Patent Publication Number: US-2019171150-A1

Title: Image forming apparatus

Description:
The entire disclosure of Japanese patent Application No. 2017-042302, filed on Mar. 7, 2017, is incorporated herein by reference in its entirety. 
     BACKGROUND 
     Technological Field 
     The present invention relates to an image forming apparatus. 
     Description of the Related Art 
     An image forming apparatus generally includes a plurality of paper feed trays, and forms an image by feeding a paper sheet from one of the paper feed trays. It is designed such that recording materials such as cut papers stacked on a paper feed tray are fed one by one onto a conveying path by a paper feed roller or the like. However, depending on a paper type, there may be occurrence of a misfeed jam in which feeding of a paper sheet is inhibited at a time of paper feeding from a paper feed tray, an double feed jam in which multiple paper sheets are conveyed while being stacked, or the like. 
     Conventionally, when a jam is detected, control has been performed to stop the image forming apparatus after ejecting a paper sheet downstream of the jam occurrence position. At this time, a user has been required to remove the jammed paper. Furthermore, after removing the jammed paper, the user operates an operation part to select and display a desired paper feed adjustment screen as required, performs paper feed adjustment, and restarts the job. 
     It has been a problem that downtime occurs during this work. In particular, in a field of production printing, since productivity of a printed matter is directly linked to profitability of a project, it is strongly desired not to generate downtime as much as possible. 
     Therefore, J P 2010-66692 A discloses a technique of changing a paper feed tray to continue printing when a jam occurs. 
     Specifically, when it is determined that a double feeding has occurred at a time of paper feeding from a paper feed tray, the printing operation is stopped. Then, when there is another paper feed tray storing a paper sheet having a same size and type as a paper sheet stored in the paper feed tray in which the double feeding has occurred, the paper feed source is switched to this another paper feed tray, and the printing operation is executed again. This can suppress a decrease in productivity as compared with a case where image formation is stopped immediately after a double feeding occurs. 
     In the invention described in JP 2010-66692 A, printing can be continued by switching the paper feed tray, and productivity can be improved. However, in order to execute paper feed adjustment, a user himself has been required to display a paper feed adjustment screen to select an appropriate adjustment item, taking time and effort. 
     SUMMARY 
     The present invention has been made in view of the above problems, and it is an object of the present invention to provide an image forming apparatus capable of easy paper feed adjustment without requiring a user to perform a complicated operation for a paper jam at a time of paper feeding. 
     To achieve the abovementioned object, according to an aspect of the present invention, an image forming apparatus reflecting one aspect of the present invention comprises: 
     a display part that displays information related to image formation; 
     a detection part that detects an abnormal paper feeding when a paper sheet is fed from a paper feed tray storing a paper sheet; and 
     a hardware processor that causes the display part to display a paper feed adjustment screen to which a user can input an adjustment of a paper feed condition at a time of paper feeding, when the detection part detects an abnormal paper feeding. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages and features provided by one or more embodiments of the invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention: 
         FIG. 1  is a view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention; 
         FIG. 2  is a block diagram showing a functional configuration of the image forming apparatus according to an embodiment of the present invention; 
         FIG. 3  is a view showing a schematic configuration of a paper feeding part; 
         FIG. 4  is a flowchart showing an example of a paper feed adjustment operation of the image forming apparatus according to an embodiment of the present invention; 
         FIG. 5  is a flowchart showing an example of an operation at a time of paper feed adjustment when a paper feed tray is changed; 
         FIG. 6  is a flowchart showing an example of an operation at a time of paper feed adjustment when the paper feed tray is not changed; 
         FIG. 7  is a view showing an example of a method of calculating an adjustment value; 
         FIG. 8  is a view showing an example of an operation panel displaying a selection screen; 
         FIG. 9  is a view showing an example of the operation panel displaying jam occurrence information and a release instruction; 
         FIG. 10  is a view showing an example of the operation panel at a time of normal image formation; 
         FIG. 11  is a view showing an example of the operation panel displaying a paper feed adjustment screen; 
         FIG. 12  is a view showing an example of the operation panel displaying a selection screen; and 
         FIG. 13  is a view showing an example of the operation panel displaying the paper feed adjustment screen. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a first embodiment of an image forming apparatus  1  according to the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. 
     [Configuration of Image Forming Apparatus] 
       FIG. 1  is a schematic configuration view of the image forming apparatus  1 .  FIG. 2  is a block diagram showing a functional configuration of the image forming apparatus  1 . 
     The image forming apparatus  1  is made up of a main body  100  and a post-processing apparatus  200 . 
     The main body  100  includes a control part  110 , a storage part  111 , a communication part  112 , an operation panel  120 , an image reading part  130 , an image forming part  140 , a paper feeding part  150 , and a paper conveying part  160 . 
     The control part  110  includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and the like. The CPU reads out various processing programs stored in the ROM in accordance with an operation signal input from an operation part  121 , or an instruction signal received by the communication part  112 , to develop the processing programs in the RAM and provide a centralized control of operation of each part of the main body  100  in accordance with the developed programs. 
     Upon receiving a print instruction via the communication part  112 , the control part  110  causes the storage part  111  to store image data and paper information such as a type of a paper sheet stored in each paper feed tray, a paper basis weight, and a paper size. 
     The storage part  111  includes a dynamic random access memory (DRAM), which is a semiconductor memory, a hard disk drive (HDD), or the like, and the storage part  111  stores image data acquired by the image reading part  130 , image data input from outside via the communication part  112 , paper type information such as a type of a paper sheet stored in each paper feed tray, a paper basis weight, and a paper size, paper profile data to be described later, paper feed tray adjustment data, and the like. 
     The communication part  112  exchanges data with an external device connected to a communication network such as a local area network (LAN). 
     The operation panel  120  includes the operation part  121  and a display part  122 . 
     The operation part  121  includes a touch panel formed to cover a display screen of the display part  122 , and various operation buttons such as a number button and a start button, and the operation part  121  outputs an operation signal based on a user operation to the control part  110 . 
     The display part  122  is formed by a liquid crystal display (LCD), and displays various screens according to an instruction of a display signal input from the control part  110 . 
     The image reading part  130  includes an automatic document feeding device (ADF), a scanner, and the like, and outputs image data acquired by reading an image of a document, to the control part  110 . 
     The image forming part  140  forms an image on a paper sheet fed from the paper feeding part  150  based on the image data read by the image reading part  130  or the image data received from the external device. 
     The image forming part  140  includes photoreceptor drums  141 Y,  141 M,  141 C, and  141 K corresponding to respective colors of yellow (Y), magenta (M), cyan (C), and black (K), an intermediate transfer belt  142 , a secondary transfer roller  143 , a fixing part  144 , a registration roller  145 , and the like. 
     After the photoreceptor drum  141 Y is uniformly charged, the photoreceptor drum  141 Y is scanned and exposed by a laser beam based on yellow color image data, and an electrostatic latent image is formed. Then, yellow toner is applied to the electrostatic latent image on the photoreceptor drum  141 Y, and development is performed. 
     Since the photoreceptor drums  141 M,  141 C, and  141 K are similar to the photoreceptor drum  141 Y, except that the colors to be handled are different, the description will be omitted. 
     The toner images of the respective colors formed on the photoreceptor drums  141 Y,  141 M,  141 C, and  141 K are sequentially transferred onto the rotating intermediate transfer belt  142  (primary transfer). That is, on the intermediate transfer belt  142 , there is formed a color toner image in which four color toner images are superimposed. 
     The color toner image on the intermediate transfer belt  142  is collectively transferred onto a paper sheet by the secondary transfer roller  143  (secondary transfer). 
     The fixing part  144  includes a heating roller that heats a paper sheet transferred with the color toner image, and a pressure roller that pressurizes the paper sheet, and the fixing part  144  fixes the color toner image to the paper sheet by heating and pressurization. 
     The paper feeding part  150  includes paper feed trays Ta and Tb, a plurality of paper feed trays Tc to Tk disposed in three paper feeders  150   a  connected in series, a feeding part  151  disposed at each of the paper feed trays, an air blower  152 , a regulating member  153 , and the like, and the paper feeding part  150  feeds a paper sheet from one paper feed tray among the paper feed trays Ta to Tk. 
     Each of the paper feed trays Ta to Tk stores a paper sheet of a type (a size, a paper type, a basis weight, and the like) predetermined in advance for each paper feed tray. The paper sheet stored in each of the paper feed trays Ta to Tk is fed to the image forming part  140  by driving of the feeding part  151 . 
     Each of the paper feed trays Ta to Tk is provided to be capable of being drawn out, and the paper sheet is refilled with each of the paper feed trays Ta to Tk drawn out. 
       FIG. 3  is a perspective view showing an outline of the paper feed tray Tc. While the paper feed trays Tc to Tk are provided to be vertically aligned in three stages in the paper feeder  150   a  as described above, since they all are identical in configuration, the one paper feed tray Tc is explained here. 
     The paper feed tray Tc includes a paper loading base  154  as a horizontally oriented paper loading part placed with a plurality of paper sheets P in a stacked state, a rear-end regulating member  153   a  provided rearward of the paper loading base  154 , namely, upstream of a paper feed direction a, and a front-end regulating member  153   b  provided forward of the paper loading base  154 , namely, downstream of the paper feed direction a. The regulating member  153  is made up of the rear-end regulating member  153   a  and the front-end regulating member  153   b , and a lateral regulating member  153   c  to be described later. 
     In the following description of the paper feed tray Tc, a direction of a left hand side in a horizontal direction orthogonal to the paper feed direction a, in a state directed in the paper feed direction a, is defined as “left”, while a direction of a right hand side in the horizontal direction orthogonal to the paper feed direction a, in a state directed in the paper feed direction a, is defined as “right”. Further, in vertical directions orthogonal to the paper feed direction a, an upward direction is defined as “upper” and a downward direction is defined as “lower”. 
     The paper loading base  154  is vertically movably supported in the paper feed tray Tc, and the rear-end regulating member  153   a  and the front-end regulating member  153   b  are fixedly installed in the paper feed tray Tc. 
     An upper end part of the front-end regulating member  153   b  is somewhat lower in height than an upper end part of the rear-end regulating member  153   a . Meanwhile, the paper loading base  154  is lifted and lowered by an actuator (not shown), and the actuator is controlled by the control part  110  such that an uppermost part of the paper sheet P stacked on the paper loading base  154  is maintained at a specified height slightly lower than the upper end part of the front-end regulating member  153   b . The height control with the actuator is performed based on sensing of a sensor (not shown) that is provided on the rear-end regulating member  153   a  side and detects a height of the uppermost paper sheet P. 
     Further, at a time of non-feeding, such as a time of supplying the paper sheet P, the paper loading base  154  can be lowered. 
     Being adjacent to the front-end regulating member  153   b , a separation air blower  152   a  is provided downstream of the front-end regulating member  153   b  in the paper feed direction a. Further, a floating air blower  152   b  is provided on each of both a right and left sides of the paper loading base  154 , and the air blower  152  is made up of the separation air blower  152   a  and the floating air blower  152   b . An inner side surface of this floating air blower  152   b  is smooth and along a vertical direction, and functions as the lateral regulating member  153   c  that regulates a position of the paper sheet in a lateral direction. 
     A blowing fan is provided each inside of the separation air blower  152   a  and the floating air blower  152   b , and configured to blow air from an air blowing port. 
     The separation air blower  152   a  is provided with a nozzle to blow air from the air blowing port toward a direction inclined somewhat upward from a direction of the downstream side in the paper feed direction a. The separation air blower  152   a  blows air to a front end part in the paper feed direction a of a plurality of the paper sheets P lifted by the floating air blower  152   b , to blow air between the lifted paper sheet P and the paper sheet P, enabling separation and lowering of the paper sheet P excluding the uppermost paper sheet P. 
     As shown in  FIG. 3 , the floating air blower  152   b  includes a nozzle to blow air toward the paper sheet P from the left side and the right side of the uppermost paper sheet P positioned at a regulation height, in the horizontal direction or in a direction inclined slightly upward from the horizontal direction. The air blowing port of each nozzle is formed such that its upper edge part is higher than the uppermost paper sheet P positioned at the regulation height, and its lower edge part is lower than the uppermost paper sheet P. 
     This enables lifting of the upper paper sheet P by blowing air from each air blowing port of the floating air blower  152   b  to apply air to the upper paper sheet P in the stacked state. 
     As shown in  FIG. 3 , the feeding part  151  is provided above the paper loading base  154 .  FIG. 3  illustrates the feeding part  151  shifted to a position indicated by arrows so as not to hide a surrounding configuration, but the feeding part  151  is actually arranged above a downstream side end part of the paper feed direction a of the paper loading base  154 . 
     The feeding part  151  includes four sets of belt mechanisms aligned in a horizontal direction orthogonal to the paper feed direction a, and a motor (not shown) serving as a paper feeding driving source to drive these belt mechanisms. 
     Each of the belt mechanisms has a large-diameter roller  151   a  provided upstream in the paper feed direction a, two small-diameter rollers  151   b  provided downstream in the paper feed direction a, and a belt  151   c  stretched over these rollers. Torque is applied from the motor to the large-diameter roller  151   a  of each belt mechanism in a direction in which a lower part of the each belt  151   c  advances toward the paper feed direction a. Note that a sprocket may be used instead of each roller. 
     With the configuration above, when the upper paper sheet P on the paper loading base  154  is lifted by air blown by the floating air blower  152   b  described above, the feeding part  151  causes the lifted uppermost paper sheet P to attach below the each belt  151   c , enabling feeding of the paper sheet P toward the paper feed direction a by rotationally driving the each belt  151   c.    
     The paper conveying part  160  includes a conveying roller or the like to convey the paper sheet on a paper conveyance path, and conveys the paper sheet. 
     Further, the paper conveying part  160  has JAM detection sensors SE 1 , SE 2 , and SE 3  on the paper conveyance paths on downstream of the paper feed trays Tc to Te, Tf to Th, and Ti to Tk respectively, in the paper sheet conveying direction. The JAM detection sensors SE 1 , SE 2 , and SE 3  include a sensor such as an ultrasonic sensor that can detect a double feed jam and a misfeed jam. 
     The post-processing apparatus  200  includes a control part  210 , a paper conveying part  260 , and a post-processing part  270 . 
     The control part  210  includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and the like. The CPU reads out various processing programs stored in the ROM to develop the processing programs in the RAM and provide a centralized control of operation of each part of the post-processing apparatus  200  in accordance with the developed programs. 
     The paper conveying part  260  includes a conveying roller or the like to convey the paper sheet on the paper conveyance path, conveys the paper sheet in the post-processing apparatus  200 , and discharges the paper sheet to a paper discharging tray T 11  or T 12  provided outside the post-processing apparatus  200 . 
     The post-processing part  270  performs paper sheet processing such as a sorting process, a staple process, a punching process, a folding process, and a bookbinding process as required, on a paper sheet subjected to image formation by the image forming part  140 . 
     [Method of Performing Paper Feed Adjustment] 
     Next, with reference to the flowcharts of  FIGS. 4 to 6 , a method of performing paper feed adjustment in the image forming apparatus  1  according to the present embodiment will be described. 
     First, as shown in  FIG. 4 , the control part  110  determines whether a paper jam has occurred (step S 401 ). When the control part  110  determines that a paper jam has occurred (step S 401 : Yes), the control part  110  (a specification part) specifies a cause of the paper jam (step S 402 ). 
     Here, the paper jam includes a misfeed jam in which feeding of a paper sheet is inhibited, a double feeding in which multiple paper sheets are fed while being stacked, and the like. The control part  110  determines which type of a paper jam has occurred, based on a detection result of the JAM detection sensor. 
     When the cause of the paper jam is specified, the control part  110  (a calculation part, a change part) calculates an adjustment value of a paper feed condition, and changes the paper feed condition to the calculated adjustment value (step S 403 ). 
     Here, the paper feed condition is to perform at least one of: an air volume, an air direction, and an air blowing timing by the air blower  152 ; selection of the air blower  152  to be operated (either one or both of the separation air blower  152   a  and the floating air blower  152   b ); an operating time of the feeding part  151 ; a position of the regulating member  153 ; and presence/absence of re-execution of a paper feeding operation. 
     Further, the adjustment value of the paper feed condition is calculated based on the cause of the paper jam, and at least one of a paper type, a paper basis weight, a paper size, and a number of paper sheets fed before the paper jam occurs. 
       FIG. 7  shows an example of a method of calculating an adjustment value of the paper feed condition. The adjustment value is calculated using a correction amount stored in advance in the storage part  111  in a form of a table. 
     For example, when the paper size is B4 or larger, the paper basis weight is less than 105 g/m, and the number of the paper sheets fed before the paper jam occurs is 10 or less, an air-blowing volume of the separation air blower  152   a  is changed to a value added with  3 , and an air-blowing volume of the floating air blower  152   b  is changed to a value added with  3  (an adjustment value). 
     That is, it is effective to increase the air-blowing volume of the floating air blower  152   b  when the paper size is large, and to increase the air-blowing volume of the separation air blower  152   a  and the floating air blower  152   b  as the paper basis weight is larger, and as the number of paper sheets fed before the paper jam occurs is less. 
     When the adjustment value is calculated, the control part  110  (a job execution control part) determines whether there is a switchable paper feed tray (step S 404 ). That is, the control part  110  determines whether there is a paper feed tray storing a paper sheet of a same type and same size as that of the paper feed tray where the paper jam has occurred. 
       FIG. 8  shows the operation panel  120  displaying a selection screen  124  of the paper feed tray. For example, as shown in  FIG. 8 , when a misfeed jam occurs during feeding of an A3-sized paper sheet stored in the tray  5 , and when a same A3-sized paper sheet is stored in the tray  2  and the tray  2  is set as an automatic selection tray in “Presence/absence of automatic selection”, it is possible to automatically switch the feeding to the tray  2  to continue the image formation. 
     When the control part  110  determines that there is a switchable paper feed tray (step S 404 : Yes), the process proceeds to step S 501  in  FIG. 5 . When the control part  110  determines that there is no switchable paper feed tray (step S 404 : No), the process proceeds to step S 601  in  FIG. 6 . 
     In step S 401 , when it is determined that a paper jam has not occurred (step S 401 : No), the control part  110  determines whether printing has been completed (step S 405 ). When determining that the printing has been completed (step S 405 : Yes), the control part  110  ends the control. When the control part  110  determines that the printing has not been completed (step S 405 : No), the process returns to step S 401 . 
     Next, with reference to  FIG. 5 , a control when there is a switchable paper feed tray will be described. 
     In step S 501 , the control part  110  switches to the switchable paper feed tray to continue the job. Subsequently, the control part  110  causes the operation panel  120  to display occurrence information of the paper jam and a release instruction (step S 502 ). 
       FIG. 9  shows the operation panel  120  displaying the occurrence information of a paper jam and the release instruction. As shown in  FIG. 9 , the paper feed tray in which the paper jam has occurred is clearly indicated, and a user is prompted to release the paper jam. 
     The control part  110  determines whether the paper jam has been released by the user who has recognized the display (step S 503 ). When it is determined that the paper jam has not been released (step S 503 : No), the control part  110  repeats the process of step S 503 . When it is determined that the jam has been released (step S 503 : Yes), the process proceeds to step S 504 . 
     In step S 504 , the control part  110  (a display control part) causes a paper feed adjustment screen  123  to be displayed on the operation panel  120 . 
     Here,  FIG. 10  shows a normal operation panel  120  at a time of image formation, and  FIG. 11  shows an operation panel  120  in a state of displaying the paper feed adjustment screen  123 . As shown in  FIG. 11 , the paper feed adjustment screen  123  can be displayed as a pop-up on a part of the operation panel  120 . However, the present invention is not limited to this, and the paper feed adjustment screen  123  may be displayed on the entire operation panel  120 . 
     Here, the paper feed adjustment screen  123  is to display at least one of: an air volume, an air direction, and an air blowing timing by the air blower  152 ; selection of the air blower  152  to be operated (either one or both of the separation air blower  152   a  and the floating air blower  152   b ); an operating time of the feeding part  151 ; a position of the regulating member  153 ; and presence/absence of re-execution of a paper feeding operation. In  FIG. 11 , the “Front-end air volume setting” of the separation air blower  152   a  and the “Side air volume setting” of the floating air blower  152   b  are displayed, and a user can operate the operation panel  120  to adjust these values. Upon completion of inputting the adjustment value, the user presses “Complete adjustment” at lower right of the paper feed adjustment screen  123 , to complete the paper feed adjustment. 
     Here, on the paper feed adjustment screen  123 , the adjustment value of the paper feed condition calculated in step S 403  is displayed as a default value. 
     Further, the operation panel  120  displays the paper feed adjustment screen  123  most related to the paper jam depending on the type of the paper jam. Further, when there are a plurality of related paper feed adjustment screens  123 , they are displayed in descending order of relevance. 
     In step S 505 , the control part  110  determines whether the paper feed adjustment by the user has been completed. When it is determined that the paper feed adjustment has not been completed (step S 505 : No), the control part  110  repeats the process of step S 505 . When it is determined that the paper feed adjustment has been completed (step S 505 : Yes), the control part  110  (the job execution control part) causes the operation panel  120  to display the selection screen  124  of the paper feed tray (step S 506 ). 
       FIG. 12  shows the operation panel  120  in a state of displaying a selection screen  124 . When the user presses “Complete adjustment” in step S 504 , the selection screen  124  is displayed, allowing the user to select whether to return the paper feed tray to the tray  5 , which has been originally used for paper feeding. 
     In step S 507 , the control part  110  determines whether to return to the original paper feed tray. When it is determined to return to the original paper feed tray (step S 507 : Yes), the process proceeds to step S 508 , and when it is determined not to return to the original paper feed tray (step S 507 : No), the process proceeds to step S 516 . 
     In step S 508 , the control part  110  closes the paper feed adjustment screen  123  and the selection screen  124 . In step S 509 , the control part  110  switches to the original paper feed tray to continue the job. 
     Next, in step S 510 , the control part  110  determines whether a paper jam has occurred. When the control part  110  determines that a paper jam has occurred (step S 510 : Yes), the process proceeds to step S 402  in  FIG. 4 , and the above-described process is repeated. 
     When the control part  110  determines that no paper jam has occurred (step S 510 : No), the control part  110  determines whether printing has been completed (step S 511 ). When the control part  110  determines that printing has not been completed (step S 511 : No), the process returns to step S 510 . When the control part  110  determines that printing has been completed (step S 511 : Yes), the control part  110  determines whether proper paper passing has been performed for a predetermined number or more of the paper sheets after the paper feed adjustment (step S 512 ). 
     When determining that proper paper passing has been performed for the predetermined number or more of the paper sheets (step S 512 : Yes), the control part  110  causes the storage part  111  to store the paper feed adjustment value as paper profile data corresponding to the fed paper sheet (step S 513 ). Further, the control part  110  causes the storage part  111  to store the paper feed adjustment value as adjustment data of the paper feed tray used for paper feeding (step S 514 ), and ends the control. 
     Here, the storage part  111  stores the adjustment value of the paper feed condition for each paper sheet type as the paper profile data. When the paper feed adjustment is performed by a user, the storage part  111  updates the adjustment value to a new adjustment value, and stores the adjustment value, in accordance with the control of the control part  110 . Therefore, when feeding a same paper sheet next time, the control part  110  can perform paper feed adjustment with reference to the updated paper profile data stored in the storage part  111 . 
     In addition, the storage part  111  similarly stores paper feed tray adjustment data for each paper feed tray, and updates the paper feed tray adjustment data to a new adjustment value, and stores the adjustment value under the control of the control part  110 , after the paper feed adjustment by the user. 
     When the control part  110  determines that proper paper passing has not been performed for the predetermined number or more of paper sheets (step S 512 : No), that is, when the printing has been completed before reaching the predetermined number of paper sheets, the control part  110  causes the storage part  111  to store the number of printed sheets after the paper feed adjustment (step S 515 ), and ends the control. That is, when a paper sheet of the same paper size is fed or when a paper sheet is fed from the same paper feed tray next time, counting can be continued from the number of printed sheets stored in step S 515 . 
     In step S 507 , when the control part  110  determines not to return to the original paper feed tray (step S 507 : No), the control part  110  closes the paper feed adjustment screen  123  and the selection screen  124  (step S 516 ), continues feeding of a paper sheet from the paper feed tray currently being used, and ends the control. 
     Next, with reference to  FIG. 6 , a control when there is no switchable paper feed tray will be described. 
     In step S 601 , the control part  110  stops the image forming apparatus  1  after completing image formation of a paper sheet being conveyed. 
     Since the processing in steps S 602  to S 605  is similar to the processing in steps S 502  to S 505  in  FIG. 5 , the description will be omitted. 
     In step S 605 , when the control part  110  determines that the paper feed adjustment by the user has been completed (step S 605 : Yes), the control part  110  restarts the image formation (step S 606 ), and the process proceeds to step S 607 . 
     Since the processing in steps S 607  to S 612  is similar to the processing in steps S 510  to S 515  in  FIG. 5 , the description will be omitted. 
     [Effect] 
     As described above, the image forming apparatus  1  according to the present embodiment includes: the paper feeding part  150  having a plurality of paper feed trays; the JAM detection sensors SE 1 , SE 2 , and SE 3  that detect a paper jam; the operation panel  120  that displays the paper feed adjustment screen  123 ; and the control part  110 . When a paper jam occurs, the control part  110  causes the operation panel  120  to display the paper feed adjustment screen  123 . Therefore, when a paper jam occurs, the paper feed adjustment screen  123  is automatically displayed. This enables reduction of user&#39;s time and effort and enables paper feed adjustment during execution of a job, inhibiting downtime and allowing suppression of a decrease in productivity. 
     Further, in the present embodiment, when there is a paper feed tray storing a same paper sheet as the paper sheet to which a paper jam occurs, the paper feed tray is switched and the job is continued. Therefore, in such a case, the image forming apparatus  1  is not required to be stopped, inhibiting downtime and allowing suppression of a decrease in productivity. 
     Further, in the present embodiment, when paper feed adjustment and release of the paper jam are completed, the user can select whether to return to the original paper feed tray. Therefore, paper feeding can be performed with the paper feed tray reset to a suitable adjustment value, enabling reduction of risk of occurrence of a paper jam. 
     In the present embodiment, a related paper feed adjustment screen  123  is exclusively displayed according to the type of a paper jam. Further, when there are a plurality of related paper feed adjustment screens  123 , they are displayed in descending order of relevance. This can improve efficiency of paper feed adjustment. 
     Further, in the present embodiment, the adjustment value of the paper feed adjustment is calculated and displayed on the paper feed adjustment screen  123 , and the value is adjusted based on the adjustment value. Therefore, it is easier to obtain a more suitable adjustment value than when the user optionally sets the value, and it is possible to reduce the time and effort of the user, and the time required for paper feed adjustment. 
     Further, in the present embodiment, the storage part  111  stores the set adjustment value of the paper feed adjustment as the paper profile data and the paper feed tray adjustment data. Accordingly, this adjustment value is reflected at a time of paper feeding of a same paper sheet or paper feeding from a same paper feed tray next time, enabling paper feeding in a more suitable state and reduction of risk of occurrence of a paper jam. 
     OTHER EMBODIMENTS 
     While specific description has been given above with reference to the embodiment of the present invention, the above-described embodiment is a suitable example of the present invention and is not limited thereto. 
     For example, in the above embodiment, the paper feed adjustment screen  123  is displayed every time a jam occurs. However, the present invention is not limited to this, and the paper feed adjustment screen  123  may be displayed every predetermined number of times. The predetermined number of times can be optionally set by the user. 
     Further, when an occurrence frequency of a jam increases after the paper feed adjustment is performed, there may be displayed a value before adjustment, or an adjustment value in a direction opposite to the previous adjustment with the value before adjustment as a reference. 
     In addition, after occurrence of a paper jam, the user selects whether to switch or not when there is a switchable paper feed tray, but it may be automatically switched under the control of the control part  110 . 
     Further, in a case where a paper jam further occurs in the paper feed tray switched after the occurrence of the paper jam, when there is another switchable paper feed tray, it is also possible to further switch to the another paper feed tray. 
     Besides, the detailed configuration of each device constituting the image forming apparatus and detailed operation of the each device can be appropriately changed without departing from the gist of the present invention. 
     Although embodiments of the present invention have been described and illustrated in detail, the disclosed embodiments are made for purposes of illustration and example only and not limitation. The scope of the present invention should be interpreted by terms of the appended claims.