Patent Publication Number: US-8983311-B2

Title: Image forming system with an image inspection device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2011-279926 filed in Japan on Dec. 21, 2011, Japanese Patent Application No. 2012-059339 filed in Japan on Mar. 15, 2012 and Japanese Patent Application No. 2012-159967 filed in Japan on Jul. 18, 2012. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an image forming system. 
     2. Description of the Related Art 
     In the production-oriented printer market, printed materials themselves serve as the products. Hence, emphasis is on the productivity capability of image forming apparatuses that generate printed materials. Moreover, the image forming apparatuses are increasingly having an enhanced productivity so as to generate printed materials at high speed. Furthermore, since printed materials generated by the image forming apparatuses themselves serve as the products; maintaining the quality of the printed materials is also an important factor. 
     As a measure for maintaining the quality of printed materials, an image inspection device has been developed that inspects whether or not defects such as abnormal images are present in a printed material generated by an image forming apparatus. The image inspection device reads images from the printed material that is generated by an image forming apparatus, compares the image data that is obtained by reading images with the original image data that was used in generating the printed material, and determines whether or not there are any defects in the images formed on the printed material (i.e., performs a defect determination process). 
     As described above, when printed materials themselves serve as the products, it becomes necessary to ensure that any defective printed material, which has a defective image printed thereon, does not get mixed with normal printed materials having a non-defective image printed thereon. Therein, in the image inspection device, a typically-known technology is implemented to make sure that a defective printed material is discharged to a different discharge destination than the discharge destination for discharging normal printed materials. 
     There, in an image inspection device that is connected to a device which includes a separate discharge destination for defective printed materials, the defect determination process for determining whether or not there are any defects in the images formed on a printed material needs to be completed before that printed material reaches the device which includes a separate discharge destination for defective printed materials. However, depending on the image data or depending on the inspection details, it takes time to perform the defect determination process. Thus, there are times when the defect determination process does not get completed before a printed material reaches the device which includes a separate discharge destination for defective printed materials. The measures to tackle this issue are being studied. 
     As a proposed measure to tackle the case in which the defect determination process does not get completed before a printed material reaches the device which includes a separate discharge destination for defective printed materials, a technology has been proposed with the aim of securing sufficient time to ensure completion of the defect determination process. According to that technology, after the images formed on a printed material have been read, the printed material is conveyed forward at a lower conveying speed. 
     For example, an image forming apparatus has been disclosed that includes an image inspection device having a unit for determining whether or not there are defects in the images formed on a printed material, a discharge destination switching unit for switching between a discharge destination for defective printed materials and a discharge destination for normal printed materials, and a conveying speed control unit being capable of controlling the conveying speed of the printed material. In the image forming apparatus, during a period starting from the reading of the images formed on the printed material until the determination of defects in images is completed, the printed material is conveyed at a lower conveying speed than the specified conveying speed. Hence, it is ensured that a defective printed material is discharged to the discharge destination for defective printed materials, and the productivity is prevented from declining (see Japanese Patent Application Laid-open No. 2010-041430). 
     Apart from that, for example, an image inspection device has been disclosed that includes a reading unit that reads images; a discharge destination switching unit that switches the discharge destination for printed materials; a printed material storing unit that temporarily stores a printed material and that is disposed in between the reading unit and the discharge destination switching unit; and an image information storing unit that temporarily stores the read image data before the defect determination process is performed. With that, the defect determination process is performed in an asynchronous manner with respect to the conveying of the printed material. That makes it possible to perform the defect determination process having a high degree of freedom in terms of time. As a result, it becomes possible to invest an arbitrary amount of time for inspecting images without hindering the continuous operation of image formation (see Japanese Patent Application Laid-open No. 2009-230046). 
     However, in the technology disclosed in Japanese Patent Application Laid-open No. 2010-041430, the only countermeasure is to reduce the conveying speed of the printed material to be inspected. Consequently, the productivity of printed materials also decreases. That is, the specified productivity cannot be maintained. Moreover, in the technology disclosed in Japanese Patent Application Laid-open No. 2009-230046, the printed material to be inspected is temporarily stored in the printed material storing unit. Consequently, the specified productivity cannot be maintained as is the case for the technology disclosed in Japanese Patent Application Laid-open No. 2010-041430. 
     Therefore, there is a need for an image forming system capable of accurately separating a discharge destination for normal printed materials from a discharge destination for defective printed materials while maintaining the productivity of printed materials. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to at least partially solve the problems in the conventional technology. 
     According to an embodiment, there is provided an image forming system that includes an image forming apparatus; an image inspection device connected to the image forming apparatus; a discharge device connected to the image inspection device; an image forming unit configured to output image data onto a recording medium; a first conveying unit configured to convey the recording medium onto which the image data has been output; a reading unit configured to read an image from the recording medium that is conveyed; a defect determining unit configured to determine whether the read image has a defect; a plurality of conveying paths arranged to convey the recording medium whose image has been read, the conveying paths having different lengths; a device connection determining unit configured to determine whether, at a downstream side of the image inspection device in a direction in which the recording medium is conveyed, the discharge device is directly connected to the image inspection device without another device in between or is connected to the image inspection device via another device; a second conveying unit configured to convey the recording medium to the discharge device by using a longer conveying path from among the plurality of conveying paths, when the discharge device is directly connected to the image inspection device at the downstream side without another device in between; a defective recording medium discharge tray unit to which the recording medium having a defective image output thereon is discharged; a normal recording medium discharge tray unit to which the recording medium having a non-defective image output thereon is discharged; and a discharging unit configured to discharge the recording medium to the defective recording medium discharge tray unit, when the read image is determined to have a defect, and discharge the recording medium to the normal recording medium discharge tray unit, when the read image is determined to have no defect. 
     According to another embodiment, there is provided an image forming system that includes an image forming apparatus; an image inspection device connected to the image forming apparatus; an image forming unit configured to output image data onto a recording medium; a first conveying unit configured to convey the recording medium onto which the image data has been output; a reading unit configured to read an image from the recording medium that is conveyed; a conveying path including a first reverse path for reversing the recording medium whose image has been read and a second reverse path for reversing the recording medium that has been reversed in the first reverse path; a defect determining unit configured to determine whether the read image has a defect while the recording medium is in the second reverse path; and a second conveying unit configured to convey the recording medium to a discharge destination based on a determination result by the defect determining unit. 
     The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a configuration diagram illustrating an example of an image forming system according to a first embodiment; 
         FIG. 2  is a configuration diagram illustrating another example of the image forming system according to the first embodiment; 
         FIG. 3  is a block diagram illustrating a functional configuration of the image forming system illustrated in  FIG. 1 ; 
         FIG. 4  is a block diagram illustrating a functional configuration of the image forming system illustrated in  FIG. 2 ; 
         FIGS. 5 and 6  illustrate a flowchart of a printed material conveying operation performed in the image forming system according to the first embodiment; 
         FIG. 7  is a configuration diagram illustrating an example of an image forming system according to a second embodiment; 
         FIG. 8  is a block diagram illustrating a functional configuration of the image forming system illustrated in  FIG. 7 ; 
         FIGS. 9A and 9B  illustrate a flowchart of a printed material conveying operation performed in the image forming system according to the second embodiment; 
         FIG. 10  is a configuration diagram illustrating an example of an image forming system according to a third embodiment; 
         FIG. 11  is a block diagram illustrating a functional configuration of the image forming system illustrated in  FIG. 10 ; 
         FIGS. 12A and 12B  illustrate a flowchart of a printed material conveying operation performed in the image forming system according to the third embodiment; 
         FIG. 13  is a configuration diagram illustrating an example of an image forming system according to a fourth embodiment; 
         FIG. 14  is a configuration diagram illustrating another example of the image forming system according to the fourth embodiment; 
         FIG. 15  is a block diagram illustrating a functional configuration of the image forming system illustrated in  FIG. 13 ; 
         FIG. 16  is a block diagram illustrating a functional configuration of the image forming system illustrated in  FIG. 14 ; and 
         FIG. 17  illustrates a flowchart of a printed material conveying operation performed in the image forming system according to the fourth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Exemplary embodiments of an image forming system according to the present invention are described in detail below with reference to the accompanying drawings. 
     First Embodiment 
       FIG. 1  is a configuration diagram illustrating an example of an image forming system according to a first embodiment. The image forming system illustrated in  FIG. 1  includes an image forming apparatus  1 ; an image inspection device  100  that is connected to the image forming apparatus  1 ; and a post-processing device  200  (a discharge device: a device which includes a discharge destination for defective printed materials) that is connected to the image inspection device  100 . Herein, the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100 . 
     In the first embodiment described below, the configuration is such that, to the image inspection device  100 , the post-processing device  200  is connected as the device which includes a discharge destination for defective printed materials. However, any other device which includes a discharge destination for defective printed materials can be connected to the image inspection device  100 . Meanwhile, the image forming apparatus  1  according to the first embodiment can be applied to a multifunction peripheral that has at least two functions from among the copying function, the printing function, the scanning function, and the facsimileing function; or can be applied to an image forming apparatus such as a copying machine or a printer that outputs (prints) image data. Explained below with reference to  FIG. 1  is a configuration and operations of the image forming system. 
     Firstly, the explanation is given regarding the image forming apparatus  1 . Near the central portion in the image forming apparatus  1  is disposed an intermediate transfer belt  2 , which is an endless belt. The intermediate transfer belt  2  is wound around a plurality of support rollers in such a way that the intermediate transfer belt  2  can rotate in the clockwise direction with reference to  FIG. 1 . Above the intermediate transfer belt  2  is configured a tandem-type image forming device  4  in which a plurality of image forming units  3  is horizontally arranged along the conveying direction of the intermediate transfer belt  2 . Moreover, as illustrated in  FIG. 1 , above the tandem-type image forming device  4  are disposed exposure devices  5 . 
     Each image forming unit  3  of the tandem-type image forming device  4  includes a photosensitive drum  6  that serves as an image conveying member for conveying toner images of a particular color. The positions at which toner images are transferred from the photosensitive drums  6  onto the intermediate transfer belt  2  are called primary transfer positions. At each primary transfer position, a primary transfer roller  7  is disposed opposite to the corresponding photosensitive drum  6  and across the intermediate transfer belt  2 . The primary transfer rollers  7  constitute a primary transfer unit. Meanwhile, a support roller  8  is a driving roller that rotary-drives the intermediate transfer belt  2 . 
     On the opposite side of the tandem-type image forming device  4  and across the intermediate transfer belt  2 , a secondary transfer device  9  is disposed. In the example illustrated in  FIG. 1 , in the secondary transfer device  9 , a secondary transfer roller  11  is pressed against a secondary transfer-facing roller  10 , and a transfer electric field is applied therebetween. As a result, an image formed on the intermediate transfer belt  2  is transferred onto a recording member (recording medium) (not illustrated). In the secondary transfer device  9 , depending on the recording member, changes are made in the transfer current of the secondary transfer roller  11  that serves as a transfer condition parameter. 
     Alongside the secondary transfer device  9  is disposed a fixing mechanism  12  that performs thermal fusion adhesion of the transferred image (toner image) that has been transferred onto the recording member. The fixing mechanism  12  includes a halogen lamp (not illustrated) functioning as a heat source; and includes a pressure roller  14  pressed against a fixing belt  13  that is an endless belt. 
     In the fixing mechanism  12 , depending on the recording member, changes are made to the following transfer condition parameters: the temperature of the fixing belt  13  and the temperature of the pressure roller  14 ; the nip width between the fixing belt  13  and the pressure roller  14 ; and the speed of the pressure roller  14 . The recording member on which an image has been transferred is conveyed to the fixing mechanism  12  by a conveying belt  15 . 
     Regarding the operations performed by the image forming apparatus  1 , firstly, image data is sent to the image forming apparatus  1 . Upon receiving a signal as an instruction to start the operations, a driving motor (not illustrated) rotary-drives the support roller  8 . As a result, a plurality of other support rollers gets driven, thereby resulting in the rotation of the intermediate transfer belt  2 . At the same time, each image forming unit  3  forms a monochromatic image on the corresponding photosensitive drum  6 . Then, due to the rotation of the intermediate transfer belt  2 , the monochromatic images are sequentially transferred onto the intermediate transfer belt  2  at the respective primary transfer rollers  7 . Consequently, a composite color image gets formed on the intermediate transfer belt  2 . 
     Meanwhile, in a paper feeding table  16 , when one of two paper feeding rollers  17  is selectively rotated, a recording member gets fed from one of paper feeding cassettes  18  and is conveyed by carriage rollers  19 . Then, the recording member reaches a registration roller  20  and stops thereat. At the same timing at which a composite color image formed on the intermediate transfer belt  2  reaches the secondary transfer device  9 , the registration roller  20  is rotated so that the composite color image gets transferred onto the recording member at the secondary transfer device  9 . As a result, a color image is formed on the recording member. 
     After the image is transferred, the secondary transfer device  9  sends the recording member to the fixing mechanism  12 , which applies heat and pressure to perform fusion adhesion of the transfer image. Then, in the case of performing duplex printing in which an image is printed not only on the first side of the recording member but also on the second side that is the reverse side of the first side; the recording member is conveyed to a paper reverse path  23  and a duplex conveying path  24  by a branching claw  21  and a flip roller  22 . Subsequently, in the same manner as described above, a composite color image is formed on the reverse side of the recording member. 
     If a recording member is to be reversed, the branching claw  21  conveys the recording member to the paper reverse path  23 ; and the flip roller  22  conveys the recording member toward a discharge roller  25 . As a result, the recording member gets reversed and the front side becomes the rear side and vice versa. On the other side, if a recording member is not to be reversed, the branching claw  21  conveys the recording member to a discharge conveying path that is the path for conveying the recording member toward the discharge roller  25 . 
     Then, the discharge roller  25  conveys the recording member to a de-curler unit  26 . Then, depending on the recording member, a de-curler amount serving as a paper feeding evaluation parameter is altered in the de-curler unit  26 . The de-curler amount is adjusted by changing the pressure of a de-curler roller  27 , which conveys the recording member to the image inspection device  100 . Meanwhile, once a recording member has an image formed (printed) thereon, it is a printed material. 
     Given below is the explanation regarding the image inspection device  100 . Herein, in the image inspection device  100 , an inlet roller  101  conveys a printed material to reading units  102  and  103 . Then, each of the reading units  102  and  103  reads the composite color image recorded on one of the sides of the printed material. More particularly, the reading unit  102  is positioned above the printed material being conveyed and reads the image recorded on the upper surface of the printed material; the reading unit  103  is positioned below the printed material being conveyed and reads the image recorded on the lower surface of the printed material. 
     Then, a defect determining unit  109  determines whether or not there are defects (determines the presence or absence of defects) in the composite color images which have been read. That is, the defect determining unit  109  determines whether a printed material is a normal printed material not having defective images printed thereon or a defective printed material having defective images printed thereon. In the image forming system illustrated in  FIG. 1 , the post-processing device  200 , which includes a discharge destination for defective printed materials, is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100 . For that reason, a printed material from which images have been read is conveyed to the post-processing device  200  using an inversion conveying path that passes through a reverse path  106 . That is, an outlet roller  104  and a branching claw  105  convey the printed material to the reverse path  106  so that the printed material is reversed. Then, a flip roller  107  and a discharge roller  108  convey the reversed printed material to the post-processing device  200 . 
     Given below is the explanation regarding the post-processing device  200 . Herein, the post-processing device  200  obtains the determining result of the defect determining unit  109 . If the determining result indicates that there are defects in the images which have been read, the post-processing device  200  switches a branching claw  202  so that the printed material (the defective printed material) is discharged to a defective printed material discharge tray  206 . On the other hand, if the determining result indicates that there is no defect in the images which have been read, the post-processing device  200  switches the branching claw  202  so that the printed material (the normal printed material) is discharged to a normal printed material discharge tray  205 . 
     Thus, while discharging a printed material as a normal printed material; an inlet roller  201 , the branching claw  202 , and a discharge roller  203  discharge the printed material to the normal printed material discharge tray  205 . In contrast, while discharging a printed material as a defective printed material; the inlet roller  201 , the branching claw  202 , and a discharge roller  204  discharge the printed material to the defective printed material discharge tray  206 . 
     Given below is the explanation regarding another example of the image forming system according to first embodiment.  FIG. 2  is a configuration diagram illustrating another example of the image forming system according to the first embodiment. In  FIG. 1 , the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100 .  FIG. 2  illustrates a configuration example for a case in which the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via a paper cooling device  300 . The image forming system illustrated in  FIG. 2  includes the image forming apparatus  1 ; the image inspection device  100  that is connected to the image forming apparatus  1 ; the paper cooling device  300  (a device which does not include a discharge destination for defective printed materials) that is connected to the image forming apparatus  1 ; and the post-processing device  200  (a discharge device: a device which includes a discharge destination for defective printed materials) that is connected to the paper cooling device  300 . 
     In the configuration described below according to first embodiment, to the image inspection device  100 , a paper cooling device is connected as the device which does not include a discharge destination for defective printed materials. However, any other device which does not include a discharge destination for defective printed materials can be connected to the image inspection device  100 . Explained below with reference to  FIG. 2  is a configuration and operations of the image forming system. 
     The constituent elements of the image forming apparatus  1  illustrated in  FIG. 2  have configurations and relations of connection identical to the image forming apparatus  1  illustrated in  FIG. 1 . Moreover, the constituent elements of the image forming apparatus  1  illustrated in  FIG. 2  function in the same manner as in the image forming apparatus  1  illustrated in  FIG. 1 . Thus, in the image forming apparatus  1  illustrated in  FIG. 2 , a composite color image is recorded on the recording member and the de-curler roller  27  conveys the recording member to the image inspection device  100 . Therefore, the detailed explanation of the image forming apparatus  1  is not repeated. 
     Furthermore, since the image inspection device  100  has the same functions as described with reference to  FIG. 1 , the constituent elements thereof are referred to by the same reference numerals and the explanation thereof is not repeated. In the image forming system illustrated in  FIG. 2 , the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300 , which does not include a discharge destination for defective printed materials. For that reason, a printed material from which images have been read is conveyed to the paper cooling device  300  using a normal conveying path that does not pass through the reverse path  106 . That is, the outlet roller  104 , the flip roller  107  and the discharge roller  108  convey the printed material without inversion to the paper cooling device  300 . 
     Meanwhile, since post-processing device  200  has the same functions as described with reference to  FIG. 1 , the constituent elements thereof are referred to by the same reference numerals and the explanation thereof is not repeated. 
     Given below is the explanation regarding a configuration of the image forming system illustrated in  FIG. 1 .  FIG. 3  is a block diagram illustrating an example of the functional configuration of the image forming system illustrated in  FIG. 1 . As illustrated in  FIG. 3 , the image forming system illustrated in  FIG. 1  includes the image forming apparatus  1 , the image inspection device  100 , and the post-processing device  200 . 
     The image forming apparatus  1  includes an image data receiving unit  51 , an image forming unit  52 , a conveying path selecting unit  53 , and a conveying unit  54 . 
     The image data receiving unit  51  receives the image data that is to be printed on the recording member. Regarding the method by which the image data receiving unit  51  receives image data; for example, the image data receiving unit  51  receives image data from a personal computer (PC) that is connected to the image forming apparatus  1  via a network. Then, the image data receiving unit  51  performs a predetermined analysis with respect to the received image data, converts the received image data into image data for printing (for example, into bitmap data), and sends the image data for printing to the image inspection device  100 . 
     Once the image data receiving unit  51  receives image data; the image forming unit  52  prints the received image data on the recording member using the tandem-type image forming device  4 , the exposure devices  5 , the intermediate transfer belt  2 , and the fixing mechanism  12 . 
     The conveying path selecting unit  53  selects, from a plurality of conveying paths laid in the image forming apparatus  1 , a conveying path for conveying the printed material on which the image data is already printed by the image forming unit  52 . The conveying path selecting unit  53  selects a conveying path on the basis of a determination result and a print condition sent by a device connection determining unit  158  (described later). Herein, the conveying paths laid in the image forming apparatus  1  include, firstly, a discharge conveying path in which the branching claw  21  conveys the printed material toward the discharge roller  25 , and then the discharge roller  25  and the de-curler unit  26  convey the printed material to the image inspection device  100 . Other than that, the conveying paths include the paper reverse path  23  in which the branching claw  21  conveys the printed material toward the flip roller  22 , and then the flip roller  22  conveys the printed material toward the discharge roller  25 . With that, the upper surface and the lower surface of the printed material are reversed. Then, the discharge roller  25  and the de-curler unit  26  convey the printed material to the image inspection device  100 . 
     Regarding the conveying path selecting unit  53 ; more particularly, when the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  in the image forming system (see  FIG. 1 ) and when single-sided printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing down; the conveying path selecting unit  53  selects a discharge conveying path in which the printed material is conveyed to the image inspection device  100  without being reversed. 
     Alternatively, when the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  in the image forming system (see  FIG. 1 ) and when single-sided printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing up; the conveying path selecting unit  53  selects the paper reverse path  23  in which the printed material is conveyed to the image inspection device  100  after being reversed. 
     Still alternatively, when the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  in the image forming system (see  FIG. 1 ) and when duplex printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing down; the conveying path selecting unit  53  selects the paper reverse path  23  in which the printed material is conveyed to the image inspection device  100  after being reversed. 
     Still alternatively, when the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  in the image forming system (see  FIG. 1 ) and when duplex printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing up; the conveying path selecting unit  53  selects a discharge conveying path in which the printed material is conveyed to the image inspection device  100  without being reversed. 
     Moreover, the conveying path selecting unit  53  selects a conveying path for conveying the recording member on which image data is printed by the image forming unit  52 . More particularly, in the case of duplex printing, after an image is printed on the first side of the recording member, the conveying path selecting unit  53  selects the duplex conveying path  24  for conveying the recording member. 
     The conveying unit  54  conveys the printed material, which has an image printed thereon, to the image inspection device  100  using the conveying path (the discharge conveying path or the paper reverse path  23 ) that is selected by the conveying path selecting unit  53 . Moreover, in the case of duplex printing, the conveying unit  54  conveys the recording member to the duplex conveying path  24  that is selected by the conveying path selecting unit  53 . 
     The image inspection device  100  includes an image data storing unit  170 , an image data obtaining unit  151 , a reading unit  152 , the defect determining unit  109 , a conveying path selecting unit  156 , a conveying unit  157 , and the device connection determining unit  158 . 
     The image data storing unit  170  is a memory medium such as a hard disk drive or a memory that is used to store image data that the image forming apparatus  1  prints. The image data obtaining unit  151  obtains the image data sent by the image data receiving unit  51 , and stores it in the image data storing unit  170 . 
     The reading unit  152  obtains the images printed on the printed material that is conveyed from the image forming apparatus  1 . Moreover, the reading unit  152  includes a first reader  153  and a second reader  154 . 
     The first reader  153  makes use of the reading unit  102 , which is disposed above the printed material being conveyed, to read from above the image printed on the upper surface of the printed material. More particularly, when the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  in the image forming system (see  FIG. 1 ) and when single-sided printing is performed to print an image on the first side of the recording member followed by discharging the printed material with the first side thereof facing down; the first reader  153  reads the image printed on the first side, that is, the upper surface of the printed material. 
     Alternatively, when the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  in the image forming system (see  FIG. 1 ) and when duplex printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing down; the first reader  153  reads the image printed on the first side, that is, the upper surface of the printed material. 
     Still alternatively, when the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  in the image forming system (see  FIG. 1 ) and when duplex printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing up; the first reader  153  reads the image printed on the second side, that is, the upper surface of the printed material. 
     The second reader  154  makes use of the reading unit  103 , which is disposed below the printed material being conveyed, to read from below the image printed on the lower surface of the printed material. More particularly, when the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  in the image forming system (see  FIG. 1 ) and when single-sided printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing up; the second reader  154  reads the image printed on the first side, that is, the lower surface of the printed material. 
     Alternatively, when the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  in the image forming system (see  FIG. 1 ) and when duplex printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing down; the second reader  154  reads the image printed on the second side, that is, the lower surface of the printed material. 
     Still alternatively, when the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  in the image forming system (see  FIG. 1 ) and when duplex printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing up; the second reader  154  reads the image printed on the first side, that is, the lower surface of the printed material. 
     The defect determining unit  109  determines the presence or absence of defects in the images obtained by the reading unit  152 . For example, the defect determining unit  109  compares the image data read by the reading unit  152  with the image data that is the original image data of the printed material and that is stored in the image data storing unit  170 ; extracts the difference in the two sets of image data; and determines whether the extracted difference is greater or smaller than a predetermined threshold value so as to determine the presence or absence of defects in the images printed on the printed material. Meanwhile, an original image of the printed material is in the CMYK format, while the image data that is read is in the RGB format. Hence, the defect determining unit  109  first performs conversion and standardizes the image data to one of the formats and then determines the presence or absence of defects in the images printed on the printed material. Then, the defect determining unit  109  sends the determination result to the post-processing device  200 . 
     The device connection determining unit  158  determines whether the post-processing device  200 , which includes a discharge destination for defective printed materials, is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  or is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300 , which does not include a discharge destination for defective printed materials. Then, the device connection determining unit  158  sends the determination result to the image forming apparatus  1 . With reference to  FIG. 3 , the device connection determining unit  158  determines that the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100 . Meanwhile, the device connection determining unit  158  can be disposed inside the image forming apparatus  1 . 
     Based on the determination result of the device connection determining unit  158 , the conveying path selecting unit  156  selects, from among the conveying paths laid in the image inspection device  100 , a conveying path for conveying the printed material from which the image data has been read by the reading unit  152 . Herein, the conveying paths laid in the image inspection device  100  include, firstly, a normal conveying path (a shorter conveying path) in which the outlet roller  104 , the branching claw  105 , and the discharge roller  108  convey the printed material to the post-processing device  200 . Other than that, the conveying paths include an inversion conveying path (a longer conveying path) in which the outlet roller  104  and the branching claw  105  convey the printed material to the reverse path  106  so that the printed material is reversed, and then the flip roller  107  and the discharge roller  108  convey the reversed printed material to the post-processing device  200 . 
     More particularly, as illustrated in  FIG. 3 , when the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  in the image forming system (see  FIG. 1 ), the conveying path selecting unit  156  selects the inversion conveying path in which the printed material is reversed in the reverse path  106  and then conveyed to the post-processing device  200 . 
     The conveying unit  157  sends the printed material, from which the image data has been read by the reading unit  152 , to the post-processing device  200  using the conveying path (the normal conveying path or the inversion conveying path) that is selected by the conveying path selecting unit  156 . 
     Meanwhile, when the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100 , the time taken by the conveying unit  157  to reverse a printed material using the inversion conveying path is longer than the time taken by the defect determining unit  109  to determine the presence or absence of defects in the images which have been read. 
     In the image inspection device  100  according to the first embodiment, two conveying paths (the normal conveying path and the inversion conveying path) are laid. However, alternatively, it is also possible to have three or more conveying paths. In a configuration in which three or more conveying paths are laid, when a post-processing device is directly connected at the downstream side of the printed material conveying direction, the purpose is served as long as the printed material is conveyed using such a conveying path in which the time taken for conveying the printed material is longer than the time taken to determine the presence or absence of defects in the images which have been read. 
     The post-processing device  200  includes the normal printed material discharge tray  205 , the defective printed material discharge tray  206 , a determination result obtaining unit  251 , a discharge destination switching unit  252 , and a discharging unit  253 . 
     The normal printed material discharge tray  205  is a tray in which a normal printed material, which has non-defective images printed thereon, is discharged. The defective printed material discharge tray  206  is the tray in which a defective printed material, which has defective images printed thereon, is discharged. 
     The determination result obtaining unit  251  obtains the determination result sent by the defect determining unit  109  of the image inspection device  100 . 
     The discharge destination switching unit  252  switches the discharge destination according to the determination result obtained by the determination result obtaining unit  251 . More particularly, if the determination result indicates that there are defects in the images which have been read, then the discharge destination switching unit  252  switches the branching claw  202  so that the printed material is discharged to the defective printed material discharge tray  206 . On the other hand, if the determination result indicates that there is no defect in the images which have been read, then the discharge destination switching unit  252  switches the branching claw  202  so that the printed material is discharged to the normal printed material discharge tray  205 . 
     The discharging unit  253  conveys and discharges the printed material, which has been conveyed from the image inspection device  100 , to the discharge destination (either the defective printed material discharge tray  206  or the normal printed material discharge tray  205 ) that is set by the discharge destination switching unit  252 . 
     Given below is the explanation regarding a configuration of the image forming system illustrated in  FIG. 2 .  FIG. 4  is a block diagram illustrating an example of the functional configuration of the image forming system illustrated in  FIG. 2 . As illustrated in  FIG. 4 , the image forming system illustrated in  FIG. 2  includes the image forming apparatus  1 , the image inspection device  100 , the paper cooling device  300 , and the post-processing device  200 . 
     The image forming apparatus  1  includes the image data receiving unit  51 , the image forming unit  52 , the conveying path selecting unit  53 , and the conveying unit  54 . Herein, the image data receiving unit  51 , the image forming unit  52 , and the conveying unit  54  have the same configurations and functions as described with reference to  FIG. 3 . Hence, that explanation is not repeated. 
     In the configuration illustrated in  FIG. 4  ( FIG. 2 ), the conveying path selecting unit  53  selects a conveying path in the following manner. Herein, as a plurality of conveying paths laid in the image forming apparatus  1 ; the discharge conveying path and the paper reverse path  23  are laid in an identical manner to that illustrated in  FIG. 3 . 
     More particularly, when the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300  in the image forming system (see  FIG. 2 ) and when single-sided printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing down; the conveying path selecting unit  53  selects the paper reverse path  23  in which the printed material is reversed before being conveyed to the image inspection device  100 . 
     Alternatively, when the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300  in the image forming system (see  FIG. 2 ) and when single-sided printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing up; the conveying path selecting unit  53  selects the discharge conveying path in which the printed material is conveyed to the image inspection device  100  without being reversed. 
     Still alternatively, when the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300  in the image forming system (see  FIG. 2 ) and when duplex printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing down; the conveying path selecting unit  53  selects the discharge conveying path in which the printed material is conveyed to the image inspection device  100  without being reversed. 
     Still alternatively, when the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300  in the image forming system (see  FIG. 2 ) and when duplex printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing up; the conveying path selecting unit  53  selects the paper reverse path  23  in which the printed material is reversed before being conveyed to the image inspection device  100 . 
     The conveying path selecting unit  53  selects a conveying path for conveying the printed material on which the image forming unit  52  prints the image data. More particularly, in the case of duplex printing, after an image is printed on the first side of the recording member, the conveying path selecting unit  53  selects the duplex conveying path  24  for conveying the recording member. 
     The image inspection device  100  includes the image data storing unit  170 , the image data obtaining unit  151 , the reading unit  152 , the defect determining unit  109 , the conveying path selecting unit  156 , the conveying unit  157 , and the device connection determining unit  158 . Herein, the image data storing unit  170 , the image data obtaining unit  151 , the defect determining unit  109 , the conveying unit  157 , and the device connection determining unit  158  have the same configurations and functions as described with reference to  FIG. 3 . Hence, that explanation is not repeated. 
     Since the reading unit  152  has the same configuration and functions as described with reference to  FIG. 3 , the explanation thereof is not repeated. In the configuration illustrated in  FIG. 4  ( FIG. 2 ), the first reader  153  and the second reader  154  of the reading unit  152  read images in the following manner. 
     The first reader  153  makes use of the reading unit  102 , which is disposed above the printed material being conveyed, to read from above the image printed on the upper surface of the printed material. More particularly, when the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300  in the image forming system (see  FIG. 2 ) and when single-sided printing is performed followed by discharging the printed material with the first side thereof facing up; the first reader  153  reads the image printed on the first side, that is, the upper surface of the printed material. 
     Alternatively, when the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300  in the image forming system (see  FIG. 2 ) and when duplex printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing down; the first reader  153  reads the image printed on the second side, that is, the upper surface of the printed material. 
     Still alternatively, when the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300  in the image forming system (see  FIG. 2 ) and when duplex printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing up; the first reader  153  reads the image printed on the first side, that is, the upper surface of the printed material. 
     The second reader  154  makes use of the reading unit  103 , which is disposed below the printed material being conveyed, to read from below the image printed on the lower surface of the printed material. More particularly, when the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300  in the image forming system (see  FIG. 2 ) and when single-sided printing is performed followed by discharging the printed material with the first side thereof facing down; the second reader  154  reads the image printed on the first side, that is, the lower surface of the printed material. 
     Alternatively, when the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300  in the image forming system (see  FIG. 2 ) and when duplex printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing down; the second reader  154  reads the image printed on the first side, that is, the lower surface of the printed material. 
     Still alternatively, when the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300  in the image forming system (see  FIG. 2 ) and when duplex printing is performed followed by discharging the printed material with the first side thereof (i.e., the side on which an image is printed) facing up; the second reader  154  reads the image printed on the second side, that is, the lower surface of the printed material. 
     Since the reading unit  152  has the same configuration and functions as described with reference to  FIG. 3 , the explanation thereof is not repeated. In the configuration illustrated in  FIG. 4  ( FIG. 2 ), the conveying path selecting unit  156  selects a conveying path in the following manner. 
     More particularly, as illustrated in  FIG. 4 , when the post-processing device  200  is connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  via the paper cooling device  300  in the image forming system (see  FIG. 2 ), the conveying path selecting unit  156  selects the normal conveying path in which the printed material is conveyed to the post-processing device  200  without being reversed. 
     The paper cooling device  300  cools the printed material, which has been conveyed from the image inspection device  100 , by letting the printed material pass through a conveying path laid therein. More particularly, the paper cooling device  300  includes a conveying unit  351  that allows the printed material, which has been conveyed from the image inspection device  100 , to pass through a conveying path laid in the paper cooling device  300  and then reach the post-processing device  200 . 
     The post-processing device  200  includes the normal printed material discharge tray  205 , the defective printed material discharge tray  206 , the determination result obtaining unit  251 , the discharge destination switching unit  252 , and the discharging unit  253 . Herein, the normal printed material discharge tray  205 , the defective printed material discharge tray  206 , the determination result obtaining unit  251 , the discharge destination switching unit  252 , and the discharging unit  253  have the same configurations and functions as described with reference to  FIG. 3 . Hence, that explanation is not repeated. 
     Given below is the explanation regarding a printed material conveying operation performed in the image forming system (illustrated in  FIG. 1  or  FIG. 2 ) according to the first embodiment.  FIGS. 5 and 6  are flowcharts for explaining the printed material conveying operation performed in the image forming system according to the first embodiment. 
     Firstly, the device connection determining unit  158  of the image inspection device  100  determines whether or not the post-processing device  200  is directly connected to the image inspection device  100  at the downstream side of the printed material conveying direction in the image inspection device  100  without using another device (such as the paper cooling device  300 ) in between (Step S 100 ). If the post-processing device  200  is directly connected without using another device in between (Yes at Step S 100 ), then the system control proceeds to (A) described with reference to  FIG. 6 . The explanation regarding  FIG. 6  is given later in detail. 
     On the other hand, if the post-processing device  200  is not connected without using another device in between, that is, if the post-processing device  200  is connected via the paper cooling device  300  (No at Step S 100 ); then the conveying path selecting unit  156  selects the normal conveying path in which the printed material is conveyed to the post-processing device  200  without being reversed (Step S 101 ). 
     Subsequently, the image forming unit  52  of the image forming apparatus  1  determines whether or not single-sided printing is to be performed (Step S 102 ). That determination is performed according to a print instruction received from the user. If single-sided printing is not to be performed, that is, if duplex printing is to be performed (No at Step S 102 ); then the image forming unit  52  firstly prints an image on the first side of a recording member (Step S 103 ). 
     Then, the conveying path selecting unit  53  selects the duplex conveying path  24  for the purpose of duplex printing (Step S 104 ), and the conveying unit  54  conveys the recording member to the duplex conveying path  24 . Subsequently, the image forming unit  52  prints an image on the second side of the recording member (Step S 105 ). 
     Then, the conveying path selecting unit  53  determines whether or not the recording member (printed material) is to be discharged with the first side thereof facing down (Step S 106 ). That determination is performed according to the print instruction received from the user. 
     If the printed material is not to be discharged with the first side thereof facing down, that is, if the printed material is to be discharged with the first side thereof facing up (No at Step S 106 ); then the conveying path selecting unit  53  selects the paper reverse path  23  in which the printed material is conveyed to the image inspection device  100  after being reversed (Step S 107 ). Then, the conveying unit  54  reverses the printed material using the paper reverse path  23  (Step S 108 ) and conveys the reversed printed material to the image inspection device  100 . 
     The first reader  153  of the image inspection device  100  makes use of the reading unit  102  to read the image printed on the first side of the printed material (Step S 109 ), while the second reader  154  of the image inspection device  100  makes use of the reading unit  103  to read the image printed on the second side of the printed material (Step S 110 ). Then, the system control proceeds to Step S 114 . 
     Meanwhile, if the printed material is to be discharged with the first side thereof facing down (Yes at Step S 106 ); then the conveying path selecting unit  53  selects the discharge conveying path in which the printed material is conveyed to the image inspection device  100  without being reversed (Step S 111 ). Then, the conveying unit  54  conveys the printed material to the image inspection device  100  using the discharge conveying path. 
     Subsequently, the first reader  153  of the image inspection device  100  makes use of the reading unit  102  to read the image printed on the second side of the printed material (Step S 112 ), while the second reader  154  of the image inspection device  100  makes use of the reading unit  103  to read the image printed on the first side of the printed material (Step S 113 ). Then, the system control proceeds to Step S 114 . 
     Meanwhile, at Step S 102 , if single-sided printing is to be performed (Yes at Step S 102 ); then the image forming unit  52  prints an image on the first side of a recording member (Step S 201 ). Then, the conveying path selecting unit  53  determines whether or not the recording member (printed material) is to be discharged with the first side thereof facing down (Step S 202 ). That determination is performed according to the print instruction received from the user. 
     If the printed material is not to be discharged with the first side thereof facing down, that is, if the printed material is to be discharged with the first side thereof facing up (No at Step S 202 ); then the conveying path selecting unit  53  selects the discharge conveying path in which the printed material is conveyed to the image inspection device  100  without being reversed (Step S 203 ). Then, the conveying unit  54  conveys the printed material to the image inspection device  100  using the discharge conveying path. The first reader  153  of the image inspection device  100  makes use of the reading unit  102  to read the image printed on the first side of the printed material (Step S 204 ). Then, the system control proceeds to Step S 114 . 
     On the other hand, if the printed material is to be discharged with the first side thereof facing down (Yes at Step S 202 ); then the conveying path selecting unit  53  selects the paper reverse path  23  in which the printed material is conveyed to the image inspection device  100  after being reversed (Step S 205 ). Then, the conveying unit  54  reverses the printed material using the paper reverse path  23  (Step S 206 ) and conveys the reversed printed material to the image inspection device  100 . The second reader  154  of the image inspection device  100  makes use of the reading unit  103  to read the image printed on the first side of the printed material (Step S 207 ). Then, the system control proceeds to Step S 114 . 
     Subsequently, the conveying unit  351  of the paper cooling device  300  allows the printed material to pass through a conveying path laid in the paper cooling device  300  and reach the post-processing device  200  (Step S 114 ). 
     Then, according to the determination result of the defect determining unit  109  of the image inspection device  100 , the discharge destination switching unit  252  of the post-processing device  200  determines whether or not the printed material that has been conveyed is a normal printed material (Step S 115 ) and accordingly switches the conveying destination for printed materials. 
     If the printed material is not a normal printed material, that is, if the printed material is a defective printed material (No at Step S 115 ); then the discharging unit  253  discharges the printed material to the defective printed material discharge tray  206  (Step S 116 ). On the other hand, if the printed material is a normal printed material (Yes at Step S 115 ); then the discharging unit  253  discharges the printed material to the normal printed material discharge tray  205  (Step S 117 ). That marks the end of the operations. 
     Explained below with reference to  FIG. 6  are the operations performed in the case when the post-processing device  200  is directly connected without using another device in between at Step S 100 . When the post-processing device  200  is directly connected without using another device in between (Yes at Step S 100 ), the conveying path selecting unit  156  selects an inversion conveying path in which the printed material conveyed to the post-processing device  200  after being reversed (Step S 300 ). 
     Subsequently, the image forming unit  52  of the image forming apparatus  1  determines whether or not single-sided printing is to be performed (Step S 301 ). That determination is performed according to the print instruction received from the user. If single-sided printing is not to be performed, that is, if duplex printing is to be performed (No at Step S 301 ); then the image forming unit  52  firstly prints an image on the first side of a recording member (Step S 302 ). 
     Then, the conveying path selecting unit  53  selects the duplex conveying path  24  for the purpose of duplex printing (Step S 303 ), and the conveying unit  54  conveys the recording member to the duplex conveying path  24 . Subsequently, the image forming unit  52  prints an image on the second side of the recording member (Step S 304 ). 
     Then, the conveying path selecting unit  53  determines whether or not the recording member (printed material) is to be discharged with the first side thereof facing down (Step S 305 ). That determination is performed according to the print instruction received from the user. 
     If the printed material is not to be discharged with the first side thereof facing down, that is, if the printed material is to be discharged with the first side thereof facing up (No at Step S 305 ); then the conveying path selecting unit  53  selects the discharge conveying path in which the printed material is conveyed to the image inspection device  100  without being reversed (Step S 306 ). Then, the conveying unit  54  conveys the printed material to the image inspection device  100  using the discharge conveying path. 
     The first reader  153  of the image inspection device  100  makes use of the reading unit  102  to read the image printed on the second side of the printed material (Step S 307 ), while the second reader  154  of the image inspection device  100  makes use of the reading unit  103  to read the image printed on the first side of the printed material (Step S 308 ). Then, the system control proceeds to Step S 313 . 
     Meanwhile, at Step S 305 , if the printed material is to be discharged with the first side thereof facing down (Yes at Step S 305 ); then the conveying path selecting unit  53  selects the paper reverse path  23  in which the printed material is conveyed to the image inspection device  100  after being reversed (Step S 309 ). Then, the conveying unit  54  reverses the printed material using the paper reverse path  23  (Step S 310 ) and conveys the reversed printed material to the image inspection device  100 . 
     The first reader  153  of the image inspection device  100  makes use of the reading unit  102  to read the image printed on the first side of the printed material (Step S 311 ), while the second reader  154  of the image inspection device  100  makes use of the reading unit  103  to read the image printed on the second side of the printed material (Step S 312 ). Then, the system control proceeds to Step S 313 . 
     Meanwhile, at Step S 301 , if single-sided printing is to be performed (Yes at Step S 301 ); then the image forming unit  52  prints an image on the first side of the recording member (Step S 401 ). Then, the conveying path selecting unit  53  determines whether or not the recording member (printed material) is to be discharged with the first side thereof facing down (Step S 402 ). That determination is performed according to the print instruction received from the user. 
     If the printed material is not to be discharged with the first side thereof facing down, that is, if the printed material is to be discharged with the first side thereof facing up (No at Step S 402 ); then the conveying path selecting unit  53  selects the paper reverse path  23  in which the printed material is conveyed to the image inspection device  100  after being reversed (Step S 403 ). Subsequently, the conveying unit  54  reverses the printed material using the paper reverse path  23  (Step S 404 ) and conveys the reversed printed material to the image inspection device  100 . Then, the second reader  154  of the image inspection device  100  makes use of the reading unit  103  to read the image printed on the first side of the printed material (Step S 405 ). The system control then proceeds to Step S 313 . 
     On the other hand, if the printed material is to be discharged with the first side thereof facing down (Yes at Step S 402 ); then the conveying path selecting unit  53  selects the discharge conveying path in which the printed material is conveyed to the image inspection device  100  without being reversed (Step S 406 ). Then, the conveying unit  54  conveys the printed material to the image inspection device  100  using the discharge conveying path. The first reader  153  of the image inspection device  100  makes use of the reading unit  102  to read the image printed on the first side of the printed material (Step S 407 ). Then, the system control proceeds to Step S 313 . 
     Subsequently, the conveying unit  157  conveys the printed material, from which the image has been read, to the inversion conveying path (Step S 313 ); reverses the printed material using the inversion conveying path (Step S 314 ); and conveys the reversed printed material to the image inspection device  100 . Then, the system control proceeds to Step S 115  illustrated in  FIG. 5 . 
     In this way, according to the first embodiment, in the image forming system in which a printed material is conveyed to the post-processing device  200  that is connected to the image inspection device  100  without using another device in between ( FIG. 1 ); the inversion conveying path is selected in the image inspection device  100  so that the printed material, from which the images have been read, is reversed in the reverse path  106  and then conveyed to the post-processing device  200 . On the other hand, according to the first embodiment, in the image forming system in which a printed material is conveyed to the post-processing device  200  that is connected to the image inspection device  100  via the paper cooling device  300  ( FIG. 2 ); the normal conveying path is selected in the image inspection device  100  so that the printed material, from which the images have been read, is conveyed to the post-processing device  200  without being reversed. 
     Thus, In the image forming system illustrated in  FIG. 1 , the defect determining unit  109  can determine the presence or absence of defects in images while the printed material is being reversed in the reverse path  106 ; and the determination result can be used in ensuring that a discharge destination for normal printed materials and a discharge destination for defective printed materials are separately secured. In the image forming system illustrated in  FIG. 2 ), even if the printed material is conveyed to the paper cooling device  300  without being reversed, the defect determining unit  109  can determine the presence or absence of defects in images while the printed material is being conveyed through the paper cooling device  300 ; and the determination result can be used in ensuring a discharge destination for normal printed materials and a discharge destination for defective printed materials are separately secured. Hence, it becomes possible to convey the printed material in accordance with the configuration of any of the two types of the image forming system. As a result, it becomes possible to accurately separate the discharge destination for normal printed materials from the discharge destination for defective printed materials while maintaining the productivity of printed materials. 
     Second Embodiment 
     In the first embodiment, the conveying path in an image inspection device is selected according to whether a post-processing device (a discharge device) is connected directly to the image inspection device or whether the post-processing device is connected to the image inspection device via a paper cooling device. In contrast, in a second embodiment, an image inspection device is configured to have two reverse paths, and defect determination with respect to a printed material is performed while the printed material is being reversed using the two reverse paths. Then, the conveying destination for printed materials is determined on the basis of the determination result. 
     Firstly, the explanation is given regarding an image forming system according to the second embodiment.  FIG. 7  is a configuration diagram illustrating an example of the image forming system according to the second embodiment. Herein, the image forming system illustrated in  FIG. 7  includes an image forming apparatus  1 - 2 ; an image inspection device  500  that is connected to the image forming apparatus  1 - 2 ; and a post-processing device  600  (a discharge device) that is connected to the image inspection device  500 . 
     In the second embodiment described below, the configuration is such that, to the image inspection device  500 , the post-processing device  600  is connected as the device which includes a discharge destination for normal printed materials. However, any other device which includes a discharge destination for normal printed materials can be connected to the image inspection device  500 . Meanwhile, the image forming apparatus  1 - 2  according to the second embodiment can be applied to a multifunction peripheral or to an image forming apparatus such as a copying machine or a printer that outputs (prints) image data. Explained below with reference to  FIG. 7  is a configuration and operations of the image forming system. 
     The constituent elements of the image forming apparatus  1 - 2  illustrated in  FIG. 7  have configurations and relations of connection identical to the image forming apparatus  1  illustrated in  FIG. 1 . Moreover, the constituent elements of the image forming apparatus  1 - 2  illustrated in  FIG. 7  function in the same manner as in the image forming apparatus  1  illustrated in  FIG. 1 . Thus, in the image forming apparatus  1 - 2  illustrated in  FIG. 7 , a composite color image is recorded on the recording member and the de-curler roller  27  conveys the recording member to the image inspection device  500 . Therefore, the detailed explanation of the image forming apparatus  1 - 2  is not repeated. 
     Given below is the explanation regarding the image inspection device  500 . Herein, in the image inspection device  500 , the inlet roller  101  conveys a printed material to the reading units  102  and  103 . Then, each of the reading units  102  and  103  reads the composite color image recorded on one of the sides of the printed material. Herein, in an identical manner to the configuration illustrated in  FIG. 1 , the reading unit  102  is positioned above the printed material being conveyed and reads the image recorded on the upper surface of the printed material; while the reading unit  103  is positioned below the printed material being conveyed and reads the image recorded on the lower surface of the printed material. 
     Then, a defect determining unit  509  determines whether or not there are defects in the composite color images which have been read. That is, the defect determining unit  509  determines whether the composite color images point to a normal printed material not having any defects or to a defective printed material having defects. 
     A carriage roller  504  conveys the printed material by a branching claw  505  and a running sensor  506 . Then, a flip roller  507  is made to perform positive rotation so that the printed material is conveyed to a first reverse path  508  and stops thereat. Herein, positive rotation of the flip roller  507  points to rotating the flip roller  507  in a direction that enables conveying the printed material to the first reverse path  508 , which is a conveying path for reversing the printed material from which images have been read. 
     After waiting for a period of time required by the flip roller  507  to be able to perform reverse rotation, the flip roller  507  is reverse-rotated so that the print material again passes by the branching claw  505  and is conveyed to a carriage roller  514 . Then, the carriage roller  514  conveys the printed material by a branching claw  510  and a running sensor  511 . Subsequently, a flip roller  512  is made to perform positive rotation so that the printed material is conveyed to a second reverse path  513  and stops thereat. Herein, positive rotation of the flip roller  512  points to rotating the flip roller  512  in a direction that enables conveying the printed material to the second reverse path  513 , which is a conveying path for reversing the printed material that has been reversed once at the first reverse path  508 . 
     If the determination result of the defect determining unit  509  indicates that there is no defect in the images which have been read, then the printed material is discharged to the normal printed material discharge tray  205  that is disposed in the post-processing device  600 . In this case, the branching claw  510  and the flip roller  512  are reverse-rotated so that an outlet roller  515  conveys the printed material to the post-processing device  600 . 
     On the other hand, if the determination result of the defect determining unit  509  indicates that there are defects in the images which have been read, then the printed material is discharged to a defective printed material discharge tray  516  that is disposed in the image inspection device  500 . In this case, the flip roller  512  is made to perform positive rotation so that the printed material is conveyed to the defective printed material discharge tray  516  that is connected to the second reverse path  513 . 
     Given below is the explanation regarding the post-processing device  600 . In the post-processing device  600 , when a printed material (a normal printed material) is conveyed from the image inspection device  500 ; the inlet roller  201  and the discharge roller  203  discharge the printed material to the normal printed material discharge tray  205 . 
     Given below is the explanation regarding a configuration of the image forming system illustrated in  FIG. 7 .  FIG. 8  is a block diagram illustrating an example of the functional configuration of the image forming system illustrated in  FIG. 7 . As illustrated in  FIG. 8 , the image forming system illustrated in  FIG. 7  includes the image forming apparatus  1 - 2 , the image inspection device  500 , and the post-processing device  600 . 
     The image forming apparatus  1 - 2  includes the image data receiving unit  51 , the image forming unit  52 , a conveying path selecting unit  53 - 2 , and the conveying unit  54 . Herein, the image data receiving unit  51  and the image forming unit  52  have the same configurations and functions as described with reference to  FIG. 3  according to the first embodiment. Hence, that explanation is not repeated. 
     The conveying path selecting unit  53 - 2  selects, from a plurality of conveying paths laid in the image forming apparatus  1 - 2 , a conveying path for conveying the printed material on which the image data is already printed by the image forming unit  52 . In the second embodiment, since the image inspection device  500  does not include the device connection determining unit  158 ; the conveying path selecting unit  53 - 2  selects a conveying path without referring to the determination result of the device connection determining unit  158 . More particularly, while conveying to the image inspection device  500  a printed material on which the image data has been printed; the conveying path selecting unit  53 - 2  selects a conveying path in which the branching claw  21  conveys the printed material toward the discharge roller  25 , and the discharge roller  25  and the de-curler unit  26  convey the printed material to the image inspection device  500 . In the case of performing duplex printing, after an image is printed on the first side of a recording member, the conveying path selecting unit  53 - 2  selects the duplex conveying path  24  for conveying the recording member. 
     The conveying unit  54  conveys the printed material, which has an image printed thereon, to the image inspection device  500  using the conveying path that is selected by the conveying path selecting unit  53 - 2 . Moreover, in the case of duplex printing, the conveying unit  54  conveys a recording member to the duplex conveying path  24  that is selected by the conveying path selecting unit  53 - 2 . 
     The image inspection device  500  includes the defective printed material discharge tray  516 , the image data storing unit  170 , the image data obtaining unit  151 , a reading unit  552 , the defect determining unit  509 , and a conveying unit  557 . Herein, the image data storing unit  170  and the image data obtaining unit  151  have the same configurations and functions as described with reference to  FIG. 3  according to the first embodiment. Hence, that explanation is not repeated. 
     The defective printed material discharge tray  516  is connected to the second reverse path  513 , and serves as the tray to which is discharged a defective printed material that has defective images printed thereon. 
     The reading unit  552  reads the image printed on the printed material that is conveyed from the image forming apparatus  1 - 2 . Moreover, the reading unit  552  includes a first reader  553  and a second reader  554 . The first reader  553  makes use of the reading unit  102 , which is disposed above the printed material being conveyed, to read from above the image printed on the upper surface of the printed material. The second reader  554  makes use of the reading unit  103 , which is disposed below the printed material being conveyed, to read from below the image printed on the lower surface of the printed material. 
     While a printed material, from which the images have been read by the reading unit  552 , is present in the second reverse path  513 ; the defect determining unit  509  determines whether or not there are defects in the images which have been read by the reading unit  552 . The method of determining the presence or absence of defects is, for example, identical to that described in the first embodiment. 
     The conveying unit  557  conveys the printed material that has been conveyed from the image forming apparatus  1 - 2 . Moreover, based on the result of determination performed by the defect determining unit  509  to determine the presence or absence of defects in the read images; the conveying unit  557  conveys the printed material, from which the images have been read by the reading unit  552 , either to the defective printed material discharge tray  516  serving as the conveying destination or to the post-processing device  600  that includes the normal printed material discharge tray  205 . 
     More particularly, if the defect determining unit  509  determines that there are defects in the images which have been read, the corresponding printed material is a defective printed material. Hence, the conveying unit  557  conveys and discharges that printed material (the defective printed material) to the defective printed material discharge tray  516  that is connected to the second reverse path  513 . On the other hand, if the defect determining unit  509  determines that there is no defect in the images which have been read, the corresponding printed material is a normal printed material. Hence, the conveying unit  557  conveys and discharges that printed material (the normal printed material) to the post-processing device  600 . With that, the normal printed material is discharged to the normal printed material discharge tray  205 . 
     Meanwhile, in the image inspection device  500 , the time taken by the conveying unit  557  to reverse the printed material using the first reverse path  508  and the second reverse path  513  is longer than the time taken by the defect determining unit  509  to determine the presence or absence of defects in the images which have been read. 
     The post-processing device  600  includes the normal printed material discharge tray  205  and a discharging unit  653 . 
     The normal printed material discharge tray  205  is the tray to which is discharged a normal printed material that is conveyed from the image inspection device  500  and that has non-defective images printed thereon. 
     The discharging unit  653  discharges the printed material, which is conveyed from the image inspection device  500 , to the normal printed material discharge tray  205 . 
     Given below is the explanation regarding a printed material conveying operation performed in the image forming system according to the second embodiment.  FIGS. 9A and 9B  are flowcharts for explaining the printed material conveying operation performed in the image forming system according to the second embodiment. 
     Firstly, in the conveying unit  557  of the image inspection device  500 , the inlet roller  101  conveys a printed material to the reading units  102  and  103 . Then, the reading unit  552  makes use of the reading units  102  and  103  and reads the composite color images printed on the sides (the upper surface and the lower surface) of the printed material (Step S 500 ). Subsequently, the defect determining unit  509  starts determining the absence or presence of defects in the images which have been read (Step S 501 ). 
     Then, the conveying unit  557  moves the branching claw  505  in the direction in which the printed material is to be conveyed toward the first reverse path  508 ; and conveys the printed material to the running sensor  506  using the carriage roller  504  and the branching claw  505  (Step S 502 ). 
     The conveying unit  557  determines whether or not the running sensor  506  has detected the leading end of the printed material (Step S 503 ). If the leading end of the printed material has not been detected (No at Step S 503 ), then the conveying unit  557  waits until the leading end is detected. When the leading end of the printed material is detected (Yes at Step S 503 ), the conveying unit  557  makes the flip roller  507  perform positive rotation so that the printed material is conveyed to the first reverse path  508  (Step S 504 ). 
     Then, the conveying unit  557  determines whether or not the running sensor  506  has detected the rear end of the printed material (Step S 505 ). If the rear end of the printed material has not been detected (No at Step S 505 ), then the conveying unit  557  waits until the rear end is detected. When the rear end of the printed material is detected (Yes at Step S 505 ), the conveying unit  557  stops the positive rotation of the flip roller  507  (Step S 506 ). 
     The conveying unit  557  keeps the flip roller  507  stopped until the flip roller  507  can be subjected to reverse rotation, and determines whether or not the timing is right to start the reverse rotation of the flip roller  507  (Step S 507 ). If the timing is not right to start the reverse rotation of the flip roller  507  (No at Step S 507 ), then the conveying unit  557  waits until the right timing. 
     On the other hand, when the timing is right to start the reverse rotation of the flip roller  507  (Yes at Step S 507 ); the conveying unit  557  makes the flip roller  507  perform reverse rotation, moves the branching claw  505  in the direction in which the printed material is to be conveyed toward the second reverse path  513 , and conveys the printed material to the carriage roller  514  (Step S 508 ). 
     Then, the conveying unit  557  moves the branching claw  510  in the direction in which the printed material is to be conveyed toward the second reverse path  513 ; and conveys the printed material to the running sensor  511  using the carriage roller  514  and the branching claw  510  (Step S 509 ). 
     The conveying unit  557  determines whether or not the running sensor  511  has detected the leading end of the printed material (Step S 510 ). If the leading end of the printed material has not been detected (No at Step S 510 ), then the conveying unit  557  waits until the leading end is detected. When the leading end of the printed material is detected (Yes at Step S 510 ), the conveying unit  557  makes the flip roller  512  perform positive rotation so that the printed material is conveyed to the second reverse path  513  (Step S 511 ). 
     Then, the conveying unit  557  determines whether or not the running sensor  511  has detected the rear end of the printed material (Step S 512 ). If the rear end of the printed material has not been detected (No at Step S 512 ), then the conveying unit  557  waits until the rear end is detected. When the rear end of the printed material is detected (Yes at Step S 512 ), the conveying unit  557  stops the positive rotation of the flip roller  512  (Step S 513 ). 
     The conveying unit  557  keeps the flip roller  512  stopped until the flip roller  512  can be subjected to reverse rotation, and determines whether or not the timing is right to start the reverse rotation of the flip roller  512  (Step S 514 ). If the timing is not right to start the reverse rotation of the flip roller  512  (No at Step S 514 ), then the conveying unit  557  waits until the right timing. 
     On the other hand, when the timing is right to start the reverse rotation of the flip roller  512  (Yes at Step S 514 ); the conveying unit  557  determines whether or not the determination result of the defect determining unit  509  indicates that there is no defect in the images which have been read (Step S 515 ). 
     If the determination result indicates that there is no defect in the image, that is, if the printed material is a normal printed material (Yes at Step S 515 ); then the conveying unit  557  makes the flip roller  512  perform reverse rotation, moves the branching claw  510  in the direction in which the printed material is to be conveyed toward the post-processing device  600 , and conveys the printed material to the post-processing device  600  (Step S 516 ). Then, the discharging unit  653  of the post-processing device  600  discharges the printed material, which is conveyed from the image inspection device  500 , to the normal printed material discharge tray  205  (Step S 517 ). 
     On the other hand, if the determination result indicates that there are defects in the image, that is, if the printed material is a defective printed material (No at Step S 515 ); then the conveying unit  557  makes the flip roller  512  perform positive rotation so that the printed material (the defective printed material) is discharged to the defective printed material discharge tray  516  (Step S 518 ). 
     In this way, in the image forming system according to the second embodiment, two reverse paths (the first reverse path  508  and the second reverse path  513 ) are laid in the image inspection device  500 . Then, while a printed material is being reversed using the two reverse paths, it is determined whether or not there are defects in the images read from the printed material. If the determination result indicates that the printed material is a defective printed material, it is discharged to the discharge tray disposed in the image inspection device  500 . On the other hand, if the determination result indicates that the printed material is a normal printed material; it is conveyed to the post-processing device  600  and, after being subjected to post-processing if necessary, is discharged to the discharge tray disposed in the post-processing device  600 . Thus, while the printed material is being reversed using the two reverse paths, it is determined whether or not there are defects in the images printed on the printed material. With that, it becomes possible to convey the printed material to a predetermined conveying destination. As a result, it becomes possible to accurately separate the discharge destination for normal printed materials from the discharge destination for defective printed materials while maintaining the productivity of printed materials as well as without having to terminate the operations of the devices. 
     Third Embodiment 
     In the second embodiment, the image inspection device has two reverse paths used for reversing a printed material. The defect determination process with respect to a printed material is performed while that printed material is being reversed in the two reverse paths. If the determination result indicates that the printed material is a defective printed material, then that defective printed material is discharged to a discharge tray disposed in the image inspection device. In contrast, in a third embodiment, the post-processing device also includes a discharge tray for discharging defective printed materials. Thus, if the determination result indicates that the printed material is a defective printed material, then it is possible to select whether that defective printed material is to be discharged to the discharge tray disposed in the image inspection device or to the discharge tray disposed in the post-processing device. 
     Firstly, the explanation is given regarding an image forming system according to the third embodiment.  FIG. 10  is a configuration diagram illustrating an example of the image forming system according to the third embodiment. Herein, the image forming system illustrated in  FIG. 10  includes the image forming apparatus  1 - 2 ; an image inspection device  700  that is connected to the image forming apparatus  1 - 2 ; and a post-processing device  800  (a discharge device) that is connected to the image inspection device  700 . 
     In the second embodiment described below, the configuration is such that, to the image inspection device  700 , the post-processing device  800  is connected as the device which includes a discharge destination for normal printed materials as well as a discharge destination for defective printed materials. However, any other device which includes a discharge destination for normal printed materials as well as a discharge destination for defective printed materials can be connected to the image inspection device  700 . Meanwhile, the image forming apparatus  1 - 2  according to the third embodiment can be applied to a multifunction peripheral or to an image forming apparatus such as a copying machine or a printer that outputs (prints) image data. Explained below with reference to FIG.  10  is a configuration and operations of the image forming system. 
     The constituent elements of the image forming apparatus  1 - 2  illustrated in  FIG. 10  have configurations and relations of connection identical to the image forming apparatus  1  illustrated in  FIG. 1 . Moreover, the constituent elements of the image forming apparatus  1 - 2  illustrated in  FIG. 10  function in the same manner as in the image forming apparatus  1  illustrated in  FIG. 1 . Thus, in the image forming apparatus  1 - 2  illustrated in  FIG. 10 , a composite color image is recorded on the recording member and the de-curler roller  27  conveys the recording member to the image inspection device  700 . Therefore, the detailed explanation of the image forming apparatus  1 - 2  is not repeated. 
     Given below is the explanation regarding the image inspection device  700 . Herein, in the image inspection device  700 , the inlet roller  101  conveys a printed material to the reading units  102  and  103 . Then, each of the reading units  102  and  103  reads the composite color image recorded on one of the sides of the printed material. Herein, in an identical manner to the configuration illustrated in  FIG. 1 , the reading unit  102  is positioned above the printed material being conveyed and reads the image recorded on the upper surface of the printed material; the reading unit  103  is positioned below the printed material being conveyed and reads the image recorded on the lower surface of the printed material. 
     Then, a defect determining unit  709  determines whether or not there are defects in the composite color images which have been read. That is, the defect determining unit  709  determines whether the composite color images point to a normal printed material not having any defects or to a defective printed material having defects. 
     The carriage roller  504  conveys the printed material by the branching claw  505  and the running sensor  506 . Then, the flip roller  507  is made to perform positive rotation so that the printed material is conveyed to the first reverse path  508  and stops thereat. Herein, regarding the positive rotation of the flip roller  507  and regarding the first reverse path  508 , the same explanation given in the second embodiment is applicable. 
     After waiting for a period of time required by the flip roller  507  to be able to perform reverse rotation, the flip roller  507  is reverse-rotated so that the print material again passes by the branching claw  505  and is conveyed to the carriage roller  514 . Then, the carriage roller  514  conveys the printed material by the branching claw  510  and the running sensor  511 . Subsequently, the flip roller  512  is made to perform positive rotation so that the printed material is conveyed to the second reverse path  513  and stops thereat. Herein, regarding the positive rotation of the flip roller  512  and regarding the second reverse path  513 , the same explanation given in the second embodiment is applicable. 
     If the determination result of the defect determining unit  709  indicates that there is no defect in the images which have been read, then the printed material is discharged to the normal printed material discharge tray  205  that is disposed in the post-processing device  800 . In this case, the branching claw  510  and the flip roller  512  are reverse-rotated so that the outlet roller  515  conveys the printed material to the post-processing device  800 . 
     On the other hand, if the determination result of the defect determining unit  709  indicates that there are defects in the images which have been read, then the printed material is discharged to a discharge destination for defective printed materials according to an instruction from a controller (not illustrated). More particularly, in the case when the image inspection device  700  serves as the discharge destination for defective printed materials, the flip roller  512  is made to perform positive rotation so that the printed material is conveyed to the defective printed material discharge tray  516  that is connected to the second reverse path  513 . On the other hand, in the case when the post-processing device  800  serves as the discharge destination for defective printed materials, the branching claw  510  and the flip roller  512  are reverse-rotated so that the outlet roller  515  conveys the printed material to the post-processing device  800 . 
     Given below is the explanation regarding the post-processing device  800 . In the post-processing device  800 , depending on the determination result of the defect determining unit  709 , it is selected whether to discharge the printed material that has been conveyed to the normal printed material discharge tray  205  or to the defective printed material discharge tray  206 ; and then the printed material is conveyed to the selected discharge destination using the branching claw  202 . 
     More particularly, in the post-processing device  800 , if the determination result of the defect determining unit  709  indicates that there is no defect in the images which have been read; then the inlet roller  201 , the branching claw  202 , and the discharge roller  203  discharge the printed material to the normal printed material discharge tray  205 . On the other hand, in the post-processing device  800 , if the determination result of the defect determining unit  709  indicates that there are defects in the images which have been read; then the inlet roller  201 , the branching claw  202 , and the discharge roller  204  discharge the printed material to the defective printed material discharge tray  206 . 
     Given below is the explanation regarding a configuration of the image forming system illustrated in  FIG. 10 .  FIG. 11  is a block diagram illustrating an example of the functional configuration of the image forming system illustrated in  FIG. 10 . As illustrated in  FIG. 11 , the image forming system illustrated in  FIG. 10  includes the image forming apparatus  1 - 2 , the image inspection device  700 , and the post-processing device  800 . 
     The image forming apparatus  1 - 2  includes the image data receiving unit  51 , the image forming unit  52 , the conveying path selecting unit  53 - 2 , and the conveying unit  54 . Herein, the image data receiving unit  51  and the image forming unit  52  have the same configurations and functions as described with reference to  FIG. 3  according to the first embodiment. Hence, that explanation is not repeated. Moreover, the conveying path selecting unit  53 - 2  and the conveying unit  54  have the same configurations and functions as described with reference to  FIG. 8  according to the second embodiment. Hence, that explanation is not repeated. 
     The image inspection device  700  includes the defective printed material discharge tray  516 , the image data storing unit  170 , the image data obtaining unit  151 , the reading unit  552 , the defect determining unit  709 , a conveying destination determining unit  755 , and a conveying unit  757 . Herein, the image data storing unit  170  and the image data obtaining unit  151  have the same configurations and functions as described with reference to  FIG. 3  according to the first embodiment. Hence, that explanation is not repeated. Moreover, the defective printed material discharge tray  516  and the reading unit  552  have the same configurations and functions as described with reference to  FIG. 8  according to the second embodiment. Hence, that explanation is not repeated. 
     While a printed material, from which the images have been read by the reading unit  552 , is present in the second reverse path  513 ; the defect determining unit  709  determines whether or not there are defects in the images which have been read by the reading unit  552 . The determination of presence or absence of the defects is, for example, identical to that described in the first embodiment. Then, if it is determined that there are defects in the images which have been read and that the conveying destination determining unit  755  (described later) discharges the defective printed material using the post-processing device  800 , then the defect determining unit  709  sends the determination result to the post-processing device  800 . 
     If the determination result of the defect determining unit  709  indicates that there are defects in the images which have been read; then the conveying destination determining unit  755  determines the conveying destination for printed materials (the defective printed materials). More particularly, the conveying destination determining unit  755  determines whether to set the conveying destination for defective printed materials either to the defective printed material discharge tray  516  that is disposed in the image inspection device  700  or to the defective printed material discharge tray  206  that is disposed in the post-processing device  800 . That determination can be performed, for example, in the following manner: at the time of performing image formation (printing), a selection input can be received from the user as an indication of the discharge tray to be considered as the discharge destination for defective printed materials, and that selection input can be followed when a printed material is determined to be a defective printed material. Alternatively, for example, that determination can be performed by setting in advance the discharge tray to be considered as the discharge destination for defective printed materials, and that setting can be followed when a printed material is determined to be a defective printed material. 
     The conveying unit  757  conveys the printed material that has been conveyed from the image forming apparatus  1 - 2 . Moreover, based on the result of determination performed by the defect determining unit  709  to determine the presence or absence of defects in the images that have been read; the conveying unit  757  conveys the printed material, from which the images have been read by the reading unit  552 , to the conveying destination. 
     More particularly, in the case when the defect determining unit  709  determines that there are defects in the images which have been read and when the conveying destination determining unit  755  determines the defective printed material discharge tray  516  to be the conveying destination; the conveying unit  757  conveys and discharges the printed material (the defective printed material) to the defective printed material discharge tray  516  that is connected to the second reverse path  513 . Alternatively, in the case when the defect determining unit  709  determines that there are defects in the images which have been read and when the conveying destination determining unit  755  determines the defective printed material discharge tray  206  in the post-processing device  800  as the conveying destination; the conveying unit  757  conveys the printed material (the defective printed material) to the post-processing device  800 . Meanwhile, if the defect determining unit  709  determines that there is not defect in the images which have been read, the corresponding printed material is a normal printed material. Hence, the conveying unit  757  conveys the printed material (the normal printed material) to the post-processing device  800 . Consequently, the normal printed material is discharged to the normal printed material discharge tray  205 . 
     Meanwhile, in the image inspection device  700 , the time taken by the conveying unit  757  to reverse the printed material using the first reverse path  508  and the second reverse path  513  is longer than the time taken by the defect determining unit  709  to determine the presence or absence of defects in the images which have been read. 
     The post-processing device  800  includes the normal printed material discharge tray  205 , the defective printed material discharge tray  206 , a determination result obtaining unit  851 , a discharge destination switching unit  852 , and a discharging unit  853 . 
     The normal printed material discharge tray  205  is the tray to which is discharged a normal printed material that is conveyed from the image inspection device  700  and that has non-defective images printed thereon. The defective printed material discharge tray  206  is the tray to which is discharged a defective printed material that has defective images printed thereon. 
     The determination result obtaining unit  851  obtains the determination result that is sent by the defect determining unit  709  in the image inspection device  700 . If it is determined in the image inspection device  700  that there are defects in the images which have been read and if the conveying destination determining unit  755  determines that the defective printed material is to be discharged using the post-processing device  800 , then the determination result sent from the defect determining unit  709  is obtained by the determination result obtaining unit  851 . 
     Once the determination result obtaining unit  851  obtains the determination result; the discharge destination switching unit  852  switches the discharge destination according to that determination result. More particularly, when the determination result indicates that there are defects in the images which have been read, the discharge destination switching unit  852  switches the branching claw  202  so that the printed material is discharged to the defective printed material discharge tray  206 . On the other hand, when the determination result indicates that there is no defect in the images which have been read, the discharge destination switching unit  852  switches the branching claw  202  so that the printed material is discharged to the normal printed material discharge tray  205 . 
     The discharging unit  853  conveys and discharges the printed material, which has been conveyed from the image inspection device  700 , to the discharge destination set by the discharge destination switching unit  852 . More particularly, if it is determined that there are defects in the images which have been read in the image inspection device  700 , then the printed material (the defective printed material) is discharged to the defective printed material discharge tray  206 . On the other hand, if it is determined that there is no defect in the images which have been read in the image inspection device  700 , then the printed material (the normal printed material) is discharged to the normal printed material discharge tray  205 . 
     Given below is the explanation regarding a printed material conveying operation performed in the image forming system according to the third embodiment.  FIGS. 12A and 12B  are flowcharts for explaining the printed material conveying operation performed in the image forming system according to the third embodiment. Herein, the operations starting from reading composite color images by the reading units  102  and  103  to determining the right timing to perform reverse-rotation of the flip roller  512  by the conveying unit  757  (i.e., operations from Step S 600  to Step S 614 ) are identical to the operations from Step S 500  to Step S 514  described with reference to  FIGS. 9A and 9B . Hence, that explanation is not repeated. 
     Then, the conveying unit  757  determines whether or not the determination result of the defect determining unit  709  indicates that there is no defect in the images which have been read (Step S 615 ). If the determination result indicates that there is no defect in the images, that is, if the printed material is a normal printed material (Yes at Step S 615 ); then the conveying unit  757  makes the flip roller  507  perform reverse rotation and moves the branching claw  510  in the direction in which the printed material is to be conveyed toward the post-processing device  800 , so that the printed material is conveyed to the post-processing device (Step S 616 ). 
     On the other hand, if the determination result indicates that there are defects in the images, that is, if the printed material is a defective printed material (No at Step S 615 ); then the conveying destination determining unit  755  determines whether or not the post-processing device  800  is the conveying destination for defective printed materials (Step S 617 ). If the post-processing device  800  is the conveying destination for defective printed materials (Yes at Step S 617 ), then the system control proceeds to Step S 616  and the printed material is conveyed to the post-processing device  800 . 
     On the other hand, if the post-processing device  800  is not the conveying destination for defective printed materials, that is, if the defective printed material discharge tray  516  of the image inspection device  700  is the conveying destination for defective printed materials (No at Step S 617 ); then the conveying unit  757  makes the flip roller  512  perform positive rotation so that the printed material (the defective printed material) is discharged to the defective printed material discharge tray  516  (Step S 618 ). 
     Subsequent to Step S 616 , the discharge destination switching unit  852  of the post-processing device  800  determines whether or not the determination result obtained by the determination result obtaining unit  851  indicates that there is no defect in the images which have been read (Step S 619 ). If the determination result indicates that there is no defect in the images, that is, if the printed material is a normal printed material (Yes at Step S 619 ); then the discharge destination switching unit  852  switches the branching claw  202  so that the printed material is discharged to the normal printed material discharge tray  205 , and the discharging unit  853  discharges the printed material to the normal printed material discharge tray  205  that is the conveying destination set by the branching claw  202  (Step S 620 ). 
     On the other hand, if the determination result indicates that there are defects in the images, that is, if the printed material is a defective printed material (No at Step S 619 ); then the discharge destination switching unit  852  switches the branching claw  202  so that the printed material is discharged to the defective printed material discharge tray  206 , and the discharging unit  853  discharges the printed material to the defective printed material discharge tray  206  that is the conveying destination set by the branching claw  202  (Step S 621 ). 
     In this way, in the image forming system according to the third embodiment, two reverse paths (the first reverse path  508  and the second reverse path  513 ) are laid in the image inspection device  700 . Then, while a printed material is being reversed using the two reverse paths, it is determined whether or not there are defects in the images read from the printed material. If the determination result indicates that the printed material is a defective printed material and if that printed material is to be discharged using the image inspection device  700 , then the printed material is discharged to the discharge tray disposed in the image inspection device  700 . Alternatively, if the determination result indicates that the printed material is a defective printed material and if that printed material is to be discharged using the post-processing device  800 , then the printed material is conveyed to the post-processing device  800  and is discharged to the defective printed material discharge tray disposed in the post-processing device  800 . On the other hand, if the determination result indicates that the printed material is a normal printed material; then the printed material is conveyed to the post-processing device  800  and, after being subjected to post-processing if necessary, is discharged to the normal printed material discharge tray disposed in the post-processing device  600 . Thus, while the printed material is being reversed using the two reverse paths, it is determined whether or not there are defects in the images printed on the printed material. With that, it becomes possible to convey the printed material to a predetermined conveying destination. As a result, it becomes possible to accurately separate the discharge destination for normal printed materials from the discharge destination for defective printed materials while maintaining the productivity of printed materials as well as without having to terminate the operations of the devices. 
     Fourth Embodiment 
     In the first embodiment, depending on whether a post-processing device (a discharge device) is connected directly to the image inspection device or whether the post-processing device is connected to the image inspection device via a paper cooling device (another device); either a normal conveying path is selected for conveying the printed material as it is or an inversion conveying path is selected for conveying the printed material after being reversed. In contrast, in a fourth embodiment, depending on whether a post-processing device (a discharge device) is connected directly to the image inspection device or whether the post-processing device is connected to the image inspection device via a paper cooling device (another device); either a conveying path is selected for conveying a printed material as it is or a conveying path is selected for conveying the printed material upon being cooled. 
     Firstly, the explanation is given regarding an image forming system according to the fourth embodiment.  FIG. 13  is a configuration diagram illustrating an example of the image forming system according to the fourth embodiment. Herein, the image forming system illustrated in  FIG. 13  includes the image forming apparatus  1 ; an image inspection device  900  that is connected to the image forming apparatus  1 ; and the post-processing device  200  (a discharge device) that is connected to the image inspection device  900 . 
     In the fourth embodiment described below, the configuration is such that, to the image inspection device  900 , the post-processing device  200  is connected as the device which includes a discharge destination for normal printed materials. However, any other device which includes a discharge destination for normal printed materials can be connected to the image inspection device  900 . Meanwhile, the image forming apparatus  1  according to the second embodiment can be applied to a multifunction peripheral or to an image forming apparatus such as a copying machine or a printer that outputs (prints) image data. Explained below with reference to  FIG. 13  is a configuration and operations of the image forming system. 
     The constituent elements of the image forming apparatus  1  illustrated in  FIG. 13  have configurations and relations of connection identical to the image forming apparatus  1  illustrated in  FIG. 1 . Moreover, the constituent elements of the image forming apparatus  1 - 2  illustrated in  FIG. 13  function in the same manner as in the image forming apparatus  1  illustrated in  FIG. 1 . Thus, in the image forming apparatus  1  illustrated in  FIG. 13 , a composite color image is recorded on the recording member and the de-curler roller  27  conveys the recording member to the image inspection device  900 . Therefore, the detailed explanation of the image forming apparatus  1  is not repeated. 
     Given below is the explanation regarding the image inspection device  900 . Herein, in the image inspection device  900 , while a printed material (i.e., a recording member having images printed thereon) that is conveyed from the image forming apparatus  1  is being conveyed along a conveying path; the reading unit  152  reads the images from the printed material. Then, it is determined whether or not there are defects in the images that have been read. Depending on the determination result regarding defects (i.e., depending on whether the printed material is a normal printed material or a defective printed material), the discharge destination for printed materials in the post-processing device  200  is switched. The reading unit  152  includes, for example, the reading units  102  and  103  for reading images as illustrated in  FIG. 1 . 
     As illustrated in  FIG. 13 , in the image inspection device  900 , the conveying paths for conveying printed materials include a first conveying path  903 ; a cooling conveying path  904  and a second conveying path  905  that are connected in a branching manner at the downstream side of the printed material conveying direction in the first conveying path  903 ; and a third conveying path  906  that is formed when the cooling conveying path  904  and the second conveying path  905  converge again at the downstream side of the printed material conveying direction. 
     At the upstream side of the printed material conveying direction in the first conveying path  903 ; a conveying inlet  911  is formed for conveying the printed material to the image inspection device  900 . The conveying inlet  911  connects the image inspection device  900  to a conveying path in the image forming apparatus  1 . At the downstream side of the printed material conveying direction in the third conveying path  906 ; a discharge roller  912  is disposed for discharging the printed material from the image inspection device  900 . The discharge roller  912  connects the image inspection device  900  to a conveying path in the post-processing device  200 . 
     At the branching position of the second conveying path  905  and the cooling conveying path  904  is disposed a branching claw  907  that, under the control of a control unit  909 , rotates around a driving shaft which receives a driving force from a motor (not illustrated). As a result, the printed material that is passing over the branching position of the second conveying path  905  and the cooling conveying path  904  is guided to either one of the second conveying path  905  and the cooling conveying path  904 . 
     In the conveying paths laid in the image inspection device  900 , a plurality of carriage rollers represented by a carriage roller  913  is appropriately disposed. Under the control of the control unit  909 , those rollers rotate by receiving a driving force from a motor (not illustrated) and convey the printed material. 
     The cooling conveying path  904  is configured with a metal guide plate (not illustrated) in a cooled state. The cooling conveying path  904  conveys the printed material while cooling it with the air that is produced by a cooling fan  908  under the control of the control unit  909 . 
     The printed material that is discharged from the image forming apparatus  1  reaches the first conveying path  903  via the conveying inlet  911  of the image inspection device  900 , and is then conveyed forward by the carriage rollers. While passing through the first conveying path  903 ; when the printed material passes by the position at which the reading unit  152  is disposed, the images printed thereon are read by the reading unit  152 . 
     The images read from the printed material by the reading unit  152  are sent to the control unit  909 . Then, in the control unit  909 , the defect determining unit  109  (see  FIG. 15 ) determines whether or not there are defects in the images which have been read. 
     Subsequently, in the image forming system illustrated in  FIG. 13 , at the downstream side of the printed material conveying direction in the image inspection device  900 , the post-processing device  200  is directly connected without using another device (such as a paper cooling device) in between. In this case, the printed material is conveyed using the cooling conveying path  904 , so that the printed material which has been cooled is conveyed to the post-processing device  200 . 
     The printed material passing through the cooling conveying path  904  gets cooled by coming in contact with the abovementioned metal guide plate (not illustrated) in a cooled state. Meanwhile, as far as cooling the printed material is concerned, one method is to cool the metal guide plate with the air produced by the cooling fan  908  and then to cool the printed material using the cold metal guide plate, while the other method is to cool the printed material by directly exposing it to the air produced by the cooling fan  908 . 
     The constituent elements of the post-processing device  200  illustrated in  FIG. 13  have configurations and relations of connection identical to the post-processing device  200  illustrated in  FIG. 1 . Moreover, the constituent elements of the post-processing device  200  illustrated in  FIG. 13  function in the same manner as in the post-processing device  200  illustrated in  FIG. 1 . Thus, in the case of discharging a printed material as a normal printed material; the inlet roller  201 , the branching claw  202 , and the discharge roller  203  discharge that printed material to the normal printed material discharge tray  205 . On the other hand, in the case of discharging a printed material as a defective printed material; the inlet roller  201 , the branching claw  202 , and the discharge roller  204  discharge that printed material to the defective printed material discharge tray  206 . 
     Given below is the explanation regarding another example of the image forming system according to the fourth embodiment.  FIG. 14  is a configuration diagram illustrating another example of the image forming system according to the fourth embodiment. In  FIG. 13 , the post-processing device  200  is directly connected to the image inspection device  900  at the downstream side of the printed material conveying direction in the image inspection device  900 .  FIG. 14  illustrates a configuration example for a case in which the post-processing device  200  is connected to the image inspection device  900  at the downstream side of the printed material conveying direction in the image inspection device  900  via the paper cooling device  300 . The image forming system illustrated in  FIG. 14  includes the image forming apparatus  1 ; the image inspection device  900  that is connected to the image forming apparatus  1 ; the paper cooling device  300  (a device which does not include a discharge destination for defective printed materials) that is connected to the image forming apparatus  1 ; and the post-processing device  200  (a discharge device: a device which includes a discharge destination for defective printed materials) that is connected to the paper cooling device  300 . 
     In the fourth embodiment described below, the configuration is such that, to the image inspection device  900 , a paper cooling device is connected as the device which does not include a discharge destination for defective printed materials. However, any other device which does not include a discharge destination for defective printed materials can be connected to the image inspection device  900 . Explained below with reference to  FIG. 14  is a configuration and operations of the image forming system. 
     The constituent elements of the image forming apparatus  1  illustrated in  FIG. 14  have configurations and relations of connection identical to the image forming apparatus  1  illustrated in  FIG. 1 . Moreover, the constituent elements of the image forming apparatus  1  illustrated in  FIG. 14  function in the same manner as in the image forming apparatus  1  illustrated in  FIG. 1 . Thus, in the image forming apparatus  1  illustrated in  FIG. 14 , a composite color image is recorded on the recording member and the de-curler roller  27  conveys the recording member to the image inspection device  900 . Therefore, the detailed explanation of the image forming apparatus  1  is not repeated. 
     Given below is the explanation regarding the image inspection device  900 . The constituent elements of the image inspection device  900  illustrated in  FIG. 14  have configurations and relations of connection identical to the image inspection device  900  illustrated in  FIG. 13 . Moreover, the constituent elements of the image inspection device  900  illustrated in  FIG. 14  function in the same manner as in the image inspection device  900  illustrated in  FIG. 13 . 
     That is, the printed material discharged from the image forming apparatus  1  reaches the first conveying path  903  via the conveying inlet  911  of the image inspection device  900 , and is then conveyed forward by the carriage rollers. While passing through the first conveying path  903 ; when the printed material passes by the position of the reading unit  152 , the images printed thereon are read by the reading unit  152 . Then, the images read from the printed material by the reading unit  152  are sent to the control unit  909 . Then, in the control unit  909 , the defect determining unit  109  (see  FIG. 16 ) determines whether or not there are defects in the images which have been read. 
     Subsequently, in the image forming system illustrated in  FIG. 14 , the post-processing device  200  is connected to the image inspection device  900  at the downstream side of the printed material conveying direction in the image inspection device  900  via the paper cooling device  300  that does not include a discharge destination for defective printed materials. In this case, after the printed material is conveyed using the second conveying path  905 , it gets conveyed to the paper cooling device  300 . 
     The constituent elements of the paper cooling device  300  illustrated in  FIG. 14  have configurations and relations of connection identical to the paper cooling device  300  illustrated in  FIG. 1 . Moreover, the constituent elements of the paper cooling device  300  illustrated in  FIG. 14  function in the same manner as in the paper cooling device  300  illustrated in  FIG. 1 . Hence, that explanation is not repeated. 
     Similarly, the constituent elements of the post-processing device  200  illustrated in  FIG. 14  have configurations and relations of connection identical to the post-processing device  200  illustrated in  FIG. 1 . Moreover, the constituent elements of the post-processing device  200  illustrated in  FIG. 14  function in the same manner as in the post-processing device  200  illustrated in  FIG. 1 . Hence, that explanation is not repeated. 
     Given below is the explanation regarding a configuration of the image forming system illustrated in  FIG. 13 .  FIG. 15  is a block diagram illustrating an example of the functional configuration of the image forming system illustrated in  FIG. 13 . As illustrated in  FIG. 15 , the image forming system illustrated in  FIG. 13  includes the image forming apparatus  1 , the image inspection device  900 , and the post-processing device  200 . Herein, the image forming apparatus  1  and the post-processing device  200  have the same configurations and functions as in the image forming system according to the first embodiment (see  FIG. 3 ). Hence, that explanation is not repeated. 
     The image inspection device  900  includes the image data storing unit  170 , the image data obtaining unit  151 , the reading unit  152 , the control unit  909 , a conveying path selecting unit  956 , a conveying unit  957 , and the device connection determining unit  158 . Herein, the image data storing unit  170 , the image data obtaining unit  151 , the reading unit  152 , and the device connection determining unit  158  have the same configurations and functions as described with reference to  FIG. 3 . Hence, that explanation is not repeated. 
     The control unit  909  controls the driving of a motor (not illustrated) so that the printed material passing over the branching position of the second conveying path  905  and the cooling conveying path  904  is guided to either one of the second conveying path  905  and the cooling conveying path  904 . Moreover, the control unit  909  controls the driving of a motor (not illustrated) so that the printed material is conveyed via the conveying unit  957 . Furthermore, the control unit  909  controls the driving of a motor (not illustrated) so that the cooling fan  908  rotates and produces air. 
     The control unit  909  includes the defect determining unit  109 . In an identical manner to the first embodiment, the defect determining unit  109  determines whether or not there are defects in images which have been read by the reading unit  152 , and sends the determination result to the post-processing device  200 . 
     Based on the determination result of the device connection determining unit  158 ; the conveying path selecting unit  956  selects, from among the conveying paths laid in the image inspection device  900 , a conveying path for conveying the printed material from which the image data has been read by the reading unit  152 . Herein, the conveying paths laid in the image inspection device  900  include, firstly, a conveying path (a shorter conveying path) in which the printed material is conveyed to the post-processing device  200  using the first conveying path  903 , the second conveying path  905 , and the third conveying path  906 . Other than that, the conveying paths include a conveying path (a longer conveying path) in which the printed material is conveyed to the post-processing device  200  using the first conveying path  903 , the cooling conveying path  904 , and the third conveying path  906 . 
     As illustrated in  FIG. 15 , when the post-processing device  200  is directly connected to the image inspection device  900  at the downstream side of the printed material conveying direction in the image inspection device  900  in the image forming system (see  FIG. 13 ), the conveying path selecting unit  956  selects the longer conveying path in which the printed material is conveyed to the post-processing device  200  after being cooled in the cooling conveying path  904 . 
     The conveying unit  957  sends the printed material, from which the image data has been read by the reading unit  152 , to the post-processing device  200  using the conveying path, which is selected by the conveying path selecting unit  956  and in which the printed material passes through the cooling conveying path  904 . 
     Meanwhile, when the post-processing device  200  is directly connected to the image inspection device  900  at the downstream side of the printed material conveying direction in the image inspection device  900 , the time taken by the conveying unit  957  to convey the printed material using the conveying path in which the printed material passes through the cooling conveying path  904  is longer than the time taken by the defect determining unit  109  to determine the presence or absence of defects in the images which have been read. 
     Given below is the explanation regarding a configuration of the image forming system illustrated in  FIG. 14 .  FIG. 16  is a block diagram illustrating an example of the functional configuration of the image forming system illustrated in  FIG. 14 . As illustrated in  FIG. 16 , the image forming system illustrated in  FIG. 16  includes the image forming apparatus  1 , the image inspection device  900 , the paper cooling device  300 , and the post-processing device  200 . Herein, the image forming apparatus  1 , the paper cooling device  300 , and the post-processing device  200  have the same configurations and functions as in the image forming system according to the first embodiment (see  FIG. 4 ). Hence, that explanation is not repeated. 
     The image inspection device  900  includes the image data storing unit  170 , the image data obtaining unit  151 , the reading unit  152 , the control unit  909 , the conveying path selecting unit  956 , the conveying unit  957 , and the device connection determining unit  158 . Herein, the image data storing unit  170 , the image data obtaining unit  151 , the reading unit  152 , and the device connection determining unit  158  have the same configurations and functions as described with reference to  FIG. 4 . Hence, that explanation is not repeated. Moreover, the control unit  909  is identical to the control unit  909  described with reference to  FIG. 15 . Hence, that explanation is not repeated. Meanwhile, although the conveying path selecting unit  956  and the conveying unit  957  have the same configurations and functions as described with reference to  FIG. 15 , they perform operations in the manner explained below. 
     As illustrated in  FIG. 16 , when the post-processing device  200  is connected to the image inspection device  900  at the downstream side of the printed material conveying direction in the image inspection device  900  via the paper cooling device  300  in the image forming system (see  FIG. 14 ), the conveying path selecting unit  956  selects the conveying path in which the printed material is conveyed to the post-processing device  200  using the first conveying path  903 , the second conveying path  905 , and the third conveying path  906 . 
     The conveying unit  957  sends the printed material, from which the image data has been read by the reading unit  152 , to the post-processing device  200  using the conveying path, which is selected by the conveying path selecting unit  956  and in which the printed material passes through the second conveying path  905 . 
     Given below is the explanation regarding a printed material conveying operation performed in the image forming system (illustrated in  FIG. 13  or  FIG. 14 ) according to the fourth embodiment.  FIG. 17  is a flowchart for explaining the printed material conveying operation performed in the image forming system according to the fourth embodiment. 
     Firstly, the conveying unit  957  of the image inspection device  900  conveys the printed material, which has been conveyed from the image forming apparatus  1 , to the reading unit  152 ; and the reading unit  152  reads the images which have been printed on the printed material (Step S 700 ). Then, the defect determining unit  109  starts determining the absence or presence of defects in the images which have been read (Step S 701 ). 
     Subsequently, the device connection determining unit  158  determines whether or not the post-processing device  200  is directly connected to the image inspection device  900  at the downstream side of the printed material conveying direction in the image inspection device  900  without using another device (such as the paper cooling device  300 ) in between (Step S 702 ). 
     If the post-processing device  200  is directly connected without using another device in between, that is, if the image forming system has the configuration illustrated in  FIG. 13  (Yes at Step S 702 ); then the conveying path selecting unit  956  selects the cooling conveying path  904 , and the conveying unit  957  conveys the printed material using the first conveying path  903 , the cooling conveying path  904 , and the third conveying path  906  (Step S 703 ). Subsequently, the conveying unit  957  conveys the printed material to the post-processing device  200  (Step S 704 ). 
     On the other hand, if the post-processing device  200  is connected using another device (the paper cooling device  300 ) in between, that is, if the image forming system has the configuration illustrated in  FIG. 14  (No at Step S 702 ); then the conveying path selecting unit  956  selects the second conveying path  905 , and conveys the printed material using the first conveying path  903 , the second conveying path  905 , and the third conveying path  906  (Step S 705 ). Then, the conveying unit  957  conveys the printed material to the paper cooling device  300 ; and the conveying unit  351  of the paper cooling device  300  allows the printed material to pass through a conveying path laid in the paper cooling device  300  and then reach the post-processing device  200  (Step S 706 ). 
     Then, according to the determination result of the defect determining unit  109  of the image inspection device  900 , the discharge destination switching unit  252  of the post-processing device  200  determines whether or not the printed material that has been conveyed is a normal printed material (Step S 707 ), and accordingly switches the discharge destination for printed materials. 
     If the printed material is not a normal printed material, that is, if the printed material is a defective printed material (No at Step S 707 ); then the discharging unit  253  discharges the printed material to the defective printed material discharge tray  206  (Step S 708 ). On the other hand, if the printed material is a normal printed material (Yes at Step S 707 ); then the discharging unit  253  discharges the printed material to the normal printed material discharge tray  205  (Step S 709 ). That marks the end of the operations. 
     In this way, according to the fourth embodiment, in the image forming system in which a printed material is conveyed to the post-processing device  200  that is connected to the image inspection device  900  without using another device in between ( FIG. 13 ); a conveying path including the cooling conveying path  904  is selected in the image inspection device  900 , so that the printed material is conveyed to the post-processing device  200  after being cooled in the cooling conveying path  904 . On the other hand, in the image forming system in which a printed material is conveyed to the post-processing device  200  that is connected to the image inspection device  900  via the paper cooling device  300  ( FIG. 14 ); a conveying path including the second conveying path  905  is selected in the image inspection device  900 , so that the images printed on the printed material are read and then the printed material is conveyed without being cooled to the paper cooling device  300  and the post-processing device  200 . 
     Thus, in the image forming system illustrated in  FIG. 13 , the defect determining unit  109  can determine the presence or absence of defects in images while the printed material is being cooled and conveyed in the cooling conveying path  904 ; and the determination result can be used in ensuring that a discharge destination for normal printed materials and a discharge destination for defective printed materials are separately secured in the post-processing device  200 . In the image forming system illustrated in  FIG. 14 , even if the printed material is conveyed to the paper cooling device  300  through the second conveying path  905 ; the defect determining unit  109  can determine the presence or absence of defects in images while the printed material is being conveyed through the paper cooling device  300 , and the determination result can be used in ensuring that a discharge destination for normal printed materials and a discharge destination for defective printed materials are separately secured in the post-processing device  200 . Hence, it becomes possible to convey the printed material in accordance with the configuration of any of the two types of the image forming system. As a result, it becomes possible to accurately separate the discharge destination for normal printed materials from the discharge destination for defective printed materials while maintaining the productivity of printed materials. 
     According to an aspect of the present invention, it is possible to accurately separate a discharge destination for normal printed materials from a discharge destination for defective printed materials while maintaining the productivity of printed materials. 
     Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.