Patent Publication Number: US-2023140588-A1

Title: Image forming apparatus

Description:
INCORPORATION BY REFERENCE 
     This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2021-176541 filed on Oct. 28, 2021, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     The present disclosure relates to an image forming apparatus. 
     For example, a conventional image reading apparatus determines whether a type of a document sheet is a thick sheet or a thin sheet based on image data of the read document sheet. A state of a shadow that occurs on an edge portion of the document sheet differs depending on a thickness of the document sheet. Therefore, in the image data, a deviation of a gradation value corresponding to the edge portion of the document sheet differs depending on the thickness of the document sheet. In a conventional image reading apparatus, a central processing unit (CPU) determines the thickness of a document sheet according to deviation of gradation values in image data. Such a CPU is an example of a document sheet thickness detection portion. [0004] 
     On the other hand, in a conventional image reading apparatus it is not possible, based on image data, to determine a size of a document sheet with good accuracy. 
     SUMMARY 
     A first image forming apparatus according to the present disclosure includes a reading portion, a document sheet thickness detection portion, a first document sheet end detection portion, a second document sheet end detection portion, and a document sheet size determination portion. The reading portion generates an original image including an image of a document sheet. The document sheet thickness detection portion detects a thickness of the document sheet. The first document sheet end detection portion, in a case where the thickness detected by the document sheet thickness detection portion is equal to or greater than a threshold value, identifies a peripheral edge shape of the document sheet by detecting a shadow portion that occurs at a peripheral edge portion of the document sheet in the original image. The second document end detection portion, in a case where the thickness detected by the document sheet thickness detection portion is less than the threshold value, presents the original image to a user and identifies the peripheral edge shape of the document sheet based on a specification by the user. The document sheet size determination portion determines a size of the document sheet according to a result of shape identification by the first document sheet end detection portion or a result of shape identification by the second document sheet end detection portion. 
     A second image forming apparatus according to the present disclosure includes a reading portion, a document sheet thickness detection portion, a first document sheet end detection portion, a third document sheet end detection portion, and a document sheet size determination portion. The reading portion generates an original image including an image of a document sheet. The document sheet thickness detection portion detects a thickness of the document sheet. The first document sheet end detection portion, in a case where the thickness detected by the document sheet thickness detection portion is equal to or greater than a threshold value, identifies a peripheral edge shape of the document sheet by detecting a shadow portion that occurs at a peripheral edge portion of the document sheet in the original image. The third document sheet end detection portion, in a case where the thickness detected by the document sheet thickness detection portion is less than the threshold value, identifies a peripheral edge shape of the document sheet by detecting a partial image included in the document sheet in the original image. A document sheet size determination portion determines a size of the document sheet in accordance with a result of the shape identification by the first document sheet end detection portion or a result of the shape identification by the third document sheet end detection portion. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description with reference where appropriate to the accompanying drawings. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram showing an example of a configuration of an image forming apparatus according to an embodiment. 
         FIG.  2    is a block diagram showing an example of circuit configuration of an image forming apparatus. 
         FIG.  3    is a flowchart showing an example of an operation of a control portion. 
         FIG.  4    is a diagram showing an example of an operation procedure of a first document sheet end detection portion. 
         FIG.  5    is a diagram showing an example of an operation procedure of a second document sheet end detection portion. 
         FIG.  6    is a diagram showing an example of an operation procedure of a third document sheet end detection portion. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments according to the present disclosure will be described with reference to the drawings. Note that in the drawings, the same or corresponding parts are denoted by the same reference numerals, and descriptions thereof will not be repeated. 
     An image forming apparatus  100  according to an embodiment will be described with reference to  FIG.  1   .  FIG.  1    is a schematic diagram showing an example of a configuration of an image forming apparatus  100 . The image forming apparatus  100  is, for example, a copier, a printer, a facsimile machine, or a multifunction peripheral having these functions. 
     As shown in  FIG.  1   , image forming apparatus  100  includes a reading portion  1 , a feeding portion  2 , a conveying portion  3 , an image forming portion  4 , a fixing portion  5 , and a discharging portion  6 . 
     The reading portion  1  reads an image of a document sheet G. The reading portion  1  generates image data from the read image. For example, the reading portion  1  has an auto document feeder (ADF), a platen cover, a contact glass, and an optical reading mechanism. The document sheet G set in the ADF with the platen cover closed is automatically conveyed, and an image of the document sheet G is read. The user may also open the platen cover, place a document sheet G such as an ID card on the contact glass, and have the image of the document sheet G read. 
     The feeding portion  2  accommodates a plurality of sheets S and feeds the sheets S to the conveying portion  3 . The sheet S is made of paper or synthetic resin, for example. The conveying portion  3  includes a plurality of conveying roller pairs and conveys the sheet S to the image forming portion  4 . 
     The image forming portion  4  forms a toner image on the sheet S by an electrophotographic method. The image forming portion  4  includes a photoconductor drum, a charging device, an exposure device, a developing device, a supply device, a transfer device, a cleaning device, and an electrostatic neutralizing device. The fixing portion  5  heats and presses the toner image to fix the toner image onto the sheet S. The conveying portion  3  conveys the sheet S on which the toner image is fixed to the discharging portion  6 . The discharging portion  6  discharges the sheet S to the outside of the image forming apparatus  100 . 
     Next, the circuit configuration of the image forming apparatus  100  will be described with reference to  FIGS.  1  and  2   .  FIG.  2    is a block diagram showing an example of the circuit configuration of the image forming apparatus  100 . 
     As shown in  FIG.  2   , the image forming apparatus  100  further includes an operation portion  10 , a control portion  60  and a storage portion  70 . 
     The operation portion  10  serves both as an input device for various user operations and as a display device for displaying messages to a user. The operation portion  10  includes, for example, a touch panel  11  and a plurality of push buttons. 
     The storage portion  70  includes a storage device and stores data and computer programs. The storage portion  70  includes a main storage device such as a semiconductor memory and an auxiliary storage device such as a hard disk drive (HDD). 
     The storage portion  70  has, for example, an input image memory  71  and an output image memory  72 . The reading portion  1  generates an original image including the image of the document sheet G. The input image memory  71  stores data of the original image memory. The output image memory  72  stores data representing the image of the document sheet G clipped from the original image. 
     The control portion  60  includes a processor such as a CPU, and by executing computer programs stored in the storage portion  70 , controls each component of the image forming apparatus  100 . In addition, the control portion  60 , by executing computer programs stored in the storage portion  70 , functions as a document sheet thickness detection portion  61 , a first document sheet end detection portion  62 , a second document sheet end detection portion  63 , and a third document sheet end detection portion  64 , a document sheet size determination portion  65 , and an image clipping portion  66 . The user, via the operation portion  10 , can give the image forming apparatus  100  a selection related to whether or not it is desired to automatically detect a peripheral edge shape of the document sheet G. Hereinafter, a selection for which automatic detection is not desired is referred to as a first selection, and a selection for which automatic detection is desired is referred to as a second selection. The first selection means that automatic detection of the peripheral edge shape of the document sheet G is not effective, and the second selection means that automatic detection of the peripheral edge shape of the document G is effective. 
     The document sheet thickness detection portion  61  detects the thickness of the document sheet G. In the original image, a deviation of a gradation value corresponding to a shadow portion occurring at an edge portion of the document sheet G differs depending on the thickness of the document sheet G. For example, the document sheet thickness detection portion  61  determines the thickness of the document sheet G according to the deviation of the gradation value corresponding to the shadow portion in the original image. 
     In a case where the detected thickness of the document sheet G is equal to or greater than a threshold value, the first document sheet end detection portion  62  detects a portion corresponding to a shadow occurring at the peripheral edge portion of the document sheet G in the original image. Further, the first document sheet end detection portion  62  identifies the peripheral edge shape of the document sheet G according to a detected position of the shadow portion. The first document sheet end detection portion  62 , in a case where the thickness of the document sheet G is equal to or greater than the threshold value, automatically identifies the peripheral edge shape of the document sheet G in both the first selection and the second selection. 
     The second document sheet end detection portion  63  executes the following process in a case where the selection by the user is the first selection. That is, in a case where the detected thickness of the document sheet G is less than the threshold value, the second document sheet end detection portion  63  presents the original image including the image of the document sheet G to the user, and identifies the peripheral edge shape of the document sheet G based on a specification by the user. The second document sheet end detection portion  63  presents the original image to the user via a display device of the operation portion  10 . 
     On the other hand, the third document sheet end detection portion  64  automatically executes the following process in a case where the user selects the second selection. That is, in a case where the detected thickness of the document sheet G is less than the threshold value, the third document sheet end detection portion  64  detects a partial image included in the document sheet G from the original image. Further, the third document sheet end detection portion  64  identifies the peripheral edge shape of the document sheet G based on the shape of the detected partial image. 
     The document size determination portion  65  determines the size of the document sheet G according to the result of shape identification by the first document sheet end detection portion  62 , the result of shape identification by the second document sheet end detection portion  63 , or the result of shape identification by the third document sheet end detection portion  64 . 
     The image clipping portion  66 , according to the size of the document sheet G determined by the document size determination portion  65 , clips the image of the document sheet G from the original image including the image of the document sheet G. 
     Next, the operation of the control portion  60  will be described with reference to  FIG.  1    to  FIG.  3   .  FIG.  3    is a flowchart showing an example of operation of the control portion  60 . The user, via the operation portion  10 , can request the image forming apparatus  100  to execute cropping of the document sheet size. 
     Step S 101   
     As shown in  FIG.  3   , the control portion  60  causes the reading portion  1  to start scanning the document sheet G. When the processing of step S 101  is completed, the processing by the control portion  60  proceeds to step S 103 . 
     Step S 103   
     The control portion  60  determines whether or not cropping of the document sheet size is effective. In a case where the control portion  60  determines that cropping of the document sheet size is effective (YES in step S 103 ), processing by the control portion  60  proceeds to step S 105 . In a case where the control portion  60  determines that cropping of the document sheet size is not effective (NO in step S 103 ), the processing by the control portion  60  ends. 
     Step S 105   
     The control portion  60  derives the deviation of the gradation value of the portion corresponding to the shadow occurring at the peripheral edge portion of the document sheet G in the original image. Further, the control portion  60  determines the thickness of the document sheet G according to the derivation result of the deviation of the gradation value. The process of step S 105  is executed by the document sheet thickness detection portion  61 . 
     Step S 107   
     The control portion  60  determines whether or not the thickness of the document sheet G is equal to or greater than the threshold value. In a case where the control portion  60  determines that the thickness of the document sheet G is equal to or greater than the threshold value (YES in step S 107 ), the processing by the control portion  60  proceeds to step S 109 . In case where the control portion  60  determines that the thickness of the document sheet G is less than the threshold value (NO in step S 107 ), the processing by the control portion  60  proceeds to step S 111 . 
     Step S 109   
     The control portion  60  executes a procedure for detecting a first document sheet end, which will be described later (see  FIG.  4   ). When the processing of step S 109  is completed, the processing by the control portion  60  proceeds to step S 117 . 
     Step S 111   
     The control portion  60  determines whether or not automatic detection of the peripheral edge shape of the document sheet G is effective. In a case where the control portion  60  determines that the automatic detection of the peripheral edge shape is effective (YES in step S 111 ), the processing by the control portion  60  proceeds to step S 115 . In a case where the control portion  60  determines that the automatic detection of the peripheral edge shape is not effective (NO in step S 111 ), the processing by the control portion  60  proceeds to step S 113 . 
     Step S 113   
     The control portion  60  executes a procedure for detecting a second document sheet end, which will be described later (see  FIG.  5   ). When the processing of step S 113  is completed, the processing by the control portion  60  proceeds to step S 117 . 
     Step S 115   
     The control portion  60  executes a procedure for detecting a third document sheet end, which will be described later (see  FIG.  6   ). When the processing of step S 115  is completed, the processing by the control portion  60  proceeds to step S 117 . 
     Step S 117   
     The control portion  60  determines the size of the document sheet G according to the result of the first document sheet end detection, the second document sheet end detection, or the third document sheet end detection. 
     Step S 119   
     The control portion  60 , according to the size of the document G determined in step S 117 , clips the image of the document sheet G from the original image including the image of the document sheet G. When the processing of step S 119  is completed, the processing by the control portion  60  ends. 
     Next, referring to  FIG.  4   , the operation procedure of the first document sheet end detection portion  62  will be described.  FIG.  4    is a diagram showing an example of the operation procedure by the first document sheet end detection portion  62 . The document sheet G is, for example, an ID card placed on the contact glass. 
     Step S 201   
     As shown in  FIG.  4   , the first document sheet end detection portion  62  acquires the original image including the image of the document sheet G from the input image memory  71 . The thickness of the document sheet G is equal to or greater than the threshold value, and thus a clear shadow occurs at the peripheral edge portion of the document sheet G in the original image. The processing by the control portion  60  proceeds from step S 201  to step S 203 . 
     Step S 203   
     Subsequently, the first document sheet end detection portion  62  executes an edge extraction process on the original image. The processing by the control portion  60  proceeds from step S 203  to step S 205 . 
     Step S 205   
     Next, the first document sheet end detection portion  62  deletes unnecessary data that does not contribute to the peripheral edge shape of the document sheet G from among the extracted edges. The processing by the control portion  60  proceeds from step S 205  to step S 207 . 
     Step S 207   
     Subsequently, the first document sheet end detection portion  62  executes a straight line extraction process on the original image from which unnecessary data has been deleted. As a result, a plurality of straight line images are extracted. The processing by the control portion  60  proceeds from step S 207  to step S 209 . 
     Step S 209   
     Continuing, the first document sheet end detection portion  62  executes a process that extracts four contour line images from among the plurality of extracted straight line images The processing by the control portion  60  proceeds from step S 209  to step S 211 . 
     Step S 211   
     Finally, the first document sheet end detection portion  62 , based on the positions of the four extracted contour line images, identifies a rectangle representing the peripheral edge shape of the document sheet G. This completes the procedure for detecting the first document sheet end. 
     The thickness of the document sheet G is less than the threshold value, and thus the image of the shadow at the peripheral edge portion of the document sheet G is less likely to appear in the original image. Therefore, there is a possibility that the peripheral edge shape of the document sheet G may be erroneously identified in the processing by the first document sheet end detection portion  62 . Therefore, the processing by the second document sheet end detection portion  63  or the third document sheet end detection portion  64  is executed. 
     Next, referring to  FIG.  5   , the operation procedure of the second document sheet end detection portion  63  will be described.  FIG.  5    is a diagram showing an example of the operation procedure by the second document sheet end detection portion  63 . 
     Step S 301   
     As shown in  FIG.  5   , the second document sheet end detection portion  63  presents the original image including the image of the document sheet G to the user via the display device of the operation portion  10 . Further, the second document sheet end detection portion  63  prompts the user to use the touch panel  11  to designate three points on the original image corresponding to three corners of the document sheet. 
     Step S 303   
     When the user designates three points corresponding to the three corners on a screen, the second document sheet end detection portion  63  acquires position information of the designated three points. 
     Step S 305   
     Finally, the second document sheet end detection portion  63 , based on the acquired position information of the three points, identifies a rectangle representing the peripheral edge shape of the document sheet G 
     Next, referring to  FIG.  6   , the operation procedure by the third document sheet end detection portion  64  will be described.  FIG.  6    is a diagram showing an example of the operation procedure by the third document sheet end detection portion  64 . 
     Step S 401   
     As shown in  FIG.  6   , the third document sheet end detection portion  64  acquires the original image including the image of the document sheet G from the input image memory  71 . The processing by the control portion  60  proceeds from step S 401  to step S 403 . 
     Step S 403   
     Subsequently, the third document sheet end detection portion  64  executes a process that binarizes the original image. The processing by the control portion  60  proceeds from step S 403  to step S 405 . 
     Step S 405   
     Next, the third document sheet end detection portion  64  detects one or more isolated areas from among the binarized original image. An isolated area represents an area in which black is connected to a white background, and includes partial images of objects such as characters and figures included in the document sheet G. Further, the third document sheet end detection portion  64  identifies one or more unit rectangles that are rectangles circumscribing each isolated area. The processing by the control portion  60  proceeds from step S 405  to step S 407 . 
     Step S 407   
     Continuing, the third document sheet end detection portion  64  then joins one or more unit rectangles. Further, the third document sheet end detection portion  64  identifies a combined rectangle, which is a rectangle circumscribing a shape formed by combining one or more unit rectangles. The combined rectangle encompasses all objects. 
     Step S 409   
     Continuing, the third document sheet end detection portion  64 , based on the image in the combined rectangle, detects an inclination of and positions of four edges of the document sheet G. 
     Step S 411   
     Finally, the third document sheet end detection portion  64 , based on the detected inclination of and the positions of the four edges of the document sheet G, identifies a rectangle representing the peripheral edge shape of the document sheet G. 
     According to the embodiment, an image forming apparatus  100  is provided that can determine with good precision the size of a document sheet G regardless of the thickness of the document sheet G. 
     An embodiment of the technique according to the present disclosure has been described above with reference to the drawings. However, the technique according to the present disclosure is not limited to the embodiments described above, and can be embodied in various aspects without departing from the scope of the present disclosure. 
     In addition, various forms of the technique according to the disclosure are possible by appropriately combining a plurality of component disclosed in the above embodiment. For example, some components may be omitted from the components in the embodiment described above. In order to make the drawings easier to understand, the drawings mainly show each component schematically, and the numbers and the like of each component shown in the figures may differ from the actual ones for the convenience of making the drawings. In addition, each component shown in the above-described embodiment is an example and is not particularly limited, and various modifications are possible within a range that does not substantially deviate from the effects of the present disclosure. 
     In the embodiment, the image forming apparatus  100  is an electrophotographic type. However, the present invention is not limited to such. For example, the image forming apparatus  100  may be an inkjet type. 
     In addition, in the embodiment, the thickness of the document sheet G is detected according to the magnitude of the gradation deviation of the shadow occurring at the peripheral edge portion of the document sheet G. However, the embodiment is not limited to this. The ADF may include a multi-feed detection sensor that detects multi-feeding of document sheets G by detecting a degree of attenuation when ultrasonic waves pass through the document sheets G. In this case, a multi-feed detection sensor may be used to detect the thickness of the document sheet G 
     The technique according to the present disclosure may be used in the field of image forming apparatuses. 
     It is to be understood that the embodiments herein are illustrative and not restrictive, since the scope of the disclosure is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims.