Patent Publication Number: US-2023161286-A1

Title: Recording material conveying device and image forming system

Description:
The entire disclosure of Japanese patent Application No. 2021-189468, filed on Nov. 22, 2021, is incorporated herein by reference in its entirety. 
     BACKGROUND 
     Technological Field 
     The present invention relates to a recording material conveying device and an image forming system including the recording material conveying device. 
     Description of the Related Art 
     In an image forming device, there is a case where a plurality of types of recording materials is used. In this case, the quality of a formed image can be improved by appropriately setting image forming conditions such as the transfer voltage and the fixing temperature of toner at the time of image formation according to the type and physical properties of the recording material. In addition, by conveying the recording material under more appropriate conveyance conditions according to the type and physical properties of the recording material, it is possible to suppress occurrence of conveyance failure of the recording material such as jam, image deviation, offset of the recording material, and the like. 
     As an image forming device that optimizes image forming conditions according to the type and physical properties of such a recording material, for example, a configuration has been proposed in which a detector for detecting characteristics such as the type and physical property values of the recording material (hereinafter, recording material characteristics) is arranged in a recording material conveyance path (see, for example, JP 2020-128269 A). 
     However, with the image forming device in which the detector is arranged in the above-described recording material conveyance path, when the recording material characteristics are detected, the conveyance of the recording material is stopped or the low-speed conveyance is performed so that the detection accuracy is enhanced and erroneous detection does not occur. For this reason, in an image forming job, it is necessary to perform the detection of the recording material characteristics before execution of image formation, and delay the start of the image formation during the period in which the recording material characteristics of the recording material are measured to make the recording material stand by. As a result, productivity decreases in the image forming device. 
     SUMMARY 
     In order to solve the above-described problem, the present invention provides a recording material conveying device and an image forming system capable of suppressing a decrease in productivity when characteristics of a recording material are sensed. 
     To achieve the abovementioned object, according to an aspect of the present invention, a recording material conveying device reflecting one aspect of the present invention comprises: a first conveyor that constitutes a conveyance path of a recording material; a second conveyor that branches from the first conveyor and constitutes a conveyance path of the recording material different from the conveyance path of the first conveyor; and a detector that detects recording material characteristics of the recording material, the detector being arranged in the second conveyor on a downstream side in a conveyance direction of the recording material with respect to a branch portion where the first conveyor and the second conveyor branch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages and features provided by one or more embodiments of the invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention: 
         FIG.  1    is a diagram illustrating a schematic configuration diagram of an image forming system of a first embodiment; 
         FIG.  2    is a system block diagram of the image forming system of the first embodiment; 
         FIG.  3    is a functional block diagram of a controller of the image forming system of the first embodiment; and 
         FIG.  4    is a flowchart of a method for detecting recording material characteristics in the image forming system of the first embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. 
     &lt;Embodiment of Recording Material Conveying Device and Image Forming System&gt; 
       FIG.  1    illustrates a schematic configuration diagram of an image forming system including a recording material conveying device of the present embodiment. 
     An image forming system  10  illustrated in  FIG.  1    includes a recording material supply device  100 , a recording material conveying device  400 , an image forming device  200 , and a post-processing device  300 . 
     In the image forming system  10 , a recording material S loaded in the recording material supply device  100  is supplied to the image forming device  200  via the recording material conveying device  400 . Then, after an image is formed on the recording material S in the image forming device  200 , the recording material S is carried out of the image forming device  200  to the post-processing device  300 . Then, after predetermined post-processing is performed on the recording material S after the image forming processing in the post-processing device  300 , the recording material S is discharged from the post-processing device  300 . 
     [Recording Material Supply Device] 
     The recording material supply device  100  accommodates a recording material for image formation in the image forming system  10 , and supplies the recording material S to the image forming device  200  according to an image forming job. As illustrated in  FIG.  1   , the recording material supply device  100  includes a conveyor  50 , recording material supply units  70 , which are recording material storage units, and the like. 
     The recording material supply unit  70  includes, for example, a plurality of sheet feeding trays arranged in the recording material supply device  100 . On the recording material supply unit  70 , a plurality of recording materials S can be loaded in a stacked state.  FIG.  1    illustrates a configuration including four recording material supply units  70  arranged vertically. In each recording material supply unit  70 , recording materials having different types and sizes are individually accommodated. 
     The conveyor  50  includes a taking-out roller (not illustrated) for taking out a recording material from each recording material supply unit  70 , a plurality of conveying rollers  53  for conveying the recording material provided along a predetermined recording material conveyance path, and the like. Therefore, the conveyance paths of the conveyor  50  join to be one path from the plurality of recording material supply units  70 , and the path is connected to the recording material conveying device  400 . Thus, the conveyor  50  drives the conveying rollers  53  to convey the recording material S fed from the recording material supply unit  70  to the recording material conveying device  400 . 
     [Recording Material Conveying Device] The recording material conveying device  400  includes a carry-in port  54  through which the recording material S is carried into the recording material conveying device  400 , a first conveyor  51  and a second conveyor  52  that convey the recording material S, a carry-out port  55  that carries out the recording material S, and medium sensors  71  as detectors that detect characteristics of the recording material S. 
     The first conveyor  51  constitutes a conveyance path through which the recording material S carried in through the carry-in port  54  is carried out through the carry-out port  55 . Then, the second conveyor  52  branches from the first conveyor  51  at a branch portion  58  on the downstream side of the carry-in port  54 . Moreover, the second conveyor  52  joins the first conveyor  51  again at a joining portion  59  on the upstream side of the carry-out port  55 . 
     The first conveyor  51  and the second conveyor  52  include a plurality of conveying rollers  53  and the like for conveying the recording material S provided along the first conveyor  51  and the second conveyor  52 . 
     In the second conveyor  52 , medium sensors  71  are arranged as detectors that detect recording material characteristics of the recording material S. A plurality of medium sensors  71  is provided on the second conveyor  52 . 
     The second conveyor  52  branches from the first conveyor  51  on the upstream side of the most upstream medium sensor  71  arranged on the second conveyor  52 . 
     The second conveyor  52  joins the first conveyor  51  again on the downstream side of the most downstream medium sensor  71  arranged on the second conveyor  52  to form one path. Then, on the downstream side of the joining position of the second conveyor  52 , the first conveyor  51  is connected to the carry-out port  55  that discharges the recording material S from the recording material conveying device  400  to the image forming device  200 . 
     The first conveyor  51  is configured such that a conveyance distance of the recording material S is shorter than that of the second conveyor  52 . In particular, the first conveyor  51  is configured such that the conveyance distance of the recording material S from the branch portion  58  with respect to the second conveyor  52  to the joining portion  59  is shorter than that of the second conveyor  52 . The first conveyor  51  is preferably configured to have the minimum length of the recording material conveyance distance between the carry-in port  54  and the carry-out port  55  of the recording material conveying device  400 . 
     In addition, the second conveyor  52  is configured such that the conveyance distance of the recording material S is longer than that of the first conveyor  51 . The second conveyor  52  is preferably configured such that the conveyance distance of the recording material S is equal to or longer than the length of the long side of the recording material S that can be accommodated in the recording material supply device  100  and conveyed in the recording material conveying device  400 . For example, the second conveyor  52  is preferably configured to have a length equal to or longer than the long side of a standard maximum size except for a long sheet such as a roll sheet. 
     The recording material S the recording material characteristics of which are detected by the medium sensors  71  is conveyed to the second conveyor  52 . The recording material characteristics of the recording material S conveyed to the second conveyor  52  are detected by the medium sensors  71  arranged in the path. In the second conveyor  52 , the recording material characteristics are detected by the medium sensors  71  in a state where the conveyance of the recording material S is stopped or the recording material S is conveyed at a speed lower than a normal conveyance speed at the time of image formation. 
     On the other hand, the recording material S the recording material characteristics of which are not detected by the medium sensors  71  is conveyed to the first conveyor  51 . In the first conveyor  51 , the recording material S is conveyed at the normal conveyance speed at the time of image formation. 
     (Medium Sensor) 
     The medium sensor  71  detects the recording material characteristics of the recording material S conveyed to the second conveyor  52  on the basis of the control of a controller  90  ( FIG.  2   ). In the second conveyor  52 , the medium sensors  71  that detect the recording material characteristics in a state where the conveyance of the recording material S is stopped or in a state where the conveyance speed is reduced such that the detection accuracy of the recording material characteristics can be improved are arranged. 
     The medium sensor  71  detects the type (for example, plain paper, high-quality paper, glossy paper, and the like) and the size of the recording material S, the physical properties of the recording material S, and the like. As the physical properties of the recording material S, for example, the thickness, the basis weight, the state of the surface such as smoothness, the rigidity, the charge amount, the water content, the paper grain (the angle of the fiber direction of the recording material), and the like are detected. 
     In addition, the medium sensor  71  includes various sensors for detecting the recording material characteristics. For example, the medium sensor  71  includes an imaging sensor for detecting the type of the recording material S. The imaging sensor includes a light source that irradiates the front surface of the recording material S with light, a light source that irradiates the back surface of the recording material S with light, and an imaging element that images the front surface of the recording material S. Then, an image in a reflection state at the time of front irradiation of the recording material S and an image in a transmission state at the time of back irradiation of the recording material S are acquired. 
     It is possible to identify the type of the recording material S from the features and characteristics of the acquired image. 
     In addition, the medium sensor  71  includes an optical sensor and a weight sensor for detecting the size, the weight, and the basis weight of the recording material S. The optical sensor includes a light receiving element that detects an end portion of the recording material S on an inspection table over which the conveyed recording material S passes. In addition, the weight sensor detects the weight of the recording material S in a unit area from a change in weight of the inspection table when the recording material S passes. Then, the size and area of the recording material S can be detected from the output of the optical sensor, and the basis weight can be acquired from the weight of the recording material S in a unit area detected by the weight sensor. 
     [Image Forming Device] 
     The image forming device  200  illustrated in  FIG.  1    includes an operation display unit  220 , a scanner  230 , an image forming unit  240 , a conveyor  250 , and the like. 
     The operation display unit  220  includes an operation unit and a display unit. 
     The display unit includes, for example, a display device such as a liquid crystal display (LCD), and displays various screens in accordance with an instruction of a display signal input from the controller  90  ( FIG.  2   ). 
     The operation unit includes a touch panel formed to cover a display screen of the display unit, and various operation buttons such as a numeric button and a start button, and outputs an operation signal based on a user&#39;s operation to the controller  90  to be described below. The operation unit receives an operation instruction from the user. 
     The scanner  230  optically scans a document conveyed onto contact glass from an auto document feeder (ADF) or a document placed on the contact glass, forms an image of reflected light of light illuminated and scanned from a light source to the document on a light receiving surface of a charge coupled device (CCD) sensor, reads a document image, and performs A/D conversion on the read image to generate image data. 
     The image forming unit  240  forms an image on the recording material S on the basis of the image data. The image forming unit  240  includes photoconductor drums  241 Y,  241 M,  241 C, and  241 K, charging units  242 Y,  242 M,  242 C, and  242 K, exposure units  243 Y,  243 M,  243 C, and  243 K, developing units  244 Y,  244 M,  244 C, and  244 K, primary transfer rollers  245 Y,  245 M,  245 C, and  245 K, which correspond to the respective colors of yellow (Y), magenta (M), cyan (C), and black (K). In addition, the image forming unit  240  includes an intermediate transfer belt  246 , a secondary transfer roller  247 , and a fixing unit  248 . 
     The charging units  242 Y,  242 M,  242 C, and  242 K uniformly charge the photoconductor drums  241 Y,  241 M,  241 C, and  241 K. 
     The exposure units  243 Y,  243 M,  243 C, and  243 K include a laser light source, a polygon mirror, a lens, and the like, and scan and expose the surfaces of the photoconductor drums  241 Y,  241 M,  241 C, and  241 K with a laser beam on the basis of image data of each color to form electrostatic latent images. 
     The developing units  244 Y,  244 M,  244 C, and  244 K attach toners of the respective colors to the electrostatic latent images on the photoconductor drums  241 Y,  241 M,  241 C, and  241 K to perform development. 
     The primary transfer rollers  245 Y,  245 M,  245 C, and  245 K sequentially transfer the toner images of the respective colors formed on the photoconductor drums  241 Y,  241 M,  241 C, and  241 K onto the intermediate transfer belt  246  (primary transfer). That is, a color toner image in which the toner images of four colors are superimposed is formed on the intermediate transfer belt  246 . 
     The secondary transfer roller  247  collectively transfers the color toner image on the intermediate transfer belt  246  onto one surface of the recording material S supplied from the supply tray (secondary transfer). The fixing unit  248  causes the recording material S to pass through a nip portion formed by a fixing roller and a pressure roller, thereby fixing the toner image on the recording material S by heating and pressurization. 
     The conveyor  250  includes a plurality of conveying rollers  53  and the like provided along a predetermined conveyance path for conveying the recording material S. The conveyor  250  drives the conveying rollers  53  to convey the recording material along the predetermined conveyance path in the image forming device  200 . Then, the recording material S after the image formation is carried out to the post-processing device  300 . 
     [Post-Processing Device] 
     The recording material S on which an image is formed in the image forming device  200  is carried into the post-processing device  300 . The post-processing device  300  includes, for example, a plurality of post-processing units, and predetermined post-processing is performed in the post-processing unit designated by a job. For example, the post-processing device  300  includes a post-processing unit that performs processing such as perforation processing, folding processing, foil stamping processing, binding, cutting processing, stapling, gluing, and stitching. 
     In the post-processing device  300 , the recording material S having been subjected to the image forming processing and conveyed from the image forming device  200  is conveyed to a post-processing unit, which is not illustrated, by a conveyor  350 , and predetermined post-processing is performed on the recording material S. The conveyor  350  is conveyed by a conveying roller  351  or the like provided along the conveyance path, and is discharged to a discharge tray  352 . 
     [System Block Diagram] 
       FIG.  2    illustrates a system block diagram of each device constituting the above-described image forming system illustrated in  FIG.  1   . 
     The controller  90  includes, for example, a central processing unit (CPU)  91 , read only memory (ROM)  92 , random access memory (RAM)  93 , and the like. The CPU  91  reads various processing programs stored in the ROM  92 , loads the programs onto the RAM  93 , and centrally controls the operation of each unit of the image forming system  10  according to the loaded programs. 
     The ROM  92  stores various processing programs for controlling each unit of the image forming system  10 , parameters and table data necessary for executing the programs, various files, and the like. 
     The RAM  93  includes volatile semiconductor memory, and forms a work area for temporarily storing various processing programs, input or output data, parameters, and the like read from the ROM  92  in various processing executed and controlled by the CPU  91 . 
     A storage unit  98  stores, for example, image data received from an external device. In addition, the storage unit  98  stores various processing programs executed by the CPU  91 , information regarding a processing function of the own device necessary for executing the programs, image data read by the scanner  230 , image data input from a client device, which is not illustrated, a characteristic value of the recording material S detected by the medium sensor  71 , and the like. The storage unit  98  may include, for example, nonvolatile memory such as a hard disk drive (HDD), a solid state drive (SSD), or flash memory. 
     A communication unit  99  includes a network interface card (NIC), a modem, or the like, connects the recording material supply device  100 , the recording material conveying device  400 , the image forming device  200 , and the post-processing device  300  to a communication network such as a local area network (LAN) or a wide area network (WAN), and transmits and receives various data to and from external information equipment (for example, a client device). 
     The operation display unit  220  includes a touch panel or the like provided with a pressure-sensitive or capacitive operation unit (touch sensor) in which transparent electrodes are arranged in a grid pattern on a display unit such as a liquid crystal display (LCD) or an organic electro luminescence (EL) display, and functions as the display unit and the operation unit. The display unit displays various operation screens in accordance with a display control signal input from the controller  90 . The operation unit receives various input operations by the user and outputs an operation signal to the controller  90 . 
     The scanner  230  optically scans a document placed on the contact glass, forms an image of reflected light from the document on the light receiving surface of the charge coupled device (CCD) sensor, and reads a document image. The image (analog image signal) read by the scanner  230  is subjected to predetermined image processing in an image processing unit  80 . 
     The image processing unit  80  includes a circuit that performs analog-digital (A/D) conversion processing, a circuit that performs digital image processing, and the like. The image processing unit  80  generates digital image data by performing A/D conversion processing on an analog image signal from the scanner  230 . In addition, the image processing unit  80  analyzes a print job acquired from external information equipment (for example, a client device), rasterizes each page of the document, and generates digital image data. Then, the image processing unit  80  performs image processing such as color conversion processing, correction processing (shading correction or the like) according to initial setting or user setting, and compression processing on the image data as necessary, and outputs the image data after the image processing to the image forming unit  240 . 
     [Functional Configuration of Controller] 
     Next, a functional configuration of the controller  90  will be described.  FIG.  3    is a functional block diagram of the controller  90 . As illustrated in  FIG.  3   , the controller  90  includes a sheet feed control unit  94 , a conveyance control unit  95 , a medium sensing control unit  96 , and an image formation control unit  97 . 
     The sheet feed control unit  94  controls the supply of the recording material S from the recording material supply unit  70  to the conveyor  50  in the recording material supply device  100 . The sheet feed control unit  94  supplies the recording material S to the conveyor  50  in accordance with the conveyance control of the recording material S by the conveyance control unit  95 . 
     The conveyance control unit  95  controls the operation of the conveyance mechanism for the recording material S between the devices and in the device in the recording material supply device  100 , the recording material conveying device  400 , the image forming device  200 , and the post-processing device  300  constituting the image forming system  10 . Specifically, the conveyance control unit  95  controls driving of the conveyor  50  of the recording material supply device  100 , the first conveyor  51  and the second conveyor  52  of the recording material conveying device  400 , the conveyor  250  of the image forming device  200 , and the conveyor  350  of the post-processing device  300 . The conveyance control unit  95  controls the conveyance of the recording material S by interlocking the drive units between the respective devices by controlling the stop of the driving of each drive unit, the adjustment of the drive start timing and the drive speed, and the like according to the conveyance conditions in accordance with the recording material characteristics of the recording material S. 
     The conveyance control unit  95  sets the conveyance conditions of the recording material S according to the recording material characteristics acquired by the medium sensing control unit  96 . For example, the conveyance control unit  95  acquires conveyance conditions according to the recording material characteristics from data stored in the storage unit  98  or the like. Then, the conveyance control unit  95  sets conveyance conditions of each configuration of the conveyor  50 , the first conveyor  51 , the second conveyor  52 , the conveyor  250 , and the conveyor  350  on the basis of the data acquired from the storage unit  98  or the like. 
     In addition, the conveyance control unit  95  selects the conveyance path of the recording material S from one of the first conveyor  51  and the second conveyor  52  in the recording material conveying device  400 , and switches the conveyance path of the recording material S at the branch portion  58 . Then, the driving of the first conveyor  51  or the second conveyor  52  selected as the conveyance path is controlled to convey the recording material S. The conveyance control unit  95  conveys at least one recording material S to the second conveyor  52  when conveying the plurality of recording materials S in a print job. 
     In the first conveyor  51 , the conveyance control unit  95  drives the conveyance speed of the recording material S at a normal speed at the time of image formation. Then, the conveyance control unit  95  conveys the recording material S from the recording material conveying device  400  to the image forming device  200  by conveying the recording material S with the first conveyor  51 . 
     In addition, in the second conveyor  52 , the conveyance control unit  95  reduces the conveyance speed after the entire recording material S is conveyed to the second conveyor  52 , that is, after the rear end of the recording material S passes through the branch portion  58 . Then, after the recording material S reaches the medium sensor  71  that detects the recording material characteristics, the recording material S is conveyed while being lowered to a speed at which highly accurate detection can be performed by the medium sensor  71 . In addition, the conveyance control unit  95  may stop the conveyance of the recording material S until the detection of the recording material characteristics by the medium sensor  71  ends after the recording material S is conveyed to the position where the recording material characteristics can be detected by the medium sensor  71 . 
     Moreover, the conveyance control unit  95  conveys the recording material S the recording material characteristics of which have been detected in the second conveyor  52 , and conveys the recording material S from the second conveyor  52  to the first conveyor  51  at the joining portion  59 . The conveyance control unit  95  conveys the recording material S conveyed to the first conveyor  51  from the recording material conveying device  400  to the image forming device  200 . 
     The medium sensing control unit  96  controls detection of recording material characteristics of the recording material S by the medium sensor  71 . For example, when the recording material S is conveyed to the conveyance path on which the medium sensor  71  is provided, the medium sensing control unit  96  instructs the medium sensor  71  to execute the detection of the recording material characteristics. Based on this instruction, the medium sensor  71  starts detecting the recording material characteristics of the recording material S. 
     In addition, the medium sensing control unit  96  receives various data detected by each sensor of the medium sensor  71 , and calculates the recording material characteristics of the recording material S on the basis of these pieces of data. For example, with the configuration in which the image forming system  10  includes the plurality of medium sensors  71 , the medium sensing control unit  96  combines the data acquired from the plurality of medium sensors  71  and calculates the recording material characteristics of the recording material S. 
     The image formation control unit  97  controls an image forming operation in the image forming unit  240  of the image forming device  200 . In addition, the image formation control unit  97  sets image forming conditions according to the recording material characteristics acquired by the medium sensing control unit  96 . For example, the image formation control unit  97  acquires image forming conditions according to the recording material characteristics from data stored in the storage unit  98  or the like. Then, the image formation control unit  97  sets operation conditions for each configuration of the image forming unit  240  on the basis of data acquired from the storage unit  98  or the like. Then, the operation of each configuration of the image forming unit  240  is controlled according to the set operation conditions, and an image is formed on the recording material S on the basis of the image data. 
     [Detection of Recording Material Characteristics] 
     Next, a method of detecting the recording material characteristics in the image forming system  10  will be described.  FIG.  4    is a flowchart of a method of detecting recording material characteristics. Note that, in the flowchart illustrated in  FIG.  4   , conveyance of the recording material in the recording material conveying device  400  and detection of recording material characteristics will be mainly described. 
     First, in the image forming system  10 , the controller  90  determines whether a measurement mode for measuring recording material characteristics of the recording material S is set according to an instruction of a user or the like (step S 10 ). 
     When the measurement mode is not set (No in step S 10 ), the conveyance control unit  95  causes the recording material S (first sheet or first recording material S) conveyed from the recording material supply device  100  to the first conveyor  51  of the recording material conveying device  400  to pass through the branch portion  58  as it is and continues conveyance in the first conveyor  51  (step S 11 ). 
     When the measurement mode is set (Yes in step S 10 ), the conveyance control unit  95  conveys the first recording material S conveyed from the recording material supply device  100  to the first conveyor  51  of the recording material conveying device  400  to the second conveyor  52  by switching the conveyance path at the branch portion  58  (step S 12 ). 
     Next, the medium sensing control unit  96  activates the medium sensor  71  and detects the recording material characteristics of the first recording material S conveyed to the second conveyor  52  (step S 13 ). At this time, the conveyance control unit  95  stops the conveyance of the first recording material S in the second conveyor  52 , or conveys the first recording material S at a speed lower than the normal conveyance speed at the time of image formation. The medium sensing control unit  96  detects recording material characteristics using the medium sensor  71  with respect to the first recording material S that is stopped or conveyed at a low speed. 
     Next, the conveyance control unit  95  determines whether the rear end portion of the first recording material S has passed through the branch portion  58  (step S 14 ). The passage of the first recording material S through the branch portion  58  is determined from, for example, the sensing of the rear end portion of the first recording material S by the medium sensor  71  arranged on the most upstream side of the second conveyor  52 , the conveyance speed and the conveyance time of the first recording material S after being carried into the recording material conveying device  400 , and the like. 
     In a case where the rear end portion of the first recording material S has not passed through the branch portion  58  (No in step S 14 ), the processing of step S 13  is continued until the rear end portion of the first recording material S passes through the branch portion  58 . 
     When the rear end portion of the first recording material S has passed through the branch portion  58  (Yes in step S 14 ), the conveyance control unit  95  conveys a next recording material S (second sheet or second recording material S) conveyed from the recording material supply device  100  to the recording material conveying device  400  to the first conveyor  51  (step S 15 ). Here, the conveyance control unit  95  continues the conveyance of the second recording material S on the first conveyor  51  side without conveying to the second conveyor  52  side at the branch portion  58 . Then, it is preferable that the second recording material S be conveyed by the first conveyor  51  to a position where the second recording material S is carried in from the recording material conveying device  400  to the image forming device  200  by being conveyed in the first conveyor  51 . In addition, in the image forming device  200 , the conveyed second recording material S is preferably conveyed to a position before the image forming position of the image forming unit  240  by the conveyor  250  of the image forming device  200 . For example, the second recording material S is conveyed to a registration roller immediately before the secondary transfer roller  247  of the image forming unit  240 . 
     Next, the conveyance control unit  95  determines whether detection of all recording material characteristics of the first recording material S has been completed (step S 16 ). When the detection of all the recording material characteristics has not been completed (No in step S 16 ), the conveyance control unit  95  continues the processing of detecting the recording material characteristics of the first recording material S. 
     When the detection of all the recording material characteristics of the first recording material S is completed (Yes in step S 16 ), the conveyance control unit  95  conveys the first recording material S the recording material characteristics of which have been detected from the second conveyor  52  to the first conveyor  51  (step S 17 ). In the conveyance of the first recording material S here, the first recording material S is conveyed from the joining portion  59  to the first conveyor  51  by conveying the first recording material S to the downstream side of the second conveyor  52 . In addition, the first recording material S the recording material characteristics of which have been detected joins the rear side (upstream side in the conveyance direction) of the second recording material S conveyed to the first conveyor  51  in step S 15  described above in the first conveyor  51 . Note that the joining position of the first recording material S is not necessarily limited to the position immediately after the second recording material S, and can be changed according to the number of recording materials S that can stay up to the position of the registration roller and the conveyance interval of the recording materials S. In a case where there is no margin in the conveyance interval of the recording materials S, the first recording material S can be joined as the recording material S on which the image is formed last in the job. 
     After the first recording material S is conveyed from the second conveyor  52  to the first conveyor  51 , the processing according to the present flowchart ends. 
     After this processing, the recording materials S (first recording material S and second recording material S) conveyed by the first conveyor  51  in the image forming system  10  are conveyed from the recording material conveying device  400  to the registration roller of the image forming device  200 . In the image forming device  200  to which the recording material S has been conveyed, image forming conditions corresponding to the detected recording material characteristics are set by the image formation control unit  97 , and image formation is executed in the image forming unit  240 . 
     In the processing according to the above-described flowchart, the recording material S (first sheet or first recording material S) first conveyed to the recording material conveying device  400  is conveyed to the second conveyor  52 , and the recording material characteristics are detected in a state where the recording material S is stopped or conveyed at a low speed. Then, in a period in which the recording material characteristics of the first recording material S are detected, a subsequent recording material S, which is a next recording material S (second sheet or second recording material S), is conveyed from the recording material conveying device  400  to the image forming device  200  by the first conveyor  51 . 
     In this manner, by providing the second conveyor  52  and arranging the medium sensors  71  on the second conveyor  52 , the next, second recording material S can be conveyed to the image forming device  200  by the first conveyor  51  during the detection of the recording material characteristics of the first recording material S conveyed to the second conveyor  52 . Therefore, after the detection of the recording material characteristics of the first recording material S is completed in the second conveyor  52 , before the first recording material S is conveyed from the second conveyor  52  to the image forming device  200 , image formation can be executed on a condition that the recording material characteristics are reflected on the second recording material S conveyed to the image forming device  200  in advance. 
     Accordingly, it is possible to suppress a loss of time generated when the recording material characteristics are detected, and it is possible to improve the image forming accuracy by detecting the recording material characteristics and to suppress a decrease in image forming productivity. 
     Although embodiments of the present invention have been described and illustrated in detail, the disclosed embodiments are made for purposes of illustration and example only and not limitation. The scope of the present invention should be interpreted by terms of the appended claims, and various modifications and changes can be made without departing from the configuration of the present invention.