Patent Publication Number: US-8971789-B2

Title: Development device and image forming apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is related to, claims priority from and incorporates by reference Japanese Patent Application No. 2011-215376, filed on Sep. 29, 2011. 
     TECHNICAL FIELD 
     The present invention relates to a development device and an image forming apparatus. For example, the present invention may be applied in the image forming apparatus that forms an image on a medium and the development device that configures the image forming apparatus. 
     BACKGROUND 
     In a conventional image forming apparatus, a development device forms a toner image on a medium. The medium on which the unfixed toner image is formed is carried to a fuser. The fuser fixes the unfixed toner image on the medium. 
     The medium from the development device can be curled since a pressure is applied to the medium by various rollers. Accordingly, the medium cannot be correctly carried to a fuser and thereby the unfixed toner image can be scraped, or a jam of the medium can occur prior to the fixture of the toner image. 
     Japanese Laid-Open Patent Application Nos. H11-338290 and 2009-7080 describe a guide means that correctly guides a curled medium to a fuser while the medium is carried from a development device to the fuser. 
     The above-discussed Japanese Laid-Open Patent Application Nos. H11-338290 and 2009-7080 recite that the medium, which is to be carried to the fuser, is guided so that the medium is correctly carried to the fuser. 
     However, even immediately after the medium has been exited from the development device, the curled medium touches a housing of the development device on the medium exit side. Thereby, the unfixed toner image on the medium surface can be scraped. 
     For example, degrees of the curls on media significantly differ depending on qualities of the media used. For example, in a case when a recycled sheet or special sheet is used as media, a large curl can be generated. When a medium having such curl is exited from the development device, the medium can contact the housing of the development device. 
     In such a case, when the toner image has been transferred to the medium by a transfer part and when the medium has been exited from the development device, the curled medium surface touches the housing that is on the downstream side of the exit and thereby an image scrape can occur, meaning that the unfixed toner image on the medium surface is scraped. 
     Therefore, one of objects of the present invention is to provide a development device and an image forming apparatus that prevent a curled medium from contacting a housing of the development device on a medium exit side and an unfixed toner image on the medium surface from being scraped after the medium has been exited from the development device. 
     SUMMARY 
     Considering the above drawbacks, a development device of the invention includes a development part configured to develop a developer image on a surface of an electrostatic latent image carrier based on an image signal, a transfer part configured to transfer the developer image to a medium; and a guide part configured to regulate a contact of the medium, on which the developer image has been transferred and been exited, to a housing of the development part, and to guide the medium to a carrying path. 
     In another view of the invention, an image forming apparatus is provided, including a development part configured to develop a developer image on a surface of an electrostatic latent image carrier based on an image signal, a transfer part configured to transfer the developer image to a medium, a fusion part configured to fix the developer image that has been transferred to the medium on the medium, and a guide part configured to regulate a contact of the medium, on which the developer image has been transferred and been exited, to a housing of the development part, and to guide the medium to a carrying path to the fusion part. 
     According to the present invention, the curled medium is prevented from contacting the housing of the development device on the medium exit side after the medium has been exited from the development device, and the unfixed toner image (developer image) on the medium surface from being scraped. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an internal configuration diagram of an internal configuration of an image forming apparatus according to a first embodiment. 
         FIG. 2  is an external side view of an external side surface of a development device according to the first embodiment. 
         FIG. 3  is a cross-sectional view of an internal configuration of the development device according to the first embodiment. 
         FIG. 4  is an external perspective view of the development device according to the first embodiment seen from a lower side. 
         FIGS. 5A-5C  are explanatory diagrams for explaining the carrying of a medium in a case when a curl is not generated in a conventional image forming apparatus. 
         FIGS. 6A-6F  are explanatory diagrams for explaining the carrying of a medium in a case when the curl is generated in the conventional image forming apparatus. 
         FIGS. 7A-7F  are explanatory diagrams for explaining the carrying of the medium in the case when the curl has been generated in the image forming apparatus that includes a guide plate according to the first embodiment. 
         FIG. 8  is a cross-sectional view of an image forming part of the image forming apparatus according to a second embodiment and an explanatory diagram for explaining the movement of a medium (Part 1). 
         FIG. 9  is a cross-sectional view of the image forming part of the image forming apparatus according to the second embodiment and an explanatory diagram for explaining the movement of the medium (Part 2). 
         FIG. 10  is an enlarged cross-sectional view of an internal configuration of a modified embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     (A) First Embodiment 
     A development device and an image forming apparatus according to a first embodiment of the present invention are explained in detail below with reference to the drawings. 
     (A-1) Configuration According to First Embodiment 
     (A-1-1) Configuration of Image Forming Apparatus 
       FIG. 1  is an internal configuration diagram illustrating an internal configuration of the image forming apparatus  100  according to the first embodiment. 
     In  FIG. 1 , the image forming apparatus  100  includes a cassette part  202 , a sheet supply roller  201 , carrying rollers  207 , a development device  110 , an image fuser  20  that includes a heat application roller  21  and a pressure application roller  22 , a controller  130 , a separation frame part  204 , a passage sensor lever  208 , a medium exit sensor lever  210 , an ejection sensor lever  215 , ejection rollers  216 , and a stacker  220 . 
     The development device  110  forms a toner image (developer image) on a photosensitive drum  9  (electrostatic latent image carrier) based on image data, and transfers the toner image thereon to a medium  203 . As shown in  FIG. 1 , the development device  110  includes a development unit  10  (development part) that includes the photosensitive drum  9  and a transfer roller  8  (transfer part). 
     An image forming part  120  includes the development device  110  and the image fuser  20  (fusion part) that includes the heat application roller  21  and the pressure application roller  22 .  FIG. 1  illustrates a case that the image forming part  120  includes the development device  110  and the image fuser  20  as well as a medium carrying device  30  between the development device  110  and the image fuser  20 . 
     In  FIG. 1 , the image forming apparatus  100  according to the first embodiment is connected to a host device such as a personal computer (PC) and the like, receives image data and control information from the host device, and forms an image on the medium  203  based on the image data in accordance with the control information. The image forming apparatus  100  includes the controller  130  that controls an image formation process of the image forming apparatus  100 . 
     The controller  130  is, for example, a device that is configured to include a microcomputer and the like. The controller  130  performs a power supply control to respective configuration elements, a motor drive control for rotating various rollers, a suction instruction of the medium  203  to the medium carrying device  30  and a print control based on sensor information from various sensors (for example, a medium exit sensor, a passage sensor, an ejection sensor) and the like. 
     In the image forming apparatus  100 , when the image data is given from the host device, the image data is stored in a memory. Then, due to the control by the controller  130 , the sheet supply roller  201  rotates and the media  203  put on the cassette part  202  are supplied. 
     At this time, while the sheet supply roller  201  supplies the media  203 , the photosensitive drum  9 , the transfer roller  8 , the ejection rollers  216 , a fan  301  (medium suction part) included in the medium carrying device  30 , and the heat application roller  21  and the pressure application roller  22  included in the image fuser  20  start to rotate due to the control by the controller  130 . 
     The media  203  that are supplied by the sheet supply roller  201  are given to the separation frame part  204 . The separation frame part  204  separates each of the media  203 . Each medium  203  is carried toward the downstream of a medium carrying path by the rotation of the sheet supply roller  201 . Here, in the medium carrying path of the medium  203 , the cassette  202  side is the upstream, and the stacker  220  side is the downstream. 
     The medium  203  that has been separated by the separation frame part  204  is sent to two pairs of the carrying rollers  207 . The medium  203  is carried by the rotation of the lower pair of the carrying rollers  207  of the two pairs of the carrying rollers  207 . The passage sensor lever  208  detects arrival of a leading edge of the carried medium  203 . 
     The development unit  10  forms on the photosensitive drum  9  the toner image of the image that is to be formed onto the medium  203  when the medium  203  is detected by the passage sensor lever  208 . That is, the development unit  10  forms the toner image on the surface of the photosensitive drum  9  based on the image date stored in the memory. 
     When the medium  203  that is carried by the carrying rollers  207  is given to the development unit  10 , the photosensitive drum  9  and the transfer roller  8  rotate, and the toner image on the surface of the photosensitive drum  9  is transferred to the medium  203  in the development device  110 . 
     When the toner image is transferred to the medium  203  in the development device  110 , the medium  203  is carried to the image fuser  20  on the downstream side of the carrying path by the medium carrying device  30 . For example, the medium carrying device  30  includes a medium suction part such as the fan  301  and the like. The curled medium  203  is sucked into the carrying path by a suction force of the medium suction part. 
     In the image fuser  20 , a fix process is performed on the carried medium  203  by the heat application roller  21  and the pressure application roller  22 . 
     After the fusion process has been performed by the image fuser  20 , the medium  203  is carried by the rotating ejection rollers  216 , and is ejected on the stacker  220  provided on the upper surface of the image forming apparatus  100 . Thereby, the printing process in the image forming apparatus  100  ends. 
     (A-1-2) Configuration of Development Device  110   
     Next, a configuration of the development device  110  is explained with reference to the drawings. 
       FIG. 2  is an external side view of an external side surface of the development device  110 . In  FIG. 2 , the development device  110  includes a toner container  7  that accommodates and seals toner, the housing  11  that covers the development unit  10 , a guide plate  1  (guide part), which is provided on the carrying downstream side of the housing  11  and is disposed to face the carrying path, and the transfer roller  8 . 
       FIG. 3  is a cross-sectional view of an internal configuration of the development device  110 . In  FIG. 3 , the development unit  10  includes the photosensitive drum  9  in the housing  11 . In  FIG. 3 , an arrow illustrated on the photosensitive drum  9  indicates a rotation direction of the photosensitive drum  9 . In addition, an arrow illustrated on the transfer roller  8  in  FIG. 3  indicates a rotation direction of the transfer roller  8 . 
     The guide plate  1  is a plate that contacts a horizontal contact part  12  of the housing  11  on the carrying downstream side. In a case that the curled medium  203  is exited from the photosensitive drum  9  and the transfer roller  8 , the guide plate  1  contacts the leading edge of the curled medium  203  to regulate the medium  203  not to contact the housing  11 . Thereby, the conventional scrape of the image that occurs when the medium  203  that intensely curled in the upper direction contacts the housing  11  is prevented. 
     Various methods may be applied in installation methods of the guide plate  1  as long as the curled medium  203  is prevented from contacting the housing  11 . For example, the methods may be applied as shown in  FIG. 3 . 
     For example, as shown in  FIG. 3 , the development unit  10  includes a contact part  12  in approximately horizontal direction as the configuration of the housing  11  on the carrying downstream side. The guide plate  1  is provided so that one surface of the guide plate  1  contacts the contact part  12  of the housing  11 . The guide plate  1  is adhered to the contact part  12  by adhesion members or the like, for example. Alternatively, the guide plate  1  may also be removed from the contact part  12  by providing fitting parts or the like, for example. 
     In addition, materials of the guide plate  1  are not especially limited, and may be resin members, for example, polyester, or polyethylene terephthalate (PET) and the like, or may be metal materials. 
     Moreover, as shown in  FIG. 3 , the guide plate  1  is provided so that a gap between one end part (right end part in  FIG. 3 ) of the guide plate  1  and the photosensitive drum  9  is minimized as much as possible. This is to avoid the leading edge of the medium  203  entering between the photosensitive drum  9  and the guide plate  1 . For example, in  FIG. 3 , when a length between a point at which an extension line of the guide plate  1  contacts the photosensitive drum  9  and the one end part of the guide plate  1  is defined as L 2 , the length L 2  is preferably approximately 1 mm to 3 mm, and is especially preferably approximately 1 mm. 
     In addition, a length of the guide plate  1  in the medium carrying direction is a length to the extent that the leading edge of the medium  203  is removed from the guide plate  1  by the weight of the medium  203 . For example, in the example of the first embodiment, when the length of the guide plate  1  in the medium carrying direction is defined as L 1 , the length L 1  is preferably approximately 10 mm to 15 mm. 
       FIG. 4  is an external perspective view of the development device  110  seen from the lower side. As shown in  FIG. 4 , a length L 3  of the guide plate  1  in the long side is approximately the same as that of the transfer roller  8  in the longitudinal direction, and may be approximately 250 mm to 350 mm, for example. 
     (A-2) Operation in First Embodiment 
     Next, an operation of the development device  110  in the image forming apparatus  100  according to the first embodiment is explained with reference to the drawings. 
       FIGS. 5A-5C  are explanatory diagrams for explaining the carrying of the medium  203  in the case when a curl is not generated in a conventional image forming apparatus. 
     In  FIGS. 5A-5C , in the case that the curl has not been generated on the medium  203 , when the medium  203  is carried to the development unit  10  (see  FIG. 5A ), the toner image is transferred onto the medium  203  while the medium  203  is sandwiched and carried by the photosensitive drum  9  and the transfer roller  8  (see  FIG. 5B ). Accordingly, the medium  203  is exited from the development device  110  to the medium carrying device  30 , and is carried to the image fuser  20  (see  FIG. 5C ). 
       FIGS. 6A-6F  are explanatory diagrams for explaining the carrying of the medium  203  in the case when the curl is generated in the conventional image forming apparatus. 
     In  FIGS. 6A-6F , in the case that the curl has been generated, when the medium  203  is carried to the development unit  10  (see  FIG. 6A ), the toner image is transferred onto the medium  203  while the medium  203  is sandwiched and carried by the photosensitive drum  9  and the transfer roller  8  (see  FIG. 6B ). 
     When the medium  203  is sandwiched and carried by the photosensitive drum  9  and the transfer roller  8  and the curl has been generated on the medium  203 , the leading edge of the curled medium  203  contacts a portion  11   a  in the housing  11  of the development unit  10  that covers the photosensitive drum  9  (see  FIG. 6C ). 
     Thereafter, when the medium  203  has been exited from the photosensitive drum  9  and the transfer roller  8 , the curled leading edge of the medium  203  moves while scraping the bottom part of the housing  11  of the development unit  10  (see  FIG. 6D ). As a result, the unfixed toner image on the surface of the curled medium  203  is scraped by the housing  11  of the development unit  10  (see  FIG. 6E ). That is, the scrape of the image occurs by the unfixed toner image on the medium  203  being scraped. 
     Furthermore, as the exit of the medium  203  proceeds, the curvature of the medium  203  becomes larger due to the weight of the medium  203 . Thereby, the portion of the medium  203  that has contacted the housing  11  separates from the housing  11 , and the medium  203  is exited as is (see  FIG. 6F ). 
     As mentioned above, in the conventional image forming apparatus, once the curl occurred, portions any other than the leading edge of the medium  203  contacts the bottom of the housing  11 . As a result, the image on the portions, which has been scraped with the housing  11 , is scraped. 
       FIGS. 7A-7F  are explanatory diagrams for explaining the carrying of the medium  203  in the case when the curl has been generated in the image forming apparatus  100  that includes the guide plate  1  according to the first embodiment. 
     In  FIGS. 7A-7F , when the medium  203  is carried to the development unit  10  (see  FIG. 7A ), the toner image is transferred onto the medium  203  while the medium  203  is sandwiched and carried by the photosensitive drum  9  and the transfer roller  8  (see  FIG. 7B ). 
     When the medium  203  is sandwiched and carried by the photosensitive drum  9  and the transfer roller  8  and the curl has been generated on the medium  203 , the curled leading edge of the medium  203  contacts the guide plate  1  (see  FIG. 7C ). 
     Thereafter, when the medium  203  has been exited from the photosensitive drum  9  and the transfer roller  8 , while the curled leading edge of the medium  203  scrapes the guide plate  1 , the medium  203  moves in the downstream direction (see  FIG. 7D ). As the medium  203  travels after passing the photosensitive drum  9 , the leading edge of the medium  203  moves upward in the drawing for a while. 
     Furthermore, as the exit of the medium  203  proceeds, the curvature of the medium  203  becomes larger due to the weight of the medium  203 . Also, in this time, the leading edge of the medium  203  moves simultaneously with contacting the guide plate  1  (see  FIG. 7E ). 
     In this time, since the surface of the medium  203  is concave due to the curl, only the leading edge of the medium  203  contacts the guide plate  1 , the portion on the surface of the medium  203  on which the image is transferred does not contact the guide plate  1 . 
     Then, as the curled leading edge of the medium  203  moves along the guide plate  1 , the curvature of the medium  203  becomes larger due to the weight of the medium  203 . As a result, the leading edge of the medium  203  that has contacted the guide plate  1  separates from the guide plate  1  and the medium  203  is exited as it is (see  FIG. 7F ). 
     (A-3) Effects of First Embodiment 
     As mentioned above, according to the first embodiment, the leading edge of the medium is received by the surface of the guide plate and the medium moves to the carrying direction by providing the guide plate on the medium exit side of the housing of the development unit. As a result, according to the first embodiment, even when the curled medium is exited from the development device, a phenomenon where the medium surface contacts the housing of the development device and thereby the image scrape occurs is prevented. 
     In addition, according to the first embodiment, by making a length of the guide plate in the medium carrying direction a length to the extent that the leading edge of the medium separates the guide plate  1  by the weight of the medium, the transfer surface does not contact the guide plate while the leading edge of the medium is received by the surface of the guide plate, since the transfer surface of the medium is concave due to the curl. Accordingly, the image scrape is prevented. 
     (B) Second Embodiment 
     Next, a development device and an image forming apparatus according to a second embodiment of the present invention are explained with reference to the drawings. 
     (B-1) Configuration According to Second Embodiment 
     A difference of the second embodiment from the first embodiment is that lengths of guide plates in the medium carrying direction are extended from the development unit to the vicinity of the image fuser. Other configurations are the same as those of the first embodiment. Thereafter, characteristic configurations of the second embodiment are mainly explained. 
       FIG. 8  is a first cross-sectional view of the image forming part  120  of the image forming apparatus  100  according to the second embodiment and an explanatory diagram for explaining the movement of the medium. 
     In the  FIG. 8 , the image forming part  120  of the second embodiment includes the development unit  10  that includes the photosensitive drum  9 , the transfer roller  8 , the medium carrying device  30  and the image fuser  20  that includes the heat application roller  21  and the pressure application roller  22  in the same manner as the first embodiment. 
     A guide plate  2  is provided so as to contact the contact part  12  on the carrying downstream side of the housing  11  of the development unit  10 . The guide plate  2  only needs contact the contact part  12  in the same manner as the first embodiment. For example, similar to the first embodiment, the guide plate  2  may be adhered to the contact part  12  by adhesion members and the like. The guide plate  2  may also be configured removable from the contact part  12  by providing fitting parts and the like, for example. 
     The guide plate  2  guides the carrying of the medium  203  from the vicinity of an exit position in the development unit  10  to the vicinity of an entrance position in the image fuser  20 . By extending the guide plate  2  to the vicinity of the entrance position in the image fuser  20 , a curled medium  203  is accurately carried to the image fuser  20 . In addition, the guide plate  2  may be provided so that an end part of the guide plate  2  contacts the housing of the image fuser  20 . 
     The length L 4  of the guide plate  2  in the carrying direction depends on the positional relationship between the development unit  10  and the image fuser  20 , and may be, for example, approximately 180 mm to 220 mm. 
     In addition, the guide plate  2  is provided so that a carrying space (space configured by the guide plate  2  and the upper surface of the medium carrying device) of the medium  203  widens along the carrying direction (that is, a direction from the upstream to the downstream). 
     For example, in the example in the  FIG. 8 , the guide plate  2  is provided so as to extend in the horizontal direction by a predetermined length from the exit position of the medium  203  in the development unit  10 , and thereafter to extend in an obliquely upward direction along the carrying direction. Alternatively, the guide plate  2  may be provided so as to have an incline extending in an obliquely upward direction from the development unit  10  to the image fuser  20  without an interval extending in the horizontal direction. 
     In addition, in the example in the  FIG. 8 , a following case is illustrated. The interval length of the guide plate  2  in the horizontal direction is about ⅓ of the entire length. The interval length of the guide plate  2  in the obliquely upward direction is about ⅔ of the entire length. The interval length in the horizontal direction and the interval length in the obliquely upward direction are not limited especially, and may be determined according to the configuration of the image forming apparatus  100 . 
     (B-2) Operation in Second Embodiment 
     Next, an operation of the development device  110  in the image forming apparatus  100  according to the second embodiment is explained with reference to the drawings. 
     The operation of the development device  110  according to the second embodiment is basically the same as that of the first embodiment. The movement of the medium  203  provided with the guide plate  2  of the second embodiment is mainly explained below. 
       FIG. 9  is a second cross-sectional view of the image forming part  120  of the image forming apparatus  100  according to the second embodiment and an explanatory diagram for explaining the movement of the medium. 
     A difference of the image forming part  120  shown in  FIG. 9  from the image forming part  120  shown in  FIG. 8  is that the guide plate  2  shown in  FIG. 8 , as discussed above, extends in the obliquely upward direction so that the carrying space of the medium  203  widens, while a guide plate  3  shown in  FIG. 9  extends in the horizontal direction to the vicinity of the entrance position in the image fuser  20 . 
     The curled medium  203  can be exited from the development unit  10 . At this time, a large curl may be generated on the entire medium. For example, there is a case that the medium  203 , such as a recycled sheet or special sheet and the like, is used, on which different fabrication processes are performed on the back surface and the front surface on the sheet. Since the stretch of the back surface and the front surface are significantly different, a curl may be generated on the entire medium. 
     In such a case, the leading edge of the medium does not falls by the weight of the medium  203  and the medium  203  can move with the leading edge contacting the guide plate. 
     In a case that guide plate  3  shown in  FIG. 9  extends in the horizontal direction, the entire medium  203  on which the large curl has generated moves in the carrying direction with the leading edge thereof contacting the guide plate  3 . 
     However, as shown in  FIG. 9 , in a duct-shaped carrying space that is sandwiched by the guide plate  3  and the medium carrying device  30 , since the large curl has been generated on the entire medium, the leading edge of the medium  203  is pushed into a narrow space, the medium  203  warps near the center part thereof. Accordingly, the surface of the medium  203  near the center part (portion indicated by the arrow) contacts the guide plate  3  and an unfixed toner image on the portion thereof may be scraped. 
     On the other hand, in the case that the guide plate  2  shown in  FIG. 8  is provided so that the carrying space widens toward the carrying direction. Since the narrow space widens in the carrying direction of the medium  203 , the warping of the medium  203  is moderated. Accordingly, the surface of the medium  203  near the center part does not contact the guide plate  3  and the unfixed toner image on the portion thereof is prevented from being scraped. 
     (B-3) Effects of Second Embodiment 
     As mentioned above, according to the second embodiment, by connecting the upper parts of the carrying path of the medium from the development unit to the image fuser and widening the carrying path from the upstream to the downstream of the carrying of the medium, the image scrape on the entire medium on which the large curl has generated is prevented. 
     (C) Other Embodiments 
     In the above-discussed first and second embodiments, the guide plates that guide a carrying path from the development device that includes the photosensitive drum and the transfer roller to the image fuser are exemplified. However, the above-mentioned guide plates may be applied in devices/method in which the surfaces of the media are not scraped. 
     In the above-discussed first embodiment, it is disclosed that the guide plate as a guide part is provided as an independent part to the housing of the development unit. Herein, the guide plate extends straight along the carrying direction of the medium. It is noted that providing the guide part as a different part from the housing bring an advantage that is an easy adjustment of the distance between the guide part and the rollers. However, as a modified embodiment, a shape of the contact portion of the housing (for example,  11   a  in  FIG. 6C ) itself may be made to extend along the carrying direction of the medium. Namely, in the invention, it is not necessary to form the guide part and the housing separately. It may be practical to integrate the guide part with the housing as long as the guide part functions. On the other hand, the guide part may be configured with two or three components. For example, a first part is on the upstream side and a second part on the downstream side. In addition, it is also practical, as shown in  FIG. 10 , a upstream part with a length L 12  is realized with a part  12   a  of housing. A downstream part with a length L 11  is realized with the guide plate  1   a . Further, the guide part does not necessarily have a plate shape as long as it functions to guide the leading edge of the medium. For example, the guide part may be configured with two to five rails that are arranged in substantially parallel each other along in the carrying direction of the medium. The outer two rails are arranged with a space that is a little narrower than the width of the medium. According to a degree of hardness of the medium, a sole rail may be used as the guide part, which is arranged in a middle of the carrying path with respect to the width direction because a width curl of the medium can be ignored. The width curl means a curl occurring in the width direction of the medium. 
     In the image forming apparatus shown in the above-discussed first and second embodiments may be any of various devices such as printers, multifunction peripherals (MFP) and the like that form an image on the medium, for example. 
     Regarding the guide plate shown in the above-discussed second embodiment, the guide plate that extends in the obliquely upward direction in the delivery direction is exemplified as one example of the case that the guide plate is disposed so that the carrying space widens along the carrying direction. The configurations of the guide plates are not limited to such a configuration. For example, as another configuration, a guide plate may have a curved shape that is a downward concave by a predetermined curvature.