JP2019066616A - Image forming apparatus and paper jam processing method - Google Patents

Abstract

To provide an image forming apparatus and a paper jam processing method that can improve workability in removing paper at the time of occurrence of a paper jam.SOLUTION: An image forming apparatus comprises: an image forming unit that forms images on a sheet; a sheet conveyance path that is provided with first conveyance rollers and second conveyance rollers in a conveyance direction of the sheet and continuous from the image forming unit; and a conveyance control unit that controls conveyance of the sheet so as to pass the sheet through the sheet conveyance path. When the conveyance is stopped due to a paper jam occurring when the sheet is conveyed by the first and second conveyance rollers, the image forming apparatus forms a slack on the sheet with rotation of at least one of the first conveyance rollers and second conveyance rollers.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus and a jam handling method.

  2. Description of the Related Art Conventionally, an image forming apparatus that forms an image on a sheet using toner is known. In such an image forming apparatus, in order to reverse the front and back of the sheet to form an image on both sides, a transport path is configured to reverse the front and back of the sheet in the transport direction of the sheet by switchback (that is, reverse). Japanese Patent Application Laid-Open Publication No. H11-324118 discloses a reverse conveyance path.

  In the conventional image forming apparatus, a sheet of a size that can be stored in the sheet feeding tray unit can be switchback reversed through the reverse transport path.

Unexamined-Japanese-Patent No. 2006-124100

  In recent years, there has been an increasing demand for forming an image on both sides of a so-called long sheet which can be stored in a sheet feeding tray unit. On the other hand, in order to realize double-sided printing of long paper, it is necessary to make the path length of the reverse conveyance path longer than in the past. Then, when the path length of the reverse conveyance path is made longer than in the past, measures against jamming, which is more likely to occur as compared to fixed paper and the like, become an important issue. That is, when the long paper is jammed, the working space may be narrow in order to jam the longer paper than usual in the machine space. In this case, in order to facilitate the work such as removal of jammed long paper It is necessary to secure a space for

  As a configuration for facilitating jam processing when paper jams during double-sided printing, for example, a member for double-sided printing such as the above-described reverse conveyance path or conveyance roller is configured as one unit, and such a unit is an apparatus main body There is one that is configured to be able to put in and out. This unit is called, for example, an automatic duplex unit (ADU).

  However, even with the configuration provided with such an ADU, depending on the position of the jam generated in the ADU, the sheet size, and the like, an operation for removing the jammed sheet when the ADU is pulled out from the apparatus, ie, removing the jammed sheet is performed. It may be difficult. As a typical example, when jamming of a long sheet of paper occurs in the ADU, the conveyance is stopped while being pinched by more conveyance rollers, so there is a problem that the work of removing such a long sheet of paper tends to be complicated .

  An object of the present invention is to provide an image forming apparatus and a jam processing method capable of improving the workability of sheet removal at the time of jam occurrence.

The image forming apparatus according to the present invention is
An image forming unit that forms an image on a sheet;
A sheet conveyance path provided with a first conveyance roller and a second conveyance roller along the conveyance direction of the sheet, and connected to the image forming unit;
And a conveyance control unit configured to control conveyance of the sheet so as to pass the sheet through the sheet conveyance path.
When the sheet is conveyed by the first and second conveyance rollers and the conveyance is stopped due to a jam, the rotation of at least one of the first conveyance roller and the second conveyance roller causes the sheet to be slackened. Form.

The jam processing method according to the present invention is
A jam processing method in an image forming apparatus, comprising: a sheet conveyance path provided with a first conveyance roller and a second conveyance roller connected to an image forming unit for forming an image on a sheet and conveying the sheet;
When the sheet is conveyed by the first and second conveyance rollers and the conveyance is stopped due to a jam, the rotation of at least one of the first conveyance roller and the second conveyance roller causes the sheet to be slackened. Form.

  According to the present invention, the workability of paper removal at the time of jam occurrence can be improved.

FIG. 1 is a block diagram showing an example of an image forming apparatus in the present embodiment. FIG. 2 is a diagram showing a main part of a control system in the image forming apparatus of FIG. FIG. 5 is a diagram showing ADU and the like extracted and shown in the image forming apparatus of FIG. 1, illustrating a case where a paper jam occurs in ADU. It is a figure explaining the process which forms a slack in the jammed sheet in this embodiment. It is a flowchart which shows an example of the slack formation process in this Embodiment.

  Hereinafter, embodiments of an image forming apparatus to which the present invention is applied will be described with reference to the drawings.

  FIG. 1 is a view schematically showing an entire configuration of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 shows the main part of the control system of the image forming apparatus 1 in the present embodiment. Further, FIG. 3 extracts and shows a conveyance path for double-sided printing in the image forming apparatus 1.

  The image forming apparatus 1 of the present embodiment is an apparatus for forming an image on the long paper LS or the paper S using the long paper LS or the paper S (non-long paper) as a recording medium.

  In the present embodiment, the long paper LS is a sheet of paper having a length in the transport direction longer than that of commonly used A4 size, A3 size, etc., and is stored in the paper feed tray units 51a to 51c in the machine. Has a length that can not. The size of the long paper LS, that is, the dimension such as the length in the transport direction is stored as definition data in a memory or the like of the image forming apparatus 1. Hereinafter, when simply referred to as "paper", both long paper LS and paper S may be included.

  The image forming apparatus 1 is an intermediate transfer type color image forming apparatus using an electrophotographic process technology. That is, the image forming apparatus 1 primarily transfers the toner images of Y (yellow), M (magenta), C (cyan), and K (black) formed on the photosensitive drum 413 onto the intermediate transfer belt 421. After superimposing toner images of four colors on the intermediate transfer belt 421, the toner image is formed by secondary transfer onto a sheet.

  Further, in the image forming apparatus 1, photosensitive drums 413 corresponding to four colors of Y, M, C, and K are arranged in series in the traveling direction of the intermediate transfer belt 421, and each color toner image is sequentially transferred onto the intermediate transfer belt 421 in one procedure. A tandem system is adopted.

  As shown in FIG. 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a sheet conveyance unit 50, a fixing unit 60, a control unit 100, and the like.

  The control unit 100 includes a central processing unit (CPU) 101, a read only memory (ROM) 102, a random access memory (RAM) 103, and the like. The CPU 101 reads out a program corresponding to the processing content from the ROM 102, develops it in the RAM 103, and cooperates with the developed program to centrally control the operation of each block of the image forming apparatus 1. At this time, various data stored in the storage unit 72 are referred to. The storage unit 72 includes, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

  The control unit 100 transmits / receives various data to / from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 71. Do. For example, the control unit 100 receives image data transmitted from an external device, and forms a toner image on a sheet based on the image data (input image data). The communication unit 71 is configured of, for example, a communication control card such as a LAN card.

  The image reading unit 10 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.

  The automatic document feeder 11 transports the document D placed on the document tray by the transport mechanism and sends it to the document image scanning device 12. The automatic document feeder 11 can continuously read the images (including both sides) of a large number of documents D placed on the document tray at once.

  The document image scanning device 12 optically scans a document conveyed on the contact glass from the automatic document feeder 11 or a document placed on the contact glass, and reflects light reflected from the document as a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and an original image is read. The image reading unit 10 generates input image data based on the reading result of the document image scanning device 12. The image processing unit 30 applies predetermined image processing to the input image data.

  The operation display unit 20 is configured of, for example, a liquid crystal display (LCD) with a touch panel, and functions as the display unit 21 and the operation unit 22. The display unit 21 displays various operation screens, image status display, operation status of each function, and the like according to a display control signal input from the control unit 100. The operation unit 22 includes various operation keys such as a ten key and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 100.

  The image processing unit 30 includes a circuit or the like that performs digital image processing according to initial setting or user setting on input image data. For example, the image processing unit 30 performs tone correction based on the tone correction data (tone correction table LUT) in the storage unit 72 under the control of the control unit 100. Further, the image processing unit 30 performs various correction processing such as color correction and shading correction, compression processing, and the like in addition to gradation correction on input image data. The image forming unit 40 is controlled based on the image data subjected to these processes.

  The image forming unit 40 forms an image forming unit 41 Y, 41 M, 41 C, 41 K, and an intermediate transfer unit 42 for forming an image with each color toner of Y component, M component, C component and K component based on input image data. Etc.

  The image forming units 41Y, 41M, 41C, and 41K for the Y component, the M component, the C component, and the K component have the same configuration. For convenience of illustration and description, common components are denoted by the same reference numerals, and when the respective components are distinguished, they are indicated by adding Y, M, C, or K to the reference numerals. In FIG. 1, reference numerals are attached only to the components of the image forming unit 41Y for the Y component, and reference numerals of the components of the other image forming units 41M, 41C, and 41K are omitted.

  The image forming unit 41 includes an exposure device 411, a developing device 412, a photosensitive drum 413, a charging device 414, a drum cleaning device 415, and the like.

  The photosensitive drum 413 is, for example, an undercoat layer (UCL: Under Coat Layer), a charge generation layer (CGL: Charge Generation Layer), and a charge transport layer (Charge generation layer) on the circumferential surface of a conductive cylindrical body (aluminium tube) made of aluminum. It is a negatively charged organic photoreceptor (OPC: Organic Photo-conductor) in which CTL: Charge Transport Layer is sequentially laminated. The charge generation layer is made of an organic semiconductor in which a charge generation material (for example, phthalocyanine pigment) is dispersed in a resin binder (for example, polycarbonate), and generates a pair of positive charge and negative charge by exposure by the exposure device 411. The charge transport layer is formed by dispersing a hole transport material (electron donating nitrogen-containing compound) in a resin binder (for example, polycarbonate resin), and transports the positive charge generated in the charge generation layer to the surface of the charge transport layer Do.

  The control unit 100 controls the drive current supplied to a drive motor (not shown) for rotating the photosensitive drum 413 to rotate the photosensitive drum 413 at a constant circumferential velocity (linear velocity).

  The charging device 414 uniformly negatively charges the surface of the photoconductive drum 413 having photoconductivity. The exposure device 411 is formed of, for example, a semiconductor laser, and irradiates the photosensitive drum 413 with a laser beam corresponding to the image of each color component. The positive charge is generated in the charge generation layer of the photosensitive drum 413 and transported to the surface of the charge transport layer, whereby the surface charge (negative charge) of the photosensitive drum 413 is neutralized. An electrostatic latent image of each color component is formed on the surface of the photosensitive drum 413 due to the potential difference with the surroundings.

  The developing device 412 is, for example, a developing device of a two-component developing method, and causes toner of each color component to adhere to the surface of the photosensitive drum 413 to visualize an electrostatic latent image to form a toner image.

  The drum cleaning device 415 includes a drum cleaning blade (hereinafter simply referred to as a cleaning blade) 416 as a cleaning member which is in sliding contact with the surface of the photosensitive drum 413. The drum cleaning device 415 removes the transfer residual toner remaining on the surface of the photosensitive drum 413 after the primary transfer by the cleaning blade 416.

  The intermediate transfer unit 42 includes an intermediate transfer belt 421 as an image carrier, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like.

  The intermediate transfer belt 421 is an endless belt, and is stretched around a plurality of support rollers 423 in a loop. At least one of the plurality of support rollers 423 is configured by a drive roller, and the other is configured by a driven roller. For example, it is preferable that the roller 423A disposed downstream of the primary transfer roller 422 for the component K in the belt traveling direction is a driving roller. As a result, the traveling speed of the belt in the primary transfer portion can be easily maintained constant. As the drive roller 423A rotates, the intermediate transfer belt 421 travels at a constant speed in the arrow A direction.

  The primary transfer roller 422 is disposed on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photosensitive drums 413 of the respective color components. The primary transfer roller 422 is in pressure contact with the photosensitive drum 413 with the intermediate transfer belt 421 interposed therebetween, whereby a primary transfer nip for transferring a toner image from the photosensitive drum 413 to the intermediate transfer belt 421 is formed.

  The secondary transfer roller 424 is disposed on the outer peripheral surface side of the intermediate transfer belt 421 so as to face the backup roller 423B disposed on the downstream side of the drive roller 423A in the belt traveling direction. The secondary transfer roller 424 is pressed against the backup roller 423 B with the intermediate transfer belt 421 interposed therebetween, thereby forming a secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the sheet S.

  When the intermediate transfer belt 421 passes through the primary transfer nip, the toner image on the photosensitive drum 413 is sequentially superimposed on the intermediate transfer belt 421 and primarily transferred. Specifically, the toner image is formed by applying a primary transfer bias to the primary transfer roller 422 and applying charges of the reverse polarity to the toner on the back side of the intermediate transfer belt 421 (the side that contacts the primary transfer roller 422). The toner image is electrostatically transferred to the intermediate transfer belt 421.

  Thereafter, when the sheet passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the sheet. Specifically, the toner image is formed by applying a secondary transfer bias to the secondary transfer roller 424 and applying charges of the reverse polarity to the toner on the back side of the sheet (the side in contact with the secondary transfer roller 424). It is electrostatically transferred to the paper. The sheet on which the toner image has been transferred is conveyed toward the fixing unit 60.

  The belt cleaning device 426 has a belt cleaning blade or the like in sliding contact with the surface of the intermediate transfer belt 421, and removes transfer residual toner remaining on the surface of the intermediate transfer belt 421 after secondary transfer. Here, instead of the secondary transfer roller 424, a configuration in which the secondary transfer belt is stretched in a loop shape (a so-called secondary transfer unit of a belt type) is adopted to a plurality of support rollers including the secondary transfer roller. It is also good.

  The fixing unit 60 is disposed on the upper fixing unit 60A having a fixing surface side member disposed on the fixing surface (surface on which a toner image is formed) side of the sheet, and on the back surface of the sheet (surface opposite to the fixing surface) side. And a lower fixing unit 60B having a back side support member, and a heating source 60C. By pressing the back surface side supporting member against the fixing surface side member, a fixing nip for nipping and conveying the sheet is formed.

  The fixing unit 60 fixes the toner image on the sheet by heating and pressing the sheet on which the toner image has been secondarily transferred and conveyed at the fixing nip. The fixing unit 60 is disposed as a unit in the fixing device F. Further, in the fixing unit F, an air separation unit (not shown) for separating the sheet S from the fixing surface side member by blowing air is disposed.

  The sheet conveyance unit 50 includes a sheet feeding unit 51, a sheet discharge unit 52, a conveyance path unit 53, and the like. The three paper feed tray units 51a to 51c that constitute the paper feed unit 51 have the paper S (standard paper, special paper) identified based on basis weight (rigidity), size, and the like for each type set in advance. Be housed. The conveyance path portion 53 has a plurality of conveyance rollers such as a pair of registration rollers 53 a, a double-sided conveyance path for forming an image on both sides of a sheet, and the like.

  The sheets S accommodated in the sheet feeding tray units 51 a to 51 c are fed one by one from the top and conveyed by the conveyance path unit 53 to the image forming unit 40. At this time, the inclination of the fed sheet S is corrected and the transport timing is adjusted by the registration roller unit in which the registration roller pair 53a is disposed. Then, the toner image of the intermediate transfer belt 421 is secondarily transferred collectively on one side of the sheet S in the image forming unit 40, and the fixing process is performed in the fixing unit 60. The sheet S on which an image has been formed is discharged outside the apparatus by the discharge unit 52 provided with a discharge roller 52a.

  Next, the transport path unit 53 will be described in detail.

  The conveyance path unit 53 is a path along which the sheet is conveyed when an image is formed on one side, and includes a main conveyance path 530 through which the sheet on which the image is formed by the image forming unit 40 is conveyed. The main conveyance path 530 is a path for conveying the sheet via the registration roller pair 53 a, the secondary transfer nip of the image forming unit 40, and the fixing unit 60. In addition, the transport path unit 53 includes a reverse transport path 533 that reverses the front and back of the sheet.

  Conveyance path portion 53 is fed from external paper feed conveyance path 531 for conveying a sheet such as a long sheet LS fed from external paper feed port 2a to main conveyance path 530, and paper feed tray units 51a to 51c. The sheet feeding / conveying path 532 for conveying the sheet S to the main conveyance path 530 is provided.

  The main conveyance path 530 is provided above the paper feed tray units 51 a to 51 c inside the apparatus main body 2, and extends from one side of the apparatus main body 2 to the other side. One end of the main conveyance path 530 is connected to the external paper feeding conveyance path 531 and the paper feeding conveyance path 532. Further, the other end of the main conveyance path 530 is connected to the discharge port of the discharge portion 52 provided on the other side of the apparatus main body 2.

  One end of the external paper feeding and conveying path 531 is connected to the external paper feeding port 2 a, and the other end is connected to the main conveying path 530. The sheet feeding and conveying path 532 is provided in the vicinity of one side portion in the apparatus main body 2 and extends in the vertical (substantially vertical) direction from the sheet feeding tray units 51a to 51c to the main conveying path 530. In the sheet feeding / conveying path 532, a part of the path of the sheet feeding / conveying path 532 is exposed outward by opening an open / close door (not shown) provided on one side of the apparatus main body 2. Etc. becomes possible. The upper end of the sheet feeding / conveying path 532 is connected to the main conveying path 530, and the lower end is connected to the sheet feeding tray units 51a to 51c.

  The reverse conveyance path 533 is provided between the paper feed tray units 51 a to 51 c and the main conveyance path 530 inside the apparatus main body 2 and extends from the other side of the apparatus main body 2 to one side. The reverse conveyance path 533 includes a first return conveyance path 533 a that branches downward from the main conveyance path 530 downstream of the fixing unit 60 in the conveyance direction of the sheet conveyed on the main conveyance path 530, and the image forming unit 40. A second reflux transport path 533b is provided which merges with the main transport path 530 on the upstream side of the secondary transfer nip.

  One end of the reverse conveyance path 533 is connected to the first reflux conveyance path 533a and the second reflux conveyance path 533b. Here, one end of the reverse conveyance path 533 connected to the first reflux conveyance path 533a and the second reflux conveyance path 533b is a switchback in which the forward and reverse of the paper traveling direction (conveyance direction) is switched during double-sided printing. It becomes point SBP. Hereinafter, in the reverse conveyance path 533, the conveyance direction indicated by the arrow a by which the sheet is conveyed from the first reflux conveyance path 533a is referred to as a positive direction, and indicated by the arrow b by which the sheet is conveyed to the second circulation conveyance path 533b. The transport direction is referred to as the reverse direction.

  Further, the reverse conveyance path 533 includes a conveyance roller 53b as a switchback roller on the downstream side in the conveyance direction in the forward direction with respect to the switchback point SBP. The conveying roller 53 b is transmitted with a driving force of a motor (not shown), and conveys the sheet in both the forward direction and the reverse direction.

  Furthermore, the downstream side of the transport roller 53b in the transport direction of the reverse transport path 533 in the positive direction has a curved transport path 533c that is curved so as to be folded upward. The curved conveyance path 533 c is a double-sided path that joins the main conveyance path 530 and connects (bypasses) the reverse conveyance path 533 and the main conveyance path 530.

  The curved conveyance path 533c is a double-sided path used for double-sided printing of a sheet (mainly long sheet LS), and the main conveyance path 530 upstream of the registration roller 53a in the conveyance direction of the sheet conveyed in the forward direction. Merge with. In this example, the curved conveyance path 533c joins on the upstream side of the joining point of the main conveyance path 530 and the second reflux conveyance path 533b. The curved conveyance path 533 c joins the main conveyance path 530 in the direction in which the sheet is conveyed in the left direction in the drawing of the main conveyance path 530.

  The curved conveyance path 533c is provided with a conveyance roller 53c mainly for conveying the long sheet LS. The conveyance roller 53c is driven by a drive source (motor) separate from the conveyance roller 53b, and plays a role of compensating the conveyance force of the conveyance roller 53b when performing double-sided printing of the long paper LS. As described above, by providing the drive source of the transport roller 53c separately from the drive source of the transport roller 53b, the drive source (motor) for the transport roller 53b after the leading end of the long sheet LS rushes into the transport roller 53c. The load can be reduced.

  As described above, in the present embodiment, by providing the downstream side of the conveyance path in the conveyance direction before switchback to be folded back in the apparatus main body 2, the image forming apparatus 1 (the apparatus main body 2 etc.) is enlarged The path length of the reverse conveyance path 533 can be made longer than before, while Further, by connecting the curved conveyance path 533c of the reverse conveyance path 533 to the upstream side of the image forming unit 40 in the main conveyance path 530, it is possible to print on both sides of the long paper LS having a longer size in the conveyance direction. .

  As indicated by the dotted line in FIG. 1, the fixing unit 60, most of the main conveyance path 530, the reverse conveyance path 533, and the rollers disposed in these conveyance paths are automatic duplex unit (Auto Duplex Unit: ADU). As a component part of), it can be pulled out to the front side with respect to the apparatus main body 2.

  In one example, a plate-like frame (not shown) is provided on the back side of the device, and the above-described components are attached to the frame. Then, for example, by pulling out the operation lever (not shown) of the ADU at the time of jam processing, the above-mentioned frame and components are pulled out.

  Further, in the present embodiment, of the pair of upper and lower sheet guide members constituting the reverse conveyance path 533, a member 534 of the lower (outside) sheet guide (hereinafter referred to as the main body lower guide 534) is , Is fixed to the device body 2 side. By fixing (remaining) a portion of the guide member to the apparatus main body 2 in this way, the jammed sheet is extracted by pulling out the ADU when a jam occurs in the reverse conveyance path 533 during double-sided printing. , Visible from the lower opening of the ADU (ie, the area without the lower guide 534 on the main body side).

  Thus, in the image forming apparatus 1, by passing the long paper LS through the curved conveyance path 533c before and after the switchback operation, double-sided printing of the long paper LS having a longer size in the conveyance direction can be performed. Further, according to the present embodiment, since the double-sided conveyance route is substantially annular, the long paper LS is inside when the paper (long paper LS) is jammed during double-sided print job execution. It is held so as to be wound around the guide member. Therefore, according to the present embodiment, there is an advantage that breakage of the jammed sheet is less likely to occur when ADU is pulled out at the time of jam occurrence.

  Next, the case where double-sided printing of the long paper LS is performed using the curved conveyance path 533c will be described. The following is an example of the case of transporting the long paper LS having a length transported to the main transport path 530 through the curved transport path 533c in the forward transport in the reverse transport path 533.

  The long sheet LS is conveyed in the main conveyance path 530 in the forward direction (left direction in FIG. 1) from the external sheet feeding port 2a of the apparatus main body 2 via the external sheet feeding conveyance path 531. Thereafter, the long paper LS passes through the image forming unit 40 and the fixing unit 60, whereby the toner image is transferred and fixed on the first surface on the upper side, and from the main conveyance passage 530 to the first reflux conveyance passage 533a. It is conveyed to the reverse conveyance path 533 via When the long paper LS is conveyed in the forward direction indicated by the arrow a in the reverse conveyance path 533, the control unit 100 controls the conveyance roller 53b to drive the leading end of the conveyance direction into the curved conveyance path 533c. Thereafter, the leading end of the long sheet LS contacts the sheet guide forming the curved conveyance path 533c, moves (rises) along the curved shape of the sheet guide, and enters the conveyance roller 53c.

  The control unit 100 outputs a drive signal to the drive source so as to start the rotation of the transport roller 53c when the leading end of the long sheet LS rushes into the transport roller 53c, and both of the transport rollers 53b and 53c Transport the LS in the forward direction. Here, the control unit 100 outputs drive signals to the respective drive sources so that the peripheral speeds of the transport roller 53b and the transport roller 53c become the same. Thereafter, the long sheet LS passes through the curved conveyance path 533c and enters the main conveyance path 530 while being conveyed by both the conveyance rollers 53b and 53c.

  When the trailing end of the long paper LS in the conveyance direction passes the switchback point SBP, the control unit 100 separates (retracts) the conveyance roller 53c from the long paper LS and switches the conveyance roller 53b to rotate and convey Execute switchback operation to reverse the direction.

  By such conveyance control, the long paper LS is conveyed in the reverse direction with the advancing direction reversed, and the rear end of the conveyance direction moves the main conveyance path 530 in the reverse direction (right direction in FIG. 1). The front end is conveyed from the reverse conveyance path 533 to the main conveyance path 530 via the second reflux conveyance path 533 b.

  After that, the long paper LS passes through the second reflux conveyance path 533b, and is conveyed to the main conveyance path 530 with the first surface, which is the image forming surface, facing downward, and the toner is discharged onto the second surface that faces upward. The image is transferred and fixed. The control unit 100 controls the conveyance of the long paper LS having the toner image formed on both sides so as to be discharged from the main conveyance path 530 to the paper discharge unit 52.

  By the way, in the image forming apparatus 1 configured as described above, depending on the position of the jam generated in the ADU, the sheet size, and the like, it is difficult to perform processing after pulling out the ADU from the apparatus, that is, work to remove the jammed sheet. There is a case. In particular, as shown in FIG. 3, when a jam of the long paper LS occurs in the ADU, the conveyance is stopped in a state of being pinched by more conveyance rollers, so the work of removing the long paper is complicated. There is a problem that tends to be.

  Here, FIG. 3 exemplifies a case where a jam occurs while the double-sided print job of the long paper LS is being performed in the image forming apparatus 1. In the example shown in FIG. 3, when the switchback operation of the long paper LS finished printing on the first side, the leading end (the end on the left side in FIG. 3) of the long paper LS in the transport direction is the switchback point SBP. This is a case where a jam occurs due to being caught by a branch path or a gate (not shown).

  In this case, since the end of the long paper LS is not inserted into the second reflux conveyance path 533b within a predetermined time, the control unit 100 outputs the output of the sheet sensor or the like in the second reflux conveyance path 533b. By monitoring, it is possible to detect that a jam has occurred on the long paper LS. Thus, when detecting the occurrence of a jam, the control unit 100 stops (immediately cuts off) the print job and controls the display unit 21 to issue a warning that the jam has occurred.

  Here, after pulling out the ADU from the apparatus main body 2, the operator grasps, for example, both ends in the width direction of the jammed long paper LS, pulls it outward (in this example, downward) of the ADU, and removes it from the ADU There is a need to. On the other hand, in the double-sided conveyance path having the curved shape as described above, since the long paper LS is stuck to the inner (upper) paper guide, an operation such as gripping the long paper LS is performed. There are disadvantages such as difficulty.

  More specifically, as described above, a part of the outer (lower or bottom) sheet guide (main body lower guide 534) of the pair of sheet guides constituting the linear conveyance path in the reverse conveyance path 533. ) Is fixed to the device body side. Therefore, when the ADU is pulled out, a part (lower surface) of the long paper LS can be viewed from the opening corresponding to the area of the lower guide 534 on the main body side. On the other hand, in this example, the path for double-sided conveyance is substantially annular, and the long paper LS is wound around the inner guide member, in other words, stuck on the upper side, the paper is drawn downward. There is a problem that it is difficult to work.

  In addition, the operator needs to remove the jammed sheet (long sheet LS) from the ADU so as not to damage it as much as possible. That is, if a sheet breakage or the like occurs in the removal operation, fragments or powder of the sheet may remain in the ADU, which may cause deterioration of a print image, a failure of the apparatus, or the like later.

  In the example of FIG. 3, the long paper LS is in a state of being curved by the curved conveyance path 533c, and not only the conveyance roller 53b and the conveyance roller 53c, but also a plurality of conveyance rollers in the main conveyance path 530 (resist It is in the state of being pinched by the roller pair 53a etc.). For this reason, in order to remove the long paper LS from the ADU so as not to break it, it is necessary to work in a predetermined direction, for example, the lower right direction indicated by the arrow in FIG. Work effort can be significant.

  Therefore, in the image forming apparatus 1 according to the present embodiment, the sheet is jammed when the print job and the sheet conveyance are stopped due to the sheet jam in order to improve the workability of sheet removal after pulling out the ADU. It was configured to form sag. More specifically, in the present embodiment, by rotating (driving or rotating) at least one of the two transport rollers (first and second transport rollers) transporting the jammed sheet. And forming a slack at a portion of the sheet between the two conveyance rollers.

  Hereinafter, with reference to FIG. 4, slack formation of the sheet will be described more specifically. In the present embodiment, when the long paper LS is being conveyed by (both of) the conveyance roller 53 b and the conveyance roller 53 c in the reverse conveyance path 533, the control unit 100 causes a jam of the long paper LS. And a process of forming a slack on the sheet portion between the conveying roller 53b and the conveying roller 53c.

  Specifically, the control unit 100 drives the conveyance roller on the side where jamming does not occur among the conveyance roller 53b and the conveyance roller 53c, and forms the slack on the long sheet LS. The timing for driving the transport rollers 53b or 53c is, in one example, at the time of stopping the print job when the jam occurs. Alternatively or additionally, the timing of driving the transport roller 53b or 53c may be after the ADU is pulled out.

  In the example shown in FIGS. 3 and 4, since the jam occurs on the side of the conveyance roller 53b, when the conveyance roller 53b is driven, the load generated on the drive source of the conveyance roller 53b may be increased. Therefore, in such a case, the control unit 100 does not drive the transport roller 53b, and drives the transport roller 53c to form a slack on the long paper LS. At this time, the other conveyance roller (other than the conveyance roller 53b) holding the long paper LS may be driven in the same direction as the conveyance roller 53c.

  By performing such a slack formation process, as shown in FIG. 4, in a state where the ADU is pulled out from the apparatus main body 2, a part of the jammed sheet (long sheet LS) passes through the above-mentioned opening portion By exposing to the outside (lower side) of the ADU, the labor of the operator for removing the sheet is reduced.

  In the control example described above, when a jam occurs on the transport roller 53c side, the control unit 100 drives the transport roller 53b to form a slack on the long paper LS, thereby achieving the above The same effect is obtained.

  Next, another configuration example for forming the sheet slack in the present embodiment will be described.

  As another example for forming the slack, when a jam occurs, the timing at which the downstream conveyance roller in the conveyance direction is stopped is made earlier than the timing at which the upstream conveyance roller is stopped. More specifically, in the example shown in FIG. 3, since the jam occurs when the long paper LS advances to the left side in the drawing, the transport roller 53b (switchback roller) is on the downstream side in the transport direction. (The front end side of the sheet), and the conveyance roller 53c is on the upstream side (the rear end side of the sheet).

  In this case, when the control unit 100 receives the jam detection signal and stops the print job, the control unit 100 stops the conveyance roller 53b on the downstream side, and then stops the conveyance roller 53c and the conveyance roller on the upstream side thereof. Thus, the control signal is output to the drive source of each transport roller. In this manner, by setting different timings for stopping the transport roller 53b and the transport roller 53c, slack can be formed on the sheet.

  Generally, jamming is more likely to occur on the downstream side, that is, the front end side of the sheet than on the upstream side in the sheet conveyance direction, that is, the rear end side of the sheet. Therefore, the control unit 100 can form the slack of the sheet simply and quickly by performing the control as described above.

  Also in this case, slack is formed in the portion between the transport rollers 53b and 53c in the long paper LS, as described above. Also, when the ADU is pulled out, as shown in FIG. 4, the sheet slacks downward so that a part of the sheet is exposed to the outside from the opening area without the sheet guide (main body side lower guide 534). Paper removal work is facilitated.

  As another example for forming the slack, when ADU is pulled out from the apparatus main body 2 at the time of jam processing, the transport roller 53b or 53c is rotated by a fixed amount without performing drive control by the control unit 100, and the transport roller 53b And a mechanism for forming a slack on the paper portion between 53c and 53c. By this mechanism, the transport roller 53b or 53c is rotated by an amount of rotation corresponding to the amount by which the ADU is pulled out from the apparatus main body 2, and the slack described above is formed on the sheet.

  As such a configuration example, a mechanism for converting the movement (position change) of the ADU into the rotation of the transport roller 53b or 53c is provided alternatively or additionally. More specifically, a change in position when the ADU is pulled out is converted to a rotation of the gear by the rack fixedly provided on the apparatus body side and the ADU side gear (each not shown) engaged with the rack, A mechanism for transmitting the rotation of the gear to the transport roller 53b and / or the transport roller 53c is provided. In addition, it is preferable to provide a mechanism in which the drive of the motor or the like for driving the transport rollers 53b and 53c is released when the transport is stopped or when the ADU is pulled out.

  In addition, for example, the inertia (inertial force) of the conveyance rollers 53b and 53c at the time of stopping the jam may be used to form a slack in the sheet portion between the conveyance rollers 53b and 53c. Specifically, by providing a difference in the time until the rotation stop of both rollers (53b and 53c) or the conveyance distance at the time of driving stop (immediate disconnection) of the transfer rollers 53b and 53c at the time of jam stop, the transfer rollers 53b and 53c A slack is formed on the portion of the long paper LS in between.

  Hereinafter, an example of processing executed by the control unit 100 when a jam of the long paper LS occurs will be described with reference to the flowchart at the time of jam processing shown in FIG. The flowchart shown in FIG. 5 is premised on a configuration example in which a slack is formed by driving and controlling one of the two conveyance rollers 53b and 53c among the above-described various slack formation methods.

  In step S110 after inputting the jam detection signal, the control unit 100 stops each component (image forming unit 40, sheet conveyance unit 50, fixing unit 60, etc.) in operation so as to stop (immediately cut off) the print job. Control.

  In the subsequent step S120, the control unit 100 acquires positional information of the jammed sheet. Here, as the positional information of the sheet, information indicating the current position of the sheet stopped by the jam is included. In this example, as information indicating the current position of the sheet (long sheet LS), information indicating the position of the end (the leading end and the rear end in the transport direction) of the long sheet LS is included. Such positional information can be acquired by a known method such as acquiring from a position sensor (not shown) in the apparatus or calculating from the sheet conveyance timing.

  Further, information indicating the current position of the long sheet LS includes information indicating a jammed position of the sheet, that is, a position on the conveyance path where the sheet is jammed (hereinafter referred to as jam position information). Such jam position information can be obtained by a known method, and for example, a torque value or current among various drive sources for sheet conveyance (a motor for driving the conveyance roller, a solenoid for switching the conveyance path of the sheet, etc.) The position of the jam can be identified from a value or the like that has jumped.

  At this time, the control unit 100 causes the display unit 21 to display a warning screen indicating that a jam has occurred. Further, the control unit 100 displays a jam occurrence location based on the above-described jam position information in the warning screen, and displays on the display unit 21 the procedure etc. which the operator should perform in order to remove the sheet (long sheet LS). indicate.

  In the subsequent step S130, the control unit 100 determines whether or not the jammed sheet is between the two conveying rollers A and B adjacent to each other. In this example, the control unit 100 determines whether the jammed long sheet LS is present in each nip of the transport rollers 53b and 53c.

  Here, when the control unit 100 determines that the jammed long sheet LS is not in the nip of both the transport rollers 53b and 53c (step S130, NO), the removal operation of the jammed sheet is easy. The processing ends without performing the processing for forming slack (step S140).

  On the other hand, when the control section 100 determines that the jammed long sheet LS is in each nip of the transport rollers 53b and 53c (that is, sandwiched by two transport rollers 53b and 53c) (step S130, Yes) ), Shift to step S140.

  In step S140, the control unit 100 performs a process of forming a slack on the long sheet LS. In this example, the control unit 100 stands by until the ADU is pulled out of the apparatus body 2, and when the ADU is pulled out of the apparatus body 2, the transport roller 53c is rotationally driven to form a slack on the long sheet LS. Perform the process (see FIG. 4).

  By this processing, the long sheet LS is exposed to the outside (downward) from the above-mentioned opening of the ADU, and the operator can easily pull out the long sheet LS. The amount of rotation (that is, the amount of slack of the sheet) of the transport roller 53c at the time of forming the slack may be arbitrarily adjusted in advance by the user through a setting screen or the like (not shown).

  After that, when the control unit 100 detects that the ADU is closed (is returned to the apparatus main body 2), whether or not the paper remains in the ADU based on the output of each paper sensor in the ADU judge. Then, if the control unit 100 determines that no sheet remains in the ADU, the series of processing ends.

  As described above, according to the present embodiment, when the ADU is pulled out of the apparatus main body 2 at the time of jamming of the long paper LS (paper) during double-sided printing operation, a part of the jammed paper is By exposing the ADU to the outer side (lower side), the workability of the paper removal can be improved.

  In the embodiment described above, among the pair of upper and lower sheet guides between the two conveyance rollers 53b and 53c, a part of the lower sheet guide (main body lower guide 534) is fixed to the apparatus main body 2 side The structure is illustrated (see Fig. 1 etc.). As another example, a part of the lower sheet guide may be a part of the ADU (that is, can be inserted into and removed from the apparatus main body 2), and a left end in the figure may be hinged. In such a structure, when the ADU is pulled out, a part (right side portion) of the lower sheet guide moves downward, and the slack portion of the long sheet LS where the jam occurs is exposed downward, as described above. Similarly, the work of pulling in the direction of the arrow in FIG. 4 can be easily performed.

  The above-mentioned embodiment and modification are merely examples of implementation for carrying out the present invention, and the technical scope of the present invention should not be interpreted limitedly by these. . That is, the present invention can be implemented in various forms without departing from the scope or main features of the present invention.

Reference Signs List 1 image forming apparatus 2 apparatus main body 2a external sheet feeding port 10 image reading section 20 operation display section 30 image processing section 40 image forming section 50 sheet conveying section 51 sheet feeding section 51a to 51c sheet feeding tray unit 52 sheet discharging section 53 conveying path Section 53a Registration roller pair 53b Transport roller (first or second transport roller)
53c Conveying roller (second or first conveying roller)
530 main conveyance path 531 external paper feeding conveyance path 532 paper feeding conveyance path 533 reverse conveyance path 533a first return conveyance path 533b second return conveyance path 533c curved conveyance path 534 main body lower guide (part of paper guide)
60 fixing unit 100 control unit (transport control unit)
ADU Automatic Two-sided Reversing Transport Unit SBP Switch Back Point LS Long Paper

Claims (11)

An image forming unit that forms an image on a sheet;
A sheet conveyance path provided with a first conveyance roller and a second conveyance roller along the conveyance direction of the sheet, and connected to the image forming unit;
And a conveyance control unit configured to control conveyance of the sheet so as to pass the sheet through the sheet conveyance path.
When the sheet is conveyed by the first and second conveyance rollers and the conveyance is stopped due to a jam, the rotation of at least one of the first conveyance roller and the second conveyance roller causes the sheet to be slackened. Form,
Image forming apparatus. The conveyance control unit forms the slack on the sheet by changing the stop timings of the first conveyance roller and the second conveyance roller.
An image forming apparatus according to claim 1. The conveyance control unit stops the conveyance roller on the downstream side in the direction in which the sheet is conveyed among the first and second conveyance rollers earlier than the other conveyance rollers.
An image forming apparatus according to claim 2. The sheet conveyance path can be taken in and out of the apparatus main body.
The image forming apparatus according to any one of claims 1 to 3. A slack is formed on the sheet by rotating at least one of the first conveyance roller and the second conveyance roller in conjunction with the sheet conveyance path being pulled out from the apparatus main body.
The image forming apparatus according to claim 4. The sheet conveyance path includes a pair of sheet guides configured to form an opening that exposes slack formed on the sheet to the outside when the sheet conveyance path is pulled out from the apparatus main body.
The image forming apparatus according to claim 4. The sheet conveyance path is a double-sided conveyance path that reverses the front and back of the sheet and conveys the sheet to the upstream side of the image forming unit by reversing the sheet conveyance direction at a switchback point,
Of the pair of sheet guides, the inner sheet guide is disposed in a unit that can be inserted into and removed from the apparatus body, and a part of the outer sheet guide is fixed to the apparatus body.
The image forming apparatus according to claim 6. The conveyance control unit is configured to cause at least the first conveyance roller and the second conveyance roller to expose the slack portion of the sheet outward from the opening when the sheet conveyance path is pulled out of the apparatus main body. Control one rotation,
The image forming apparatus according to claim 6. When the conveyance is stopped, a slack is formed on the sheet by providing a difference in the conveyance distance until the rotation is stopped by the inertial force of the first conveyance roller and the second conveyance roller.
An image forming apparatus according to any one of claims 1 to 8. The sheet is a long sheet,
The image forming apparatus according to any one of claims 1 to 9. A jam processing method in an image forming apparatus, comprising: a sheet conveyance path provided with a first conveyance roller and a second conveyance roller connected to an image forming unit for forming an image on a sheet and conveying the sheet;
When the sheet is conveyed by the first and second conveyance rollers and the conveyance is stopped due to a jam, the rotation of at least one of the first conveyance roller and the second conveyance roller causes the sheet to be slackened. Form,
Jam handling method.

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