JP2016085260A - Image forming apparatus, image forming system, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that prevents damage to the apparatus when abnormality occurs to the conveyance of sheets without stopping the conveyance of continuous form paper as much as possible and reducing productivity in print processing.SOLUTION: An image forming apparatus includes: a conveying part that conveys continuous form paper; an image forming part that forms an image on an image carrier; a transfer part that transfers the image formed by the image forming part to the continuous form paper; a fixing part that fixes the image transferred to the continuous form paper by the transfer part; a conveyance abnormality detection part that detects abnormality in the conveyance of the continuous form paper; and a control part that controls an image forming operation. The control part determines whether or not the continuous form paper can be conveyed on the basis of a result of the detection by the conveyance abnormality detection part.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an image forming apparatus, an image forming system, and an image forming method for printing an image on continuous paper.

  Conventionally, an image forming apparatus and an image forming system for printing an image on a long paper such as continuous paper (roll paper) are known. In the case of printing an image on continuous paper, it is possible to improve productivity by printing the image intervals as close as possible.

  In Patent Document 1, in an image forming system that forms an image on continuous paper, a jam occurs during execution of a print job, the print job is interrupted, and then, when the print job is resumed, the continuous paper retained by the jam is disclosed. It is disclosed that after performing the process of removing the print, the printing on the single-sided print job is resumed after the continuous paper is applied to the apparatus again.

JP 2012-116153 A

  However, in the image forming system disclosed in Patent Document 1, when a jam occurs during an image forming operation and the operation is stopped, a process for removing the continuous paper retained by the jam is performed, and then the continuous paper is applied to the apparatus. Since the image formation is resumed after the correction, it is never easy to remove the paper staying in the paper conveyance path in the apparatus like an image forming apparatus using the paper cut into a fixed form (hereinafter referred to as cut paper). Absent. Therefore, when continuous paper is used, it is necessary to rework the continuous paper on the apparatus in addition to the jam processing work, so the productivity of the printing process is reduced. Therefore, it is desirable to restart the image forming operation without removing the continuous paper as much as possible, and cut and discard the defective portion of the image due to the interruption as a waste paper (dirt paper) in a later process. However, for example, as shown in FIG. 7, when a jam (accordion jam) in which the continuous paper is completely jammed is generated, if the image forming operation is restarted as it is, the members related to the paper conveyance in the apparatus are damaged. There was a problem that.

  The object of the present invention is made in view of the above problems, and prevents damage to the apparatus without reducing the productivity of the printing process without stopping the continuous paper as much as possible when a paper conveyance abnormality occurs. An image forming apparatus is provided.

  According to the present invention, in the image forming apparatus, a conveying unit that conveys continuous paper, an image forming unit that forms an image on an image carrier, and a transfer unit that transfers an image formed by the image forming unit to continuous paper, A fixing unit that fixes the image transferred onto the continuous sheet by the transfer unit, a conveyance abnormality detection unit that detects conveyance abnormality of the continuous sheet, and a control unit that controls the image forming operation. It is characterized in that it is determined whether or not the continuous paper can be conveyed based on the detection result of the abnormality detection unit.

  According to the invention, in the image forming system, a conveying unit that conveys the continuous paper, an image forming unit that forms an image on the image carrier, transfers the image onto the continuous paper, and fixes it, and conveys the continuous paper. A conveyance abnormality detection unit that detects an abnormality and a control unit that controls the operation of the image forming system. The control unit determines whether or not continuous paper can be conveyed based on the detection result of the conveyance abnormality detection unit. It is characterized by that.

  Further, according to the present invention, in the image forming method for forming an image on the image carrier and transferring and fixing the image on the continuous paper to be conveyed, the conveyance abnormality detection process for detecting the conveyance abnormality of the continuous paper, and the conveyance And a determination process for determining whether or not the continuous paper can be conveyed based on a detection result of the abnormality detection process.

  According to the present invention, when a jam occurs, the degree of abnormality in paper conveyance can be detected. Therefore, even if some paper conveyance abnormality occurs, paper conveyance is continued if paper conveyance is possible. Therefore, it is possible to prevent the productivity of the printing process from being lowered. On the other hand, if it is determined that the degree of abnormality in paper conveyance is difficult, paper conveyance is not permitted, so that the apparatus can be prevented from being damaged.

1 is a cross-sectional view illustrating a schematic configuration of an image forming system according to the present invention. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to the present invention. FIG. 2 is a cross-sectional view illustrating a schematic configuration of a fixing unit according to the present invention. 1 is a control block diagram of an image forming system according to the present invention. It is a flowchart figure which shows the operation control of 1st Embodiment which concerns on this invention. It is a flowchart figure which shows the operation control of 2nd Embodiment which concerns on this invention. FIG. 6 is a simplified cross-sectional view showing a state in which continuous paper is jammed in a bellows shape at the position of a conveyance roller. 6 is a toner contamination avoidance table showing the relationship between image forming conditions during a printing operation and a corresponding toner contamination avoidance mode. 6 is a table showing types of toner contamination avoidance modes.

(Configuration of image forming system)
FIG. 1 is a diagram showing a schematic configuration of an image forming system according to the present invention. The image forming system 1 includes a paper feeding device 2, an image forming device 3, a paper buffer device 4, a winding device 5, and the like.

  The paper feeding device 2 supplies continuous image paper for image formation to the image forming device 3. The continuous paper of this embodiment is specifically the continuous paper P, and the paper feeding device 2 stores the continuous paper P in a roll shape, and the continuous paper P is stored in the image forming system 1. Supply continuously.

  The paper buffer device 4 transports the continuous paper P that has passed through the image forming apparatus 3, and in order to absorb fluctuations in the paper distance between the devices due to deviations in the transport timing of the continuous paper P, the paper buffer device 4 It functions as a paper buffer. The specified amount of the paper buffer is determined so as not to reach the limit amount of the paper buffer in consideration of the fluctuation of the transport amount of the continuous paper P due to the timing and speed difference of the continuous paper P between the apparatuses. Yes.

  Further, the paper buffer device 4 is provided with a paper cutting unit 6 capable of cutting continuous paper. For example, when a problem occurs in paper conveyance and the continuous paper needs to be cut, the continuous paper P is loaded. It is possible to cut. In addition, depending on the customer's request to store the output paper on which the image has been formed, the paper cutting unit 6 can also deliver the cut paper obtained by cutting the continuous paper into a predetermined paper size. In that case, a stacking device such as a stacker capable of stacking a large amount of cut sheets may be connected instead of the winding device 5 arranged on the downstream side in the sheet transport direction.

  In the form of the image forming system according to the present invention, the paper buffer device 4 including the paper cutting unit 6 is disposed between the image forming device 3 and the winding device 5. It is also possible to adjust the transport amount of each of the front and rear devices by giving a slack of the paper as in the paper transport path 7 between the paper feeding device 2 and the image forming apparatus 3. Further, the paper buffer device 4 may be connected to the position of the paper transport path 7.

  The winding device 5 is wound into the form of roll paper again by attaching and rotating the leading end of the continuous paper P on which the toner image is formed to the winding shaft.

(Configuration of image forming apparatus)
FIG. 2 is a diagram illustrating a schematic configuration of the image forming apparatus 3.
The image forming apparatus 3 includes an image forming unit 20, a conveyance unit 30, a fixing unit 40, an operation display unit 105, and the like.

  The image forming unit 20 includes four image forming units 20Y, 20M, 20C, and 20K that form images of each color of yellow (Y), magenta (M), cyan (C), and black (K). . A toner image of each color is formed on the photosensitive drum 11 corresponding to each color based on the image data, and a color image is formed by transferring and superimposing the toner images of each color onto the intermediate transfer belt 16 by the primary transfer unit 13. A series of image forming operations until the primary-transferred color image is secondarily transferred and fixed on the continuous paper P is performed.

The configuration and operation around the photosensitive drum 11 will be briefly described.
Here, the description is made for the yellow (Y) image forming unit 20Y, and the configuration of the other colors is the same as that of the yellow (Y) image forming unit 20Y.

  The charging unit 23Y uniformly charges the surface of the photosensitive drum 11Y.

  The exposure unit 22Y exposes the area where the toner adheres to the surface of the photoreceptor drum 11Y, and forms an electrostatic latent image by removing the charge of the exposed part.

  The developing unit 21Y develops a toner image by attaching toner to the electrostatic latent image on the photosensitive drum 11Y.

  The primary transfer unit 13Y transfers a toner image developed on the photosensitive drum 11Y to the intermediate transfer belt 16 by applying a bias voltage having a polarity opposite to the polarity of the toner.

  The cleaning unit 25Y removes residual toner adhering to the photosensitive drum 11Y without being transferred to the intermediate transfer belt 16 with a blade or the like.

  The intermediate transfer belt 16 is an endless belt, is constructed by a plurality of rollers, and is supported so as to be able to run. The toner images of the respective colors formed on the image forming units 20Y, 20M, 20C, and 20K are sequentially transferred onto the intermediate transfer belt 16 that travels by the primary transfer units 13Y, 13M, 13C, and 13K, and each color (Y, M , C, K), a color image (toner image) is formed on the intermediate transfer belt 16.

  The intermediate transfer belt 16 includes an intermediate transfer cleaning unit 19 having a belt cleaning roller 17 and a belt cleaning blade 18 that are in sliding contact with the surface of the intermediate transfer belt 16. After the secondary transfer, residues including transfer residual toner remaining on the surface of the intermediate transfer belt 16 are scraped off and removed by the belt cleaning roller 17 and the belt cleaning blade 18.

  The secondary transfer roller 13A is disposed in contact with the secondary transfer counter roller 16a via the intermediate transfer belt 16, and is formed between the secondary transfer roller 13A and the secondary transfer counter roller 16a. As the continuous paper P passes through, the toner image on the intermediate transfer belt 16 is secondarily transferred to the continuous paper P. The secondary transfer roller 13A is in contact with the secondary transfer counter roller 16a during the image forming operation, but is separated from the secondary transfer counter roller 16a when the image forming operation ends.

  The transport unit 30 transports the continuous paper P fed from the paper feeder 2 to the secondary transfer roller 13 </ b> A through the paper roller 31, the loop forming roller 32, and the registration roller 33. The toner image formed on the intermediate transfer belt 16 is secondarily transferred onto the continuous paper P by the secondary transfer roller 13A. Torque sensors 32a, 32b, and 33c that can detect torque during driving are connected to the paper passing roller 31, the loop forming roller 32, and the registration roller 33, respectively, and the degree of load applied to each roller is always detected. . The torque sensor 32 is connected to each roller related to paper conveyance. For example, the torque sensor 32 is connected to a secondary transfer roller 13A disposed downstream of the registration roller 31c in the paper conveyance direction and a fixing member of the fixing unit 40 described later. The driving torque is constantly monitored.

  A fixing unit 40 is disposed on the discharge side of the continuous paper P in the secondary transfer roller 13A, and the toner image formed on the conveyed continuous paper P is nipped and conveyed to form a toner image on the continuous paper P. Let it settle. The continuous paper P on which the toner image is fixed is conveyed to a pair of paper discharge rollers 31d on the downstream side in the conveyance direction.

  The operation display unit 105 is a touch panel including a display such as an LCD (Liquid Crystal Display) or an organic ELD (Electro Luminescence Display). The operation display unit 105 displays an instruction menu for the user, information about the acquired image data, and the like.

  In the present embodiment, the torque sensor 32 is connected to each roller related to paper conveyance of the image forming apparatus 3. However, the connection destination of the torque sensor 32 is connected to each roller related to paper conveyance of the image forming apparatus 3. It is not limited. For example, a torque sensor 32 is connected to a roller that conveys paper in each device constituting the image forming system 1 such as the paper feeding device 2, the paper buffer device 4, and the winding device 5, and the driving torque of each roller is monitored. It doesn't matter. In the following description, a generic term for each roller related to paper conveyance of each apparatus constituting the image forming system 1 will be referred to as a conveyance roller.

(Configuration of fixing unit)
FIG. 3 is a diagram illustrating a schematic configuration of the fixing unit according to the first embodiment.
The fixing unit 40 includes a heating roller 41, a fixing belt 42, an upper pressure roller 43, and a lower pressure roller 44.
Inside the heating roller 41, a halogen heater 45 is provided as a heating member, and the heating roller 41 supplies heat to the continuous paper P via the fixing belt 42. The toner image is fixed on the continuous paper P by nipping and conveying the continuous paper P at the fixing nip N formed by the upper pressure roller 43 and the lower pressure roller 44 being pressed against each other.

The fixing belt 42 is formed in an endless shape. For example, PI (polyimide) having a thickness of 70 μm is used as a base, and a heat-resistant silicone rubber having a thickness of 200 μm is used as the outer peripheral surface of the base (hardness JIS-A 30 °). Further, the surface layer is covered with a PFA (perfluoroalkoxy) tube, which is a heat-resistant resin having a thickness of 30 μm. The outer diameter of the fixing belt 42 is 120 mm, for example.
The fixing belt 42 is stretched around the heating roller 41 and the upper pressure roller 43 by a tension of 200 N.

  The heating roller 41 heats the fixing belt 42. That is, the heating roller 41 has a built-in halogen heater 45 extending in the axial direction as a heating means for heating the fixing belt 42. For example, the outer periphery of a cylindrical metal core having a thickness of 4 mm formed of aluminum or the like. The surface is configured as a hard roller whose surface is covered with a resin layer coated with 30 μm thick PTFE (polytetrafluoroethylene). The outer diameter dimension of the heating roller 41 is, for example, 70 mm.

  The halogen heater 45 is disposed inside the heating roller 41, and energization of the halogen heater 45 is controlled by a control unit S described later. The heating roller 41 is heated by the halogen heater 45, and as a result, the fixing belt 42 is heated. The fixing belt 42 may be configured to be heated by electromagnetic induction heating (IH: Induction Heating) or a resistance heating element.

  The upper pressure roller 43 and the lower pressure roller 44 are arranged in a state where a load of a total pressure of 2000 N is applied via the fixing belt 42, and a pressure contact portion between the upper pressure roller 43 and the lower pressure roller 44. As a result, a fixing nip N is formed.

  The upper pressure roller 43 is a soft roller in which a solid metal core made of metal such as iron is covered with a heat-resistant silicone rubber (SRIS 0101-ASKER C35 °) having a thickness of 20 mm as an elastic layer. It is configured. The outer diameter of the upper pressure roller 43 is, for example, 70 mm.

  The lower pressure roller 44 covers the outer peripheral surface of a cylindrical core metal having a thickness of 4 mm made of aluminum or the like with a heat-resistant silicone rubber (SRIS 0101-ASKER C68 °) having a thickness of 20 mm as an elastic layer. Furthermore, it is covered with a resin layer of a PFA tube having a thickness of 50 μm as a release layer. The outer diameter of the lower pressure roller 44 is, for example, 70 mm.

  The fixing speed of the fixing unit 40 is, for example, 300 mm / s. The fixing speed here is a speed at which the continuous paper P passes through the fixing nip N formed by the upper pressure roller 43 and the lower pressure roller 44.

(Control block diagram of image forming system)
FIG. 4 is a block diagram showing control connections of the image forming system according to the present invention. The image forming apparatus 3 includes, for example, a central processing unit (CPU) 101 that centrally controls each unit of the image forming apparatus 3, a read only memory (ROM) 102 that stores programs executed by the CPU 101, and the CPU 101. RAM (Random Access Memory) 103 used as a work area. Furthermore, an HDD (Hard disk drive) 104 as a mass storage device and an operation display unit 105 for operating settings and operations of the image forming system 1 are provided.

  A CPU 101 is connected to a ROM 102, a RAM 103, an HDD 104, and an operation display unit 105 via a system bus 106, and controls the entire apparatus. The CPU 101 is connected to the image processing unit 110, the image forming unit 20, the transport unit 30, and the fixing unit 40 via the system bus 106. Further, an external connection device interface (hereinafter referred to as “I / F”) 107 a that communicates between the image forming device 3 and an external device of the image forming device 3 is connected to the system bus 106. The external devices such as the paper feeding device 2, the paper buffer device 4, and the winding device 5 can be controlled via the I / F 107a.

  The HDD 104 stores, for example, image data transmitted from a PC (Personal Computer) 108, which is an external information processing apparatus, and stores output image data and the like. The operation display unit 105 is a touch panel including a display such as an LCD or an organic ELD. The operation display unit 105 displays an instruction menu for the user, information about the acquired image data, and the like. Further, the operation display unit 105 includes a plurality of keys, receives input of various instructions, data such as characters and numbers by user's key operation, and outputs an input signal to the CPU 101.

  Image data transmitted from an external device connected to the image forming apparatus 3, such as the PC 108, is sent to the image processing unit 110 for image processing. The image processing unit 110 performs image processing such as shading correction, image density adjustment, and image compression on the received image data as necessary.

  The image forming unit 20 receives the image data processed by the image processing unit 110, performs exposure on the photosensitive member 11 by the exposure unit 22 and development by the developing unit 21 based on the image data, and applies the image data to the continuous paper P. Form an image.

  For example, the communication unit 109 receives job information transmitted from the PC 108 via a communication line. Then, the received job information is sent to the CPU 101 via the system bus 106.

  The sheet feeding device 2 includes a sheet feeding control unit 111 that controls the entire sheet feeding device 2. The paper feed control unit 111 is connected with an I / F 107 b that is an interface for communicating with an external device of the paper feed device 2. In addition, each drive unit 114 b and each sensor 115 b of the sheet feeding device 2 are connected to the sheet feed control unit 111.

  The sheet buffer device 4 includes a buffer control unit 112 that controls the entire sheet buffer device 4. Connected to the buffer control unit 112 is an I / F 107 c that is a communication interface for communicating with an external device of the paper buffer device 4. The buffer control unit 112 is connected to the paper cutting unit 118 and can control the operation of the paper cutting unit 118. Further, each drive unit 114 c and each sensor 115 c of the paper buffer device 4 are connected to the buffer control unit 112.

  The winding device 5 includes a winding control unit 113 that controls the entire winding device 5. The winding control unit 13 is connected to an I / F 107 d that is a communication interface for communicating with an external device of the winding device 5. In addition, each drive unit 114d and each sensor 115d of the winding device 5 are connected to the winding control unit 113.

(Flowchart of the first embodiment)
A flowchart of operation control according to the first embodiment will be described with reference to FIG.
FIG. 5 is a flowchart illustrating operation control of the image forming apparatus according to the first embodiment.

  The start timing of the operation control according to the first embodiment is synchronized with the start timing of the printing operation. When the operation control of the image forming apparatus according to the present embodiment is started, the operation roller starts to convey the continuous paper P. The connected torque sensors 32a, 32b, 32c, 32d, 32e, and 32f always detect the driving torque of each roller during the printing operation (step S10). The drive torque values detected by the torque sensors 32a, 32b, 32c, 32d, 32e, and 32f are always input to the CPU 101.

  During the printing operation, it is determined whether or not the driving torque value of the transport roller is equal to or greater than a first predetermined value (step S11). If the drive torque value of the transport roller is smaller than the first predetermined value in step S11 (step S11_NO), it is determined that the continuous paper P is being transported smoothly, and the drive torque value is equal to or greater than the first predetermined value. Until it becomes, the process of step S10 and the determination of step S11 are repeated. On the other hand, when the drive torque value is equal to or greater than the first predetermined value (step S11_YES), it is determined that the drive torque is abnormal and the sheet conveyance is stopped (step S12). In the first embodiment, when it is determined that the driving torque is abnormal, the degree of abnormality at this point is unknown, and therefore the paper conveyance is temporarily stopped from the idea of giving priority to safety.

  In step S12, after the paper conveyance is stopped, it is determined whether or not the driving torque value is equal to or greater than a second predetermined value (step S13). In step S13, the degree of abnormality is determined.

  Here, the first predetermined value and the second predetermined value will be described. The first predetermined value indicates a criterion as to whether or not the driving torque applied to the transport roller is within a normal range. When the driving torque is smaller than the first predetermined value, it indicates that the driving torque applied to the conveyance roller is within a normal range in normal sheet conveyance. On the other hand, when the drive torque is equal to or greater than the first predetermined value, it indicates that an abnormality has occurred and indicates that the load applied to the transport roller is higher than that during normal transport.

  The second predetermined value is higher than the first predetermined value and is a reference indicating whether or not to permit paper conveyance. If the drive torque applied to the transport roller is greater than or equal to the second predetermined value, there is a possibility that the device may be damaged if the paper is transported. For example, an accordion jam occurs and the transport roller is completely driven. It can be in a stopped state.

  On the other hand, the case where it is smaller than the second predetermined value indicates a state where the paper can be conveyed. That is, from the relationship with the first predetermined value, when the driving torque applied to the conveying roller is equal to or higher than the first predetermined value and smaller than the second predetermined value, the driving torque is higher than that during normal paper conveyance. Although an abnormality has occurred, the paper can be conveyed.

  In step S13, if the drive torque value is equal to or greater than the second predetermined value (step S13_YES), there is a risk that the apparatus will be damaged if the sheet conveyance is resumed. While the state is stopped, the occurrence of paper jam is displayed on the screens of the operation display unit 105 and the PC 108 (step S16), and prompts the user that the process of removing the paper jam is necessary. After the occurrence of a paper jam is displayed on the screens of the operation display unit 105 and the PC 108, the control is terminated.

  On the other hand, when the driving torque value of the conveying roller is smaller than the second predetermined value (step S13_NO), it is determined that the sheet can be conveyed and the unfixed toner in the sheet conveying path from the secondary transfer roller 13A to the fixing unit 40 is determined. A toner contamination avoiding operation corresponding to the print condition is selected in order to execute a toner contamination avoiding operation for cleaning the toner contamination that has been scattered and transferred (offset) to the fixing member (step S14). The toner contamination avoidance mode will be described in detail later.

The necessity of the toner contamination avoidance mode will be described below.
In step S12, since the sheet conveyance is stopped during the printing operation, there is a toner image that is already transferred and unfixed on the continuous sheet P in the sheet conveyance path between the secondary transfer roller 13A and the fixing unit 40. doing. In the fixing unit 40, when the sheet conveyance is stopped, the toner that has not been properly fixed due to inertia during driving adheres to the fixing belt 42, or the conveyance roller and the winding roller on the downstream side in the sheet conveyance direction. The toner adheres to the continuous paper P taken up by the take-up device and causes toner contamination. Therefore, when the printing operation is resumed after the paper conveyance is stopped during the printing operation, it is necessary to perform an operation for removing the unfixed toner and preventing the toner from being stained.

  After the toner contamination avoidance mode is selected in step S14, the selected toner contamination avoidance mode is executed (step S15).

  After the toner contamination avoidance mode is executed to prevent toner scattering and toner contamination, the torque abnormality elimination mode is executed in order to solve the problem determined as torque abnormality in the process of step S11 (step S17).

The torque abnormality elimination mode will be described below.
The state of NO determination in step S13 indicates a case where the driving torque of the transport roller is equal to or greater than the first predetermined value and smaller than the second predetermined value. This state indicates that the driving torque is higher than that during normal sheet conveyance and is abnormal, but can be solved by taking appropriate measures. Specifically, this state can be exemplified by temporary shift of the transport position or skewing that does not affect the image quality in the width direction of the continuous paper P in the direction orthogonal to the paper transport direction by increasing the drive torque. For example, paper wrinkles and undulations that occur temporarily are applicable.

  For this reason, in the torque abnormality elimination mode, only the sheet conveyance is continued without performing the image forming operation until the torque abnormality is eliminated. While the torque abnormality elimination mode is being executed, the driving torque value of the conveying roller by the torque sensor 32 is constantly monitored to determine whether the driving torque value of the conveying roller is smaller than the first predetermined value (step) S18).

  When the driving torque value of the transport roller is equal to or greater than the first predetermined value (step S18_NO), it is determined that the torque abnormality has not been eliminated, and the torque abnormality elimination mode is continued. On the other hand, when the drive torque is smaller than the first predetermined value (step S18_YES), it is determined that the torque abnormality has been eliminated, the torque abnormality elimination mode is terminated (step S19), and the control is terminated.

  The timing for ending the torque abnormality elimination mode is the case where the driving torque of the transport roller becomes smaller than the first predetermined value, but is not limited to this. For example, if the approximate time at which the temporary problem is resolved is known, the torque abnormality elimination mode may be terminated after a predetermined time has elapsed.

(Toner contamination avoidance mode)
The toner contamination avoidance mode will be described with reference to FIGS.
FIG. 8 shows a toner contamination avoidance table showing the relationship between the image formation conditions during the printing operation and the corresponding toner contamination avoidance mode when executing the toner contamination avoidance mode, and FIG. 9 shows the types of toner contamination avoidance modes. It is the table | surface which showed. In the description of the toner contamination avoidance mode, the fixing setting indicates a fixing condition including three factors, which are important parameters for fixing toner on continuous paper, which are a fixing nip width, a fixing belt temperature, and a sheet conveyance speed. The fixing nip width indicates the width in the conveyance direction of the continuous paper at the pressure contact portion between the upper pressure roller 43 and the lower pressure roller 44. Further, the toner contamination avoidance mode indicates an operation in which the fixing condition indicating the fixing condition is combined with the sheet conveyance amount when the toner contamination avoidance mode is executed.

  As shown in FIG. 8, in the toner contamination avoidance table, as the printing conditions, the basis weight of the continuous paper P, the fixing nip width, the temperature of the fixing belt 16, the paper conveyance speed of the continuous paper P, and the setting conditions of the image printing rate during printing Thus, the toner contamination avoidance mode is set. The paper conveyance amount in the toner contamination avoidance mode depends on the image printing rate when the A4 size is converted into the printing conditions, and corresponds to three circumferences of the fixing belt 16 when the image printing rate is 20% or more. The distance to be transported. On the other hand, when the image printing rate is smaller than 20%, a distance corresponding to one circumference of the circumference of the fixing belt 16 is conveyed.

  In the first embodiment, the paper conveyance amount in the toner contamination avoidance mode is the conveyance amount converted to the circumferential length of the fixing belt 16, but is the conveyance amount converted to the distance of the paper conveyance path from the transfer nip to the fixing nip. It doesn't matter. In the configuration of the image forming apparatus, it is preferable to compare the peripheral length of the fixing member on the fixing surface side of the continuous paper P and the transport distance between the transfer and fixing, and convert them based on the longer one.

FIG. 9 shows a fixing setting in the toner contamination avoidance mode, and three settings of a fixing setting A, a fixing setting B, and a fixing setting C are provided. In the fixing setting A, the fixing nip width is 20 mm, the temperature of the fixing belt 16 is 190 ° C., and the paper conveyance speed is 150 mm / s. The characteristics of the fixing setting A are half the speed of the paper conveyance speed during printing. In the fixing setting B, the fixing nip width is 20 mm, the temperature of the fixing belt 16 is 190 ° C., and the sheet conveyance speed is 300 mm / s. In the fixing setting C, the fixing nip width is 10 mm, the temperature of the fixing belt 16 is 160 ° C., the paper conveyance speed is 150 mm / s, and the fixing nip width is halved compared to printing, so the pressure on the continuous paper P is small. Thus, the sheet conveyance speed passing through the fixing nip width becomes half speed.
Although three settings are used in the present embodiment, the number of settings is not limited to three.

  As a method of changing the fixing nip width, a mechanism capable of adjusting the pressure is provided to a pressure contact member that presses the upper pressure roller 43 and the lower pressure roller 44, and the fixing nip width is adjusted by an electric signal from the control unit S. be able to.

(Operation in toner contamination avoidance mode)
A specific operation in the toner contamination avoidance mode will be described.
If it is determined in step S13 of the flowchart shown in FIG. 5 that the driving torque of the conveying roller is smaller than the second predetermined value (step S13_NO), it is determined that the sheet can be conveyed, and the mode shifts to the toner contamination avoidance mode. An appropriate toner contamination avoidance mode is executed according to the condition of the printing operation immediately before the operation.

For example, when the basis weight of the continuous paper is 100 g / m ² and the image printing rate corresponding to the A4 size is smaller than 20%, the fixing setting is C and the continuous paper P is fixed on the fixing belt 16. A distance corresponding to one lap is conveyed. Even if the operation stops during the printing operation, the mode immediately shifts to the toner contamination avoidance mode. Therefore, scattering of unfixed toner transferred onto the continuous paper on the paper conveyance path from the secondary transfer roller 13A to the fixing unit 40 and The toner transferred (offset) to the fixing member can be fixed on the continuous paper, and the problem of fouling the continuous paper that has been printed and already taken up and the conveyance roller on the downstream side of the paper conveyance from the fixing unit is solved. Can do.

  As described above, according to the image forming apparatus of the first embodiment described above, since the degree of abnormality in paper conveyance can be detected by the torque sensor 32 connected to the conveyance roller, some abnormality in paper conveyance occurs. However, depending on the degree of abnormality, the sheet conveyance can be continued, and the sheet conveyance is not stopped as much as possible, so that the productivity of the printing process can be prevented from being lowered.

(Flowchart of the second embodiment)
FIG. 6 is a flowchart illustrating operation control of the image forming apparatus according to the second embodiment.

  As a difference from the flowchart of the operation control according to the first embodiment, the second embodiment is a productivity priority mode in which productivity is prioritized. A specific difference is that even when the driving torque value of the transport roller is equal to or greater than the first predetermined value, it is immediately determined whether or not the sheet is continuously transported without stopping and whether or not the second predetermined value is exceeded. Thus, the unfixed toner is not scattered in the paper conveyance path from the secondary transfer roller 13A to the fixing unit 40, and the toner contamination that is transferred (offset) to the fixing member does not occur. Accordingly, since the processing in the toner contamination avoidance mode is not required, productivity can be improved as compared with the operation control of the first embodiment.

A flowchart of operation control according to the second embodiment will be described with reference to FIG.
From the start timing of the operation control according to the second embodiment, the drive torque of the transport roller is detected (step S21), and it is determined whether the detected drive torque value is equal to or greater than a first predetermined value (step S21). Follows the processing of step S10 and step S11 shown in FIG.

  In step S21, when the driving torque value of the transport roller is smaller than the first predetermined value (step S21_NO), it is determined that the continuous paper P is being transported smoothly, and the driving torque value is the first predetermined value. Until it becomes above, the process of step S20 and the judgment of step S21 are repeated. On the other hand, if it is determined that the driving torque value of the transport roller is equal to or greater than the first predetermined value (step S21_YES), it is immediately determined whether it is equal to or greater than the second predetermined value (step S22).

  In step 22, if the driving torque value of the transport roller is equal to or greater than the second predetermined value (step S22_YES), it is determined that there is a risk of damaging the apparatus if the sheet transport is continued as it is, and the sheet transport is immediately stopped to operate. The occurrence of paper jam is displayed on the screens of the display unit 105 and the PC 108 (step S23), and prompts that the user needs to remove the paper jam. After the occurrence of a paper jam is displayed on the screens of the operation display unit 105 and the PC 108, the control is terminated.

  On the other hand, when the driving torque value of the conveyance roller is smaller than the second predetermined value (step S22_NO), it is determined that the sheet conveyance can be continued and the torque abnormality elimination mode is executed (step S24).

  While the torque abnormality elimination mode is being executed, the driving torque value of the conveying roller by the torque sensor 32 is constantly monitored to determine whether the driving torque value of the conveying roller is smaller than the first predetermined value (step) S25).

  When the driving torque value of the transport roller is equal to or greater than the first predetermined value (step S25_NO), it is determined that the torque abnormality has not been eliminated, and the torque abnormality elimination mode is continued. On the other hand, if the drive torque is smaller than the first predetermined value (step S25_YES), it is determined that the torque abnormality has been eliminated, the torque abnormality elimination mode is terminated (step S16), and the control is terminated.

  As described above, according to the image forming apparatus of the second embodiment described above, the degree of abnormality in paper conveyance can be detected by the torque sensor 32 connected to the conveyance roller, so that some abnormality in paper conveyance occurs. However, depending on the degree of abnormality, the sheet conveyance can be continued, and the sheet conveyance is not stopped as much as possible, so that the productivity of the printing process can be prevented from being lowered.

DESCRIPTION OF SYMBOLS 1 Image forming system 2 Paper feeding device 3 Image forming device 4 Paper buffer device 5 Winding device

Claims (19)

A transport unit for transporting continuous paper;
An image forming unit that forms an image on an image carrier;
A transfer unit that transfers the image formed by the image forming unit to the continuous paper;
A fixing unit for fixing the image transferred to the continuous paper by the transfer unit;
A conveyance abnormality detector for detecting conveyance abnormality of the continuous paper;
A control unit for controlling the image forming operation,
The image forming apparatus according to claim 1, wherein the control unit determines whether or not the continuous paper can be conveyed based on a detection result of the conveyance abnormality detection unit. The control unit determines whether or not the conveyance unit is capable of conveying the continuous sheet and a first predetermined value for determining whether or not an abnormality has occurred in the conveyance unit, and greater than the first predetermined value. A determination is made based on the second predetermined value for determining,
When it is determined that the detection value by the conveyance abnormality detection unit is equal to or greater than the first predetermined value, the operation of the conveyance unit is stopped, and when the detection value is determined to be equal to or greater than the predetermined value of the second predetermined value, The image forming apparatus according to claim 1, wherein a user is notified that the operation of the transport unit is prohibited. The control unit determines whether or not the conveyance unit is capable of conveying the continuous sheet and a first predetermined value for determining whether or not an abnormality has occurred in the conveyance unit, and greater than the first predetermined value. A determination is made based on the second predetermined value for determining,
When it is determined that the detection value by the conveyance abnormality detection unit is equal to or greater than the first predetermined value, the operation of the conveyance unit is continued without stopping, and the detection value is equal to or greater than the predetermined value of the second predetermined value. 2. The image forming apparatus according to claim 1, wherein when the determination is made, the operation of the transport unit is stopped and the user is notified that the operation of the transport unit is prohibited.   The said control part performs the operation | movement which restarts the operation | movement of the said conveyance part, when it judges that the detection value by the said conveyance abnormality detection part is smaller than a said 2nd predetermined value. Image forming apparatus.   The operation of resuming the operation of the transport unit fixes the unfixed image toner from the transfer unit to the fixing unit and the toner transferred to the fixing unit on the continuous paper. Image forming apparatus.   5. The control unit according to claim 2, wherein the control unit performs an operation to eliminate the abnormality of the transport unit when it is determined that a detection value by the transport abnormality detection unit is smaller than the second predetermined value. The image forming apparatus according to any one of the above.   The image forming apparatus according to claim 6, wherein the operation of the image forming unit is not performed in the operation of eliminating the abnormality of the conveyance unit.   The said conveyance abnormality detection part is provided with the torque detection means which detects the drive torque of the said conveyance part, and when the said drive torque is more than the said 1st predetermined value, it determines that it is abnormal. The image forming apparatus according to claim 7. A transport unit for transporting continuous paper;
An image forming unit that forms an image on an image carrier, transfers the image to the continuous paper, and fixes the image;
A conveyance abnormality detector for detecting conveyance abnormality of the continuous paper;
A control unit for controlling the operation of the image forming system,
The image forming system according to claim 1, wherein the control unit determines whether or not the continuous paper can be conveyed based on a detection result of the conveyance abnormality detection unit. The control unit determines whether or not the conveyance unit is capable of conveying the continuous sheet and a first predetermined value for determining whether or not an abnormality has occurred in the conveyance unit, and greater than the first predetermined value. A determination is made based on the second predetermined value for determining,
When it is determined that the detection value by the conveyance abnormality detection unit is equal to or greater than the first predetermined value, the operation of the conveyance unit is stopped, and when the detection value is determined to be equal to or greater than the predetermined value of the second predetermined value, The image forming system according to claim 9, wherein a user is notified that the operation of the transport unit is prohibited. The control unit determines whether or not the conveyance unit is capable of conveying the continuous sheet and a first predetermined value for determining whether or not an abnormality has occurred in the conveyance unit, and greater than the first predetermined value. A determination is made based on the second predetermined value for determining,
When it is determined that the detection value by the conveyance abnormality detection unit is equal to or greater than the first predetermined value, the operation of the conveyance unit is continued without stopping, and the detection value is equal to or greater than the predetermined value of the second predetermined value. 10. The image forming system according to claim 9, wherein when the determination is made, the operation of the transport unit is stopped to notify the user that the operation of the transport unit is prohibited.   The said control part performs the operation | movement which restarts the operation | movement of the said conveyance part, when it judges that the detection value by the said conveyance abnormality detection part is smaller than a said 2nd predetermined value. Image forming system.   13. The operation of resuming the operation of the transport unit fixes unfixed image toner from the transfer unit to the fixing unit and toner transferred to the fixing unit on the continuous paper. Image forming system.   The control unit according to claim 10, wherein when the detection value by the conveyance abnormality detection unit is determined to be smaller than the second predetermined value, the control unit performs an operation to eliminate the abnormality of the conveyance unit. The image forming system according to any one of the above.   The image forming system according to claim 14, wherein the operation of the image forming unit is not performed in the operation of eliminating the abnormality of the transport unit. In an image forming method in which an image is formed on an image carrier, and the image is transferred and fixed on a continuous paper to be conveyed.
A conveyance abnormality detection process for detecting a conveyance abnormality of the continuous paper;
An image forming method comprising: a determination process for determining whether or not the continuous paper can be conveyed based on a detection result of the conveyance abnormality detection process. In the determination process, a first predetermined value for determining whether or not the continuous paper conveyance is abnormal and a value larger than the first predetermined value and whether or not the continuous paper conveyance is possible are determined. A determination is made based on the second predetermined value for determining,
When it is determined that the detection value by the conveyance abnormality detection process is equal to or greater than the first predetermined value, the conveyance of the continuous paper is stopped, and when the detection value is determined to be equal to or greater than the predetermined value of the second predetermined value, The image forming method according to claim 16, wherein a process of notifying a user that the conveyance of the continuous paper is prohibited is performed. In the determination process, a first predetermined value for determining whether or not the continuous paper conveyance is abnormal and a value larger than the first predetermined value and whether or not the continuous paper conveyance is possible are determined. A determination is made based on the second predetermined value for determining,
When it is determined that the detection value by the conveyance abnormality detection process is equal to or greater than the first predetermined value, the conveyance of the continuous paper is continued without stopping, and the detection value is equal to or greater than the predetermined value of the second predetermined value. 17. The image forming method according to claim 16, wherein when the determination is made, the process of notifying the user that the conveyance of the continuous paper is stopped and the conveyance of the continuous paper is prohibited is performed.   18. The determination process according to claim 17, wherein the determination processing performs an operation of resuming the conveyance of the continuous sheet when it is determined that a detection value by the conveyance abnormality detection unit is smaller than the second predetermined value. Image forming method.

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