JP6256064B2 - Image forming system and image forming apparatus - Google Patents

Description

  The present invention relates to a series tandem type image forming system that shares image formation on a conveyed sheet with two image forming apparatuses connected in series, and an image forming apparatus that constitutes the image forming system.

  2. Description of the Related Art Conventionally, there is known a series tandem type image forming system in which two image forming apparatuses connected in series share image formation on a conveyed sheet.

  For example, Patent Document 1 describes a printing apparatus including a first printing unit, a second printing unit, and a relay unit that connects the first printing unit and the second printing unit. The first printing unit and the second printing unit form an image on a sheet by an electrophotographic printing method. The relay unit is provided on the side opposite to the curvature of the photosensitive member of the second printing unit so that the paper conveying unit for conveying the paper from the first printing unit to the second printing unit and the paper does not wrap around the photosensitive member of the second printing unit. A decurler device is provided so that the sheet bends. At the entrance of the decurler device, there is provided a switching device for switching whether or not the paper is passed through the decurler device depending on the thickness of the paper. The switching device does not pass the paper through the decurler device when the thickness of the paper is a predetermined value (120 g / square meter) or more.

JP 2004-256292 A

  However, in the printing apparatus described in Patent Document 1, when the thickness of the paper is thinner than a predetermined value, the paper is always bent by the decurler device. Therefore, even if the winding of the sheet does not occur in the subsequent image forming apparatus (second printing unit) among the two connected image forming apparatuses (first printing unit and second printing unit), the thickness A sheet whose thickness is thinner than a predetermined value is bent by a decurler device. For this reason, the wear of the member for bending the paper on the decurler device is promoted. Further, due to the paper being bent by the decurler device, there is a possibility that a transport failure such as a jam that jams the paper in the paper transport path behind the decurler device may occur.

  The present invention has been made in view of the above-described circumstances, and is an image forming system configured by connecting two image forming apparatuses in series, and consumption of a member for attaching a bending wrinkle to a sheet of a decurler section An object of the present invention is to provide an image forming system that suppresses the occurrence of an image transfer and reduces the occurrence of a conveyance failure and an image forming apparatus that constitutes the image forming system.

In order to solve the above problems and achieve the object of the present invention, an image forming system according to the present invention includes a first image forming apparatus and a second image forming apparatus connected in series, the first image forming apparatus, An image forming system of a series tandem system that shares image formation on sheets conveyed in the order of the second image forming apparatus, and includes a front decurler unit, a conveyance abnormality detection unit, and a control unit. The front decurler unit is provided in the first image forming apparatus and adjusts the direction in which the paper is warped and the amount of warpage of the paper. The conveyance abnormality detection unit detects a sheet conveyance abnormality in the second image forming apparatus. The control unit determines the amount of paper warpage in the front decurler unit based on the detection result of the conveyance abnormality by the conveyance abnormality detection unit. In addition, when the conveyance abnormality detection unit detects the conveyance abnormality, the control unit warps the sheet to the image forming surface side on which the image is formed by the first image forming apparatus, or When the direction and amount of warping of the paper in the front decurler unit are determined so that the paper is warped toward the non-image forming surface, which is the side on which no image is formed in one image forming apparatus, and the transport abnormality detection unit does not detect the transport abnormality Determines the amount of paper warpage in the front decurler unit so as not to warp the paper.

The image forming apparatus according to the present invention includes two image forming apparatuses connected in series, and the first in an image forming system of a series tandem system that shares image formation on paper conveyed to the two image forming apparatuses. The image forming apparatus is configured to convey a sheet of paper, and includes a front decurler unit, a communication unit, and a control unit. The front decurler adjusts the direction in which the paper is warped and the amount of warpage of the paper. The communication unit receives information indicating a paper conveyance abnormality in the other image forming apparatus from the other image forming apparatus. The control unit determines the amount of paper warpage in the front decurler unit based on whether or not the communication unit has received information indicating a conveyance abnormality. In addition, when the communication unit receives information indicating a conveyance abnormality, the control unit warps the sheet to the image forming surface side, which is the side on which the image is formed, or forms an image at the end of the sheet. The direction and amount of warping of the paper in the front decurler unit are determined so that the paper is warped to the non-image forming surface side that is not performed, and the communication unit does not warp the paper when it does not receive information indicating a conveyance abnormality Determine the amount of paper warpage in the front decurler section.

  In the image forming system and the image forming apparatus configured as described above, the control unit determines the amount of paper warpage in the front decurler unit based on whether or not a conveyance abnormality has occurred in the second image forming apparatus or the other image forming apparatus. be able to. For example, when no conveyance abnormality occurs in the second image forming apparatus or the other image forming apparatus, the control unit can determine the amount of warpage to be 0, that is, not to warp the paper. In this case, the wear of the member for bending the paper in the front decurler section is suppressed. That is, during image formation, it is possible to suppress wear of the member that bends the sheet of paper in the decurler unit as compared to the case of bending the sheet of paper at the decurler unit.

  Further, when a conveyance abnormality occurs, the control unit can determine the amount of warp of the sheet so that the conveyance abnormality is reduced. For this reason, the sheet can be bent. As a result, the occurrence of a conveyance failure can be reduced.

  According to the present invention, it is possible to suppress the wear of a member that is bent on the paper in the decurler section, and to reduce the occurrence of a conveyance failure.

1 is a schematic diagram of an image forming system according to an embodiment of the present invention. It is a principal part enlarged view which shows the upper path | route of the decurler part which concerns on embodiment of this invention. It is a principal part enlarged view which shows the lower path | route of the decurler part which concerns on embodiment of this invention. 1 is a block diagram illustrating an electrical configuration of an image forming system according to an embodiment of the present invention. 3 is a flowchart showing a main routine process of the image forming system according to the embodiment of the present invention. It is a flowchart which shows the jam risk determination process which concerns on embodiment of this invention. It is a flowchart which shows the downstream machine setting process which concerns on embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings.

<Overall configuration of image forming system>
First, an image forming system 1 of the present embodiment will be described with reference to FIG. The image forming system 1 is a tandem type image forming system in which two image forming apparatuses 100 and 200 are connected in series so as to be able to form an image by sharing either the front or back side of a sheet or an area within a page. It is. Note that “series” means that image formation is continuously performed on the same sheet by two image forming apparatuses.

  Further, the image forming system 1 has a paper feeding device 50. The sheet feeding device 50 is connected to the image forming apparatus 100. In addition, the paper feeding device 50 includes a plurality of paper feeding cassette units 51 that store various types of paper, and a paper feeding unit 52 that feeds the stored paper to the image forming apparatus 100. The paper feed cassette unit 51 has an insertion / extraction sensor 53 (see FIG. 4) for detecting that the paper has been inserted / extracted from the housing of the paper supply device 50 in order to replenish or replace paper. The paper feeding unit 52 is composed of various rollers for conveying paper, a belt, and a guide plate.

  In the image forming system 1, the two image forming apparatuses 100 and 200 share the image formation on the front surface and the back surface of the paper or the image formation on the same surface. The sheet fed from the sheet feeding device 50 to the image forming apparatus 100 moves along the transport path A in the image forming system 1. The conveyance path A includes a conveyance path A1 formed by various rollers in the image forming apparatus 100, a guide plate, a conveyance belt, and the like, and a conveyance path A2 in the image forming apparatus 200.

  In this embodiment, when an image is formed by the image forming apparatuses 100 and 200, the image forming apparatus 100 functions as a main machine that controls the operation of the entire image forming system 1, and the image forming apparatus 200 is the main machine. It functions as a sub-machine that operates according to the machine's instructions. When forming an image by sharing the image forming apparatuses 100 and 200, the image is first formed by the image forming apparatus 100, and then the image is formed by the image forming apparatus 200.

  In the image forming system 1, the image forming apparatuses 100 and 200 can share image formations of different gradations such as characters (binary images) and images (gradation images) in the same page of the paper. It is.

<Configuration of image forming apparatus>
Next, the configuration of the image forming apparatus according to the embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the same structure in the image forming apparatus 100 and the image forming apparatus 200, and the description which overlaps with the image forming apparatus 100 about the image forming apparatus 200 is abbreviate | omitted.

  The image forming apparatus 100 has functions of a copying machine, a printer, a facsimile, and the like, and forms a monochrome image on a sheet by an electrophotographic method.

  The image forming apparatus 100 can be connected to an external device 300 (see FIG. 4), for example, a personal computer, and acquires image data from the external device 300.

  The image forming apparatus 100 includes an image forming apparatus main body 101 and a reversing device 170. The reversing device 170 reverses the sheet discharged from the image forming apparatus main body 101 and conveys it to the image forming apparatus 200.

  The image forming apparatus main body 101 includes a document conveying unit 110, a document reading unit 120, an image forming unit 130, and a paper feed cassette unit 160.

  The document transport unit 110 transports a document to the document reading unit 120 in order to continuously read the document, and includes a document feed tray 111 and a document discharge tray 112. The document transport unit 110 transports a document set on the document feed tray 111 to a predetermined reading position of the document reading unit 120. Further, the document conveying unit 110 conveys the document to the document discharge tray 112 after the document reading unit 120 reads the document conveyed to a predetermined reading position.

  The document reading unit 120 optically reads a document image, converts information of the document image into an analog electrical signal, and further converts the analog electrical signal into a digital signal. Then, the document reading unit 120 outputs the converted digital signal to the control unit 180 (see FIG. 4) described later as image data.

  The image forming unit 130 is an image forming function unit including a drum-shaped photoconductor 131, a charging unit 132 provided around the photoconductor 131, an image writing unit 133, a developing unit 134, a transfer roller 135, and a cleaning unit 136. Have The image forming unit 130 includes a fixing unit 137 and a decurler unit (pre-decurler unit) 150. In the image forming unit 130, the image forming function unit, the fixing unit 137, and the decurler unit 150 may be referred to as a conveyance direction (hereinafter, simply referred to as a conveyance direction) of a sheet conveyed along the conveyance path A1. ) In this order from the upstream side.

  The specific processing operation of the image forming unit 130 is as follows. First, the image forming unit 130 acquires image data that has been subjected to predetermined processing by an image processing unit 183 described later. Next, the charging unit 132, the image writing unit 133, the developing unit 134, and the transfer roller 135 sequentially perform charging, exposure (optical writing), development, and transfer processes, respectively. By these processes, a toner image based on the acquired image data is formed on the paper transported along the transport path A1. The fixing unit 137 performs a fixing process on the paper on which the toner image is formed. The fixed sheet passes through the decurler unit 150 and is conveyed to the reversing device 170. The decurler unit 150 will be described later.

  A switching gate 162 is disposed downstream of the decurler unit 150 in the sheet conveyance direction. The switching gate 162 switches the conveyance path of the sheet that has passed through the decurler unit 150 and moves the sheet straight or guides it downward. The straight sheet is conveyed to the reversing device 170. On the other hand, the sheet guided downward by the switching gate 162 is reversed by the sheet reversing conveyance unit 163 and conveyed to the reversing device 170. When the image forming apparatus 1 prints both sides of the sheet, the sheet guided downward by the switching gate 162 is reversed by the sheet reversing conveyance unit 163 and guided to the refeed path 164 to be the image forming function unit. Is transported again.

  The paper feed cassette unit 160 includes a plurality of paper feed cassettes 161 corresponding to various types of paper, and feeds various types of paper to the image forming unit 130. Each paper cassette 161 contains various types of paper. Note that when the image forming apparatuses 100 and 200 of the image forming system 1 according to the present embodiment share the image formation on the paper, the paper used in the paper feeding device 50 is used as the paper. Do not work.

  The image forming unit 130 includes a registration sensor 138, a registration roller 139, a winding sensor 140, and a fixing sensor 141.

  The registration sensor 138 is located upstream of the photosensitive member 131 in the transport direction. The registration sensor 138 detects the leading edge of the paper that moves along the transport path A1. Further, the registration sensor 138 transmits a detection signal indicating that the leading edge of the paper has been detected to the control unit 180 described later.

  The registration roller 139 includes a pair of rollers, and is positioned upstream of the photosensitive member 131 in the transport direction. The registration roller 139 rotates and stops according to an instruction from the control unit 180 described later. When the registration sensor 138 detects the leading edge of the sheet, the registration roller 139 stops in a state where the leading edge of the sheet is sandwiched between the pair of rollers, and stops the conveyance of the sheet. In the following description, the paper stop position at this time may be referred to as a registration position. Then, the registration roller 139 resumes rotation in accordance with an instruction from the control unit 180, and conveys the sheet downstream along the conveyance path A1.

  The winding sensor 140 is located downstream of the photosensitive member 131 in the transport direction. The winding sensor is a photo sensor that detects winding of the paper around the photosensitive member 131. Further, the winding sensor 140 transmits a detection signal indicating that the winding of the paper has been detected to the control unit 180 described later.

  The fixing sensor 141 is provided in the vicinity of the fixing unit 137 and downstream of the fixing unit 137 in the transport direction. The fixing sensor 141 detects the leading edge of the paper that has passed through the fixing device. Further, the fixing sensor 141 transmits a detection signal indicating that the leading edge of the paper has been detected to the control unit 180 described later.

  Next, the decurler unit 150 will be described with reference to FIGS. The decurler unit 150 adjusts the bending habit (warping direction and warping amount) of the paper. As shown in FIG. 1, the decurler unit 150 is located downstream of the fixing unit 137 in the transport direction. In the decurler unit 150, an upper path 152, an intermediate path 153, and a lower path 154 are formed by a plurality of guide plates 151 (see FIGS. 2 and 3). The middle path 153 is formed in a substantially linear shape. The upper path 152 is formed to be curved upward. The lower path 154 is formed to curve downward.

  In addition, the decurler unit 150 includes a route switching unit 155 (see FIG. 4). The path switching unit (see FIG. 4) guides the sheet discharged from the fixing unit 137 to any one of the upper path 152, the middle path 153, and the lower path 154. In the initial state, that is, the setting state when the image forming apparatus 100 is turned on, the path switching unit 155 is set to guide the sheet to the middle path 153.

  Further, as shown in FIG. 2, the decurler unit 150 includes an upper elastic roller 156 and an upper rigid roller 157. The upper elastic roller 156 is rotatably disposed in the image forming apparatus main body 101. The surface of the upper elastic roller 156 is made of an elastic member such as sponge or elastic resin. A part of the surface of the upper elastic roller 156 is exposed to the upper path 152.

  The upper rigid roller 157 is made of a rigid member such as stainless steel or aluminum. The upper rigid roller 157 is disposed in the image forming apparatus main body 101 such that the upper rigid roller 157 can rotate and the axis of the upper rigid roller 157 can approach or separate from the axis of the upper elastic roller 156. The upper rigid roller 157 is in pressure contact with the upper elastic roller 156. A part of the surface of the upper rigid roller 157 is exposed to the upper path 152. A nip through which the sheet passes is formed between the upper rigid roller 157 and the upper elastic roller 156, and the formed nip is disposed in the upper path 152.

  Driving of the upper rigid roller 157 is controlled by a control unit 180 described later. When the axis of the upper rigid roller 157 approaches or separates from the axis of the upper elastic roller 156, the degree of pressure contact between the upper rigid roller 157 and the upper elastic roller 156 changes.

  When the sheet passes through the nip formed between the upper rigid roller 157 and the upper elastic roller 156, the sheet warps to the image forming surface side on which the image is formed on the image forming apparatus 100, and , And warps so as to be convex downward. In the following description, the warping of the paper in a downward convex shape, that is, the warping so that both end portions in the paper transport direction are located higher than the central portion is referred to as the upward warping. There is a case.

  As shown in FIG. 3, the decurler unit 150 includes a lower elastic roller 158 and a lower rigid roller 159. The lower elastic roller 158 is rotatably disposed in the image forming apparatus main body 101. The surface of the lower elastic roller 158 is made of an elastic member such as sponge or elastic resin. A part of the surface of the lower elastic roller 158 is exposed to the lower path 154.

  The lower rigid roller 159 is made of a rigid member such as stainless steel or aluminum. The lower rigid roller 159 is disposed in the image forming apparatus main body 101 such that the lower rigid roller 159 can rotate and the axis of the lower rigid roller 159 can approach or separate from the axis of the lower elastic roller 158. The lower rigid roller 159 is in pressure contact with the lower elastic roller 158. A part of the surface of the lower rigid roller 159 is exposed to the lower path 154. A nip through which a sheet passes is formed between the lower rigid roller 159 and the lower elastic roller 158, and the formed nip is disposed in the lower path 154.

  The lower rigid roller 159 is driven by a control unit 180 described later. When the axis of the lower rigid roller 159 approaches or separates from the axis of the lower elastic roller 158, the degree of pressure contact between the lower rigid roller 159 and the lower elastic roller 158 changes.

  When the sheet passes through the nip formed between the lower rigid roller 159 and the lower elastic roller 158, the sheet is warped to the non-image forming surface side on which the image is not formed by the image forming apparatus 100, and , And warps to have a convex shape upward. In the following description, when the paper is warped upward in a convex shape, that is, when the center portion in the paper transport direction is located above the both ends, it is referred to as downward warping. There is a case.

Next, the reversing device 170 will be described with reference to FIG.
The reversing device 170 has a reversing unit 171. The reversing unit 171 is formed with a straight path 172 and a reversing path 173 formed by various rollers, guide plates, a conveyor belt, and the like. The reversing unit 171 includes a path switching unit 174 that guides the sheet to the straight path 172 or the reversing path 173. The sheet guided to the straight path 172 by the path switching unit 174 is conveyed to the image forming apparatus 200. On the other hand, the sheet guided to the reversing path 173 by the path switching unit 174 is reversed and then conveyed to the image forming apparatus 200.

Next, the reversing device 270 will be described with reference to FIG.
The reversing device 270 is provided with a paper discharge tray 290 on which paper that has moved in the image forming system 1 along the transport path A is placed. The other configuration of the reversing device 270 is the same as that of the reversing device 170, and thus description thereof is omitted.

<Electrical configuration of image forming system>
Next, the electrical configuration of the image forming system 1 will be described with reference to FIG.

  First, the electrical configuration of the sheet feeding device 50 will be described. As illustrated in FIG. 4, the sheet feeding device 50 includes a communication unit 54 and a control unit 55. The control unit 55 includes a CPU (Central Processing Unit) (not shown), a ROM (Read Only Memory) for storing a program executed by the CPU, a RAM (Random Access Memory) used as a work area of the CPU, and the like. have. The control unit 55 controls driving of the paper feeding unit 52. The sheet feeding device 50 can communicate with the image forming apparatus 100 and the external device 300 via the communication unit 54.

  Next, the electrical configuration of the image forming apparatus main bodies 101 and 201 will be described. In addition, the same code | symbol is attached | subjected to the same structure in the image forming apparatus main body 101 and the image forming apparatus main body 201, and the description which overlaps with the image forming apparatus main body 101 about the image forming apparatus main body 201 is abbreviate | omitted.

  The image forming apparatus main body 101 includes a control unit 180 that controls the entire image forming apparatus main body 101 and the image forming system 1. The control unit 180 also includes a communication unit 182, a document transport unit 110, a document reading unit 120, an image processing unit 183, an image forming unit 130, a paper feed cassette unit 160, and an operation display unit 184 via the system bus 181. To control these operations.

  The control unit 180 has a CPU 185, a ROM 186 for storing programs executed by the CPU 185, and a RAM 187 used as a work area for the CPU 185.

The control unit 180 receives image data from the document reading unit 120 or the external device 300 when the image forming system 1 performs image formation. The control unit 180 controls the driving of the image processing unit 183 and the image forming unit 130 based on the content of the instruction received from the operation display unit 184 or job information described later received from the external device 300. In addition, the control unit 180 transmits a sheet feeding instruction to the sheet feeding device 50 via the communication unit 182. As a result, an image is formed on the sheet based on the image data.
When the control unit 180 directly operates the paper feeding device 50, the control unit 55 of the paper feeding device 50 can be omitted.

  When control unit 180 receives a signal indicating that the leading edge of the sheet has been detected from registration sensor 138, control unit 180 stops driving registration roller 139 and stops the sheet at the registration position. Then, the control unit 180 resumes the conveyance of the sheet by resuming the rotation of the registration roller 139 at a timing suitable for image formation. At this time, the control unit 180 starts measuring the elapsed time after resuming the conveyance of the sheet.

  When the control unit 180 receives a signal indicating that the leading edge of the sheet has been detected from the fixing sensor 141, the control unit 180 stops counting the elapsed time after resuming the conveyance of the sheet, and sets the measurement result as the conveyance time T. It is stored in the RAM 187. The RAM 187 can store a predetermined number, for example, ten conveyance times T. In addition, when ten transport times T are already stored in the RAM 187, when the new transport time T is timed, the oldest transport time T stored in the stored time is erased and newly timed. The transport time T is stored.

  Further, the control unit 180 controls driving of the path switching unit 155 of the decurler unit 150 and causes the path switching unit 155 to guide the sheet to any one of the upper path 152, the middle path 153, and the lower path 154.

  Further, the control unit 180 controls the driving of the upper rigid roller 157 so that the shaft center of the upper rigid roller 157 approaches or separates from the shaft center of the upper elastic roller 156, thereby causing the upper rigid roller 157 and the upper rigid roller 157 to move upward. The degree of pressure contact with the elastic roller 156 is adjusted. In addition, the control unit 180 controls the driving of the lower rigid roller 159 so that the shaft center of the lower rigid roller 159 approaches or separates from the shaft center of the lower elastic roller 158, thereby lowering the lower rigid roller 159 from the lower rigid roller 159. The degree of pressure contact with the elastic roller 158 is adjusted. The control unit 180 can adjust the amount of warp of the paper passing through the decurler unit 150 by adjusting the degree of pressure contact.

  The control unit 180 sets the degree of pressure contact between the upper rigid roller 157 and the upper elastic roller 156 and the degree of pressure contact between the lower rigid roller 159 and the lower elastic roller 158 as the number of steps 1 in a state where the degree of pressure contact is the lowest. Adjustment is made in 6 steps, with the highest pressure contact level being 6 steps. Hereinafter, the degree of pressure contact may be referred to as decurler strength. The greater the number of steps of decurler strength, the greater the amount of paper warp. The state of the lowest pressure contact is a state in which the shaft centers of the upper rigid roller 157 and the lower rigid roller 159 and the shaft centers of the upper elastic roller 156 and the lower elastic roller 158 are most separated. The state of the highest pressure contact is a state where the shaft centers of the upper rigid roller 157 and the lower rigid roller 159 and the shaft centers of the upper elastic roller 156 and the lower elastic roller 158 are closest to each other.

  The decurler strength in the initial state is set according to the paper type of the paper stored in each paper feed cassette unit 51 for each paper feed cassette unit 51 of the paper feed device 50. For example, the decurler strength in the initial state corresponding to the paper feed cassette unit 51 that accommodates a sheet having a thickness of 150 μm is set to 2 stages. Information regarding the paper type is input by an operator via an operation unit (not shown) provided in the image forming apparatus main body 101 when the paper is stored in the paper feed cassette unit 51. The input paper type information is stored in the RAM 187 for each paper feed cassette unit 51. Note that it corresponds to a paper feed cassette unit 51 that accommodates paper that does not require bending curl adjustment by the decurler unit 150, for example, a paper having a thickness of 90 μm in this embodiment, at normal times when no abnormality in paper conveyance occurs. The decurler strength in the initial state is set to a null value or 0.

  When the winding sensor 140 detects a winding jam, the control unit 180 sets a winding jam flag on the RAM 187 to ON. Note that the initial winding jam flag is set to OFF.

  The control unit 180 transmits image data formed by the image forming apparatus main body 201 to the image forming apparatus main body 201 via the communication unit 182 when one print job is shared by the image forming apparatuses 100 and 200. To do. Here, the print job means a series of image forming processes from the start page to the end page of the image to be formed.

For example, when the image forming apparatus 100 forms an image on the front side of the paper and the image forming apparatus 200 forms an image on the back side of the paper, the control unit 180 uses the image processing unit 183 to process the image data to be formed on the back side. Then, the data is transmitted to the communication unit 282 of the image forming apparatus 200 via the communication unit 182.

  The image forming apparatus main body 101 is connected to the paper feeding device 50, the reversing device 170, the image forming apparatus main body 201, the reversing device 270, and the external device 300 via the communication unit 182, and can communicate with them. ing.

  For example, the image forming apparatus main body 101 receives job information transmitted from the external device 300 via the communication unit 182. The job information includes image data of an image to be formed, information on paper to be used associated with the image data, and the like.

  The information transmitted / received between the image forming apparatus main bodies 101 and 201 includes, for example, the information from the image forming apparatus main body 101 when one print job is shared by the image forming apparatuses 100 and 200 as described above. Image data transmitted to the image forming apparatus main body 201 is included. The information transmitted / received between the image forming apparatus main bodies 101 and 201 includes information indicating that the winding flag on the RAMs 187 and 287 is set to ON or OFF, and the conveyance time stored on the RAMs 187 and 287. Information indicating T is included.

  The image processing unit 183 performs processing such as shading correction and image compression on the image data supplied from the control unit 180 as necessary.

  The operation display unit 184 includes a liquid crystal display unit (not shown) and a plurality of keys (not shown), and transmits various instructions input by the user via the keys to the control unit 180.

  Next, the electrical configuration of the reversing devices 170 and 270 will be described. As illustrated in FIG. 4, the reversing devices 170 and 270 include communication units 175 and 275 and control units 176 and 276. The control units 176 and 276 include a CPU (not shown), a ROM for storing a program executed by the CPU, and a RAM used as a work area for the CPU.

  The control units 176 and 276 control driving of the reversing units 171 and 271. Specifically, the control units 176 and 276 control driving of various rollers, a conveyance belt, and path switching units 174 and 274 to convey the sheet along the straight path 172 or the reverse path 173. The reversing devices 170 and 270 can communicate with the image forming apparatus main bodies 101 and 201 and the external device 300 using the communication unit 175. Note that when the reversing devices 170 and 270 are directly operated by the control units 180 and 280, the control units 176 and 276 of the reversing devices 170 and 270 can be omitted.

<Operation of image forming system>
Next, FIGS. 5 to 7 are flowcharts for explaining processing executed in the image forming system 1. The CPU 185 implements the processing shown in FIGS. 5 to 7 by executing a program stored in the ROM 186.
First, with reference to FIG. 5, a description will be given of a main routine process performed when one print job is shared by the image forming apparatuses 100 and 200. FIG. The main routine process is performed in parallel with the image forming process at the start of the image forming process based on the print job. The main routine process is repeatedly executed every predetermined time.

  First, the control unit 180 of the image forming apparatus main body 101 performs a jam risk determination process (step S1). In the jam risk determination process, the current state of the image forming apparatus 200 is a state in which a jam risk is high in which the possibility that a winding jam will occur is relatively high, or a possibility that a winding jam will occur is relatively low. This is a process for determining whether a certain jam risk is low. Details of the jam risk determination process will be described later.

  Next, the control unit 180 determines whether or not the result of step S1 is high in jam risk (step S2). When determining that the jam risk is not high (step S2: NO), the control unit 180 shifts the processing to step S8.

  On the other hand, when determining that the jam risk is high (step S2: YES), the control unit 180 sets the decurler strength of the upstream machine to the number D of steps (step S3). In the present embodiment, when an image is formed by the image forming apparatuses 100 and 200, an image is first formed by the image forming apparatus 100 and then an image is formed by the image forming apparatus 200. For this reason, the upstream machine is the image forming apparatus 100. The downstream machine is the image forming apparatus 200.

  Specifically, the control unit 180 sets the decurler strength in the decurler unit 150 of the image forming apparatus main body 101 to the number D of stages obtained by adding 2 to the current number of stages. However, when the number of steps of the decurler strength in the decurler unit 150 is six when performing the process of step S3, the number of steps D is set to six. In the process of step S <b> 3, the control unit 180 updates the initial decurler intensity level corresponding to the paper feed cassette unit 51 that stores paper fed from the paper feeding device 50 stored in the RAM 187. That is, when a sheet having a thickness of 90 μm is fed from the sheet feeding device 50, the number of stages D is updated to 2 because the current number of stages is null or the number of stages is 0. Further, when a sheet having a thickness of 150 μm is fed from the sheet feeding device 50, the number of stages D is updated to 4 because the number of stages is 2.

  The control unit 180 stores the updated stage number D in the RAM 187, and drives the upper rigid roller 157 or the lower rigid roller 159 when the decurler unit 150 is driven thereafter to set the decurler strength of the decurler unit 150 to the stage number D. To do. If the stage number D is not set on the RAM 187, the control unit 180 sets the decurler unit 150 to the initial stage number corresponding to the paper feed cassette unit 51 that accommodates the paper fed from the paper feeding device 50. To drive. The number D of stages on the RAM 187 is erased when the image forming apparatus 100 is turned off. Further, for example, when the 90 μm-thick paper on the RAM 187 is fed from the paper feeding device 50, the number of stages D is determined when the insertion / extraction sensor 53 detects the insertion / extraction of the paper feed cassette unit 51 containing the 90 μm-thick paper. Erased. However, if the insertion / extraction sensor 53 detects the insertion / extraction of the paper feed cassette unit 51 during the image formation process based on one print job, it is not erased at the insertion / extraction timing, but after the image formation process based on this print job is completed. The number D of stages on the RAM 187 is erased. As the stage number D on the RAM 187 is deleted, downstream machine setting shift stage numbers E and F (to be described later) on the RAM 187 are also deleted.

  Next, the control unit 180 determines whether or not the number of inversions after decurler is an odd number (step S4). Here, the number of times of reversal after decurler is the number of times of reversal of the paper after the paper passes through the decurler unit 150 of the image forming apparatus main body 101 and is conveyed to the image forming apparatus 200. When the image forming apparatuses 100 and 200 share the image formation on the front surface and the back surface of the paper, the paper that has passed through the decurler unit 150 is reversed by the reversing device 170. Become. Further, when the image forming apparatuses 100 and 200 share the image formation on the same surface of the sheet, the number of inversions is 0, which is an even number. When the image forming apparatuses 100 and 200 share the image formation on the same surface of the sheet, the sheet is reversed by the sheet reversing conveyance unit 163 and the reversing apparatus 170 in order to match the image forming timing of the image forming apparatus 200. There are things to do. In this case, the number of inversions is 2 and is an even number.

  When the number of inversions after decurler is an odd number (step S4: YES), the control unit 180 guides the sheet to the upper path 152 (step S5). Specifically, the control unit 180 drives the path switching unit 155 to stop the transported paper at a position where it can be guided to the upper path 152. As a result, the sheet conveyed to the decurler unit 150 passes through the nip formed between the upper rigid roller 157 and the upper elastic roller 156 in the state where the decurler strength is set to the step number D in step S3. For this reason, the sheet is warped in an upward direction so that both ends in the transport direction are positioned higher than the center by a warp amount corresponding to the number of steps D. Note that the sheet warped in the upward direction is inverted an odd number of times in the image forming apparatus 100 and then transported to the image forming apparatus 200. Therefore, the sheet transported in the image forming apparatus 200 is warped in the downward direction. .

  When the number of inversions after decurler is an even number (step S4: NO), the controller 180 guides the sheet to the lower path 154 (step S6). Specifically, the control unit 180 drives the path switching unit 155 to stop the conveyed paper at a position where it can be guided to the lower path 154. As a result, the sheet conveyed to the decurler unit 150 passes through the nip formed between the lower rigid roller 159 and the lower elastic roller 158 in a state where the decurler strength is set to the step number D in step S3. For this reason, the sheet is warped in a downward direction so that the central portion in the transport direction is positioned above the both ends with a warp amount corresponding to the number of steps D. Note that the sheet warped in the downward direction is turned into the image forming apparatus 200 after being turned evenly in the image forming apparatus 100, and thus the sheet conveyed in the image forming apparatus 200 is maintained in the state of being warped in the downward direction. Is done.

  Next, the control unit 180 performs downstream machine setting processing (step S7). The downstream machine setting process is a process for performing various settings in the decurler unit (rear decurler unit) 250 of the image forming apparatus 200 in order to correct bending wrinkles on the paper. Details of the downstream machine setting process will be described later. Then, the control unit 180 ends the main routine process.

  When it is determined in step S2 that the jam risk is low (step S2: NO), the control unit 180 refers to the RAM 187 and determines whether or not the number of steps of the initial decurler strength is null or 0 ( Step S8).

  When the number of steps of the decurler strength in the initial state is null or 0 (step S8: YES), the control unit 180 guides the sheet to the middle path 153 (step S9). In this embodiment, since the path switching unit 155 is set to guide the sheet to the middle path 153 in the initial state, the control unit 180 maintains this setting. As a result, the sheet conveyed to the decurler unit 150 passes through the intermediate path 153. Then, the control unit 180 ends the main routine process.

  When the number of steps of the initial decurler intensity is not null or 0 (step S8: NO), the control unit 180 determines whether or not the number of inversions after decurler is an odd number (step S10).

When the number of inversions after decurler is an odd number (step S10: YES), the control unit 180 guides the sheet to the upper path 152 (step S11). Specifically, the control unit 180 drives the path switching unit 155 to stop the transported paper at a position where it can be guided to the upper path 152. As a result, the sheet conveyed to the decurler unit 150 passes through a nip formed between the upper rigid roller 157 and the upper elastic roller 156 in a state where the initial decurler strength is set. For this reason, the sheet is warped in an upward direction so that both end portions in the transport direction are positioned higher than the central portion with a warp amount corresponding to the initial decurler strength. Note that the sheet warped in the upward direction is inverted an odd number of times in the image forming apparatus 100 and then transported to the image forming apparatus 200. Therefore, the sheet transported in the image forming apparatus 200 is warped in the downward direction. .
And the control part 180 transfers a process to step S7.

When the number of inversions after decurler is an even number (step S10: NO), the control unit 180 guides the sheet to the lower path 154 (step S12). Specifically, the control unit 180 drives the path switching unit 155 to stop the conveyed paper at a position where it can be guided to the lower path 154. As a result, the sheet conveyed to the decurler unit 150 passes through the nip formed between the lower rigid roller 159 and the lower elastic roller 158 in a state where the initial decurler strength is set. For this reason, the sheet is warped in a downward direction so that the central portion in the transport direction is located above the both ends with a warp amount corresponding to the initial decurler strength. Note that the sheet warped in the downward direction is turned into the image forming apparatus 200 after being turned evenly in the image forming apparatus 100, and thus the sheet conveyed in the image forming apparatus 200 is maintained in the state of being warped in the downward direction. Is done.
And the control part 180 transfers a process to step S7.

Next, a jam risk determination process will be described with reference to FIG.
First, the control unit 180 determines whether or not a winding jam has occurred in the downstream machine (step S20). Specifically, the control unit 180 winds the downstream machine based on a signal indicating the state of the wound jam flag on the RAM 287 of the image forming apparatus main body 201 received from the image forming apparatus 200 via the communication unit 182. It is determined whether or not a jam has occurred. That is, when this signal indicates that the winding jam flag is set to ON, it is determined that the winding jam has occurred in the downstream machine. On the other hand, when this signal indicates that the winding jam flag is set to OFF, it is determined that no winding jam has occurred in the downstream machine.

  When a winding jam occurs in the downstream machine (step S20: YES), the control unit 180 determines that the state of the image forming apparatus 200 is a jam risk high state where a possibility that a jam risk is generated is relatively high. (Step S21). Then, the control unit 180 ends the jam risk determination process.

  On the other hand, when the winding jam does not occur in the downstream machine (step S20: NO), the control unit 180 measures the conveyance time T in the image forming apparatus main body 201 via the communication units 182 and 282 and the control unit 280. (Step 22). Next, the control unit 180 determines whether or not the measured transport time T is shorter than the predetermined time A (step S23). The predetermined time A is longer than the designed transport time, and is set to a value that significantly delays the image forming process when the transport time T exceeds the predetermined time A, for example, 100 milliseconds.

  When the conveyance time T is equal to or longer than the predetermined time A (step S23: NO), the control unit 180 shifts the process to step S21.

  On the other hand, when the conveyance time T is shorter than the predetermined time A (step S23: YES), the control unit 180 calculates the average value Tave of the conveyance time T (step S24). Specifically, the control unit 180 calculates the average value of all information (up to 10) indicating the transport time T on the RAM 287 received from the image forming apparatus 200 via the communication unit 182 as Tave.

  Next, the control unit 180 determines whether or not the transport time Tave is shorter than the predetermined time B (step S25). The predetermined time B is longer than the designed transport time, shorter than the predetermined time A, and if the transport time T exceeds the predetermined time B, the image forming process is slightly delayed, for example, 30 milliseconds. Is set.

  When the conveyance time Tave is equal to or longer than the predetermined time B (step S25: NO), the control unit 180 moves the process to step S21.

  On the other hand, when the conveyance time Tave is shorter than the predetermined time B (step S25: YES), the controller 180 determines that the state of the image forming apparatus 200 is a low jam risk, which is a relatively low possibility of a jam risk. Determination is made (step S26). Then, the control unit 180 ends the jam risk determination process.

  As described above, in this embodiment, the winding sensor 240 that detects the winding of the paper around the photosensitive member 231 in the image forming apparatus main body 201 and the control unit 180 that detects the delay of the paper transport detect the paper transport abnormality. Functions as a conveyance abnormality detection unit.

Next, the downstream machine setting process will be described with reference to FIG.
First, the control unit 180 determines whether or not the decurler strength of the upstream machine has been changed (step S30). Specifically, the control unit 180 determines that the decurler strength of the upstream machine has changed when the decurler strength in the image forming apparatus 100 is set to the number of stages D in step S3 of the main routine process (see FIG. 5). .

When there is a change in the decurler strength of the upstream machine (step S30: YES), the control unit 180 sets the downstream machine set shift stage number E (step S31). Here, the downstream machine setting shift stage number E is the decurler strength in the image forming apparatus 200 when the decurler intensity in the image forming apparatus 100 is changed. Specifically, the control unit 180 calculates the downstream machine setting shift stage number E by the following equation.
E = int (D ÷ 2) Equation 1
That is, the downstream machine setting shift stage number E is a value obtained by dividing the decurler intensity stage number D in the image forming apparatus 100 by 2 and rounding down the decimal point. The control unit 180 stores the calculated downstream machine setting shift stage number E in the RAM 187. Further, the decurler strength of the decurler unit 250 is set to the calculated downstream machine setting shift stage number E via the communication unit 182 and the control unit 280. And the control part 180 transfers a process to step S33.

When there is no change in the decurler strength of the upstream machine (step S30: NO), that is, when the decurler intensity in the image forming apparatus 100 is the initial stage number, the control unit 180 sets the downstream machine set shift stage number F. (Step S32). Here, the downstream machine setting shift stage number F is the decurler intensity in the image forming apparatus 200 when the decurler intensity in the image forming apparatus 100 is the initial stage number. Specifically, the control unit 180 calculates the downstream machine set shift stage number F by the following equation.
F = int (number of steps of decurler strength in the initial state ÷ 2) Equation 2
That is, the downstream machine setting shift stage number F is a value obtained by dividing the stage number of the decurler strength in the initial state in the image forming apparatus 100 by 2 and rounding down the decimals. The control unit 180 stores the calculated downstream machine setting shift stage number F in the RAM 187. Further, the control unit 180 sets the decurler strength of the decurler unit 250 to the calculated downstream machine set shift stage number F via the communication unit 182 and the control unit 280. And the control part 180 transfers a process to step S33.

  After step S31 or S32, the control unit 180 guides the downstream sheet to the upper path 252 (step S33). Specifically, the control unit 180 drives the path switching unit 255 via the communication units 182 and 282 and the control unit 280 to stop the conveyed paper at a position where it can be guided to the upper path 252. This corrects bending wrinkles of the paper conveyed from the image forming apparatus 100, that is, downward warping. And the control part 180 complete | finishes a downstream machine setting process.

<Operation of image forming system>
Next, the operation of the image forming system 1 will be described.
First, the operation when the image forming apparatuses 100 and 200 perform image formation on the front and back surfaces of a 90 μm thick sheet will be described.

  The control unit 180 of the image forming apparatus main body 101 receives image data from the document reading unit 120 or the external device 300. The control unit 180 instructs the sheet feeding device 50 to feed the image forming apparatus main body 101 based on the content of the instruction received from the operation display unit 184 or job information described later received from the external device 300. Further, the control unit 180 controls driving of the image processing unit 183 and the image forming unit 130, and controls driving of the image processing unit 283 and the image forming unit 230 via the communication unit 182 to place an image on a sheet. The image forming process to be formed is started. Further, the control unit 180 starts a main routine process (see FIG. 5) in parallel with the image forming process.

  When the control unit 180 determines that the state of the image forming apparatus 100 is low in jam risk in the main routine process, the control unit 180 guides the sheet conveyed to the image forming apparatus main body 101 to the middle path 153 of the decurler unit 150. Therefore, the sheet is reversed by the reversing device 170 without being bent by the decurler unit 150 and conveyed to the image forming apparatus 200. Then, after the image is formed on the back surface by the image forming apparatus main body 201, this sheet passes through the inside path 253 of the decurler unit 250, passes through the reversing device 270, and is placed on the paper discharge tray 290.

  On the other hand, if a winding jam has occurred at the time of the previous image formation, or if the conveyance time in the image forming apparatus 200 is delayed, the control unit 180 changes the state of the image forming apparatus 200 in the main routine processing. Is determined. Then, the control unit 180 sets the decurler strength to the number of steps D. That is, the decurler strength is set to the number of stages 2 obtained by adding 2 to the number of stages (null or 0) in the initial state. In addition, the control unit 180 sets the downstream machine shift stage number E to 1 in the downstream machine setting process. Then, the control unit 180 guides the sheet conveyed to the image forming apparatus main body 101 to the upper path 152 of the decurler unit 150. As a result, the sheet is bent by the decurler unit 150 in a state of being warped upward.

  Thereafter, the sheet is reversed by the reversing device 170 and conveyed to the image forming apparatus 200. For this reason, the sheet conveyed in the image forming apparatus 200 is warped downward, that is, the sheet is warped so as to be easily peeled off from the photosensitive member 231 of the image forming apparatus 200. An image is formed on the back surface of the sheet by the image forming apparatus main body 201 and passes through the upper path 152 of the decurler unit 250 (that is, by passing the sheet through the upper path 152, the sheet is replaced with the image of the sheet. The image forming apparatus 100 is warped to the non-image forming surface side that is the side on which no image is formed). As a result, the bending wrinkles of the paper that has been warped downward when conveyed to the image forming apparatus 200 is corrected. Then, the sheet passes through the reversing device 270 and is placed on the sheet discharge tray 290.

  Next, an operation when the image forming apparatuses 100 and 200 perform image formation on the same surface of a 90 μm thick sheet will be described. Since the operation until the control unit 180 starts the main routine process (see FIG. 5) in parallel with the image forming process is as described above, the description thereof is omitted.

  When the control unit 180 determines that the state of the image forming apparatus 200 is high in the main routine process, the control unit 180 sets the decurler strength to the number D of steps. That is, the decurler strength is set to the number of stages 2 obtained by adding 2 to the number of stages (null or 0) in the initial state. In addition, the control unit 180 sets the downstream machine shift stage number E to 1 in the downstream machine setting process. Then, the controller 180 causes the sheet conveyed to the image forming apparatus main body 101 to be transferred to the bottom of the decurler unit 150 because the number of inversions after decurler is 0 (even times) when performing image formation on the same surface. Guide to path 154. As a result, the sheet is bent by the decurler unit 150 in a state of being bent downward.

  Thereafter, the sheet passes through the reversing device 170 and is conveyed to the image forming apparatus 200. Therefore, the state where the sheet conveyed in the image forming apparatus 200 is warped downward, that is, the state where the sheet is warped so as to be easily peeled off from the photosensitive member 231 of the image forming apparatus 200 is maintained. An image is formed on the sheet by the image forming apparatus main body 201 and passes through the upper path 152 of the decurler unit 250 (that is, by passing the sheet through the upper path 152, the sheet is changed into the sheet image forming apparatus. 100 is warped to the image forming surface side that is the side on which the image is formed). As a result, the bending wrinkles of the paper that has been warped downward when conveyed to the image forming apparatus 200 is corrected. Then, the sheet passes through the reversing device 270 and is placed on the sheet discharge tray 290.

  As described above, in the image forming system 1 of the present embodiment, when the control unit 180 determines that the state of the image forming apparatus 200 is low in jam risk in the main routine process, the sheet conveyed to the image forming apparatus main body 101 is removed. The decurler unit 150 leads to the middle path 153. The sheet guided to the middle path 153 passes through the decurler unit 150 without bending wrinkles. Therefore, the upper elastic roller 156, the upper rigid roller 157, the lower elastic roller 158, and the lower rigid roller 159 are less worn compared to the case where the decurler unit 150 always causes the sheet to be bent regardless of the degree of winding risk. Can be suppressed. That is, it is possible to suppress the wear of the member that causes the bending curl to the sheet of the decurler unit 150. In addition, when the state of the image forming apparatus 200 is low in jam risk, it is possible to reduce the occurrence of a conveyance failure due to unnecessary bending wrinkles on the paper.

  When the control unit 180 determines that the state of the image forming apparatus 200 is high in the main routine process, the sheet conveyed to the image forming apparatus main body 101 is guided to the upper path 152 of the decurler unit 150. Accordingly, when the jam risk is high, that is, when there is a relatively high possibility that a winding jam occurs and a winding jam occurs, the sheet is warped so as to be easily peeled off from the photosensitive member 231 of the image forming apparatus 200, and thus the conveyance failure Can be reduced.

  In addition, the control unit 180 is conveyed to the image forming apparatus 200 when the image forming apparatuses 100 and 200 perform image formation on the front surface and the back surface of the paper and when image formation is performed on the same surface of the paper. The decurler unit 150 is driven so that the sheet to be bent is bent downward. Accordingly, the sheet conveyed to the image forming apparatus 200 is warped in the downward direction, that is, the sheet is warped so that the sheet is easily peeled off from the photosensitive member 231 of the image forming apparatus 200. It is possible to reduce the occurrence of conveyance troubles.

  Further, when the paper sheet is bent by the decurler unit 150 of the image forming apparatus 100, the bending line is corrected by the decurler unit 250 of the image forming apparatus 200. For this reason, it is possible to prevent the paper from being placed on the paper discharge tray 290 in a state where the bending wrinkles are attached.

  Further, it is conceivable that the bending wrinkles of the paper stuck by the decurler unit 150 is weaker than when the paper is passed through the decurler unit 150 by being pressed against the conveying belt or roller before the paper reaches the decurler unit 250. For this reason, in this embodiment, when the bending curl is corrected by the decurler unit 250 of the image forming apparatus 200, the decurler strength in the decurler unit 250 is set lower than the decurler strength in the decurler unit 150. As a result, when the bending curl of the sheet stuck by the decurler unit 150 is weakened, it is possible to prevent the decurler unit 250 from bending the sheet to warp upward.

<Modification>
In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the summary of this invention.

  In the present embodiment, the mode of controlling the driving of the decurler units 150 and 250 according to the winding risk of the photosensitive members 131 and 231 has been described. However, the decurler unit according to the winding risk of another member, for example, the fixing roller. The driving of 150 and 250 may be controlled.

  Further, in the present embodiment, the aspect in which the winding sensors 140 and 240 are photosensors that detect the winding of the sheets of the photosensitive members 131 and 231 has been described. However, instead of this, the control unit 180 determines that the winding of the paper around the photoconductors 131 and 231 occurs when the transport time T exceeds the timer value J longer than the predetermined time A, for example, 1 second. May be.

  Further, when calculating the decurler strength in the decurler unit 150 of the image forming apparatus main body 101 in step S3 of the main routine process (see FIG. 5), the value added to the current stage number is a suitable warp corresponding to the characteristics of the device. It can be changed according to the amount.

Further, in the downstream machine setting process (see FIG. 7), the decurler strength of the downstream machine was set to a value obtained by dividing the value of the decurler intensity of the upstream machine by 2 and rounding down the decimal point. However, the calculation method of the decurler strength of the downstream machine may be changed according to a suitable warpage amount corresponding to the characteristics of the device. For example, the decurler strength of the downstream machine may be set to a value obtained by dividing the value of the decurler intensity of the upstream machine by 3 and rounding off the decimal point.

  In this embodiment, the image forming system 1 is configured with the image forming apparatus 100 as a main machine and the image forming apparatus 200 as a sub machine. However, the image forming apparatus 200 may be used as the main machine and the image forming apparatus 100 as the sub machine. Good.

  The reversing devices 170 and 270 may be omitted, and the image forming apparatus main body 101 and the image forming apparatus main body 201 may be directly connected.

  In this embodiment, the decurler unit 150 is provided in the image forming apparatus main body 101, and the decurler unit 250 is provided in the image forming apparatus main body 201. However, instead, the decurler unit 150 may be provided in the reversing device 170 and the decurler unit 250 may be provided in the reversing device 270.

  In this embodiment, the image forming apparatuses 100 and 200 constituting the image forming system are described as monochrome machines. However, a color machine that forms a color image may be used as the image forming apparatus constituting the image forming system.

  Further, in the present embodiment, a mode has been described in which the amount of warpage can be adjusted in multiple steps (six steps) in the decurler unit 150 by adjusting the decurler strength. However, instead of this, the amount of warpage may be always adjusted by a uniform decurler strength.

  In the present exemplary embodiment, the mode in which the path switching unit 155 is set to guide the sheet to the middle path 153 in the initial state, that is, the setting state when the image forming apparatus 100 is turned on has been described. However, instead of this, even in the initial state, the path switching unit 155 may be driven to guide the sheet to the upper path 152 or the lower path 154. For example, when the paper accommodated in the paper feed cassette unit 51 has already been bent, the path cutting unit is configured to guide the paper to the upper path 152 or the lower path 154 even in the initial state in order to correct the bent wrinkle. 155 may be driven. In this case, the decurler strength in the initial state is a negative value and is set in advance in six stages from -1 to -6. The decurler strength of the number of steps -1 to -6 is equal to the decurler strength of the number of steps 1 to 6 having the same absolute number. In addition, whether to lead to the upper path 152 or the lower path 154 is set in advance so that the bent wrinkles are corrected according to the bent wrinkles of the paper. Further, for example, when “−2” is set as the decurler strength in the initial state, and it is determined that the jam risk is low in step S2 in the main routine process (see FIG. 5) (step S2: In the case of NO), regardless of whether the number of inversions after the decurler is an odd number or an even number, that is, regardless of the determination result of S10, an upper path 152 set in advance for correcting the bending bend of the sheet. Alternatively, the path switching unit 155 is driven so as to lead to the lower path 154. Similarly, when “−2” is set as the decurler strength in the initial state, and it is determined that the jam risk is high in step S2 in the main routine process (see FIG. 5) (step S2: In the case of YES), if 2 is added to the current number of steps in the subsequent step S3 and the number of steps of the decurler intensity becomes “0”, the number of inversions after the decurler is odd or even. That is, the path switching unit 155 is driven so as to guide the sheet to the middle path 153 regardless of the determination result of step S4. Further, when the number of steps of the decurler strength becomes “0” in step S3 of the main routine process, the path switching unit is configured to guide the sheet to the middle path 153 instead of step S33 of the downstream machine setting process (see FIG. 7). 255 is driven.

DESCRIPTION OF SYMBOLS 1 ... Image forming system, 50 ... Paper feeding apparatus, 100 ... Image forming apparatus, 101 ... Image forming apparatus main body, 130 ... Image forming part, 131 ... Photoconductor, 137 ... Fixing part, 138 ... Registration sensor, 139 ... Registration roller 140 ... winding sensor, 141 ... fixing sensor, 150 ... decurler section (front decurler section), 151 ... guide plate, 152 ... upper path, 153 ... middle path, 154 ... lower path, 155 ... path switching section, 156 ... Upper elastic roller, 157 ... Upper rigid roller, 158 ... Lower elastic roller, 159 ... Lower rigid roller, 170 ... Reversing device, 180 ... Control unit, 200 ... Image forming device, 201 ... Image forming device body, 230 ... Image forming unit 231 ... Photoconductor, 250 ... Decurler part (rear decurler part), 252 ... Upper path, 253 ... Medium path, 255 ... Route cut-off Department, 270 ... reversing device

Claims (11)

A first image forming apparatus and a second image forming apparatus connected in series, in which the first image forming apparatus and the second image forming apparatus share the image formation on the sheet conveyed in this order. In tandem image forming system,
A pre-decurler unit that is provided in the first image forming apparatus and adjusts the direction in which the paper is warped and the amount of warping of the paper;
A conveyance abnormality detection unit for detecting a conveyance abnormality of the paper in the second image forming apparatus;
A control unit that determines the amount of paper warpage in the front decurler unit, based on the detection result of the conveyance abnormality by the conveyance abnormality detection unit ,
When the conveyance abnormality detection unit detects the conveyance abnormality, the control unit warps the sheet to the image forming surface side on which the image is formed by the first image forming apparatus, or the sheet Determining the direction and amount of warping of the sheet in the front decurler unit so that the sheet is warped toward the non-image forming surface side that is the side on which no image is formed in the first image forming apparatus, and the conveyance abnormality detecting unit is When no conveyance abnormality is detected, the amount of paper warpage in the front decurler unit is determined so as not to warp the paper.
Images forming system. A first image forming apparatus and a second image forming apparatus connected in series, in which the first image forming apparatus and the second image forming apparatus share the image formation on the sheet conveyed in this order. In tandem image forming system,
A pre-decurler unit that is provided in the first image forming apparatus and adjusts the direction in which the paper is warped and the amount of warping of the paper;
A conveyance abnormality detection unit for detecting a conveyance abnormality of the paper in the second image forming apparatus;
A control unit that determines the amount of paper warpage in the front decurler unit, based on the detection result of the conveyance abnormality by the conveyance abnormality detection unit,
The conveyance abnormality detection unit detects a winding jam in which a sheet is wound around a member in the second image forming apparatus as a conveyance abnormality,
Wherein, when the conveyance abnormality detecting unit detects the jam, the paper from members of the second image forming in the apparatus that determine a direction warping the paper in direction of easy peeling
Images forming system. A first image forming apparatus and a second image forming apparatus connected in series, in which the first image forming apparatus and the second image forming apparatus share the image formation on the sheet conveyed in this order. In tandem image forming system,
A pre-decurler unit that is provided in the first image forming apparatus and adjusts the direction in which the paper is warped and the amount of warping of the paper;
A conveyance abnormality detection unit for detecting a conveyance abnormality of the paper in the second image forming apparatus;
A control unit that determines the amount of paper warpage in the front decurler unit, based on the detection result of the conveyance abnormality by the conveyance abnormality detection unit,
The conveyance abnormality detection unit conveys a section in which a paper jam is generated in which the paper is wound around a member in the second image forming apparatus in the paper conveyance path when the time during which the paper is conveyed is longer than a predetermined time. Detect anomalies,
Wherein, when the conveyance abnormality detecting section detects the abnormal conveyance, the paper from members of the second image forming in the apparatus that determine a direction warping the paper in direction of easy peeling
Images forming system. The conveyance abnormality detection unit detects a winding jam in which a sheet is wound around a member in the second image forming apparatus as a conveyance abnormality,
When the conveyance abnormality detection unit detects the winding jam, the control unit determines a direction in which the sheet is bent in a direction in which the sheet is easily peeled off from a member in the second image forming apparatus.
The image forming system according to claim 1 . The conveyance abnormality detection unit conveys a section in which a paper jam is generated in which the paper is wound around a member in the second image forming apparatus in the paper conveyance path when the time during which the paper is conveyed is longer than a predetermined time. Detect anomalies,
When the conveyance abnormality detection unit detects the conveyance abnormality, the control unit determines a direction in which the sheet is warped in a direction in which the sheet is easily peeled off from a member in the second image forming apparatus.
The image forming system according to claim 1 . When the first image forming apparatus and the second image forming apparatus form an image on the same surface of the sheet, the control unit is a side on which the image is not formed by the first image forming apparatus. The direction in which the sheet is bent in the front decurler unit is determined so that the sheet is bent toward the non-image forming surface side, and an image is formed on the opposite surface of the sheet by the first image forming apparatus and the second image forming apparatus. any of claims 1 to 5 to determine the direction in which warp the sheet at the front decurler unit to deflect the sheet to the image forming surface side is the side on which an image is formed by the first image forming apparatus of the paper when the The image forming system according to claim 1. A rear decurler unit that is provided in the second image forming apparatus and adjusts the direction in which the paper is warped and the amount of warpage of the paper;
When the first image forming apparatus and the second image forming apparatus form an image on the same surface of the sheet, and the front decurler unit warps the sheet, the control unit is configured to form the first sheet of the sheet. In the first image forming apparatus and the second image forming apparatus, a direction in which the sheet in the rear decurler unit is warped is determined so as to be bent toward the image forming surface side that is an image forming side of the image forming apparatus. When images are formed on opposite sides of the sheet and the sheet is bent by the front decurler unit, the sheet is bent toward the non-image forming side, which is the side on which the image is not formed by the first image forming apparatus. the image forming system according to any one of claims 1 to 6 for determining the direction in which warp the sheet at the rear decurler portion. When the control unit warps the paper in the front decurler unit and the rear decurler unit, the warp amount when the paper is warped in the rear decurler unit is larger than the warp amount of the paper when the paper is warped in the front decurler unit. The image forming system according to claim 7 , wherein the rear decurler unit is controlled to be small. An image forming apparatus in which a sheet is transported first in an image forming system of a series tandem system in which two image forming apparatuses connected in series share the image formation on the sheet transported to the two image forming apparatuses. Because
A front decurler that adjusts the direction of warping and the amount of warping of the paper,
A communication unit that receives information indicating a paper conveyance abnormality in the other image forming apparatus from the other image forming apparatus;
A control unit that determines a warp amount of the sheet in the front decurler unit based on whether the communication unit has received information indicating the conveyance abnormality ;
When the communication unit receives information indicating the conveyance abnormality, the control unit warps the sheet to the image forming surface side, which is the side on which the image is formed, or the image is formed at the end of the sheet. When the direction and amount of warping of the paper in the front decurler unit are determined so as to warp the paper to the non-image forming surface side that is not formed, and the communication unit does not receive information indicating the conveyance abnormality, the paper is An image forming apparatus that determines the amount of paper warpage in the front decurler unit so as not to warp . An image forming apparatus in which a sheet is transported first in an image forming system of a series tandem system in which two image forming apparatuses connected in series share the image formation on the sheet transported to the two image forming apparatuses. Because
A front decurler that adjusts the direction of warping and the amount of warping of the paper,
A communication unit that receives information indicating a paper conveyance abnormality in the other image forming apparatus from the other image forming apparatus;
A control unit that determines a warp amount of the sheet in the front decurler unit based on whether the communication unit has received information indicating the conveyance abnormality;
When the communication unit receives the information indicating the conveyance abnormality due to the winding jam in which the sheet is wound around the member in the other image forming apparatus, the control unit receives the sheet from the member in the other image forming apparatus. The direction in which the paper is warped in the direction in which the paper is easy to peel off
Image forming apparatus. An image forming apparatus in which a sheet is transported first in an image forming system of a series tandem system in which two image forming apparatuses connected in series share the image formation on the sheet transported to the two image forming apparatuses. Because
A front decurler that adjusts the direction of warping and the amount of warping of the paper,
A communication unit that receives information indicating a paper conveyance abnormality in the other image forming apparatus from the other image forming apparatus;
A control unit that determines a warp amount of the sheet in the front decurler unit based on whether the communication unit has received information indicating the conveyance abnormality;
The control unit is configured such that when the communication unit is longer than a predetermined time in which the sheet is transported in a section where a paper jam can occur where the sheet is wound around a member in the sheet transport path in the other image forming apparatus. When the information indicating the conveyance abnormality is received and the information indicating the conveyance abnormality is received, the direction in which the sheet is warped in a direction in which the sheet is easily peeled off from the member in the other image forming apparatus is determined.
Image forming apparatus.

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