JP2018090409A - Image formation device and paper transport control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an image to be formed on both sides of a long paper without increasing a size of a device.SOLUTION: An image formation device includes, as a double-sided transport path, a path in a transport direction before a paper is switched back, namely, a path that branches into a first double-sided path leading to an upstream side of an image forming unit and a second double-sided path leading to an opening of a device body on a paper transport path. When toner images are formed on both sides of a long paper, a tranport controller controls the long paper to pass either one of the first and second double-sided paths.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an image forming apparatus and a paper conveyance control method.

  Conventionally, an image forming apparatus that forms an image on a sheet using toner is known. Such an image forming apparatus is provided with a door that opens and closes the conveyance path so that the sheet can be removed from the conveyance path when a conveyance defect of the sheet occurs or the like (see, for example, Patent Document 1). .

  Some image forming apparatuses are provided with a reversing conveyance path that forms a conveyance path by reversing the front and back of a sheet so that the image can be formed on both sides by reversing the front and back of the sheet.

  In a conventional image forming apparatus, a sheet having a size that can be stored in a sheet feeding tray unit can be reversed on the front and back sides by a reversing conveyance path.

JP 2001-0119177 A

  In recent years, there is an increasing demand for sheets that are called long paper exceeding the size that can be stored in the paper feed tray unit so that images can be formed on both sides. However, in order to be able to reverse the front and back of the long paper, it is necessary to lengthen the path length of the reverse conveyance path, and there is a problem that the apparatus is likely to be enlarged.

  An object of the present invention is to provide an image forming apparatus and a paper conveyance control method capable of forming images on both sides of a long sheet without increasing the size of the apparatus.

An image forming apparatus according to the present invention includes:
An image forming unit for forming a toner image on a long paper;
A fixing unit for fixing the toner image formed on the long paper;
A main conveyance path for conveying the long paper to the image forming unit and the fixing unit;
A paper feed conveyance path for conveying the long paper to the upstream side in the conveyance direction of the image forming unit in the main conveyance path;
Branches from the downstream side of the fixing unit in the main conveyance path in the conveyance direction, and reverses the conveyance direction of the long paper at a switchback point so that the front and back of the long paper are reversed to the upstream side of the image forming unit. A double-sided conveyance path
A conveyance control unit for controlling conveyance of the long paper,
In the double-sided conveyance path, the path in the conveyance direction before the long paper is switched back is connected to the first double-sided path connected to the upstream side of the image forming unit in the paper conveyance path and the opening of the apparatus main body. Branch to the second double-sided path,
When the toner image is formed on both sides of the long paper, the conveyance control unit controls the long paper to pass through one of the first and second double-side paths.

The paper transport method according to the present invention includes:
In order to form an image on both sides of a long paper whose length in the transport direction is equal to or longer than a predetermined length, the path in the transport direction before the transport direction of the long paper is reversed at the switchback point is A paper conveyance control method in an image forming apparatus including a double-sided conveyance path that branches into a first double-sided path connected to an upstream side and a second double-sided path connected to an opening of the apparatus main body,
When a toner image is formed on both sides of the long paper, the long paper is conveyed so as to pass through one of the first and second double-side paths.

  According to the present invention, images can be formed on both sides of a long sheet without increasing the size of the apparatus.

1 is a configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. FIG. 2 is a diagram illustrating a main part of a control system in the image forming apparatus of FIG. 1. It is a figure which illustrates the conveyance state in the case of printing a long paper on both sides. It is a figure explaining the case where double-sided printing is carried out through a 1st double-side path | route. It is a figure which illustrates the conveyance state in the case of printing a long paper on both sides. It is a figure explaining the case where double-sided printing is carried out through a 2nd double-sided path | route. It is a figure explaining the case where double-sided printing is carried out through a 1st double-side path | route. It is a figure explaining the case where double-sided printing is carried out through a 1st double-side path | route. 6 is a flowchart illustrating a sheet conveyance process of the image forming apparatus according to the present embodiment.

  Embodiments of an image forming apparatus to which the present invention is applied will be described below with reference to the drawings.

  FIG. 1 is a diagram schematically showing an overall 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.

  The image forming apparatus 1 according to the present embodiment uses a long sheet LS as a first sheet or a sheet S (non-long sheet) as a second sheet as a recording medium, and the long sheet LS or the sheet S is used as a recording medium. This is an apparatus for forming an image.

  In the present embodiment, the long paper LS is a sheet having a longer length in the transport direction than commonly used A4 size paper, A3 size paper, etc., and is stored in the paper feed tray units 51a to 51c. Has a length that cannot be. The size of the long sheet 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 system. Hereinafter, when simply referred to as “paper”, both the long paper LS and the paper S may be included.

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

  Further, in the image forming apparatus 1, the photosensitive drums 413 corresponding to the four colors of YMCK are arranged in series in the running direction of the intermediate transfer belt 421, and the respective color toner images are sequentially transferred to the intermediate transfer belt 421 in one step. 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 paper transport unit 50, a fixing unit 60, and a control unit 100.

  The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads a program corresponding to the processing content from the ROM 102 and develops it in the RAM 103, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the developed program. At this time, various data stored in the storage unit 72 is referred to. The storage unit 72 includes, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

  The control unit 100 transmits and receives various data to and 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 composed of a communication control card such as a LAN card, for example.

  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 a transport mechanism and sends it out to the document image scanning device 12. The automatic document feeder 11 can continuously read images (including both sides) of a large number of documents D placed on a document tray all 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 from the document to 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 by the document image scanning device 12. The input image data is subjected to predetermined image processing in the image processing unit 30.

  The operation display unit 20 is configured by, 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, an image status display, an operation status of each function, and the like in accordance with a display control signal input from the control unit 100. The operation unit 22 includes various operation keys such as a numeric keypad 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 that performs digital image processing on input image data according to initial settings or user settings. For example, the image processing unit 30 performs gradation correction based on the gradation correction data (gradation 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 processes such as color correction and shading correction, a compression process, and the like on the input image data in addition to the gradation correction. The image forming unit 40 is controlled based on the image data subjected to these processes.

  The image forming unit 40 is based on the input image data, and image forming units 41Y, 41M, 41C, 41K, and an intermediate transfer unit 42 for forming an image using colored toners of Y component, M component, C component, and K component. Etc.

  The Y component, M component, C component, and K component image forming units 41Y, 41M, 41C, and 41K have the same configuration. For convenience of illustration and description, common components are denoted by the same reference numerals, and in order to distinguish each, Y, M, C, or K is added to the reference numerals. In FIG. 1, only the components of the Y-component image forming unit 41Y are denoted by reference numerals, and the constituent elements 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 has, for example, an undercoat layer (UCL), a charge generation layer (CGL), a charge transport layer (CGL) on the peripheral surface of an aluminum conductive cylinder (aluminum tube). 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 charges and negative charges by exposure by the exposure device 411. The charge transport layer consists of a material in which a hole transport material (electron donating nitrogen-containing compound) is dispersed in a resin binder (for example, polycarbonate resin), and transports positive charges generated in the charge generation layer to the surface of the charge transport layer. To do.

  The control unit 100 controls the drive current supplied to a drive motor (not shown) that rotates the photosensitive drum 413 to rotate the photosensitive drum 413 at a constant peripheral speed (linear speed).

  The charging device 414 uniformly charges the surface of the photoconductive drum 413 to a negative polarity. The exposure device 411 is composed of, for example, a semiconductor laser, and irradiates the photosensitive drum 413 with laser light corresponding to the image of each color component. A positive charge is generated in the charge generation layer of the photosensitive drum 413 and is 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 a potential difference from the surroundings.

  The developing device 412 is, for example, a two-component developing type developing device, and forms a toner image by visualizing the electrostatic latent image by attaching toner of each color component to the surface of the photosensitive drum 413.

  The drum cleaning device 415 includes a drum cleaning blade (hereinafter simply referred to as a cleaning blade) 416 serving as a cleaning member that 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 shape. At least one of the plurality of support rollers 423 is configured by a driving roller, and the other is configured by a driven roller. For example, it is preferable that the roller 423A disposed downstream of the K component primary transfer roller 422 in the belt traveling direction is a drive roller. This makes it easy to keep the belt running speed constant in the primary transfer portion. As the driving roller 423A rotates, the intermediate transfer belt 421 travels in the direction of arrow A at a constant speed.

  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 drum 413 of each color component. The primary transfer roller 422 is pressed against the photosensitive drum 413 with the intermediate transfer belt 421 interposed therebetween, thereby forming a primary transfer nip for transferring a toner image from the photosensitive drum 413 to the intermediate transfer belt 421.

  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 in the belt traveling direction of the drive roller 423A. The secondary transfer roller 424 is pressed against the backup roller 423B 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 paper S.

  When the intermediate transfer belt 421 passes through the primary transfer nip, the toner images on the photoconductive drum 413 are primarily transferred onto the intermediate transfer belt 421 in sequence. Specifically, a primary transfer bias is applied to the primary transfer roller 422, and an electric charge having a polarity opposite to that of the toner is applied to the back side of the intermediate transfer belt 421 (the side in contact with the primary transfer roller 422). It 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, by applying a secondary transfer bias to the secondary transfer roller 424 and applying a charge having a polarity opposite to that of the toner to the back side of the paper (the side in contact with the secondary transfer roller 424), the toner image becomes 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 includes a belt cleaning blade that is 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 the secondary transfer. Instead of the secondary transfer roller 424, a configuration (so-called belt-type secondary transfer unit) in which a secondary transfer belt is looped around a plurality of support rollers including the secondary transfer roller is adopted. Also good.

  The fixing unit 60 is arranged on the upper fixing unit 60A having a fixing surface side member arranged on the fixing surface (surface on which the toner image is formed) side of the paper, and on the back surface (surface opposite to the fixing surface) side of the paper. A lower fixing unit 60B having a back-side support member and a heating source 60C. When the back surface side support member is pressed against the fixing surface side member, a fixing nip for nipping and transporting the sheet is formed.

  The fixing unit 60 fixes the toner image on the sheet by secondarily transferring the toner image and heating and pressurizing the conveyed sheet at the fixing nip. The fixing unit 60 is disposed in the fixing device F as a unit. The fixing device F is provided with an air separation unit 60D that separates the sheet S from the fixing surface side member by blowing air.

  The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a transport path unit 53, and the like. In the three paper feed tray units 51a to 51c constituting the paper feed unit 51, paper S (standard paper, special paper) identified based on basis weight (rigidity), size, etc. is set for each preset type. Be contained. The conveyance path unit 53 includes a plurality of conveyance rollers such as a pair of registration rollers 53a, a double-sided conveyance path for forming an image on both sides of a sheet, and the like. Details of the transport path unit 53 will be described later.

  The sheets S stored in the sheet feed tray units 51 a to 51 c are sent one by one from the top and are conveyed to the image forming unit 40 by the conveyance path unit 53. At this time, the registration roller portion provided with the registration roller pair 53a corrects the inclination of the fed paper S and adjusts the conveyance timing. In the image forming unit 40, the toner image on the intermediate transfer belt 421 is secondarily transferred onto one side of the sheet S at a time, and a fixing process is performed in the fixing unit 60. The sheet S on which the image has been formed is discharged out of the apparatus by a discharge unit 52 having a discharge roller 52a.

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

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

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

  The main transport 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 transport path 530 is connected to the external paper feed transport path 531 and the paper feed transport path 532. Further, the other end of the main transport path 530 is connected to the discharge port of the discharge unit 52 provided on the other side of the apparatus main body 2.

  One end of the external sheet feed conveyance path 531 is connected to the external sheet feed port 2 a, and the other end is connected to the main conveyance path 530. The paper feed conveyance path 532 is provided in the vicinity of one side in the apparatus main body 2, and extends in the vertical (substantially vertical) direction from the paper feed tray units 51 a to 51 c to the main conveyance path 530. In the paper feed conveyance path 532, a part of the path of the paper feed conveyance path 532 is exposed to the outside by opening the opening / closing door 54 provided on one side of the apparatus main body 2, and jamming or the like is possible. become. The paper feed transport path 532 has an upper end connected to the main transport path 530 and a lower end connected to the paper feed tray units 51a to 51c. Further, the paper feed conveyance path 532 is connected so as to intersect with an external conveyance path P2 as a second double-sided path to be described later.

  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 reflux conveyance path 533 a that branches downward from the main conveyance path 530 on the downstream side of the fixing unit 60 in the conveyance direction of the sheet conveyed through the main conveyance path 530, and the image forming unit 40. A second reflux conveyance path 533b that joins the main conveyance path 530 is provided upstream 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 that switches between forward and reverse of the paper traveling direction (conveyance direction) during duplex printing. Point SBP. Hereinafter, in the reverse conveyance path 533, the conveyance direction indicated by the arrow a in which the sheet is conveyed from the first reflux conveyance path 533a is referred to as a positive direction, and is indicated by the arrow b in which the sheet is conveyed to the second reflux conveyance path 533b. The conveyance 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 normal conveyance direction with respect to the switchback point SBP. The conveying roller 53b receives a driving force of a motor (not shown) and conveys the paper in both the forward direction and the reverse direction.

  Further, the other end side of the reverse conveyance path 533 extends to a connection conveyance path P1 as a first double-sided path that connects the reverse conveyance path 533 and the main conveyance path 530, and an external paper discharge port 2b of the apparatus main body 2. Branches to the out-of-machine conveyance path P2 as the second double-side path. The branch path is provided with a switching gate 533g as a switching mechanism that switches the transport direction of the long paper LS to either the connected transport path P1 or the external transport path P2.

  The connecting conveyance path P1 is a double-sided path used for duplex printing of paper inside the apparatus main body 2, and is connected to the main conveyance path 530 on the upstream side of the registration roller 53a in the conveyance direction of the sheet conveyed in the forward direction. Join. In this example, the connection conveyance path P1 joins upstream from the junction of the main conveyance path 530 and the second reflux conveyance path 533b. The connected conveyance path P1 merges with the main conveyance path 530 in a direction in which the sheet is conveyed in the forward direction along the main conveyance path 530.

  The out-of-machine conveyance path P2 is a double-sided path having a role of extending the traveling path at the front end of the sheet conveyance direction to the outside of the apparatus body 2, and extends linearly in the conveyance direction of the sheet conveyed in the forward direction. It is connected to an external paper discharge port 2b provided on one side surface of the main body 2. The external conveyance path P <b> 2 is connected so as to intersect with the paper feed conveyance path 532. When the open / close door 54 of the apparatus main body 2 is closed, the external discharge port 2b is closed by the open / close door 54 (see FIG. 3), and the original function of the external conveyance path P2 is limited. Therefore, in order to detect the open / closed state of the open / close door 54, a side door open / close sensor (not shown) is disposed in the vicinity of the external paper discharge port 2b.

  As described above, in the present embodiment, the double-sided conveyance path is branched into two of the coupled conveyance path P1 and the external conveyance path P2, and an image is formed on both sides of the long paper LS. Double-sided printing can be performed using either the connected transport path P1 or the external transport path P2.

  Further, in the present embodiment, as shown in FIG. 1, the branch point between the connection transport path P1 and the external transport path P2 and the switching gate 533g are provided at a position relatively close to the side of the apparatus main body 2. Both the connection conveyance path P1 and the external conveyance path P2 are relatively short paths. By adopting such a configuration, most of the two double-sided conveyance paths are shared in the apparatus main body 2, which contributes to cost reduction and size reduction of the apparatus main body 2.

  Next, a case where duplex printing is performed on the paper S fed from the paper feed tray units 51a to 51c will be described. In the image forming apparatus 1, the sheet S that has been conveyed in the forward direction (left direction in FIG. 1) through the main conveyance path 530 and passed through the image forming unit 40 and the fixing unit 60 faces upward (first surface). A toner image is transferred and fixed to the toner image. Subsequently, the sheet S is transported and controlled by the control unit 100 so that the sheet S is transported from the main transport path 530 to the reverse transport path 533 via the first reflux transport path 533a. Further, when the trailing end of the sheet S in the transport direction passes the switchback point SBP, the control unit 100 switches the rotation direction of the transport roller 53b to reverse the transport direction, and the sheet S is transferred from the reverse transport path 533 to the second reflux. The conveyance control is performed so as to convey to the main conveyance path 530 via the conveyance path 533b.

  With this transport control, the paper S, which is a non-long paper, is transported in the forward direction indicated by the arrow a before the leading edge of the paper S enters the connection transport path P1 or the external transport path P2. The rear end passes through the switchback point SBP. Subsequently, the sheet S 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 image is formed on the second surface facing upward. It will be possible. The sheet S on which the toner images are formed on both sides is transport-controlled by the control unit 100 so that the sheet S is discharged from the main transport path 530 to the paper discharge unit 52. Therefore, when the paper S, which is a non-long paper, is printed on both sides, the paper S is not transported to either the connected transport path P1 or the external transport path P2.

  Next, the case where double-sided printing of long paper LS is performed using the connection conveyance path P1 is demonstrated. The long sheet LS is conveyed in the forward direction (left direction in FIG. 1) from the external sheet feed port 2a of the apparatus main body 2 via the external sheet feed conveyance path 531. Thereafter, in the same manner as described above, the long paper LS that has passed through the image forming unit 40 and the fixing unit 60 has the toner image transferred and fixed on the upper first surface, and the first reflux conveyance path from the main conveyance path 530. It is conveyed to the reverse conveyance path 533 via 533a (see FIG. 3). When the long sheet LS is conveyed in the forward direction indicated by the arrow a in the reverse conveyance path 533, the control unit 100 performs conveyance control so that the switching gate 533g is appropriately switched and the leading end in the conveyance direction enters the connection conveyance path P1. Is done. Then, as shown in FIG. 4, when the trailing end of the long paper LS in the transport direction passes the switchback point SBP, the control unit 100 switches the rotation direction of the transport roller 53b and reverses the transport direction. Perform the action. After this operation, the long paper LS is transported and controlled by the control unit 100 so as to be transported from the reverse transport path 533 to the main transport path 530 via the second reflux transport path 533b.

  With this conveyance control, in the conveyance in the forward direction on the reverse conveyance path 533, the leading edge of the long paper LS enters the connection conveyance path P1, and depending on the size of the long paper LS (length in the conveyance direction), As shown in FIG. 4, it joins the main transport path 530. In this case, when the paper is transported in the reverse direction due to the reversal of the transport direction, the rear end of the long paper LS in the transport direction moves in the reverse direction (the right direction in FIG. 4) on the main transport path 530.

  Thereafter, as in the case of the sheet S, the long sheet LS is conveyed to the main conveyance path 530 through the second reflux conveyance path 533b with the first surface as the image forming surface facing downward ( 5), an image can be formed on the second surface facing upward. The long paper LS on which the toner images are formed on both sides is transported and controlled by the control unit 100 so as to be discharged from the main transport path 530 to the paper discharge unit 52.

  Next, a case where double-sided printing of the long paper LS is performed using the external conveyance path P2 will be described. Similarly to the above, the long paper LS is conveyed in the forward direction (left direction in FIG. 1) from the external sheet feed port 2a of the apparatus main body 2 through the external sheet feed conveyance path 531. . Thereafter, the long paper LS having passed through the image forming unit 40 and the fixing unit 60 has the toner image transferred and fixed on the upper first surface, and passes from the main conveyance path 530 via the first reflux conveyance path 533a. It is conveyed to the reverse conveyance path 533. When the long sheet LS is conveyed in the forward conveyance path 533 in the positive direction indicated by the arrow a, the switching gate 533g is appropriately switched (see FIG. 6), and the leading end in the conveyance direction is the out-of-machine conveyance path P2. The conveyance is controlled by the control unit 100 so as to enter. Then, as illustrated in FIG. 6, when the trailing end of the long paper LS in the conveyance direction passes the switchback point SBP, the control unit 100 switches the rotation direction of the conveyance roller 53 b to reverse the conveyance direction, The conveyance control is performed so that the paper LS is conveyed from the reverse conveyance path 533 to the main conveyance path 530 via the second reflux conveyance path 533b.

  With such conveyance control, in the conveyance in the forward direction on the reverse conveyance path 533, the leading edge of the long paper LS enters the external conveyance path P2, and as shown in FIG. It is exposed to the outside of the apparatus main body 2 from the external paper discharge port 2b. Thereafter, when the paper is transported in the reverse direction by the switchback operation, that is, the reversal of the transport direction, the rear end side of the long paper LS in the transport direction moves so as to be drawn into the apparatus main body 2 from the external paper discharge port 2b. To do.

  By the way, the connection conveyance path P1 and the out-of-machine conveyance path P2 have different properties and characteristics (advantages, disadvantages, etc.) as described below. In view of such different properties, in the present embodiment, in a print job for forming an image on both sides of the long paper LS, the control unit 100 preferentially passes the long paper LS through the connection conveyance path P1. Control. In the present embodiment, in a print job for forming an image on both sides of the long paper LS, the image forming conditions are referred to, and depending on the image forming conditions, the long paper LS is exceptionally passed through the external conveyance path P2. To control.

  Here, the image forming conditions include the type (length and stiffness) of the long paper LS to be subjected to double-sided printing, the image coverage (printing rate) for the long paper LS, and the setting state (power mode) of the image forming apparatus 1. , User setting state, etc.), physical state of the image forming apparatus 1 (temperature state, open / close state of various doors, etc.) and the like.

  Hereinafter, a difference in properties between the connection conveyance path P1 and the external conveyance path P2 and conveyance control during double-sided printing of the long paper LS will be described.

(Viewpoint of preventing substantial increase in size of equipment)
When double-sided printing of long paper LS is performed using the connected conveyance path P1, the conveyance path for double-sided printing is secured in the apparatus main body 2, so that the opening / closing door 54 of the apparatus main body 2 is closed. (See FIGS. 4 and 5).

  On the other hand, when performing double-sided printing of the long paper LS using the external conveyance path P2, as shown in FIG. 6, it is necessary to open the opening / closing door 54 of the apparatus main body 2 in advance, and during double-sided printing. Is substantially extended to the outside of the apparatus main body 2. For this reason, when double-sided printing of the long paper LS is performed using the external conveyance path P2, the image forming apparatus 1 is substantially increased in size.

  Therefore, from the viewpoint of preventing substantial increase in the size of the image forming apparatus 1, in other words, in order to form an image on both sides of the long paper LS without increasing the size of the apparatus, the connection conveyance path P1 is used. It is desirable.

(Viewpoint of equipment installation conditions, etc.)
When double-sided printing of the long paper LS is performed using the connection conveyance path P1, the open / close door 54 of the apparatus main body 2 can be closed as described above. The side surface on the 2b side can be made relatively close to a wall or the like.

  On the other hand, when double-sided printing of the long paper LS is performed using the external conveyance path P2, as shown in FIGS. 1 and 6, the opening / closing door 54 of the apparatus main body 2 is opened in advance, and the external paper discharge port 2b is opened. Must be open. Here, when a wall or a baggage is located on the external discharge port 2b side of the apparatus main body 2, the opening / closing door 54 may not be opened. Alternatively, even when the open / close door 54 can be opened, the long paper LS exposed to the outside of the apparatus main body 2 during the double-sided printing operation may interfere with the luggage or the like and may cause a jam.

  Therefore, it is more advantageous to use the connection conveyance path P1 from the viewpoint of the installation conditions of the image forming apparatus 1 and the like.

(Perspective from the ease of jam handling)
When performing double-sided printing of the long paper LS, there is a possibility that the long paper LS may be jammed in the apparatus, that is, jammed, regardless of whether the connection transport path P1 or the external transport path P2 is used. .

  Here, when the jam of the long paper LS occurs during the double-sided printing operation using the connection conveyance path P1, the entire long paper LS remains in the apparatus (in the apparatus main body 2) at any time point. Jam processing can be performed relatively easily. On the other hand, if jamming of the long paper LS occurs during the double-sided printing operation using the external conveyance path P2, the long paper LS is not drawn until the entire long paper LS is pulled into the apparatus main body 2 by the switchback. A part of LS is exposed to the outside of the apparatus main body 2 from the external paper discharge port 2b (see FIG. 6). For this reason, when a jam of the long paper LS occurs during the double-sided printing operation using the external conveyance path P2, it may be difficult to perform the jam processing.

  Therefore, it is more advantageous to use the connection conveyance path P1 also from the viewpoint of ease of jam processing.

(Perspective of workability during double-sided printing)
When double-sided printing of the long paper LS is performed, regardless of whether the connection conveyance path P1 or the external conveyance path P2 is used, various types provided on the front side (front side in FIG. 1) of the apparatus main body 2 By opening the door, operations such as replenishing the paper S by pulling out the paper feed tray units 51a to 51c or replenishing the toner by replacing the toner bottle can be performed during the execution of the print job.

  Here, when the double-sided printing of the long paper LS is performed using the external conveyance path P2, if the toner bottle is replaced, the long paper LS is exposed to the outside from the external paper discharge port 2b of the apparatus main body 2. When the toner in the toner bottle spills during the printing, the long paper LS may become dirty. Further, when the paper S is replenished, the exposed portion of the long paper LS is replenished while the long paper LS is exposed to the outside from the external paper discharge port 2 b of the apparatus body 2. There is a possibility that damage such as corner breakage of the long paper LS may occur due to contact with the bundle or the like. On the other hand, when double-sided printing of the long paper LS is performed using the connection conveyance path P1, such a problem is unlikely to occur.

  Therefore, it is more advantageous to use the connection conveyance path P1 from the viewpoint of workability during execution of double-sided printing.

  In view of such a point, in the present embodiment, in a print job for forming an image on both sides of the long paper LS, the control unit 100 conveys the long paper LS so as to pass through the connection conveyance path P1. Basic (default). On the other hand, as described below, depending on the image forming conditions, it may not be suitable to use the connection conveyance path P1, and in such a case, the control unit 100 transfers the long paper LS to the outside conveyance path. The conveyance is controlled so as to pass through P2.

(Perspective from the paper size)
When the connection transport path P1 is used, depending on the size of the long paper LS, the front end in the transport direction of the long paper LS re-enters the paper transport path 530 during the forward transport before the switchback as described above. (See FIG. 4). In addition, when the size of the long paper LS is longer, the front side in the transport direction of the long paper LS is the secondary of the image forming unit 40 with the image forming surface facing upward during transport in the forward direction before switchback. It reaches the transfer nip, and further reaches the fixing unit 60 as shown in FIG. Here, when the toner image on the image forming surface of the long paper LS straddles the fixing nip of the fixing unit 60, the toner image is re-fixed by the fixing nip. Problems such as increased gloss or image roughness occur (hereinafter referred to as Problem 1).

  Further, when using the coupled transport path P1, depending on the length of the long paper LS, as shown in FIG. 8, when transporting in the reverse direction after switchback, The main transport path 530 is moved in the reverse direction (right direction in FIG. 8). At this time, the leading edge in the transport direction of the long paper LS transported to the second reflux transport path 533b passes the lower surface of the own paper moving in the reverse direction on the main transport path 530, so that a jam or the like occurs. It is considered that it is likely to occur (hereinafter referred to as problem 2).

  On the other hand, when using the out-of-machine conveyance path P2, the long side paper LS is exposed to the outside in the forward direction in the conveyance direction from the external discharge port 2b during the forward conveyance before the switch back (see FIG. 6). During subsequent transport in the reverse direction, the portion exposed outside the machine is returned to the machine. Therefore, when the out-of-machine conveyance path P2 is used, the problems 1 and 2 do not occur regardless of the length of the sheet, the size of the machine body, the path length, and the like.

  From this point of view, the control unit 100 passes the long paper LS through the out-of-machine conveyance path P2 when the length of the long paper LS exceeds a threshold in a job for image formation on both sides of the long paper LS. The conveyance is controlled as follows. On the other hand, when the length of the long paper LS is equal to or smaller than the threshold, the control unit 100 controls the conveyance so that the long paper LS passes through the connection conveyance path P1.

  Here, the length threshold of the long paper LS is set so that the length of the long paper LS reaches the fixing nip from the switchback point SBP via the connection conveyance path P1 in order to cope with the above-described problem 1. It is based on whether or not it is a length (see FIG. 7).

  Alternatively, the threshold of the length of the long paper LS is set so that the length of the long paper LS is changed from the switchback point SBP to the main transport path 530 via the connection transport path P1 in order to cope with the above-described problem 2. A length equal to or greater than the value obtained by adding the length to the joining position and the length from the switchback point SBP to the joining position to the main transport path 530 via the second reflux transport path 533b (see FIG. 8). Or not.

(Perspective from paper stiffness)
As shown in FIG. 1, the connection conveyance path P1 is a path having a curvature, while the external conveyance path P2 is a linear path. For this reason, when using the long paper LS having high rigidity, the paper feeding resistance (conveying load) is relatively smaller when the connecting conveying path P2 is used than when the out-of-machine conveying path P1 is used.

  From this point of view, in the job for forming an image on both sides of the long paper LS, the control unit 100 passes the connection conveyance path P1 when the rigidity of the long paper LS is low, and externally when the rigidity is high. The long paper LS is controlled to pass through the transport path P2.

(Perspective from printing rate (coverage))
As described above, the connection conveyance path P1 is a path having a curvature and continuing to the main conveyance path 530. For this reason, when the printing rate (coverage) of the toner image formed on the first surface of the long paper LS is high, it is relatively more preferable to use the coupled transport path P2 than to the out-of-machine transport path P1. The damage (such as scratches) is unlikely to occur.

  From this point of view, the control unit 100, in a job for forming an image on both sides of the long paper LS, passes through the connecting conveyance path P1 when the printing rate (coverage) of the first side of the long paper LS is low, When the coverage is high, the conveyance control is performed so that the long paper LS passes through the out-of-machine conveyance path P2.

(Perspective from power consumption etc.)
As described above, when the connection transport path P1 is used, depending on the length of the long paper LS, a jam or the like is likely to occur due to the above-described problem 2 (see FIG. 8). In order to cope with the problem 2, when the one end side and the other end side of the long sheet LS are crossed by the main transport path 530, the roller pair of the main transport path 530 is separated from the main transport path 530, or the main transport path It is conceivable to perform control such as reversing the rotation direction of the upper roller of 530. On the other hand, when such control is performed, the possibility of jam occurrence can be reduced, but the power consumption increases.

  From this point of view, the control unit 100 determines whether the job is to form an image on both sides of the long paper LS, either in the connected conveyance path P1 or in the external conveyance path P2, depending on the power consumption setting mode in the image forming apparatus 1. The long paper LS is controlled to pass therethrough. Specifically, when the power consumption setting mode is a mode that requires energy saving (such as a power saving mode or a monochrome printing mode), the control unit 100 causes the long paper LS to pass through the out-of-machine conveyance path P2. Transport control. On the other hand, when the power consumption setting mode is not a mode for demanding energy saving, the control unit 100 controls the conveyance so that the long paper LS passes through the connection conveyance path P1.

(Viewpoint from the life of the main transport path members)
When double-sided printing is performed using the connected conveyance path P1, one end side of the long paper LS is re-entered into the main conveyance path 530, and therefore, compared with the case where double-sided printing is performed using the external conveyance path P2. The number of times of use of rollers, sensors, etc. arranged in the conveyance path 530 increases.

  From this point of view, the control unit 100 refers to the usage history of components such as rollers and sensors arranged in the main conveyance path 530 in a job for forming an image on both sides of the long paper LS, and these components are at the end of durability. If not, the long paper LS is transported and controlled so as to pass through the connection transport path P1, and if these components are in the end of durability, they pass through the external transport path P2. The determination as to whether or not such a component is at the end of durability is performed by, for example, counting the number of times the sheet has been conveyed to the main conveyance path 530 and determining that the component is at the end of durability when the number of conveyance exceeds a predetermined value. Like that.

  Alternatively, when components such as a roller and a sensor are arranged in the connection conveyance path P1 and the external conveyance path P2, the control unit 100 performs the conveyance paths P1 and P2 in a job for forming an image on both sides of the long paper LS. Refer to the usage history of parts. Then, when the durability of the components of the connection conveyance path P1 is in the final stage or when the control unit 100 has failed, the control section 100 passes through the out-of-machine conveyance path P2, and the durability of the components of the external conveyance path P2 is in the final stage. In the case of failure or failure, the long paper LS is transported and controlled so as to pass through the connected transport path P1.

(Viewpoint of temperature rise in the machine)
As described above, when performing double-sided printing using the connected conveyance path P1, the long paper LS on which the toner image heated and fixed by the fixing unit 60 is re-entered into the main conveyance path 530. Tends to rise. On the other hand, when performing duplex printing using the external conveyance path P2, a part of the long paper LS on which the toner image heated and fixed by the fixing unit 60 is formed is exposed to the outside from the external paper discharge port 2b. As a result, the temperature in the apparatus is less likely to rise than in the case of the connection conveyance path P1.

  From this point of view, the control unit 100 refers to the in-machine temperature in a job for forming an image on both sides of the long paper LS, passes through the connection conveyance path P1 when the in-machine temperature is low, and long when the in-machine temperature is high. Transport control is performed so that the paper LS passes through the external transport path P2. In this case, a configuration may be adopted in which a temperature sensor is disposed in the apparatus main body 2 and the output of the temperature sensor is monitored by the control unit 100.

  Hereinafter, an example of long paper conveyance control performed by the control unit 100 in a print job in which the long paper LS is printed on both sides will be described with reference to the flowchart of FIG. 9. FIG. 9 shows an example of conveyance control when duplex printing is performed on a plurality of long papers LS having the same size.

  In step S1 to step S3, the control unit 100 refers to the image forming conditions. In this example, as an image forming condition, the control unit 100 refers to paper information, input image information, and apparatus status information.

  In step S1, the control unit 100 refers to the sheet information. Here, the paper information is information on one long paper LS to be printed, and in the present embodiment, for example, the length in the transport direction of the long paper LS set by a paper setting profile (not shown). Information on the height and the amount of rigidity (rigidity).

  In step S2, the control unit 100 refers to input image information. The input image information referred to here includes information on the printing rate (coverage) of the toner image formed on the first surface of the long paper LS.

  In step S3, the control unit 100 refers to device state information. Here, the status information of the apparatus includes an output signal of a side door opening / closing sensor that detects opening / closing of the opening / closing door 54, and a door opening / closing sensor (not shown) that detects opening / closing of the door on the front side of the apparatus that is opened when paper S or toner is replenished. Output signals. In addition, the apparatus status information includes information on the number of times of use (durability, life) of the rollers and sensors arranged in the main conveyance path 530, information on the temperature inside the apparatus by the temperature sensor, and information on the power consumption mode of the apparatus. It is.

  In step S4, the control unit 100 determines whether or not the first double-sided path can be used based on each information (that is, image forming conditions) referred to in steps S1 to S3. When it is determined that the first double-sided path is usable (step S4, YES), the control unit 100 proceeds to step S5, and when it is determined that the first double-sided path cannot be used (step S4, NO). ) Goes to Step S6.

  In step S <b> 5, the control unit 100 performs double-sided printing on the long paper LS through the connection conveyance path P <b> 1, and performs conveyance control so that the long paper LS after double-sided printing is discharged from the main conveyance path 530 to the paper discharge unit 52. To do. On the other hand, in step S6, the control unit 100 performs double-sided printing of the long paper LS through the external conveyance path P2, and discharges the long paper LS after double-sided printing from the main conveyance path 530 to the paper discharge unit 52. The conveyance is controlled.

  In step S7 after step S5 or step S6, the control unit 100 determines whether or not the print job has ended. If it is determined that the print job has not ended yet (step S7, NO), the control unit 100 returns to step S2. The processes in steps S2 to S7 described above are repeated. On the other hand, when the control unit 100 determines that the print job is finished (step S7, YES), the series of processing is finished.

  The determination condition in step S4, in other words, the condition for using the first double-sided path (priority of each information, etc.) can have various aspects. For example, when the open / close door 54 is closed, the control unit 100 can determine that the first double-sided path can be used regardless of other conditions. Further, even when the front door of the apparatus main body 2 (such as the toner bottle outlet and the open / close doors of the paper feed tray units 51a to 51c) is open, the first double-side path is used regardless of other conditions. It can be determined that it is possible.

  As described above, in the present embodiment, when performing the double-sided printing of the long paper LS, control is performed so that the connection transport path P1 is preferentially used, so the open / close door 54 is opened and the transport path P2 outside the machine is set. By using this, it is possible to prevent the apparatus from being substantially enlarged by extending the path length of the reverse conveyance path 533.

  In addition, when performing double-sided printing on the long paper LS, the installation space for the image forming apparatus 1 can be secured by controlling the connection transport path P1 preferentially. Further, various units can be pulled out during execution of a print job, and operations such as jam processing, paper supply, and toner replenishment can be performed efficiently.

  From the viewpoint of dealing with the above-described problems 1 and 2 while suppressing power consumption, the control unit 100, for example, information on the length and stiffness of the long paper LS in the conveyance direction and information on the coverage as the image forming conditions. Increase the priority of. In this case, the control unit 100 determines that the first double-sided path can be used when the transport direction length of the long paper LS is equal to or less than the threshold value, the rigidity is low, and the coverage is low ( In step S4, YES), conveyance control is performed so that the long paper LS is printed on both sides through the connection conveyance path P1 (step S5). On the other hand, if the length of the long paper LS in the conveyance direction exceeds the threshold, the rigidity is high, or the coverage is high, the control unit 100 cannot use the first double-sided path. (Step S4, NO), and transport control is performed so that the long paper LS is printed on both sides through the external transport path P2 (step S6).

  In addition, the determination conditions in step S4 (conditions for using the first double-sided path) and the image forming conditions referred to by the control unit 100 for such determination can be in various forms. The following conditions can be added or replaced.

(When forming images on sample paper for image check)
In a print job in which double-side printing is performed on a long paper LS, for example, the first long paper LS may be desired to be collected as a sample paper for image check. In this case, the control unit 100 exposes the sample paper printed through the image forming unit 40 and the fixing unit 60 to the outside from the external paper feed port (opening) 2b of the apparatus main body 2 through the external conveyance path P2. The conveyance is controlled.

  Specifically, prior to the execution of the print job, for example, setting that the first long sheet is a sample sheet is made through an external PC, the operation display unit 20, or the like. In this case, the control unit 100 performs double-sided printing on the long paper LS set as the sample paper through either the connection conveyance path P1 or the external conveyance path P2, and then does not eject the paper from the paper ejection unit 52 again. It is conveyed to the first reflux conveyance path 533a and the reverse conveyance path 533. Further, the control unit 100 passes the long paper LS transported to the reverse transport path 533 through the external transport path P2, and is exposed or discharged from the external paper discharge port 2b without performing the switchback operation. The conveyance of the long paper LS is controlled.

(Further improvement of usability)
Furthermore, from the viewpoint of further improving usability, prior to execution of a print job for forming an image on both sides of the long paper LS, it is determined which of the connected conveyance path P1 and the off-machine conveyance path P2 is used for duplex printing. It is preferable that the user can specify. For example, when the opening / closing door 54 cannot be opened, such as when the image forming apparatus 1 is installed near a wall, or when a sufficient sheet passing space cannot be secured on the external paper discharge outlet 2b side, the connection conveyance path P1 is used. A case where only duplex printing is possible is considered.

  In view of such a case, for example, the control unit 100 displays a button for selecting either “double-sided path 1” or “double-sided path 2” on the display unit 21, and user settings selected and set through the operation unit 22. Transport control is performed based on the information. With this configuration, when the image forming apparatus 1 is installed near a wall or the like, the user selects “double-sided path 1” to perform double-sided printing of the long paper LS using the connection transport path P1, and then rearrangement, etc. Thus, when a sufficient sheet passing space is secured, the user can select the “double-sided path 2” and perform double-sided printing of the long paper LS using the external conveyance path P2.

  In addition, prior to execution of a print job for forming an image on both sides of the long sheet LS, the control unit 100 assigns either “double-sided path 1” or “double-sided path 2” to an external device such as the display unit 21 or a PC. A button to be selected may be displayed, and a preferable double-sided path may be displayed as a message on the display unit 21 with reference to the information related to the various image forming conditions described above. For example, when the length, stiffness, and coverage of the long sheet LS are less than or equal to preset values, the control unit 100 displays a message “Recommended double-sided path 1” on the display unit 21 or the like. indicate. Further, when the user selects “Double-sided path 2” and the door 54 is closed, the control unit 100 displays a message such as “Open the door on the side of the apparatus” on the display unit 21 or the like.

  With such a configuration, the usability can be further improved.

  In the present embodiment, since the two-sided paths (P1, P2) as described above are provided, the length and rigidity of the long paper LS to be printed at the time of double-sided printing of the long paper LS, the apparatus By considering various image forming conditions such as the state and setting information of the duplex path set by the user, the duplex path to be used can be appropriately switched and printed.

  In the present embodiment, since the two-sided path (P1, P2) is selectively used based on various image forming conditions and the conveyance control is performed so as to perform the double-sided printing of the long paper LS, the optimum path is used. Double-sided printing of the long paper LS can be executed, and the long paper LS image-formed on both sides can be discharged out of the machine in a good state.

  In this embodiment, when a toner image is formed on both sides of the long paper LS, the long paper LS is preferentially conveyed so as to pass through the connected conveyance path P1 (first double-sided path). Thus, images can be formed on both sides of the long paper without increasing the size of the image forming apparatus 1.

  The above-described embodiments and modifications are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. . That is, the present invention can be implemented in various forms without departing from the gist or the main features thereof.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Apparatus main body 2a External paper feed port 2b External paper discharge port 10 Image reading part 20 Operation display part 21 Display part 22 Operation part 30 Image processing part 40 Image formation part 50 Paper conveyance part 51 Paper feed part 51a-51c Paper feed tray unit 52 Paper discharge section 53 Transport path section 53a Registration roller 53b Transport roller 530 Main transport path 531 External paper feed transport path 532 Paper feed transport path 533 Reverse transport path 533a First reflux transport path 533b Second reflux transport Road 533g Switching gate 54 Opening / closing door 60 Fixing unit 71 Communication unit 72 Storage unit 100 Control unit (conveyance control unit)
101 CPU
102 ROM
103 RAM
P1 connection transport path (first double-sided path)
P2 Off-machine conveyance path (second double-sided path)
SBP switchback point LS long paper

Claims (17)

An image forming unit for forming a toner image on a long paper;
A fixing unit for fixing the toner image formed on the long paper;
A main conveyance path for conveying the long paper to the image forming unit and the fixing unit;
A paper feed conveyance path for conveying the long paper to the upstream side in the conveyance direction of the image forming unit in the main conveyance path;
Branches from the downstream side of the fixing unit in the main conveyance path in the conveyance direction, and reverses the conveyance direction of the long paper at a switchback point so that the front and back of the long paper are reversed to the upstream side of the image forming unit. A double-sided conveyance path
A conveyance control unit for controlling conveyance of the long paper,
In the double-sided conveyance path, the path in the conveyance direction before the long paper is switched back is connected to the first double-sided path connected to the upstream side of the image forming unit in the paper conveyance path and the opening of the apparatus main body. Branch to the second double-sided path,
The transport control unit controls the long paper to pass through one of the first and second double-side paths when a toner image is formed on both sides of the long paper.
Image forming apparatus. The conveyance control unit controls whether the long paper is passed through the first and second double-sided paths based on image forming conditions.
The image forming apparatus according to claim 1. The conveyance control unit, as the image forming condition, determines whether or not the length of the long paper in the conveyance direction is equal to or less than a threshold value, the long paper as the first double-side path and the second double-side path. To control which of the
The image forming apparatus according to claim 2. The threshold value of the length of the long paper in the conveyance direction is a value corresponding to the length from the switchback point in the double-sided conveyance path to the position of the fixing unit in the paper conveyance path via the first double-sided path. Is,
The image forming apparatus according to claim 3. The conveyance control unit refers to the stiffness of the long paper as the image forming condition. When the stiffness is low, the conveyance control unit passes the first duplex route, and when the stiffness is high, passes the second duplex route. The conveyance of the long paper is controlled so as to pass through.
The image forming apparatus according to claim 2. The conveyance control unit refers to the coverage for the long paper as the image forming condition, passes through the first double-side path when the coverage is low, and passes through the second double-side path when the coverage is high. The conveyance of the long paper is controlled so as to pass through,
The image forming apparatus according to claim 2. The conveyance control unit refers to a power consumption setting mode in the image forming apparatus as the image forming condition, and passes the second double-sided path when the mode is for energy saving, and is not the mode for seeking energy saving. Controls the conveyance of the long paper so that it passes through the first double-sided path,
The image forming apparatus according to claim 2. The threshold of the length in the conveyance direction of the long paper is determined by the length from the switchback point to the position where it joins the paper conveyance path via the first double-sided path, and the switchback operation from the switchback point. A length corresponding to a length obtained by adding a length to a position where the paper conveyance path is merged.
The image forming apparatus according to claim 3. The conveyance control unit refers to a use history of components arranged in a path along which the long paper is conveyed as the image forming condition, and removes the long paper from the first and second double-sided paths. Control which one to pass,
The image forming apparatus according to claim 2. The conveyance control unit refers to an in-machine temperature as the image forming condition, and passes the first double-side path when the in-machine temperature is low, and passes the second double-side path when the in-machine temperature is high. To control the transport of the long paper,
The image forming apparatus according to claim 2. The conveyance control unit controls the conveyance of the long paper so as to pass through the first double-side path when the toner or paper is being replenished as the image forming condition.
The image forming apparatus according to claim 2. An open / close door that opens and closes the opening of the apparatus main body connected to the second double-sided path;
The transport control unit controls the transport of the long paper so that the image forming condition passes through the first double-sided path when the open / close door is closed.
The image forming apparatus according to claim 2. The conveyance control unit refers to the information on the length of the long paper in the conveyance direction, the information on the rigidity of the long paper, and the information on the coverage of the long paper as the image forming condition. Controlling whether the paper is passed through the first and second duplex paths;
The image forming apparatus according to claim 2. A path setting unit for setting whether to pass the long paper through the first double-side path or the second double-side path;
The conveyance control unit controls the conveyance of the long paper according to the setting content of the path setting unit as the image forming condition.
The image forming apparatus according to claim 2. The conveyance control unit is configured according to the image forming conditions.
Determine which of the first double-sided path or the second double-sided path should be passed;
Display the judgment result on the display unit.
The image forming apparatus according to claim 14. When the image forming is performed on the image check sample paper, the transport control unit controls the transport so that the sample paper image-formed by the image forming unit is exposed from the opening of the apparatus main body through the second double-sided path. To
The image forming apparatus according to claim 1. In order to form an image on both sides of a long paper whose length in the transport direction is equal to or longer than a predetermined length, the path in the transport direction before the transport direction of the long paper is reversed at the switchback point is A paper conveyance control method in an image forming apparatus including a double-sided conveyance path that branches into a first double-sided path connected to an upstream side and a second double-sided path connected to an opening of the apparatus main body,
When a toner image is formed on both sides of the long paper, the long paper is conveyed so as to pass through either of the first and second double-side paths.
Paper transport control method.

Images