end of the sheet reaches the first predicted position after passing the image reading unit at the trailing end of the sheet. It may be.

  Further, the transport mechanism has a transport roller on the downstream side in the sheet transport direction of the image processing unit, and the stop section has the sheet leading end when the first predicted position is on the downstream side of the transport roller. The transport mechanism may be stopped before reaching the transport roller.

  Further, the image processing unit detects an edge position in the width direction of the document when the document passes through the image processing unit, and the skew amount detection unit uses the detected edge position. The skew amount may be detected, and the position detection unit may detect the position of the leading end portion of the sheet based on the skew amount and the sheet transport length in the transport direction by the transport mechanism. .

  A method disclosed in the present specification is a method for conveying the sheet in an image processing apparatus including an image processing unit that performs image processing using a sheet, and conveys the sheet along a predetermined conveyance path. A conveying step, a position detecting step for detecting a position of the leading end portion of the sheet conveyed on the conveying path, and a skew amount detecting step for detecting the skew amount of the sheet for detecting the position of the leading end portion. And in the direction orthogonal to the sheet conveyance direction based on the position of the leading edge detected last time and this time by the position detection step and the skew amount detected last time and this time by the skew amount detection step. A prediction step of predicting a predicted position where the leading edge of the sheet protrudes from the predetermined width by a predetermined amount; and a stop step of stopping the conveying step before the predicted position.

  According to the present invention, based on the position of the leading edge detected by the position detection unit and the skew feeding amount detected by the skew feeding amount detection unit, the leading edge of the sheet from a predetermined width in a direction orthogonal to the sheet conveying direction. The first predicted position where a predetermined amount protrudes is predicted. That is, the position where the jam occurs is predicted. Then, the transport mechanism is stopped before the first predicted position. Therefore, it is possible to improve image processing productivity while suppressing the occurrence of serious jam.

FIG. 3 is a perspective view illustrating an appearance of the multifunction machine according to the first embodiment. Schematic sectional view of an image reading device of a multifunction machine Block diagram schematically showing the electrical configuration of the MFP Plan view showing the positional relationship between the document and the transport path Flowchart showing a main routine of document reading Flow chart showing image reading routine in main routine Diagram showing how to detect document skew Diagram showing another method for detecting document skew Flowchart showing tip distance reference detection routine in image reading routine Flow chart showing tip detection processing in tip distance reference detection routine Flowchart showing the tip position determination routine in the image reading routine Diagram showing how to calculate the tip position FIG. 10 is a diagram illustrating a positional relationship between a document and a conveyance path in the second embodiment

<Embodiment 1>
Next, Embodiment 1 of the present invention will be described with reference to FIGS.

1. FIG. 1 is a perspective view showing an external appearance of a multifunction device 1 including an image reading device 3 according to the present invention, and FIG. 2 is a schematic sectional view of the image reading device 3. The multifunction device 1 is a multi-functional peripheral device having a printer function, a scanner function, a copy function, a facsimile function, and the like.

  As shown in FIG. 1, the multi function device 1 includes an image reading device (an example of an image processing device) 3 for reading a document above a main body unit 2. The image reading device 3 includes a reading unit (an example of an image reading unit, a position detection unit, and a skew feed amount detection unit) 30, an automatic document feeder (ADF) 40, a document placement unit 50, and the like. Note that the image reading apparatus is not limited to a part of the multifunction device 1. For example, the image reading device may be a single scanner device or a copier.

  As shown in FIG. 2, the document placing portion 50 includes a first platen glass 52 and a second platen glass 53 made of a transparent glass plate. The upper surface of the first platen glass 52 is covered with a document cover 48 so as to be opened and closed.

  The document cover 48 is pivotable between a closed position covering the first platen glass 52 and an open position opening the first platen glass 52, and is located above the rear side of the housing 2 of the multifunction machine 1 (the operation unit 11, the display unit). The side on which 12 etc. are provided is connected to the front side). An ADF 40 is provided on the document cover 48.

  As shown in FIG. 2, the ADF 40 includes an ADF cover 41, a document tray 42, a transport path (corresponding to a “transport path”) 43, a pair of first transport rollers 44, and a pair of second transport rollers (“transport rollers”). An example) 44A, various rollers such as a pair of paper discharge rollers 45, a stepping motor (not shown) that drives them, and a paper discharge tray 46 are included. The ADF 40 conveys the originals (an example of “sheets”) 5 placed on the original tray 42 one by one, passes them over the second platen glass 53, and discharges them to the paper output tray 46. Further, a document sensor 49 such as a photo sensor for detecting the document 5 set on the document tray 42 is provided. Here, the conveyance path 43, the first conveyance roller 44, the second conveyance roller 44A, and the paper discharge roller 45 correspond to a conveyance mechanism. A part of the conveyance path 43 is surrounded by a side wall (an example of a “wall”) 41A of the ADF cover 41 (see FIG. 4).

  The reading unit 30 is provided below the document placing unit 50 as shown in FIG. Here, the reading unit 30 is configured to read a document by a CIS (Contact Image Sensor) method. The reading unit 30 includes a linear image sensor 33 in which a plurality of light receiving elements are linearly arranged in a direction perpendicular to the paper surface, a light source 31 including RGB light emitting diodes, and a linear image sensor that reflects reflected light from a document. A rod lens array 32 that forms an image on each of the light receiving elements 33, a carriage 34 on which these are mounted, and a transport mechanism (not shown) that transports the carriage 34 are included. The reading unit 30 is not limited to the CIS method, and may be a so-called CCD method using a reduction optical system and a CCD (charge coupled device) image sensor.

  When reading the document placed on the first platen glass 12, the reading unit 30 moves the carriage 34 from the home position HP in the sub-scanning direction parallel to the surface of the first platen glass 52 (direction A in FIG. 2). When the document 5 conveyed by the ADF 40 is read while being conveyed at a constant speed, the carriage 34 is stopped from the home position HP just below the second platen glass 53 and read.

  The reading unit 30 operates as a position detection unit that detects the positions of the leading ends LT and RT of the document 5 conveyed in the conveyance path 43 in addition to reading the document, and the reading unit 30 includes the leading end portion. It operates as a skew amount detection unit for detecting the skew amount θ of the document 5 from which the positions of LT and RT are detected (see FIG. 4).

  Further, on the front side of the multifunction device 1, an operation unit 11 including various buttons, for example, a display unit 12 including a liquid crystal display, and a USB connection unit 13 are provided.

2. FIG. 3 is a block diagram schematically showing the electrical configuration of the multifunction device 1. As shown in FIG. 3, the multi-function device 1 includes a CPU 20 (an example of a prediction unit and a stop unit), a ROM 21, a RAM 22, an NVRAM (nonvolatile memory) 23, a network interface 24, and a facsimile interface 25. The unit 27, the reading unit 30, the operation unit 11, the display unit 12, and the rotation number counter 13 are connected. Here, the CPU 20, the image forming unit 27, and the reading unit 30 constitute an image processing unit. That is, in the present embodiment, the image processing unit performs a normal image reading operation and also serves as a position detection unit and a skew amount detection unit.

  Various programs for controlling the operation of the multifunction device 1 are stored in the ROM 21, and the CPU 20 controls each unit while storing the processing results in the RAM 22 or the NVRAM 23 according to the programs read from the ROM 21. . The rotation number counter 13 counts the number of rotations of the rotating body such as the conveyance roller 44, specifically, the total number of rotations of the rotating body in a predetermined period. Thereby, the CPU 20 calculates the transport distance of the document 5 and the like.

  The network interface 24 is connected to an external computer or the like via a communication line (not shown), and mutual data communication is possible via the network interface 24. The facsimile interface 25 is connected to a telephone line (not shown), and facsimile data can be communicated with an external facsimile apparatus or the like via the facsimile interface 25. The image forming unit 27 forms an image based on the image data on a recording medium such as paper.

3. Document Reading Processing Next, an outline of “document reading processing” by the image reading device 3 in the present embodiment will be described with reference to FIGS. FIG. 4 is a plan view showing the positional relationship between the conveyance path 43 and the document 5. FIG. 5 is a flowchart showing an original reading main routine, and FIG. 6 is a flowchart showing an “image reading routine” in the original reading main routine. FIGS. 7 and 8 are diagrams for explaining “document inclination detection processing” in the “image reading routine”. Each process is executed by the CPU 20 in accordance with a predetermined control program stored in the ROM 21 or the like.

  As shown in FIG. 2, the actual conveyance path 43 changes its conveyance direction by 180 °. In FIG. 4, the conveyance path 43 is drawn so that the conveyance direction is one direction. It is displayed in an extended form. Further, the image reading apparatus is not limited to the one in which the conveyance direction of the conveyance path 43 changes by 180 ° as in the present embodiment, and may be an image reading apparatus in which the conveyance direction is constant in one direction. Therefore, in the case of an image reading apparatus in which the transport direction is constant, it can be said that FIG. 4 shows the transport path as it is in a plane. In FIG. 4, the position of the reading unit 30, specifically, the linear image sensor 33, which is the left end of the transport path 43, is set as a coordinate reference point Po (0, 0). Further, the right end point of the transport path 43 corresponding to the reference point Po (0, 0) is defined as Pw (0, Xw).

3-1. Original Reading Main Routine When the original reading main routine is started, the CPU 20 first controls the conveying mechanism to start conveying the original 5 as shown in FIG. 5 (step S10). Next, the CPU 20 controls the rotation number counter 13 to start counting the rotation number (total rotation number) of the transport roller 44. Next, the “image reading routine” (step S30) is executed to read the image of the original 5, and when the conveyance of the original 5 is completed (step S40: YES), the original reading main routine is ended.

3-2. "Image reading routine"
In the “image reading routine” of FIG. 6, only processing related to position detection of the document 5 that is executed in addition to normal document reading processing is shown. Therefore, the normal document reading process is omitted in the flowchart of FIG. The “image reading routine” is executed every predetermined period within the period from the start to the end of conveyance of the document 5. The predetermined period is, for example, a period that is a multiple of the original reading scanning unit period.

  The CPU 20 predicts a position (first predicted position) where the leading end portion (LT or LR) of the document 5 protrudes from the width W (predetermined width) of the transport path 43 in order to suppress the occurrence of a jam, and the position. Stop the transport mechanism before this. In the flowchart of FIG. 6, the normal document reading process is omitted. Here, the width Wt of the conveyance path 43 is a distance between two ADF cover side walls 41A located on both sides in the width direction (X-axis direction) of the conveyance path 43, as shown in FIG. Further, the predetermined amount ΔWt is set here as a value that leaves room for the inclination θ of the document 5 to be restored by the ADF cover side wall 41A even if the document 5 continues to be conveyed. Note that the document 5 does not actually protrude from the conveyance path 43, but is brought into contact with the ADF cover side wall 41A and the contacted portion is bent, so that the conveyance of the document 5 is continued.

  Specifically, when starting the “image reading routine”, the CPU 20 first detects the left and right edges LA and RA of the document 5 based on the read data by the reading unit 30 as shown in FIG. That is, the X coordinates Xl and Xr of the left and right edges LA and RA are detected (step S305). Here, the coordinate reference point Po (0, 0) is the left end of the reading unit 30, specifically, the linear image sensor 33, as shown in FIG. 4.

  Next, the CPU 20 determines whether or not the distance reference between the left and right tip portions LT and LR has already been recorded (step S310). If it is determined that the distance reference has not been recorded (step S310: NO), a “tip distance reference detection routine” (step S325) for detecting the distance reference between the left and right tip portions LT and LR is executed, and “image reading” is executed. Routine "is once terminated.

On the other hand, when it is determined that the distance reference has already been recorded (step S310: YES), the CPU 20 detects the inclination θ (corresponding to the “skew amount”) of the document 5 (step S320). As shown in FIG.
θ = arctan (Xnewr−Xoldr) / Yd or θ = arctan (Xnewl−Xoldl) / Yd
Sought by.
Here, Xnewr is the X coordinate of the right edge RA2 detected this time, and Xoldr is the X coordinate of the right edge RA1 detected last time. Xnewl is the X coordinate of the left edge LA2 detected this time, and Xoldl is the X coordinate of the left edge LA1 detected last time. Yd is the distance in the Y-axis direction between this time and the previous edge detection. The distance Yd is calculated by, for example, Yd = L * ΔN based on the rotational speed difference ΔN between the current roller and the previous edge detection ΔN and the circumferential length L of the transport roller 44.

Further, in the case where the reading unit 30 is of a type provided in two places in the conveyance path 43, the inclination θ of the document 5 is detected by one edge detection, as shown in FIG.
θ = arctan (X2r−X1r) / Ys or θ = arctan (X2l−X1l) / Ys
Sought by.
Here, X2r is the X coordinate of the right edge RA2 detected by the image sensor 33B of the second reading unit, and X1r is the X coordinate of the right edge RA1 detected by the image sensor 33A of the first reading unit. . X2l is the X coordinate of the left edge LA2 detected by the image sensor 33B, and X1l is the X coordinate of the left edge LA1 detected by the image sensor 33A. Ys is a distance in the Y-axis direction between the image sensor 33A and the image sensor 33B.

  Next, the CPU 20 compares the document inclination θ detected last time with the document inclination θ detected this time, and determines whether the document inclination θ has changed by a predetermined value or more (step S330). If the document inclination θ has not changed more than a predetermined value (step S330: NO), the document 5 is predicted not to protrude a predetermined amount from the width W of the transport path 43, and jamming due to the document 5 does not occur. The “image reading routine” is temporarily terminated.

  On the other hand, when the document inclination θ changes beyond a predetermined value (step S330: YES), a “tip position determination routine” (step S335) for determining the positions of the leading ends LT and RT of the document 5 is executed. Next, from the result of the “tip position determination routine”, it is determined (predicted) based on the respective X coordinates xl and xr whether the left tip LT or the right tip RT reaches outside the transport tray range W (step S340). ).

  When it is predicted that one of the leading ends LT and RT protrudes outside the transport tray range W by a predetermined amount ΔWt (step S340: YES), the CPU 20 controls the transport mechanism to stop the transport of the document 5 (step). S345). On the other hand, if it is predicted that neither of the leading ends LT and RT will protrude outside the transport tray range W (step S340: NO), the “image reading routine” is temporarily terminated.

3-3. "Routine distance reference detection routine"
Next, the “tip distance reference detection routine” in step S325 will be described in detail with reference to FIGS. FIG. 9 is a flowchart showing a “tip distance reference detection routine”, and FIG. 10 is a flowchart showing “tip detection processing” in the “tip distance reference detection routine”.

  When starting the “tip distance reference detection routine”, the CPU 20 first executes “tip detection processing” (step S100) as shown in FIG. In the “leading edge detection process”, as shown in FIG. 10, the CPU 20 first determines whether or not the left leading edge LT of the document 5 has already been detected (step S105). If it is determined that the left front end LT has not been detected (step S105: NO), it is determined whether the right front end RT of the document 5 has already been detected (step S125).

  If it is determined that the right tip RT has not been detected (step S125: NO), it is determined whether the left and right edges LA and RA of the document 5 have been detected (step S145). When it is determined that the left and right edges LA and RA have not been detected (step S145: NO), this corresponds to the case where the document 5 has not reached the reading unit 30, and the “leading edge detection process” is temporarily ended.

  On the other hand, when it is determined that the left and right edges LA and RA are detected (step S145: YES), the CPU 20 determines whether both the left and right edges LA and RA are on the left side of the center line CL. That is, it is determined whether the X coordinates Xl, Xr of the left and right edges LA, RA are smaller than the X coordinate Xc of the center line CL (step S150).

  When it is determined that the left and right edges LA and RA are both on the left side of the center line CL (step S150: YES), the detection of the left tip LT is completed (step S155), and the left and right edge coordinates Xl and Xr at that time Is stored in the RAM 22, for example (step S160).

  On the other hand, if it is not determined that both the left and right edges LA and RA are on the left side of the center line CL (step S150: NO), the CPU 20 has both the left and right edges LA and RA on the right side of the center line CL. Determine whether or not. That is, it is determined whether or not the X coordinates Xl and Xr of the left and right edges LA and RA are larger than the X coordinate Xc of the center line CL (step S165).

  When it is determined that the left and right edges LA and RA are both on the right side of the center line CL (step S165: YES), the detection of the right tip RT is completed (step S170), and the left and right edge coordinates Xl and Xr at that time Is stored in the RAM 22, for example (step S160). On the other hand, if it is determined that both the left and right edges LA and RA are on the right side of the center line CL, that is, the left edge LA is on the left side of the center line CL, and the right edge RA is on the right side of the center line CL. If it is determined that there is (step S165: NO), the detection of the left tip LT is completed (step S175). Next, detection of the right tip RT is also completed (step S180), and the left and right edge coordinates Xl and Xr at that time are stored in, for example, the RAM 22 (step S160).

  Here, returning to step S125, if it is determined in step S125 that the right tip RT has already been detected (step S125: YES), the CPU 20 is to the left of the coordinates where the left edge coordinates Xl are stored. It is determined whether it is present, that is, whether it is smaller than the stored coordinates (step S130). If the left edge coordinate Xl is on the left side of the stored coordinate (step S130: YES), the current left edge coordinate Xl is newly stored (step S135). On the other hand, if the left edge coordinate Xl is not on the left side from the stored coordinates (step S130: NO), it is determined that the left tip LT of the document 5 has reached the reading unit 30, and the detection of the left tip LT is completed ( Step S140), “tip detection processing” is temporarily terminated.

  Returning to step S105, if it is determined in step S105 that the left tip LT has already been detected (step S105: YES), the CPU 20 is to the right of the coordinates where the right edge coordinates Xr are stored. Whether it is greater than the stored coordinates (step S110). When the right edge coordinate Xl is on the right side of the stored coordinate (step S110: YES), the current right edge coordinate Xr is newly stored (step S115). On the other hand, if the right edge coordinate Xr is not on the right side of the stored coordinates (step S110: NO), it is determined that the right tip RT of the document 5 has reached the reading unit 30, and the detection of the right tip RT is completed ( Step S120), “tip detection processing” is temporarily terminated.

Next, returning to the “tip distance reference detection routine” in FIG. 9 and completing the “tip detection process” (step S100) in this way, the CPU 20 detects the left tip LT in the “tip detection process”. It is determined whether or not (step S205).
When the left end LT is not detected (step S205: NO), the process proceeds to step S210. On the other hand, when the left tip LT is detected (step S205: YES), the current rotation speed (total rotation speed from the start of rotation) Nlo of the transport roller 44 is set as the left tip distance reference.

Next, it is determined whether or not the right tip RT has been detected (step S215).
When the right tip RT has not been detected (step S215: NO), this process ends. On the other hand, when the right tip RT is detected (step S215: YES), the current rotation speed No of the transport roller 44 is set as the right tip distance reference.

3-4. "End position judgment routine"
Next, the “tip position determination routine” in step S335 of FIG. 6 will be described in detail with reference to FIGS. FIG. 11 is a flowchart showing the “tip position determination routine”, and FIG. 12 is a diagram for explaining the calculation of the tip position in the “tip position determination routine”.

  When the CPU 20 starts the “tip position determination routine”, as shown in FIG. 11, the left and right tip distance reference No. detected in the “tip distance reference detection routine” and the current rotation speed N of the transport roller 44 are used. The y coordinates (yl, yr) of the tip positions LT, RT are calculated (step S250). Further, the CPU 20 determines the x coordinates (xl, xr) of the left and right tip positions LT, RT based on the X coordinates X1, Xr of the left and right edges LA, RA detected in step S305 and the document inclination θ detected in step S320, respectively. Calculate (step S260).

That is, each coordinate is as shown in FIG.
yr = L * (N-No)
xr = Xr-yr * cot θ = Xr-L * (N-No) * cot θ
xl = xr−W * cos θ = (Xr−L * (N−No) * cot θ) −W * cos θ
yl = yr−W * sin θ = L * (N−No) −W * sin θ
Here, No: tip distance reference, N: current transport roller rotation speed, L: transport roller circumference, θ: document tilt, W: document width (length perpendicular to the transport direction) That is). L * (N-No) corresponds to the sheet conveyance length in the conveyance direction Y.

  In this way, the coordinates (xl, yl) of the left tip position LT and the coordinates (xr, yr) of the right tip portion RT are calculated, and the left tip portion LT and the right tip position RT are determined.

  Based on the determined left leading edge position LT and right leading edge position RT, the CPU 20 determines from the width (predetermined width) Wt of the conveyance path in the X-axis direction (direction orthogonal to the sheet conveyance direction) to the leading edge (LT or LT). RT) is predicted by a predetermined amount ΔWt, and the predicted position of the protruding tip portion (corresponding to the first predicted position: for example, LTe (xe, ye)) is predicted (see FIG. 4). Then, the CPU 20 stops the operation of the transport roller 44 (an example of a transport mechanism) before the leading end of the document 5 reaches the predicted position (see step S345).

Note that the position of the leading edge (LT or RT) of the document 5, that is, the prediction of the coordinates (xl, yl or xr, yr), or the prediction of the x coordinate (xl or xr) is substantially determined by the document inclination θ. In a fixed case, it is performed by calculating each coordinate according to the coordinate calculation formula every predetermined period.
When the document inclination θ changes, the x coordinate (xl or xr) is predicted by, for example, calculating the inclination change amount Δθ in a predetermined period from the change in the document inclination θ detected every predetermined period, For each predetermined period, the coordinates are calculated according to the above coordinate calculation formula with the document inclination being (θ + Δθ). When the change amount Δθ is sequentially calculated from the change in the document inclination θ, the jam position is determined by setting the X coordinate (Xl or Xr) of the edge (LA or RA) detected by the image sensor 33 as a fixed value. It can be predicted as a position closer to the transport direction from the image sensor 33. That is, the jam position can be predicted as a position closer to the image sensor 33 than the actual jam position, and the jam can be avoided more reliably.

4). Effects of First Embodiment A position at which a jam occurs in the document 5 (LTe (xe, ye)) is predicted based on the current position (LT (xl, yl)) of the document front end (LT or RT) and the document inclination θ. To do. Since the document 5 is transported up to the predicted position (LTe (xe, ye)) and then the document 5 is stopped, image processing productivity is suppressed while suppressing the occurrence of serious jamming. Can be improved.

  Further, the “image reading routine” shown in FIG. 6 is performed every predetermined period within the document conveyance period. That is, the document inclination θ and the leading edge position are detected a plurality of times every predetermined period. Therefore, even when the reading unit 30 (the position detection unit and the skew amount detection unit) is provided only in one place, the position where the jam occurs is preferably predicted, and the position before the predicted position is preferably detected. Until the sheet is conveyed, the conveyance can be stopped.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described with reference to FIG. FIG. 13 is a diagram for explaining a document conveyance state in the second embodiment. In the second embodiment, the document 5 is predicted to protrude from the conveyance path 43 in consideration of the relationship with the second conveyance roller (an example of “conveyance roller”) 44A.

  That is, as shown in FIG. 13, the second transport roller 44 </ b> A is provided on the downstream side of the reading unit (image processing unit) 30 in the document transport direction. Then, the CPU 20 (prediction unit) predicts the position in the direction of the conveyance path width Wt (predetermined width) of the document leading end (LT or RT) when the document 5 (RT or LT) reaches the second conveyance roller 44A. .

  Then, the CPU 20 (stop unit) determines that the document 5 (RT or LT) reaches the second conveyance roller 44A from the conveyance path width Wt (conveyance path) based on the result of the “tip position determination routine”. (LT or RT) is predicted to protrude, the transport mechanism (44, 44A) is stopped before the second transport roller 44A (see state 1 and state 4).

5. Effect of Embodiment 2 When it is predicted that the document leading end (LT or RT) protrudes even slightly at the position of the second conveying roller 44A, the document 5 is entangled with the second conveying roller 44A as it continues to be conveyed. Generation can be suppressed. That is, as shown in the state 4 in FIG. 13, when the document leading end LT protrudes from the transport path 43 in the transport path width Wt direction, the document leading end LT actually contacts the side wall 41A and the document 5 is bent. It is expected that. In this case, when the distance between the position of the document leading end portion LT and the second transport roller 44A is short, the document 5 may be damaged with high probability if the document 5 reaches the second transport roller 44A while being bent. . Therefore, the document 5 can be prevented from being damaged by stopping the transport mechanism (44, 44A) in front of the second transport roller 44A.

  As shown in states 1 to 3 in FIG. 13, when it is determined by the “tip position determination routine” that the document leading end portion LT protrudes from the conveyance path 43 in the conveyance path width Wt direction. Even if there is a certain distance between the position of the document leading end portion LT and the second transport roller 44A, the transport of the document 5 may not be stopped. That is, when the document 5 is being conveyed, there is a change in the document inclination θ detected in the document inclination detection process (step S320 in FIG. 6), and it is predicted that the document leading end portion LT will be within the conveyance range Wt. Therefore, even if the document 5 is continuously conveyed, it is possible to avoid damaging the document 5.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In the first embodiment, the CPU 20 (prediction unit) predicts the skew feeding amount θ when the document leading end portion (LT or RT) protrudes from the width Wt (predetermined width) of the conveyance path 43, and the CPU 20 (stop unit). ) May continue the conveyance of the document 5 by the conveyance mechanism when the predicted skew amount is smaller than a predetermined value. Normally, the case where the document 5 protrudes with a small amount of skew so that the skew is corrected by hitting the side wall 41A can be ignored. Therefore, in this case, it is not necessary to stop the transport mechanism as much as possible, and productivity can be improved.

(2) In the second embodiment, when the first predicted position (LTe or the like; see FIG. 4) is on the downstream side of the second transport roller 44A, the CPU 20 (stop unit) transports before the second transport roller 44A. The mechanism may be stopped. in this case,
(3) In each of the above embodiments, the CPU 20 (prediction unit) determines that the document leading edge (LT or RT) protrudes from the width Wt (predetermined width) of the transport path 43 by a predetermined amount and the skew amount θ is equal to or greater than the predetermined amount. When the second predicted position is downstream of the document discharge port 47 (see FIG. 2), the CPU 20 (stop unit) continues to convey the document 5 by the transport mechanism. May be. In this case, by appropriately setting the predetermined amount of protrusion and the skew amount θ at the time of protrusion, and because the second predicted position is on the downstream side of the document discharge port 47, the document 5 may cause a serious jam. The productivity of image processing can be improved while suppressing.

  (4) In each of the embodiments described above, the CPU 20 (stop unit) determines the first predicted position (LTe etc.) after the document leading end (LT or RT) passes through the linear image sensor 33 (image reading unit) at the document trailing end. : See FIG. 4), the conveyance mechanism may be stopped after the image reading operation is performed. In this case, although the conveyance of the original 5 is interrupted, the image reading operation is executed as it is. Therefore, it is not necessary to read the image again after taking out the document 5 from the conveyance path 43, and the productivity of the operation image processing can be improved.

  (3) In the first embodiment, the CPU 20 (prediction unit) predicts the skew feeding amount θ when the document leading end portion (LT or RT) protrudes from the width Wt (predetermined width) of the conveyance path 43, and the CPU 20 (stop unit). ) May continue the conveyance of the document 5 by the conveyance mechanism when the predicted skew amount is smaller than a predetermined value. Normally, the case where the document 5 protrudes with a small amount of skew so that the skew is corrected by hitting the side wall 41A can be ignored. Therefore, in this case, it is not necessary to stop the transport mechanism as much as possible, and productivity can be improved.

  (4) In the second embodiment, when the first predicted position (LTe or the like; see FIG. 4) is on the downstream side of the second conveyance roller 44A, the CPU 20 (stop unit) has the sheet leading end portion as the second conveyance roller 44A. You may make it stop a conveyance mechanism just before reaching | attaining. In this case, it is possible to prevent a jam from occurring by the second transport roller 44A.

DESCRIPTION OF SYMBOLS 1 ... MFP, 3 ... Image reading device, 5 ... Document, 20 ... CPU, 27 ... Image forming part, 30 ... Reading part, 33, 33A, 33B ... Image sensor, 41A ... ADF cover wall, 43 ... Conveyance path, 44... First conveyance roller, 44 A... Second conveyance roller, 47.

Claims (10)

An image processing apparatus including an image processing unit that performs image processing using a sheet,
A transport mechanism having a transport path and transporting the sheet along the transport path;
At least one position detection unit for detecting the position of the leading end of the sheet conveyed on the conveyance path;
At least one skew amount detection unit for detecting the skew amount of the sheet from which the position of the leading edge is detected;
Based on the position of the leading edge detected by the position detection unit and the skew feeding amount detected by the skew feeding amount detection unit, the leading edge of the sheet is located from a predetermined width in a direction orthogonal to the sheet conveyance direction. A prediction unit for predicting a first predicted position that protrudes quantitatively;
An image processing apparatus comprising: a stop unit that stops the transport mechanism before the first predicted position. The image processing apparatus according to claim 1.
The at least one position detection unit and the at least one skew amount detection unit are configured by one position detection unit and one skew amount detection unit, respectively.
The prediction unit is based on the position and skew amount of the tip detected previously by the one position detector and skew amount detector, and the tip position and skew amount detected this time. An image processing apparatus that predicts the first predicted position. The image processing apparatus according to claim 1 or 2,
The image processing unit
An image processing apparatus comprising: an image reading unit that reads an image on the sheet to generate image data; the position detection unit; and the skew feed amount detection unit. The image processing apparatus according to claim 3.
The transport mechanism has a transport roller on the downstream side in the sheet transport direction of the image processing unit,
The predetermined width is a distance between two walls provided on both sides in the width direction of the transport path;
The predicting unit predicts a position of the sheet leading end portion in the predetermined width direction when the sheet reaches the conveying roller;
The image processing apparatus, wherein when the sheet reaches the conveying roller, the stopping unit stops the conveying mechanism before the conveying roller when it is predicted that the sheet leading edge protrudes from the predetermined width. The image processing apparatus according to claim 3.
The predetermined width is a distance between two walls provided on both sides in the width direction of the transport path;
The predicting unit predicts a skew amount when the leading end of the sheet protrudes from the predetermined width;
The said stop part is an image processing apparatus which continues conveyance of the said sheet | seat by the said conveyance mechanism, when the estimated skew feeding amount is smaller than predetermined value. The image processing apparatus according to claim 3.
The predetermined width is a distance between two walls provided on both sides in the width direction of the transport path;
The predicting unit predicts a second predicted position where the sheet leading end protrudes from the predetermined width by a predetermined amount and the skew amount becomes a predetermined amount or more,
The said stop part is an image processing apparatus which continues conveyance of the said sheet | seat by the said conveyance mechanism, when the said 2nd prediction position is a downstream from a sheet | seat discharge port. The image processing apparatus according to claim 3.
The stop unit stops the transport mechanism after an image reading operation is performed when the leading end of the sheet reaches the first predicted position after passing the image reading unit at the trailing end of the sheet. apparatus. The image processing apparatus according to claim 3.
The transport mechanism has a transport roller on the downstream side in the sheet transport direction of the image processing unit,
The said stop part is an image processing apparatus which stops the said conveyance mechanism just before the said sheet front-end | tip part reaches the said conveyance roller, when the said 1st prediction position is a downstream from the said conveyance roller. In the image processing device according to any one of claims 1 to 8,
The image processing unit detects an edge position of the document in the width direction when the document passes through the image processing unit;
The skew amount detection unit detects the skew amount using the detected edge position,
The position detection unit is an image processing apparatus that detects a position of a leading end portion of the sheet based on the skew feeding amount and a sheet conveyance length in the conveyance direction by the conveyance mechanism. A method of conveying the sheet in an image processing apparatus including an image processing unit that performs image processing using a sheet,
A conveying step of conveying the sheet along a predetermined conveying path;
A position detection step for detecting the position of the leading edge of the sheet conveyed on the conveyance path;
A skew amount detecting step for detecting a skew amount of the sheet, the position of the leading edge of which is detected;
A predetermined width in a direction orthogonal to the sheet conveyance direction based on the position of the leading edge detected last time and this time by the position detection step and the skew amount detected last time and this time by the skew amount detection step. A predicting step of predicting a predicted position where the leading end of the sheet protrudes by a predetermined amount;
A stopping step of stopping the conveying step before the predicted position;
A sheet conveying method including:

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