JP2017132599A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce erroneous detection of jams by reducing conveyance delay of a slippery sheet of printing paper mixed in sheets of printing paper used for printing.SOLUTION: A controller 4 holds a count value for the number of sheets of paper to be fed, which is obtained by counting sheets of printing paper fed from each paper feed part, (a); conveys, with an automatic document feeder, sheets of printing paper continuously from a bundle of sheets of printing paper set in an image reader 1, measures the surface roughness of each sheet of printing paper of a bundle of sheets of printing paper, and determines on the basis of the measured surface roughness whether each sheet of printing paper is slippery or not, (b); displays altogether on a display device the position of a bundle of sheets of printing paper including a sheet of printing paper determined to be slippery, a paper feed part with the lowest count value of the number of sheets of paper among the plurality of paper feed parts, and a message urging that the sheet of printing paper determined to be slippery should be accommodated in a paper feed part that has the lowest count value in the number of sheets, (c).SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus.

  When a paper detection waiting time exceeds a jam detection time (conveyance delay time determined to be a jam occurrence), a certain image forming apparatus waits for paper detection for a certain time, and if paper is detected during that time, The paper detection waiting time is changed to a time longer than the current setting (see, for example, Patent Document 1). As a result, the jam detection time is adjusted in accordance with the secular change of the paper transport mechanism, so that the frequency of detecting the jam is low even after the secular change even though the jam does not actually occur. doing.

JP-A-6-156806

  However, the above-described image forming apparatus tries to reduce the frequency of detecting a jam after aging, even though the jam does not actually occur. Since the conveyance delay further occurs due to the slip of the printing paper with respect to the conveyance roller or the like, there is a possibility that such a printing paper may detect the jam even though the jam does not actually occur. Still there.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an image forming apparatus is provided that reduces the conveyance delay of slippery printing paper mixed with printing paper used for printing and reduces false detection of jamming. Objective.

  An image forming apparatus according to the present invention includes an image reading device, a printing device, and a controller. The printing apparatus includes a plurality of paper feeding units that can store printing paper. The image reading apparatus includes an automatic document feeder and a sensor that measures the surface roughness of the printing paper conveyed by the automatic document feeder. The controller (a) holds, for each of the plurality of paper feeding units, a count value of the number of paper sheets obtained by counting the number of printing paper sheets fed from the paper feeding unit, and (b ) The printing paper is continuously conveyed from the printing paper bundle set in the image reading device by the automatic document feeder, the surface roughness of each printing paper in the printing paper bundle is measured, and the measured surface roughness And (c) the position of the printing paper determined to be slippery in the bundle of printing paper and the number of fed sheets among the plurality of paper feeding units. A message that prompts the user to store the paper feeding unit having the smallest count value and the printing paper determined to be slippery into the paper feeding unit having the smallest count value of the number of fed sheets is displayed on a predetermined display device. You .

  An image forming apparatus according to the present invention includes an image reading device, a printing device, and a controller. The printing apparatus includes a plurality of paper feeding units that can store printing paper. The image reading apparatus includes an automatic document feeder and a sensor that measures the surface roughness of the printing paper conveyed by the automatic document feeder. The automatic document feeder includes two discharge trays for a sheet after image reading, and a branch portion where a single transport path of the sheet branches into two transport paths to the two discharge trays. A branch guide that selects one of the two transport paths and guides the sheet toward the discharge tray corresponding to the selected transport path. The controller (a) holds, for each of the plurality of paper feeding units, a count value of the number of paper sheets obtained by counting the number of printing paper sheets fed from the paper feeding unit, and (b ) The printing paper is continuously conveyed from the printing paper bundle set in the image reading device by the automatic document feeder, the surface roughness of each printing paper in the printing paper bundle is measured, and the measured surface roughness (C) controlling the branch guide to discharge the printing paper determined to be slippery to a predetermined discharge tray of the two discharge trays. And (d) a message prompting the user to store the printing paper determined to be slippery in the paper feeding unit having the smallest count value of the number of fed paper is displayed on a predetermined display device.

  According to the present invention, the conveyance delay of slippery printing paper mixed with the printing paper used for printing is reduced, and erroneous detection of jam is reduced.

  These and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

FIG. 1 is a block diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a side view illustrating an example of the internal configuration of the image reading apparatus 1 according to the first embodiment. FIG. 3 is a side view showing an example of the internal configuration of the printing apparatus 2 in FIG. FIG. 4 is a flowchart for explaining the operation of the image forming apparatus according to the first embodiment. FIG. 5 is an example of a screen displayed on the operation panel 3 in the image forming apparatus according to the first embodiment. FIG. 6 is a side view illustrating an example of the internal configuration of the image reading apparatus 1 according to the second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.

  FIG. 1 is a block diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus shown in FIG. 1 is an apparatus such as a copier or a multifunction machine. The image forming apparatus shown in FIG. 1 includes an image reading apparatus 1, a printing apparatus 2, an operation panel 3, and a controller 4 that are connected to one another.

  The image reading apparatus 1 optically reads a page image of a document, generates image data of the page image (that is, an input image), and outputs it. The image data is data including image information of each pixel such as RGB values.

  FIG. 2 is a side view illustrating an example of the internal configuration of the image reading apparatus 1 according to the first embodiment.

  An image reading apparatus 1 shown in FIG. 2 includes contact glasses 11a and 11b, carriages 12 and 13, an imaging lens 14, an image sensor 15, a white reference patch 16, and an automatic document feeder (ADF) 10. A document cover 17 and a media sensor 18 are provided.

  The contact glass 11 a is installed on the upper part of the image reading device 1, and a document is placed when image reading is performed without using the automatic document feeder 10 of the document cover 17. Further, the contact glass 11b is installed on the upper part of the image reading device 1, and when the image is read while the document is automatically conveyed by the document automatic feeding device 10 of the document cover 17, the document passes over it.

  The carriage 12 is installed so as to be movable in the sub-scanning direction by a drive source (not shown). The carriage 12 has a light source 21 and a mirror 22. The light source 21 is arranged along the main scanning direction, and emits light with, for example, a plurality of light emitting diodes arranged. The light emitted from the light source 21 is reflected by an original placed on the contact glass 11a, an original passing through the contact glass 11b, or the like according to the position of the carriage 12. The mirror 22 reflects reflected light from a document or the like. The carriage 13 is installed so as to be movable in the sub-scanning direction together with the carriage 12 by a drive source (not shown). The carriage 13 has mirrors 23 and 24. The mirrors 23 and 24 reflect the light from the mirror 22 of the carriage 12 and emit it along the sub-scanning direction.

  The imaging lens 14 images the light from the mirror 24 on the image sensor 15. The image sensor 15 is a one-dimensional image sensor having light receiving elements with a predetermined number of pixels arranged in the main scanning direction, and outputs an electric signal corresponding to the amount of light received for the pixels with the number of pixels for each line. For example, a CCD (Charge Coupled Device) is used as the image sensor 15. The white reference patch 16 is a plate-like member that is disposed on the top surface inside the apparatus and used to acquire white reference data.

  The document cover 17 is a member that can be brought into surface contact with the contact glass 11a and is rotatably mounted. The document cover 17 closely contacts the document with the contact glass 11a, and ambient light enters the apparatus from the contact glass 11a during image reading. To prevent. Further, the document cover 17 has the automatic document feeder 10, and conveys the documents placed on the document tray 17a one by one by the conveyance roller 17b, and passes it over the contact glass 11b.

  The media sensor 18 measures the surface roughness of the printing paper conveyed by the automatic document feeder 10 in the document cover 17. For example, the media sensor 18 irradiates the printing paper with measurement light with a light source, receives reflected light (one or both of regular reflection light and diffuse reflection light) from the printing paper with a light receiving unit, and according to the amount of light received Generate electrical signals. Since the reflected light changes according to the surface roughness, the surface roughness is specified from this electric signal.

  Returning to FIG. 1, the printing apparatus 2 prints an image on printing paper by an electrophotographic printing mechanism (not shown).

  FIG. 3 is a side view showing an example of the internal configuration of the printing apparatus 2 in FIG.

  The image forming apparatus shown in FIG. 3 has a tandem color developing device. The color developing device includes photosensitive drums 51a to 51d, exposure devices 52a to 52d, and developing units 53a to 53d. The photoconductor drums 51a to 51d are four-color photoconductors of cyan, magenta, yellow, and black.

  The exposure devices 52a to 52d are devices that form electrostatic latent images by irradiating the photosensitive drums 51a to 51d with laser light while scanning. The laser beam is scanned in a direction (main scanning direction) perpendicular to the rotation direction (sub-scanning direction) of the photosensitive drums 51a to 51d. The exposure apparatuses 52a to 52d have a laser scanning unit including a laser diode that is a light source of laser light and optical elements (lens, mirror, polygon mirror, etc.) that guide the laser light to the photosensitive drums 51a to 51d.

  Further, a charger, a cleaning device, a static eliminator and the like are disposed around the photosensitive drums 51a to 51d. The cleaning device removes residual toner on the photosensitive drums 51a to 51d after the primary transfer, and the static eliminator neutralizes the photosensitive drums 51a to 51d after the primary transfer.

  The developing units 53a to 53d attach the toner cartridge filled with toners of four colors of cyan, magenta, yellow and black, and the toner conveyed from the toner hopper in the toner cartridge to the photosensitive drums 51a to 51d. A developing unit, and the toner is attached to the electrostatic latent images on the photosensitive drums 51a to 51d to form a toner image.

  The photosensitive drum 51a, the exposure device 52a, and the developing unit 53a develop magenta, and the photosensitive drum 51b, the exposure device 52b, and the developing unit 53b develop cyan, the photosensitive drum 51c, and the exposure device 52c. The developing unit 53c performs yellow development, and the photosensitive drum 51d, the exposure device 52d, and the developing unit 53d perform black development.

  The intermediate transfer belt 54 is an annular image carrier (intermediate transfer member) that contacts the photosensitive drums 51a to 51d and primarily transfers the toner images on the photosensitive drums 51a to 51d. The intermediate transfer belt 54 is stretched around the driving roller 55a and the tension roller 55b, and circulates by the driving force from the driving roller 55a.

  As will be described later, the transfer roller 56 brings the printing paper conveyed into contact with the intermediate transfer belt 54 and secondarily transfers the toner image on the intermediate transfer belt 54 to the printing paper. The printing paper to which the toner image has been transferred is conveyed to the fixing device 59, and the toner image is fixed to the printing paper.

  The roller 57 has a cleaning brush. The roller 57 is brought into contact with the intermediate transfer belt 54 to remove the toner remaining on the intermediate transfer belt 54 after the transfer of the toner image onto the sheet or after calibration. The sensor 58 is an optical sensor for measuring the density of the toner patch during toner gradation calibration.

  Further, the printing apparatus 2 includes a plurality of sheet feeding cassettes 61 and 62 and a manual feed tray 63 as a plurality of sheet feeding units.

  Each of the paper feeding cassettes 61 and 62 can be opened and closed, and is loaded with printing papers 101 and 102 of a certain size supplied by a user or the like in an open state, and in a closed state, the printing paper 101 is lifted by lift plates 71 and 74. , 102 are pushed up to contact the paper feed rollers 72, 75. The drive mechanism of the lift plates 71 and 74 is configured to mechanically push up the lift plates 71 and 74 when the paper feed cassettes 61 and 62 are closed, for example. The printing sheets 101 and 102 placed on the sheet feeding cassettes 61 and 62 are fed one by one by sheet feeding rollers 72 and 75 from the upper side. The transport rollers 73 and 76 are rollers that transport the print sheets 101 and 102 fed from the paper feed cassettes 61 and 62 by the paper feed rollers 73 and 76 one by one.

  Further, printing paper is placed on the manual feed tray 63 by the user. The printing paper placed on the manual feed tray 63 is fed one by one by the paper feed roller 77. The transport roller 78 is a roller for transporting the sheets fed from the manual feed tray 63 by the sheet feed roller 77 one by one.

  The conveyance roller 79 is a conveyance roller on a conveyance path common to the printing sheets 101 and 102 conveyed from the paper feed cassettes 61 and 62. The conveyance roller 80 is a conveyance roller on a conveyance path common to the printing sheets 101 and 102 conveyed from the sheet feeding cassettes 61 and 62 and the printing sheet conveyed from the manual feed tray 63.

  The remaining sheet sensors 81 and 82 are distance sensors, for example, which measure the distance to the upper surface of the stacked sheets 101 and 102 and detect the remaining amount of the sheets 101 and 102 based on the measured distance.

  Returning to FIG. 1, the operation panel 3 includes a display device (such as a liquid crystal display) that displays an operation screen or the like to the user, and an input device (such as a touch panel or a hard key) that receives a user operation.

  The controller 4 controls the image reading device 1, the printing device 2, and the operation panel 3, and performs image processing for image data obtained by the image reading device 1 and image data used by the printing device 2. For example, the controller 4 is a processor including a computer that executes a program, an ASIC (Application Specific Integrated Circuit) that executes specific processing, and the like.

  The controller 4 counts the number of fed sheets obtained by counting the number of print sheets fed from each sheet feeding unit for each of the plurality of sheet feeding units (the sheet feeding cassettes 61 and 62 and the manual feed tray 63). A non-volatile storage device (flash memory or the like) (not shown) is held.

  Further, the controller 4 uses the automatic document feeder 10 to continuously print paper from a bundle of printing paper set in the image reading device 1 (that is, a bundle of unused printing paper, not a document containing text or images). The surface roughness of each printing sheet in the bundle of printing sheets is measured, and whether or not each printing sheet is slippery is determined based on the measured surface roughness.

  After completing the determination of all the print sheets in the print sheet bundle, the controller 4 specifies (a) the sheet feed section having the smallest count value of the number of fed sheets among the above-described plurality of sheet feed sections, and (b) slippery Of the print paper determined to be in the print paper bundle (paper order such as paper number), the paper feed unit with the smallest count value of the number of paper feeds, and the count of the number of paper feeds of the print paper judged to be slippery Messages prompting to be accommodated in the sheet feeding unit having the smallest value are collectively displayed on the display device of the operation panel 3.

  Next, the operation of the image forming apparatus according to the first embodiment will be described. FIG. 4 is a flowchart for explaining the operation of the image forming apparatus according to the first embodiment.

  The user performs a predetermined operation on the operation panel 3 after setting the print sheet bundle on the document tray 17a. When the user operation is detected on the operation panel 3, the controller 4 controls the image reading apparatus 1 and starts continuous reading (step S1).

  The image reading apparatus 1 uses the automatic document feeder 10 to convey printing sheets one by one in order from the upper side of the bundle of printing sheets on the document tray 17a (step S2).

  The automatic document feeder 10 of the image reading apparatus 1 conveys the printing paper, measures the surface roughness of the printing paper with the media sensor 18, and outputs the measurement result to the controller 4 (step S3).

  Based on the measurement result, the controller 4 determines whether or not the printing paper is slippery (step S4). If it is determined that the printing paper is slippery, the controller 4 stores sheet position data indicating the order of the printing paper (step S4). S5). For example, when it is determined that the fifth printing paper from the upper side of the printing paper bundle is slippery, sheet position data indicating 5 is stored.

  Then, the image reading apparatus 1 attempts to convey the next printing sheet (step S6). If reading of the printing sheet bundle has not been completed (step S7), the process returns to step S2 to convey the next printing sheet. Similarly, the processing after step S3 is executed.

  On the other hand, when the reading of the printing paper bundle is completed (step S7), the image reading apparatus 1 notifies the controller 4 that the reading of the printing paper bundle is completed. Upon receiving this notification, the controller 4 identifies (a) the paper feed unit with the smallest count value of the number of paper feeds, and (b) the position (paper number) of the print paper determined to be slippery in the print paper bundle. (Sheet order, etc.), the message that prompts the user to store the paper feed unit with the smallest number of paper feed counts and the paper feed unit with the smallest paper feed count value that has been determined to be slippery Is displayed on the display device of the operation panel 3 (step S8).

  FIG. 5 is an example of a screen displayed on the operation panel 3 in the image forming apparatus according to the first embodiment. In the case shown in FIG. 5, it is determined that the fifth, eighth and eighteenth printing sheets are slippery, and are accommodated in “paper feeding cassette # 1” (here, paper feeding cassette 61). A message prompting you is displayed.

  As described above, according to the first embodiment, the controller 4 holds (a) the count value of the number of fed sheets obtained by counting the number of printing sheets fed from each sheet feeding unit, (B) The printing paper is continuously conveyed from the printing paper bundle set in the image reading apparatus 1 by the automatic document feeder, and the surface roughness of each printing paper in the printing paper bundle is measured. Based on whether or not each print sheet is slippery, and (c) the position of the print sheet determined to be slippery in the print sheet bundle and the count value of the number of fed sheets among the plurality of paper feed units. Messages that prompt the user to store the smallest paper feed unit and the print paper determined to be slippery into the paper feed unit having the smallest count value of the number of fed paper sheets are collectively displayed on a predetermined display device.

  As a result, slippery printing paper is extracted from the printing paper bundle and used in a paper feeding unit with a small transport delay (that is, a paper feeding unit with the smallest number of paper feeding counts). The delay in transporting slippery printing paper mixed in the paper is reduced, and erroneous detection of jam is reduced.

Embodiment 2. FIG.

  In the second embodiment, the image reading apparatus 1 sorts and discharges the printing paper determined to be slippery.

  FIG. 6 is a side view illustrating an example of the internal configuration of the image reading apparatus 1 according to the second embodiment.

  The automatic document feeder 10 of the image reading apparatus 1 according to the second embodiment further includes two discharge trays 41 and 42 for a sheet after image reading, and a branch guide 43. The branch guide 43 selects one of the two transport paths at the branch portion where the single transport path of the sheet branches into two transport paths to the two discharge trays 41 and 42. Then, the sheet is guided toward the discharge tray corresponding to the selected conveyance path. The branch guide 43 rotates around the drive shaft 43a, and closes one of the two transport paths (that is, the transport path that is not the selected transport path), so that the sheet is selected as the selected transport path. Guide it towards the discharge tray corresponding to.

  In the second embodiment, the controller 4 (a) continuously conveys the printing paper from the printing paper bundle set in the image reading apparatus 1 by the automatic document feeder 10, and the surface roughness of each printing paper in the printing paper bundle. Then, based on the measured surface roughness, it is determined whether or not each printing sheet is slippery. (B) The branch guide 43 is controlled to determine a predetermined discharge tray in the two discharge trays 41 and 42. The printing paper determined to be slippery is discharged to 42, and the printing paper not determined to be slippery is discharged to the discharge tray 41.

  After completing the determination of all the printing sheets in the printing sheet bundle, the controller 4 displays a message on the operation panel 3 prompting the user to store the printing sheets determined to be slippery in the sheet feeding unit having the smallest number of sheets fed. Display on the device.

  Since the other configuration and operation of the image forming apparatus according to the second embodiment are the same as those of the first embodiment, the description thereof is omitted.

  As described above, according to the second embodiment, the automatic document feeder 10 of the image reading apparatus 1 includes the two discharge trays 41 and 42 for the sheet after image reading and the branch guide 43. The branch guide 43 selects one of the two transport paths at the branch portion where the single transport path of the sheet is branched into two transport paths to the two discharge trays 41 and 42. Then, the sheet is guided toward the discharge tray corresponding to the selected conveyance path. The controller 4 holds (a) a count value of the number of fed sheets obtained by counting the number of printed sheets fed from each sheet feeding unit, and (b) printing set in the image reading apparatus 1. The printing paper is continuously conveyed from the sheet bundle by the automatic document feeder 10, the surface roughness of each printing sheet in the printing sheet bundle is measured, and whether each printing sheet is slippery based on the measured surface roughness. (C) the branch guide 43 is controlled to discharge the printing paper determined to be slippery to the predetermined discharge tray 42, and (d) the number of sheets of paper determined to be slippery is fed. Is displayed on the operation panel 3 to prompt the user to store the paper in the paper feed unit having the smallest count value.

  As a result, slippery printing paper is extracted from the printing paper bundle and used in a paper feeding unit with a small transport delay (that is, a paper feeding unit with the smallest number of paper feeding counts). The delay in transporting slippery printing paper mixed in the paper is reduced, and erroneous detection of jam is reduced.

  Various changes and modifications to the above-described embodiment will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing its intended advantages. That is, such changes and modifications are intended to be included within the scope of the claims.

  For example, in the first and second embodiments, when the paper feed unit having the smallest count value of the number of paper feed is the manual feed tray 63, the controller 4 stores the print paper determined to be slippery in the manual feed tray 63. After that, the jam detection time for the manual feed tray 63 may be adjusted based on the index value of slipperiness based on the measured surface roughness and the count value of the number of fed sheets.

  In the first and second embodiments, the controller 4 may display the number of print sheets determined to be slippery on the operation panel 3 together with the above message.

  Further, in the first embodiment, the sheet bundle that has been conveyed by the automatic document feeder 10 and read the surface roughness may be set and fed directly to the manual feed tray 63 without changing the order of the sheet bundle. In this case, in addition to the display shown in FIG. 5 on the operation panel 3, a [Manual Tray] selection key is displayed, and a message “Press the [Manual Tray] key to load printing paper in the manual tray” is displayed. Is displayed. When [Manual Feed Key] is selected, the image forming apparatus 1 counts the number of sheets fed from the manual feed tray 3 for the number of print sheets conveyed by the automatic document feeder 10 (“number of print sheets” displayed in FIG. 5). To do. Then, with reference to the slippery paper position stored in the controller 4, the rotational speed of the paper feed roller 77 may be reduced when slippery paper is fed. As a result, it is possible to reduce the frequency of occurrence of poor feeding of slippery paper.

  The present invention is applicable to an image forming apparatus such as a multifunction machine.

DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Printing apparatus 3 Operation panel (an example of a display apparatus)
4 Controller 18 Media sensor (an example of sensor)
41, 42 Discharge tray 43 Branch guide 61, 62 Paper feed cassette (example of paper feed unit)
63 Bypass tray (example of paper feed unit)

Claims (4)

An image reader;
A printing device;
With a controller,
The printing apparatus includes a plurality of paper feeding units capable of storing printing paper,
The image reading apparatus includes an automatic document feeder, and a sensor for measuring the surface roughness of the printing paper conveyed by the automatic document feeder,
The controller (a) holds, for each of the plurality of paper feed units, a count value of the number of paper sheets obtained by counting the number of print sheets fed from the paper feed unit, and (b) the The printing paper is continuously conveyed from the printing paper bundle set in the image reading apparatus by the automatic document feeder, and the surface roughness of each printing paper in the printing paper bundle is measured, and based on the measured surface roughness. Whether or not each print sheet is slippery, and (c) the position of the print sheet determined to be slippery in the print sheet bundle and the count of the number of sheets fed among the plurality of sheet feed units. A message prompting the user to store the paper feeding unit having the smallest value and the printing paper determined to be slippery into the paper feeding unit having the smallest count value of the number of fed papers is collectively displayed on a predetermined display device. ,
An image forming apparatus. An image reader;
A printing device;
With a controller,
The printing apparatus includes a plurality of paper feeding units capable of storing printing paper,
The image reading apparatus includes an automatic document feeder, and a sensor for measuring the surface roughness of the printing paper conveyed by the automatic document feeder,
The automatic document feeder includes two discharge trays for a sheet after image reading, a branching unit in which a single transport path of the sheet branches into two transport paths to the two discharge trays, The branching unit includes a branching guide that selects one of the two transporting paths and guides the sheet toward the discharge tray corresponding to the selected transporting path,
The controller (a) holds, for each of the plurality of paper feed units, a count value of the number of paper sheets obtained by counting the number of print sheets fed from the paper feed unit, and (b) the The printing paper is continuously conveyed from the printing paper bundle set in the image reading apparatus by the automatic document feeder, and the surface roughness of each printing paper in the printing paper bundle is measured, and based on the measured surface roughness. Determining whether each print sheet is slippery, (c) controlling the branch guide to discharge the print sheet determined to be slippery to a predetermined discharge tray in the two discharge trays, (D) displaying on a predetermined display device a message for encouraging the printing paper determined to be slippery to be stored in the paper feeding unit having the smallest count value of the number of fed paper;
An image forming apparatus.   When the paper feed unit having the smallest count value of the number of fed paper is a manual feed tray, the controller measures the surface roughness measured after the printing paper determined to be slippery is stored in the manual feed tray. 3. The image forming apparatus according to claim 1, wherein a jam detection time relating to the manual feed tray is adjusted based on an index value of slipperiness based on the value and a count value of the number of fed sheets.   4. The image forming apparatus according to claim 1, wherein the controller displays, together with the message, the number of print sheets determined to be slippery on the predetermined display device. 5. .

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