JP6376263B2 - Image forming apparatus and image forming system - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming system.

  In general, an image forming apparatus (printer, copier, facsimile, etc.) using an electrophotographic process technology generates an electrostatic latent image by irradiating (exposing) a charged photoconductor with a laser beam based on image data. Form. Then, by supplying toner from the developing device to the photosensitive drum on which the electrostatic latent image is formed, the electrostatic latent image is visualized to form a toner image. Further, after the toner image is directly or indirectly transferred to a sheet by a transfer nip, the image is formed on the sheet by heating and pressurizing and fixing at a fixing nip formed by a pressure roller and a heating roller. . In an image forming apparatus, usually continuous paper such as continuous roll paper or folding paper (hereinafter referred to as “continuous paper”), or tack paper (sticker paper) in which glue is attached between the printing surface and the mount. It is also possible to form an image on a recording medium in which there is no gap between sheets. Hereinafter, a recording medium such as continuous paper or tack paper (seal paper) without a gap is referred to as “continuous recording medium”.

  By the way, when an image is formed on continuous paper by the image forming apparatus, the continuous paper is present without interruption in the entire apparatus, and therefore remains at the fixing nip position even while printing is stopped. Since the continuous paper is heated in the fixing nip, if the continuous paper that exists in the fixing nip is still present in the fixing nip, it is damaged at the fixing nip position due to being heated at the position of the fixing nip. End up. For this reason, the image forming apparatus is configured to convey the continuous paper in the paper conveyance direction, for example, a conveyance speed of about 10 mm / sec while the temperature of the fixing device is lowered to a temperature that does not damage the continuous paper while the print job is stopped. It is necessary to carry a very small amount.

  In addition, the image forming apparatus needs to convey a small amount of continuous paper in the paper conveyance direction while raising the temperature of the fixing device to a temperature suitable for fixing in order to start a print job. As described above, the image forming apparatus transports a small amount of continuous paper in the paper transport direction, thereby preventing damage to the continuous paper due to heating at the fixing nip.

  The continuous paper that has been transported in a minute amount in the paper transport direction is discharged without forming an image, and thus becomes wasteful paper (hereinafter referred to as “sag paper”). In order to suppress the occurrence of spoiled paper, for example, before starting the next print job, the image forming apparatus transports the continuous paper to the upstream side in the paper transport direction of the transfer nip in the direction opposite to the paper transport direction, and performs the next printing. A configuration is also conceivable in which an image is formed on continuous paper conveyed in the reverse direction in a job. In this configuration, in the next print job, an image is formed on the continuous paper that has been transported in the reverse direction after being transported in a small amount in the paper transport direction, so that the continuous paper transported in a small amount in the paper transport direction can be reused. Can do.

  Patent Document 1 discloses an image forming system that forms an image on continuous paper. In the image forming system described in Patent Document 1, a buffer is provided between the image forming apparatus and a post-processing apparatus disposed at a subsequent stage of the image forming apparatus. Specifically, after the operation of the post-processing apparatus is stopped, the continuous paper is conveyed from the transfer unit to the fixing unit to form a slack of the continuous paper in the buffer, and is formed in the buffer before starting the next print job. The slack portion of the continuous paper is conveyed to the upstream side in the paper conveyance direction of the transfer nip in the direction opposite to the paper conveyance direction. This configuration suppresses image defects and jams in the slack area caused by the continuous paper slack always formed during the print job, and transports post-processed continuous paper in the reverse direction. Can be avoided.

Japanese Patent No. 3570335

  However, if the continuous paper that has passed through the fixing nip is conveyed to the upstream side of the transfer nip in the paper conveyance direction, the heat of the continuous paper heated at the position of the fixing nip is transferred to the transfer roller or transfer belt that constitutes the transfer nip, causing deformation. This causes a problem that the toner image cannot be transferred to a desired position in the transfer nip. Further, since the continuous paper is deformed by being heated at the fixing nip position, there is a problem that unevenness occurs in the toner image when the toner image is transferred onto the continuous paper deformed in the transfer nip. In addition, when an image is formed on a continuous recording medium such as tack paper (sticker paper) in which glue is adhered between the printing surface and the mount instead of continuous paper, the pressure is applied by the fixing nip. At this time, the glue that protrudes adheres to the transfer belt, which causes a problem that the glue that adheres to the transfer belt adheres to the surface of the continuous recording medium. Furthermore, since it is necessary to provide a mechanism for transporting continuous paper in the direction opposite to the paper transport direction to the upstream side of the transfer nip in the paper transport direction, the image forming apparatus becomes complicated. Occur.

  The present invention provides an image forming apparatus and an image forming system capable of solving the problems caused by transporting continuous paper that has passed through a fixing nip to the upstream side in the paper transport direction of the transfer nip with a simple configuration. That is.

An image forming apparatus according to the present invention includes:
A transport unit that transports the continuous recording medium in a first transport direction or a second transport direction that is opposite to the first transport direction;
The continuous recording medium is conveyed to the first conveying direction by front Symbol conveying unit, an image forming section for forming a toner image,
A fixing unit for fixing the first disposed on the downstream side of the image forming unit in the conveying direction, by heating the pre-Symbol the toner image formed on the continuous recording medium by the image forming unit,
A holding unit that is provided between the image forming unit and the fixing unit and holds a part of the continuous recording medium;
After the formation of the toner image by the image forming unit is completed and the toner image formed on the continuous recording medium passes through the fixing unit, the continuous recording medium is further conveyed in the first conveying direction. And after the further conveyance is finished, the continuous recording medium is conveyed in the second conveying direction, a part of the continuous recording medium is held by the holding unit, and the fixing unit is A control unit that controls the passing part that has passed through the control unit so as to return to the upstream side from the fixing unit;
Is provided.

An image forming system according to the present invention includes:
A transport unit that transports the continuous recording medium in a first transport direction or a second transport direction that is opposite to the first transport direction;
The continuous recording medium is conveyed to the first conveying direction by front Symbol conveying unit, an image forming section for forming a toner image,
A fixing unit for fixing the first disposed on the downstream side of the image forming unit in the conveying direction, by heating the pre-Symbol the toner image formed on the continuous recording medium by the image forming unit,
A holding unit that is provided between the image forming unit and the fixing unit and holds a part of the continuous recording medium;
After the formation of the toner image by the image forming unit is completed and the toner image formed on the continuous recording medium passes through the fixing unit, the continuous recording medium is further conveyed in the first conveying direction. And after the further conveyance is finished, the continuous recording medium is conveyed in the second conveying direction, a part of the continuous recording medium is held by the holding unit, and the fixing unit is A control unit that controls the passing part that has passed through the control unit so as to return to the upstream side from the fixing unit;
Is provided.

  According to the present invention, a continuous sheet conveyed in a minute amount in the sheet conveyance direction while fixing the temperature in the fixing unit to a temperature that does not damage the continuous sheet is conveyed and fixed in the direction opposite to the sheet conveyance direction. By holding between the nip and the transfer nip, it is possible to solve a problem caused by transporting the continuous paper that has passed through the fixing nip to the upstream side in the paper transport direction of the transfer nip with a simple configuration.

1 is a diagram schematically showing an image forming system according to the present embodiment. FIG. 2 is a diagram illustrating a main part of a control system of an image forming apparatus provided in the image forming system according to the present embodiment. It is a flowchart which shows the conveyance amount integration process in this Embodiment. It is a flowchart which shows the rewinding process in this Embodiment. FIG. 3 is a diagram schematically illustrating a state during a rewinding process of the image forming system. It is a figure which shows the modification of the holding | maintenance part in this Embodiment. It is a figure which shows rotation operation | movement of the modification of the holding | maintenance part in this Embodiment. It is a figure which shows another modification of the holding | maintenance part in this Embodiment.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. Note that in this embodiment, a configuration for forming an image on continuous paper is described, but the present invention is not limited to this. In the present invention, for example, an image may be formed on a continuous recording medium in which resin sheets such as tack paper (seal paper) and PET film are continuously continuous.

  FIG. 1 is a diagram schematically showing an overall configuration of an image forming system 100 according to the present embodiment. FIG. 2 is a diagram illustrating a main part of a control system of the image forming apparatus 2 provided in the image forming system 100 according to the present embodiment. The image forming system 100 is a system for forming an image on the continuous paper P using the continuous paper P indicated by a thick line in FIG. Here, the continuous paper P is a paper having a length exceeding the main body width of the image forming apparatus 2 in the transport direction, for example.

  As shown in FIG. 1, the image forming system 100 includes a paper feeding device 1, an image forming device 2, and a paper discharging device from the upstream side along the transport direction of the continuous paper P (hereinafter also referred to as “paper transport direction”). 3 are connected.

  The paper feeding device 1 is a device that feeds the continuous paper P toward the image forming apparatus 2. In the casing of the paper feeding device 1, as shown in FIG. 1, a roll-shaped continuous paper P is wound around a support shaft and held rotatably. The paper feeding device 1 feeds the continuous paper P wound around the support shaft to the image forming device 2 at a constant speed via a plurality of conveying roller pairs (for example, a feeding roller, a paper feeding roller, etc.). To do. The sheet feeding operation of the sheet feeding apparatus 1 is controlled by the control unit 101 provided in the image forming apparatus 2.

  In the paper feeding device 1, the continuous paper P is not necessarily held in a roll shape, and a plurality of continuous papers P of a predetermined size (for example, 210 [mm] × 1200 [mm]) are held. Also good.

  The image forming apparatus 2 is an intermediate transfer type color image forming apparatus using electrophotographic process technology. That is, the image forming apparatus 2 primarily transfers 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 images are formed by secondary transfer onto the continuous paper P fed from the paper feeding device 1.

  In the image forming apparatus 2, photosensitive drums 413 corresponding to four colors of YMCK are arranged in series in the running direction of the intermediate transfer belt 421, and each color toner image is sequentially transferred to the intermediate transfer belt 421 in one procedure. Tandem system is adopted.

  As shown in FIG. 2, the image forming apparatus 2 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 101.

  The control unit 101 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The CPU reads a program corresponding to the processing content from the ROM and develops it in the RAM, and centrally controls the operation of each block of the image forming apparatus 2 in cooperation with the developed program. At this time, various data stored in the storage unit 70 are referred to. The storage unit 70 is configured by, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

  The control unit 101 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 80. Do. For example, the control unit 101 receives image data transmitted from an external device, and forms an image on the continuous paper P based on the image data (input image data). The communication unit 80 is configured by 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 the 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 a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, image states, operation states of functions, and the like according to a display control signal input from the control unit 101. 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 101.

  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) under the control of the control unit 101. 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 explanation, common constituent elements are denoted by the same reference numerals, and when distinguished from each other, 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 an undercoat layer (UCL) and a charge generation layer (CGL) on the peripheral surface of an aluminum conductive cylinder (aluminum tube) having a drum diameter of 80 mm, for example. It is a negatively charged organic photoconductor (OPC) in which a generation layer (CTL) and a charge transport layer (CTL) are sequentially stacked. 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 101 rotates the photosensitive drum 413 at a constant peripheral speed by controlling a driving current supplied to a driving motor (not shown) that rotates the photosensitive drum 413.

  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 a two-component developing type developing device, and attaches toner of each color component to the surface of the photosensitive drum 413 to visualize the electrostatic latent image to form a toner image.

  The drum cleaning device 415 includes a drum cleaning blade that is slidably contacted with the surface of the photosensitive drum 413, and removes transfer residual toner remaining on the surface of the photosensitive drum 413 after primary transfer.

  The intermediate transfer unit 42 includes an intermediate transfer belt 421, 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 intermediate transfer belt 421 is a belt having conductivity and elasticity, and has a high resistance layer having a volume resistivity of 8 to 11 [log Ω · cm] on the surface. The intermediate transfer belt 421 is rotationally driven by a control signal from the control unit 101. As for the configuration of the intermediate transfer belt 421, the material, thickness, and hardness are not limited as long as they have conductivity and elasticity.

  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, whereby a secondary transfer nip for transferring a toner image from the intermediate transfer belt 421 to the continuous paper P is formed.

  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 continuous paper P passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the continuous paper P. Specifically, the toner is obtained 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 continuous paper P (the side in contact with the secondary transfer roller 424). The image is electrostatically transferred to the continuous paper P. The continuous paper P onto which the toner image has been transferred is conveyed toward the fixing unit 60.

  The belt cleaning device 426 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 includes an upper fixing unit 60A having a fixing surface side member disposed on the fixing surface (surface on which the toner image is formed) of the continuous paper P, and the back surface (the surface opposite to the fixing surface) of the continuous paper P. And a lower fixing unit 60B having a back side support member disposed on the side. When the back surface side support member is pressed against the fixing surface side member, a fixing nip for nipping and transporting the continuous paper P is formed.

  The fixing unit 60 fixes the toner image on the continuous paper P by secondarily transferring the toner image and heating and pressurizing the conveyed continuous paper P at the fixing nip. The fixing unit 60 is disposed in the fixing device F as a unit. The fixing device F may be provided with an air separation unit that separates the continuous paper P from the fixing surface side member or the back surface side support member by blowing air.

  The upper fixing unit 60A includes an endless fixing belt 61, a heating roller 62, and a fixing roller 63 which are fixing surface side members (belt heating method). The fixing belt 61 is stretched between the heating roller 62 and the fixing roller 63 with a predetermined belt tension (for example, 40 [N]).

  For example, the fixing belt 61 uses PI (polyimide) with a thickness of 80 [μm] as a base, and heat-resistant silicon rubber with a thickness of 250 [μm] with an outer peripheral surface of the base as an elastic layer (hardness JIS-A 30 °). Furthermore, the surface layer (release layer) is coated with PFA (perfluoroalkoxy), which is a heat-resistant resin having a thickness of 70 [μm]. The outer diameter of the fixing belt 61 is 100 [mm], for example. The fixing belt 61 contacts the continuous paper P on which the toner image is formed, and heat-fixes the toner image on the continuous paper P at a fixing temperature (for example, 160 to 200 [° C.]). Here, the fixing temperature is a temperature at which the amount of heat necessary to melt the toner on the continuous paper P can be supplied, and varies depending on the paper type of the continuous paper P on which an image is formed.

  The heating roller 62 includes a heating source (halogen heater) and heats the fixing belt 61. The heating roller 62 is heated by the heating source, and as a result, the fixing belt 61 is heated. The temperature of the heating source is controlled by the control unit 101 so that the temperature of the fixing belt 61 becomes a set temperature of 180 [° C.]. The outer diameter of the heating roller 62 is, for example, 50 [mm].

  The fixing roller 63 has, for example, an elastic layer (for example, thickness: 10 [mm]) made of silicon rubber or the like on a peripheral surface of a cylindrical cored bar made of aluminum or the like, and a surface layer (for example, made of fluorine resin such as PTFE). And a thickness of 70 [μm]) are sequentially stacked. The outer diameter of the fixing roller 63 is, for example, 40 [mm]. Driving control of the fixing roller 63 (for example, rotation on / off, peripheral speed, etc.) is performed by the control unit 101.

  The fixing unit 60 according to the present exemplary embodiment conveys the continuous paper P in the paper conveyance direction or in the direction opposite to the paper conveyance direction under the control of the control unit 101. When transporting the continuous paper P in the paper transport direction, the control unit 101 rotates the fixing roller 63 in the clockwise direction. As the fixing roller 63 rotates, the fixing belt 61 and the heating roller 62 are driven to rotate clockwise. On the other hand, when the continuous paper P is transported in the direction opposite to the paper transport direction, the control unit 101 rotates the fixing roller 63 in the counterclockwise direction. As the fixing roller 63 rotates, the fixing belt 61 and the heating roller 62 are driven to rotate counterclockwise.

  The lower fixing unit 60B includes a pressure roller 64 that is a back side support member (roller pressure method). The pressure roller 64 has a configuration in which, for example, an elastic layer made of silicon rubber or the like and a surface layer made of a PFA tube are sequentially laminated on the outer peripheral surface of a cylindrical cored bar made of iron or the like. The outer diameter of the pressure roller 64 is, for example, 40 [mm]. The pressure roller 64 is pressed against the fixing roller 63 with a predetermined fixing load (for example, 1000 [N]) via the fixing belt 61 by a press-contacting / separating portion (not shown). The press contact / separation unit has a known configuration and presses or separates the fixing belt 61 and the pressure roller 64 from each other. In this way, a fixing nip for nipping and transporting the continuous paper P is formed between the fixing belt 61 and the pressure roller 64. The control unit 101 performs drive control of the pressure roller 64 (for example, rotation on / off, peripheral speed, etc.) and drive control of the press contact / separation unit.

  When transporting the continuous paper P in the paper transport direction, the control unit 101 rotates the pressure roller 64 in the counterclockwise direction. On the other hand, when the continuous paper P is transported in the direction opposite to the paper transport direction, the control unit 101 rotates the pressure roller 64 in the clockwise direction.

  The paper transport unit 50 includes a paper feed transport unit 51, a paper discharge transport unit 52, and the like.

  The paper feed conveyance unit 51 conveys the continuous paper P conveyed from the paper supply device 1 to the image forming unit 40. The sheet feeding / conveying unit 51 includes a plurality of conveying roller pairs including a registration roller pair 51a. The registration roller portion in which the registration roller pair 51a is disposed corrects the inclination and deviation of the continuous paper P.

  The paper discharge conveyance unit 52 conveys the continuous paper P conveyed from the fixing unit 60 to the paper discharge device 3. The paper discharge conveyance unit 52 includes a conveyance roller pair (paper discharge roller pair) 52a. In the paper discharge conveyance unit 52 in the present embodiment, the control unit 101 controls the rotation direction of the conveyance roller pair 52a of the paper discharge conveyance unit 52, whereby the continuous paper P is fed in the paper conveyance direction or in the direction opposite to the paper conveyance direction. It is configured so that it can be transported.

  The continuous paper P fed from the paper feeding device 1 to the image forming device 2 is conveyed to the image forming unit 40 by the paper feeding and conveying unit 51. Then, in the image forming unit 40, the toner image on the intermediate transfer belt 421 is secondarily transferred to one side of the continuous paper P all at once, and a fixing process is performed in the fixing unit 60. The continuous paper P on which an image has been formed is transported to the paper discharge device 3 by a paper discharge transport unit 52 having a pair of transport rollers (a pair of paper discharge rollers) 52a.

  The paper discharge device 3 is a device that winds and stores the continuous paper P conveyed from the image forming apparatus 2. In the housing of the paper discharge device 3, for example, as shown in FIG. 1, the continuous paper P is wound around a support shaft and held in a roll shape. For this purpose, the paper discharge device 3 passes the continuous paper P conveyed from the image forming device 2 to a support shaft at a constant speed via a plurality of pairs of conveyance rollers (for example, a feeding roller and a paper discharge roller). Wind up. The winding operation of the paper discharge device 3 is controlled by the control unit 101 provided in the image forming device 2.

  Further, the paper discharge device 3 conveys the wound continuous paper P in the direction opposite to the paper conveyance direction and sends it to the image forming apparatus 2. The conveying operation in the reverse direction in the paper discharge device 3 is controlled by the control unit 101 provided in the image forming device 2.

  The holding unit 90 is provided between the image forming unit 40 and the fixing unit 60. The holding unit 90 is configured to hold a part of the continuous paper P in a hollow portion 91 that extends from the space between the image forming unit 40 and the fixing unit 60 to the space below the image forming apparatus 2.

  The holding unit 90 has an opening 92 on the image forming unit 40 side on the transport path of the continuous paper P. A transport roller pair 93 is provided in the vicinity of the opening 92. The holding unit 90 has an opening 94 on the fixing unit 60 side on the continuous paper P conveyance path. A transport roller pair 95 is provided in the vicinity of the opening 94.

  The conveyance roller pairs 93 and 95 are movable in the direction of sandwiching the continuous paper P (up and down direction in FIG. 1) under the control of the control unit 101. The conveyance roller pair 93 holds the continuous paper P under the control of the control unit 101. The transport roller pair 95 rotates in a state where the continuous paper P is sandwiched by the control of the control unit 101, and transports the continuous paper P in the paper transport direction or in the direction opposite to the paper transport direction.

  When an image is formed on the continuous paper P by the image forming apparatus 2, the continuous paper P exists in the entire apparatus without interruption, and therefore exists at the position of the fixing nip even while printing is stopped. Since the continuous paper P is heated at the fixing nip, the continuous paper P existing at the fixing nip position is deformed or altered by being heated at the fixing nip position as it is. It will take damage such as.

  In order to prevent damage such as deformation or deterioration of the continuous paper P due to heating at the fixing nip position, the control unit 101 damages the continuous paper P with the temperature in the fixing device F while the print job is stopped. While the temperature is lowered to an unappropriate temperature, a process for conveying a small amount of continuous paper P in the paper conveyance direction (hereinafter, fixing device temperature lowering process) is performed. In addition, at the start of a print job, the control unit 101 performs a process for conveying a small amount of continuous paper P in the sheet conveyance direction during the warm-up for raising the temperature in the fixing device F to the fixing temperature (hereinafter, warm-up process). I do. Here, a temperature that does not damage the continuous paper P is referred to as a stoppable temperature. Note that the stoppable temperature varies depending on the paper type of the continuous paper P and is, for example, about 100 [° C.].

  The continuous paper P that has been transported in a minute amount in the paper transport direction is discharged without forming an image, and thus becomes scraped paper. In order to suppress the occurrence of spoiled paper, for example, before starting the next print job, the image forming apparatus 2 transports the continuous paper P to the upstream side in the paper transport direction of the transfer nip in the direction opposite to the paper transport direction. A configuration is also conceivable in which an image is formed on the continuous paper P conveyed in the reverse direction in the print job. However, in this configuration, since the continuous paper P that has passed through the fixing nip is transported to the upstream side of the transfer nip in the paper transport direction, the heat of the continuous paper P heated at the position of the fixing nip damages the transfer nip. End up.

  In the image forming system 100 according to the present embodiment, in order to solve the problem caused by conveying the continuous sheet that has passed through the fixing nip to the upstream side in the sheet conveying direction of the transfer nip with a simple configuration, By control, between the fixing device temperature lowering process and the warm-up process, the continuous paper P conveyed in a small amount in the paper conveying direction in the fixing device temperature lowering process is conveyed in the direction opposite to the paper conveying direction to the holding unit 90. A holding process (hereinafter referred to as rewinding process) is performed.

  First, the fixing device temperature lowering process will be described. In the fixing device temperature lowering process in the present embodiment, the continuous paper P that is conveyed in the paper conveyance direction while the temperature in the fixing device F decreases to the stoppable temperature from the start of conveyance control. A continuous paper conveyance amount integration process for integrating the paper conveyance amount is performed. With reference to FIG. 3, the continuous paper conveyance amount integration processing in the image forming system 100 will be specifically described.

  When the print job is stopped or ended, the control unit 101 controls the fixing unit 60 to stop the heating roller 62 from heating in order to reduce the temperature in the fixing device F. The control unit 101 starts transport control for transporting the continuous paper P in the paper transport direction by controlling the paper feeding device 1, the image forming unit 40, the paper transport unit 50, the fixing unit 60, and the paper discharge device 3. (S100).

  Next, the control unit 101 sets a continuous paper conveyance amount indicating the amount of the continuous paper P conveyed in the paper conveyance direction while the temperature in the fixing device F decreases to a stoppable temperature from the time when conveyance control is started. Accumulate (S110). For example, the control unit 101 counts the number of rotations of the conveyance roller pair 52a of the paper discharge conveyance unit 52 that conveys the continuous paper P at every predetermined time interval, and conveys the continuous paper from the counted number of rotations and the diameter of the conveyance roller pair 52a. Accumulate the amount.

  For example, when the temperature in the fixing device F is 170 [° C.] and the stoppable temperature is 100 [° C.], the temperature in the fixing device F at 170 [° C.] decreases to the stoppable temperature of 100 [° C.]. Takes about 5 minutes. In this case, the control unit 101 transports the continuous paper P in the paper transport direction for about 5 minutes, and accumulates the amount of the continuous paper P transported during that time.

  Next, the control unit 101 receives the temperature in the fixing unit F from a temperature detection unit (not shown) that detects the temperature in the fixing unit F, and whether or not the temperature in the fixing unit F has decreased to a stoppable temperature. (S120). In the present embodiment, the temperature detection unit detects the temperature of the fixing belt 61 in the vicinity of the fixing nip as the temperature in the fixing device F.

  As a result of the determination, when the temperature in the fixing device F has decreased to a stoppable temperature (Yes in S120), the control unit 101 stops the conveyance of the continuous paper P in the paper conveyance direction (S130). And the control part 101 memorize | stores the integrated conveyance amount of the continuous paper P in the memory | storage part 70 as a conveyance amount integrated value (S140).

  If the temperature in the fixing device F has not decreased to the stoppable temperature (No in S120), the control unit 101 returns to S110, continues to transport the continuous paper P in the paper transport direction, and starts from the previous S110. Continue to accumulate continuous paper transport.

  By the temperature reduction process described above, the control unit 101 reduces the temperature in the fixing device F to a stoppable temperature while transporting the continuous paper P in the paper transport direction. Then, the control unit 101 accumulates the continuous paper conveyance amount indicating the amount of the continuous paper P conveyed in the paper conveyance direction while the temperature in the fixing device F is lowered to the stoppable temperature, and the conveyance amount integrated value Is stored in the storage unit 70.

  Next, the rewinding process in the image forming system 100 will be specifically described with reference to FIG.

  In the rewinding process, as described above, the continuous paper P transported in the paper transport direction in the temperature lowering process between the temperature lowering process and the warm-up process is discharged from the holding unit 90 on the transport path. 3 is a process of conveying the sheet up to 3 in the direction opposite to the sheet conveying direction and holding it in the holding unit 90. In the rewinding process, the control unit 101 performs a process of calculating the amount (rewinding amount) of the continuous paper P for reverse conveyance. Then, the control unit 101 controls the paper discharge device 3, the paper discharge conveyance unit 52 of the paper conveyance unit 50, the fixing unit 60, and the holding unit 90, so that the calculated continuous rewinding amount of the continuous paper P is conveyed in the paper conveyance direction. Then, an operation (rewinding operation) for holding in the holding unit 90 is performed.

  In the rewinding process shown in FIG. 4, first, the control unit 101 reads the integrated carry amount from the storage unit 70 (S200).

  Next, the control unit 101 calculates a required transport amount during WU, which is a transport amount of the continuous paper P required during warm-up (WU) for raising the temperature in the fixing device F to the fixing temperature (S210).

  Specifically, the control unit 101 calculates the temperature in the fixing device F at the time of calculation (hereinafter referred to as “calculation start fixing temperature”), the fixing temperature, the WU duration time indicating the duration of the WU, and The required transport amount during WU is calculated based on the WU transport speed indicating the transport speed when performing WU. The WU continuation time and the WU conveyance speed are stored in advance in the storage unit 70 as setting information of the image forming system 100. In the present embodiment, the method for calculating the required transport amount during WU differs depending on the fixing temperature at the start of calculation.

For example, when the fixing temperature at the start of calculation is 60 [° C.] or less, the required transport amount during WU is calculated by the following equation (1) using the WU duration and the WU transport speed. For example, when the WU duration is 360 [sec] and the WU conveyance speed is 10 [mm / sec], the calculated necessary conveyance amount at WU is 3600 [mm].
Necessary transport amount at WU = WU duration × WU transport speed (1)

On the other hand, when the fixing temperature at the start of calculation exceeds 60 [° C.], the required transport amount at WU is the rate at which the fixing temperature, the fixing temperature at the start of calculation, and the temperature inside the fixing device F rise due to heating of the heating roller 62 Is calculated by the following formula (2) using the temperature rising rate and the WU transport speed. For example, when the fixing temperature is 170 [° C.], the fixing temperature at the start of calculation is 100 [° C.], the heating rate is 2.5 [° C./sec], and the conveyance speed is 10 [mm / sec], the calculation is performed. The required transport amount during WU is 280 [mm].
Necessary transport amount at WU = (fixing temperature−fixing temperature at the start of calculation) / temperature increase speed × transport speed (2)

  Next, the control unit 101 calculates a maximum holding amount indicating the maximum amount of continuous paper P that can be held in the holding unit 90 (S220).

  Here, the maximum holding amount varies depending on the size of the hollow portion 91 of the holding unit 90, the paper type of the continuous paper P, the basis weight, the rigidity, and the like. For example, the maximum holding amount is determined in advance by experiments or the like, and is stored in the storage unit 70 by distinguishing the paper type, basis weight, stiffness, and the like. The control unit 101 reads the maximum holding amount from the storage unit 70 based on the paper information such as the paper type, basis weight, and stiffness of the continuous paper P.

  Next, the control unit 101 determines whether or not the carry amount integrated value is smaller than the WU required carry amount (S230). If the result of determination is that the transport amount integrated value is smaller than the WU required transport amount (Yes in S230), the control unit 101 sets the transport amount integrated value as the rewind amount (S240). Thereafter, the process proceeds to step S260. On the other hand, when the integrated conveyance amount is equal to or greater than the necessary conveyance amount during WU (No in S230), control unit 101 sets the necessary conveyance amount during WU as the rewind amount (S250). Thereafter, the process proceeds to step S260.

  In step S260, the control unit 101 determines whether or not the maximum holding amount is smaller than the rewinding amount set in S240 or S250 (S260). As a result of the determination, when the maximum holding amount is smaller than the rewinding amount (Yes in S260), the control unit 101 updates the rewinding amount by setting the maximum holding amount as the rewinding amount (S270). Thereafter, the process proceeds to step S280. On the other hand, when the maximum hold amount is equal to or greater than the rewind amount (No in S260), control unit 101 does not update the rewind amount. Then, the process proceeds to step S280.

  As described above, the control unit 101 sets the smallest carry amount as the rewind amount among the carry amount integrated value, the WU required carry amount, and the maximum hold amount by the processes of S230 to S270.

  In step S280, the control unit 101 controls the paper discharge device 3, the paper discharge conveyance unit 52 of the paper conveyance unit 50, the fixing unit 60, and the holding unit 90, thereby holding the continuous paper P on the conveyance path. The sheet is transported in the direction opposite to the sheet transport direction in the section from the sheet discharge device 3 and is started to be held by the holding unit 90 (rewinding operation). Next, the control unit 101 determines whether an instruction to start the next printing has been received (S290).

  As a result of the determination, if the next print start instruction is accepted (Yes in S290), the process proceeds to step S310. On the other hand, when the next print start instruction has not been received (No in S290), control unit 101 determines whether or not the rewinding operation has been completed (S300).

  Specifically, the control unit 101 integrates the continuous paper reverse transport amount indicating the amount of the continuous paper P transported in the direction opposite to the paper transport direction. Then, the control unit 101 determines whether or not the rewinding operation has been completed based on whether or not the integrated continuous paper reverse conveyance amount has reached the set rewinding amount.

  If the result of the determination is that the rewinding operation has not been completed (No in S300), the control unit 101 determines whether or not an instruction for starting the next printing has been received in S290 while continuing the rewinding operation. To do. On the other hand, when the rewinding operation is completed (Yes in S300), the process transitions to step S310.

  In step S310, the control unit 101 stops the rewinding operation. When the rewinding operation is stopped, the control unit 101 causes the storage unit 70 to store a continuous paper reverse transport amount indicating the amount of the continuous paper P transported in the reverse direction to the paper transport direction in the rewinding operation. The stored continuous paper reverse transport amount indicates the amount of continuous paper P held by the holding unit 90 at the time when the rewinding operation is stopped.

  By the rewinding process described above, the control unit 101 causes the holding unit 90 to hold the continuous paper P necessary for warming up the fixing unit 60.

  FIG. 5 is a diagram schematically illustrating a state during the rewinding process of the image forming system 100. 5, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The control unit 101 controls the paper discharge device 3, the paper discharge conveyance unit 52 of the paper conveyance unit 50, the fixing unit 60, and the holding unit 90, and thereby a section from the holding unit 90 to the paper discharge device 3 on the conveyance path. Then, a rewinding operation for transporting the continuous paper P in the direction opposite to the paper transport direction (in the direction of arrow X2 in FIG. 5) is performed.

  In the rewinding operation, the control unit 101 controls the holding unit 90 to hold the continuous paper P between the conveyance roller pairs 93 and 95 of the holding unit 90. Then, the control unit 101 rotates the transport roller pair 95 so as to transport the continuous paper P in the direction opposite to the paper transport direction. The control unit 101 controls the transport operations of the paper discharge device 3, the paper discharge transport unit 52, and the fixing unit 60 simultaneously with the rotation operation of the transport roller pair 95, and transports the continuous paper P in the direction opposite to the paper transport direction.

  On the other hand, the control unit 101 does not rotate the transport roller pair 93. This is to prevent the transfer nip from being damaged by the continuous paper P being transported upstream of the holding unit 90 in the paper transport direction.

  As a result, a part of the rewound continuous paper P is held in a bellows shape in the hollow portion 91 of the holding portion 90 as shown in FIG.

  Next, the warm-up process in the image forming system 100 will be specifically described.

  When receiving an instruction to start printing, the controller 101 controls the fixing unit 60 to heat the heating roller 62 in order to increase the temperature in the fixing device F.

  Further, the control unit 101 conveys the continuous paper P held by the holding unit 90 by controlling the paper discharge conveyance unit 52, the fixing unit 60, the paper discharge device 3, and the holding unit 90 of the paper conveyance unit 50. A transport operation for transporting in the paper transport direction is started in the section from the holding unit 90 to the paper discharge device 3 on the path.

  Referring to FIG. 5, the control unit 101 moves the continuous paper P held by the holding unit 90 in the paper conveyance direction (arrow X3) in the section from the holding unit 90 to the paper discharge device 3 on the conveyance path. The carrying operation is carried out.

  Further, the control unit 101 integrates the continuous paper transport amount indicating the amount of the continuous paper P transported in the paper transport direction. Then, the control unit 101 determines whether or not the continuous paper conveyance amount to be integrated has reached the continuous paper reverse conveyance amount read from the storage unit 70.

  When the continuous paper conveyance amount reaches the continuous paper reverse conveyance amount, that is, when there is no continuous paper P held by the holding unit 90, the holding unit 90 is in a state as shown in FIG. When the holding unit 90 is in the state shown in FIG. 1 during the warm-up process, the control unit 101 receives the temperature in the fixing device F from the temperature detection unit, and the temperature in the fixing device F becomes equal to or higher than the fixing temperature. It is determined whether or not. As a result of the determination, when the temperature in the fixing device F becomes equal to or higher than the fixing temperature, the control unit 101 stops the conveyance operation and starts the printing operation.

  On the other hand, when there is no continuous paper P held in the holding unit 90 and the temperature in the fixing device F has not reached the fixing temperature, the control unit 101 sets the temperature in the fixing device F to the fixing temperature or higher. The sheet feeding device 1, the image forming unit 40, the sheet feeding / conveying unit 51 and the sheet discharging / conveying unit 52, the fixing unit 60, and the sheet discharging device 3 of the sheet conveying unit 50 are controlled. Is transported in the paper transport direction (arrow X1 direction in FIG. 1) in the section from the paper feeding device 1 to the paper discharge device 3 on the transport path.

  When the temperature in the fixing device F becomes equal to or higher than the fixing temperature, the control unit 101 stops the conveyance operation and starts the printing operation.

  As described above in detail, the image forming apparatus 2 according to the present embodiment uses the continuous paper P (continuous recording medium) in the paper transport direction (first transport direction) or in the direction opposite to the paper transport direction (second transport direction). A sheet conveying section (conveying section) 50 that conveys the toner image, an image forming section 40 that forms a toner image on the continuous sheet P that is conveyed in the sheet conveying direction by the sheet conveying section 50 in the transfer nip, and an image formation in the sheet conveying direction. A fixing unit 60 provided on the downstream side of the unit 40 and configured to heat and fix the toner image formed on the continuous paper P by the image forming unit 40 in the fixing nip, and between the transfer nip and the fixing nip in the paper conveyance direction. The continuous paper P is provided so that the continuous paper P is not deformed by the heating of the fixing unit 60 when the toner image formation by the holding unit 90 that holds a part of the continuous paper P and the image forming unit 40 is completed. After the paper is transported in the paper transport direction, the paper transport unit 50 is controlled so that the passing portion of the continuous paper P that has passed through the fixing nip during the transport is transported in the direction opposite to the paper transport direction. And a control unit 101 that controls the holding unit 90 so that the passing portion is held.

  With this configuration, while the temperature in the fixing device F is lowered to a temperature that does not damage the continuous paper P, the continuous paper transported by a minute amount in the paper transport direction is transported in the direction opposite to the paper transport direction to fix the fixing nip. And the transfer nip, it is possible to solve a problem caused by conveying the continuous sheet that has passed through the fixing nip with a simple configuration to the upstream side of the transfer nip in the sheet conveyance direction.

  Further, in this configuration, the fixing unit 60 and the paper transport unit 50 are only provided with a function of transporting the continuous paper P in the reverse direction, and the image forming unit 40 and the like positioned upstream of the holding unit 90 in the paper transport direction. Since it is not necessary to provide a function capable of transporting in the reverse direction, the configuration of the apparatus can be simplified.

  Further, in the image forming apparatus 2 according to the present embodiment, the transport amount in which the passing portion is transported in the direction opposite to the paper transport direction is set within a range in which the holding unit 90 can hold a part of the continuous paper P. Is done.

  With this configuration, the amount of paper that cannot be held by the holding unit 90 is conveyed in the reverse direction, so that the continuous paper P held by the holding unit 90 can be prevented from being damaged such as folds.

  In the image forming apparatus 2 according to the present embodiment, the range in which the holding unit 90 can hold a part of the continuous paper P differs depending on the type of the continuous paper P.

  With this configuration, the amount that can be held in the holding unit 90 is determined in accordance with the basis weight, type, and stiffness of the continuous paper P. Therefore, even when the paper type of the continuous paper P is changed, an appropriate amount is given to the holding unit 90. Can hold.

  Further, in the image forming apparatus 2 according to the present embodiment, the transport amount in which the passing portion is transported in the direction opposite to the paper transport direction raises the temperature of the fixing member of the fixing unit 60 before feeding the continuous paper P to the fixing nip. During the warm-up operation, this is a necessary transport amount during warm-up for transporting the continuous paper P in the paper transport direction so that the continuous paper P is not deformed by the heating of the fixing unit 60. It is set based on the temperature of the fixing unit 60 at the time when conveyance in the direction opposite to the sheet conveyance direction is started.

  With this configuration, it is possible to hold the conveyance amount required until the temperature inside the fixing device F of the fixing unit 60 rises to the fixing temperature in the holding unit 90.

(Modification in the present embodiment)
In the present embodiment, the holding unit 90 holds a part of the continuous paper P in the hollow portion 91 that extends from the space between the image forming unit 40 and the fixing unit 60 to the space below the image forming apparatus 2. Although an example has been described, the present invention is not limited to this. The modification of the holding unit in the present embodiment has a winding mechanism for winding the continuous paper P. Below, the modification of the structure of the holding | maintenance part which has a winding mechanism is demonstrated.

  FIG. 6 is a diagram illustrating a modified example of the holding unit 190 in the present embodiment. 6A shows a state in which the continuous paper P is not held in the holding unit 190, and FIG. 6B shows a state in which the continuous paper P is held in the holding unit 190. In FIG. 6, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted. FIG. 6 shows only the holding unit 190 and the configuration around the holding unit 190.

  The holding unit 190 in FIG. 6 is provided between the image forming unit 40 and the fixing unit 60 and configured to hold a part of the continuous paper P, similarly to the holding unit 90 in FIG.

  The holding unit 190 has a winding mechanism 191. The winding mechanism 191 includes a rotating plate 191A, a winding rod 191B, and a winding rod 191C.

  The rotating plate 191 </ b> A is provided at a position where it does not contact the continuous paper P on one end side in the width direction of the continuous paper P. The rotating plate 191A has a circular shape and rotates around a rotation axis parallel to the width direction. The rotation operation of the rotating plate 191A is controlled by the control unit 101.

  The winding rods 191B and 191C are rod-shaped members each having one end connected to the rotating plate 191A. The winding rod 191B is provided on the front surface side of the continuous paper P in parallel with the width direction of the continuous paper P. The winding rod 191 </ b> C extends on the back side of the continuous paper P in parallel with the width direction of the continuous paper P. The winding rods 191B and 191C rotate around their respective axes under the control of the control unit 101.

  The control unit 101 controls the paper discharge device 3, the paper discharge conveyance unit 52, and the fixing unit 60, thereby continuously in a direction opposite to the paper conveyance direction in the section from the holding unit 190 to the paper discharge device 3 on the conveyance path. The paper P is conveyed. Then, when the control unit 101 rotates the rotating plate 191A, the winding rods 191B and 191C circulate around the rotating shaft of the rotating plate 191A while exchanging positions with each other. Further, the control unit 101 rotates the winding rod 191B counterclockwise and rotates the winding rod 191C clockwise.

  The control unit 101 rotates the winding plates 191B and 191C while rotating the rotating plate 191A, thereby winding the continuous paper P conveyed in the direction opposite to the paper conveying direction as shown in FIG. 6B. A winding operation (rewinding operation) is performed between the take-up bar 191B and the take-up bar 191C.

  Specifically, the rotation operation of the rotating plate 191A and the winding rods 191B and 191C in the holding unit 190 shown in FIG. 6 will be described with reference to FIG. 7, the same components as those in FIG. 6 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 7, when the control unit 101 rotates the rotating plate 191A clockwise (arrow B1), the take-up bar 191C is moved downstream of the take-up bar 191B in the sheet conveying direction, that is, by the fixing unit 60. Contact the continuous paper P at a close position. In this case, the control unit 101 rotates the winding rod 191C clockwise (arrow B2) and rotates the winding rod 191B counterclockwise (arrow B3).

  In other words, when the rotating plate 191A is rotated, the control unit 101 rotates the winding rod that contacts the continuous paper P at a position closer to the fixing unit 60 in the same direction as the rotating plate 191A, and is closer to the fixing unit 60. The winding rod that contacts the continuous paper P at the position is rotated in the direction opposite to that of the rotating plate 191A.

  In this way, the control unit 101 rotates the winding rod 191C counterclockwise, which is the winding direction, so that the winding mechanism 191 causes the continuous paper P to be fed from the fixing unit 60 side in the direction opposite to the paper transport direction ( Winding in the direction of arrow X2). Further, the control unit 101 rotates the winding rod 191B in the clockwise direction, which is the counterclockwise direction that is the winding direction, so that the winding mechanism 191 starts continuous paper from the image forming unit 40 side having the transfer nip. There is no need to take up P.

  In addition, a roller pair or the like that clamps and fixes the continuous paper P is provided on the image forming unit 40 side of the winding mechanism 191 to fix the continuous paper P, and the surface of the winding rods 191B and 191C is caused to have frictional force with the continuous paper P. By reducing the size, the continuous paper P can be held in the same manner as the holding unit 190 shown in FIG. 6B. In this case, the configuration in which the winding rods 191B and 191C rotate around the respective axes is not essential, and only the rotating plate 191A needs to rotate.

  In the modification in the present embodiment described above, the winding mechanism 191 is provided on the front surface (first surface) side and the back surface (second surface) side of the continuous paper P, and the continuous paper P It has two winding rods (winding members) 191B and 191C extending in parallel to the width direction, and the two winding rods 191B and 191C have a front surface side position and a back surface side position. The continuous paper P is wound up by rotating so as to alternate with each other.

  In addition, when performing the rewinding operation, the control unit 101 may control the tension of the continuous paper P based on the paper type of the continuous paper P, the paper information such as the basis weight, the stiffness, and the rewinding amount. .

  For example, when the continuous paper P is a strong paper such as a thick paper and the rewinding amount is a predetermined amount or more, the control unit 101 uses the paper in the paper discharge device 3, the paper discharge transport unit 52, and the fixing unit 60. The tension of the continuous paper P is increased by controlling the rotational speed of the rotating plate 191A and the rotational speed of the winding rods 191B and 191C to be higher than the transport speed in the direction opposite to the transport direction. By increasing the tension of the continuous paper P, the control unit 101 reduces the gap for each turn of the wound continuous paper P in the holding unit 190 and winds up a large amount of continuous paper P in a narrower space.

  Note that, as a configuration in which the tension of the continuous paper P is increased, the tension of the continuous paper P during winding is increased by applying a torque load to the paper discharge transport unit 52 in the transport in the direction opposite to the paper transport direction. Also good.

  On the other hand, even if the continuous paper P is a stiff paper such as a thick paper, the control unit 101 increases the clearance for each turn of the wound continuous paper P when the rewind amount is less than a predetermined amount. Even so, since the rewinding amount of the continuous paper P can be taken up, the control for increasing the tension of the continuous paper P is not performed. By not increasing the tension of the continuous paper P, the wound continuous paper P can be prevented from being deformed.

  Next, another modification of the holding unit in the present embodiment will be described with reference to FIG. FIG. 8 is a diagram showing a modification of the holding unit in the present embodiment. 8A shows a state where the continuous paper P is not held in the holding unit 290, FIG. 8B shows a state when the holding unit 290 starts holding the continuous paper P, and FIG. 8C shows a state where the holding unit 290 holds the continuous paper P. A state in which the continuous paper P is held is shown.

  The holding unit 290 in FIG. 8 has a winding mechanism 291. The winding mechanism 291 includes a winding rod 291A and a clamp 291B.

  The winding rod 291A is provided on the front surface side of the continuous paper P in parallel with the width direction of the continuous paper P. When starting the holding operation in the holding unit 290, the control unit 101 moves the winding rod 291A toward the clamp 291B as shown by an arrow C1 in FIG. 8B.

  The clamp 291B is provided on the back side of the continuous paper P, and opens and closes so as to cover the winding rod 291A. After moving the take-up bar 291A to the clamp 291B side, the control unit 101 holds the continuous paper P by closing the clamp 291B so as to cover the take-up bar 291A as shown by an arrow C2 in FIG. 8B. .

  The control unit 101 rotates the take-up bar 291A and the clamp 291B around the axis of the take-up bar 291A as shown by an arrow C3 in FIG. By doing so, the continuous paper P is wound up in the direction opposite to the paper transport direction (arrow X2 in FIG. 8B). As a result, as shown in FIG. 8C, the continuous paper P is wound around the outer periphery of the clamp 291B.

  In the modification example of the present embodiment described above, the winding mechanism 291 includes a winding rod (winding member) 291A provided on the front surface (first surface) side of the continuous paper P, and the continuous paper P. An openable / closable clamp (opening / closing member) 291B provided on the back surface (second surface) side, and after the winding rod 291A has moved from the front surface side to the clamp 291B side, the winding rod 291A is The clamp 291B is closed so as to cover the continuous paper P, and the continuous paper P is wound around the clamp 291B by rotating the clamp 291B and the winding rod 291A.

  According to the modification of the present embodiment described above, a larger number of recording media can be held in a smaller space, so that the size of the holding unit can be suppressed.

DESCRIPTION OF SYMBOLS 1 Paper feeder 2 Image forming apparatus 3 Paper discharge apparatus 10 Image reading part 11 Automatic document feeder 12 Original image scanning apparatus 20 Operation display part 21 Display part 22 Operation part 30 Image processing part 40 Image formation part 41 Image formation unit 42 Intermediate transfer unit 50 Paper transport section 51 Paper feed transport section 52 Paper discharge transport section 60 Fixing section 61 Fixing belt 62 Heating roller 63 Fixing roller 64 Pressure roller 70 Storage section 80 Communication section 90, 190, 290 Holding section 91 Hollow section 92 , 94 Opening portions 93, 95 Conveying roller pair 100 Image forming system 101 Control unit 191, 291 Winding mechanism 191A Rotating plate 191B, 191C, 291A Winding rod 291B Clamp 411 Exposure device 412 Developing device 413 Photosensitive drum 414 Charging device 415 Drum cleaning device 42 DESCRIPTION OF SYMBOLS 1 Intermediate transfer belt 422 Primary transfer roller 423 Support roller 424 Secondary transfer roller 426 Belt cleaning device

Claims (11)

A transport unit that transports the continuous recording medium in a first transport direction or a second transport direction that is opposite to the first transport direction;
The continuous recording medium is conveyed to the first conveying direction by front Symbol conveying unit, an image forming section for forming a toner image,
A fixing unit for fixing the first disposed on the downstream side of the image forming unit in the conveying direction, by heating the pre-Symbol the toner image formed on the continuous recording medium by the image forming unit,
A holding unit that is provided between the image forming unit and the fixing unit and holds a part of the continuous recording medium;
After the formation of the toner image by the image forming unit is completed and the toner image formed on the continuous recording medium passes through the fixing unit, the continuous recording medium is further conveyed in the first conveying direction. And after the further conveyance is finished, the continuous recording medium is conveyed in the second conveying direction, a part of the continuous recording medium is held by the holding unit, and the fixing unit is A control unit that controls the passing part that has passed through the control unit so as to return to the upstream side from the fixing unit;
An image forming apparatus comprising: The conveyance amount by which the passage portion is conveyed in the second conveyance direction is set in a range in which the holding unit can hold a part of the continuous recording medium.
The image forming apparatus according to claim 1. The range in which the holding unit can hold a part of the continuous recording medium varies depending on the type of the continuous recording medium.
The image forming apparatus according to claim 2. Transport distance the continuous recording medium is conveyed to the second conveying direction, after transporting the continuous recording medium in the second conveying direction, the warm-up operation of raising the temperature of the fixing member of the fixing unit, the continuous It is a necessary transport amount during warm-up for transporting the recording medium in the first transport direction,
The necessary conveyance amount at the time of warm-up is set based on the temperature of the fixing unit at the time when conveyance of the passage portion in the second conveyance direction is started.
The image forming apparatus according to claim 1. The control unit is configured to set the transport amount of the continuous recording medium in the second transport direction to be equal to or less than the transport amount transported by the further transport.
The image forming apparatus according to claim 1. The holding unit has a winding mechanism for winding a part of the continuous recording medium.
The image forming apparatus according to any one of claims 1-5. The winding mechanism is
Two winding members provided on the first surface side and the second surface side of the continuous recording medium, respectively, extending in the width direction of the continuous recording medium;
Winding the continuous recording medium by rotating the two winding members so as to alternate between a position on the first surface side and a position on the second surface side;
The image forming apparatus according to claim 6 . The winding mechanism is
A winding member provided on the first surface side of the continuous recording medium;
An openable and closable opening / closing member provided on the second surface side of the continuous recording medium;
Have
After the winding member moves from the first surface side to the opening / closing member side, the opening / closing member is closed so as to cover the winding member, thereby sandwiching the continuous recording medium, and the opening / closing member and the winding member Winding the continuous recording medium around the opening and closing member by rotating the take-up member;
The image forming apparatus according to claim 6 . The control unit performs the conveyance of the continuous recording medium in the second conveyance direction until the warm-up process of the fixing unit is started after the further conveyance is finished.
The image forming apparatus according to claim 1. A transport unit that transports the continuous recording medium in a first transport direction or a second transport direction that is opposite to the first transport direction;
The continuous recording medium is conveyed to the first conveying direction by front Symbol conveying unit, an image forming section for forming a toner image,
A fixing unit for fixing the first disposed on the downstream side of the image forming unit in the conveying direction, by heating the pre-Symbol the toner image formed on the continuous recording medium by the image forming unit,
A holding unit that is provided between the image forming unit and the fixing unit and holds a part of the continuous recording medium;
After the formation of the toner image by the image forming unit is completed and the toner image formed on the continuous recording medium passes through the fixing unit, the continuous recording medium is further conveyed in the first conveying direction. And after the further conveyance is finished, the continuous recording medium is conveyed in the second conveying direction, a part of the continuous recording medium is held by the holding unit, and the fixing unit is A control unit that controls the passing part that has passed through the control unit so as to return to the upstream side from the fixing unit;
An image forming system comprising: An image forming apparatus according to any one of claims 1 to 9,
A paper feeding device for feeding the continuous recording medium to the image forming apparatus;
A paper discharge device for storing the continuous recording medium on which an image is formed by the image forming device;
An image forming system comprising:

Images