SHEET CONVEYING DEVICE AND IMAGE FORMING SYSTEM

Abstract

A sheet conveying device conveys a sheet from an image forming apparatus which forms an ink image on the sheet by ejecting ink onto a surface of the sheet to a drying device which dries the ink image on the sheet. The sheet conveying device includes a suction conveying portion and an auxiliary suction portion. The suction conveying portion conveys the sheet along a guide surface while sucking the sheet onto the guide surface. The auxiliary suction portion is arranged on a downstream side of a conveying direction as viewed from the suction conveying portion on the guide surface, and sucks the sheet onto the guide surface.

Claims

1. A sheet conveying device which conveys a sheet from an image forming apparatus which forms an ink image on the sheet by ejecting ink onto a surface of the sheet to a drying device which dries the ink image on the sheet, the sheet conveying device comprising: a suction conveying portion which conveys the sheet along a guide surface while sucking the sheet onto the guide surface; and an auxiliary suction portion which is arranged on a downstream side of a conveying direction as viewed from the suction conveying portion on the guide surface, and sucks the sheet onto the guide surface.

2. The sheet conveying device according to claim 1, wherein the suction conveying portion includes a case including the guide surface, a suction portion which sucks the sheet onto the guide surface, and a conveying roller which conveys the sheet that has been sucked onto the guide surface along the guide surface.

3. The sheet conveying device according to claim 1, further comprising: an optical sensor which detects the sheet, wherein the guide surface includes an extension portion formed with the auxiliary suction portion on the downstream side of the conveying direction as viewed from the suction conveying portion, and the extension portion includes a transmissive portion through which light of the optical sensor passes.

4. The sheet conveying device according to claim 1, wherein a plurality of the auxiliary suction portions are provided on the guide surface, and sucking power of the plurality of auxiliary suction portions can be adjusted individually.

5. An image forming system, comprising: the sheet conveying device according to claim 1; the image forming apparatus; and the drying device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a schematic diagram showing a configuration of an image forming system according to Embodiment 1;

[0008] FIG. 2 is a block diagram showing a configuration of an image forming apparatus according to Embodiment 1;

[0009] FIG. 3 is a schematic diagram showing a configuration of an image forming portion of the image forming apparatus according to Embodiment 1;

[0010] FIG. 4 is a perspective view showing a schematic configuration of a sheet conveying device in the image forming system according to Embodiment 1; and

[0011] FIG. 5 is a cross-sectional view showing a schematic configuration of the sheet conveying device in the image forming system according to Embodiment 1.

DETAILED DESCRIPTION

[0012] Hereinafter, an embodiment of the present disclosure will be described with reference to the attached drawings. It is noted that the following embodiment is an example of embodying the present disclosure and does not limit the technical scope of the present disclosure.

Embodiment 1

[1] Overall Configuration of Image Forming Apparatus

[0013] First, an overall configuration of an image forming apparatus 10 according to the present embodiment will be described with reference to FIG. 1 to FIG. 3.

[0014] In the present embodiment, as an example, the image forming apparatus 10 is an inkjet recording apparatus (printer) which includes a recording head 51 that ejects ink onto a surface of a sheet Sh1 and is capable of executing print processing by an inkjet method for forming an image on the sheet Sh1 using the recording head 51. The print processing is processing of forming an image on an image forming target. The sheet Sh1 is an example of the image forming target (recording medium) on which an image is formed by the image forming apparatus 10, and is a sheet-like medium such as paper or a resin film.

[0015] The image forming apparatus 10 only needs to have a function of forming an image by the inkjet method and may be, for example, a multifunction peripheral having a plurality of functions such as a scanning function for reading image data from a document sheet, a facsimile function, and a copying function in addition to a printing function. Alternatively, the image forming apparatus 10 may be a facsimile apparatus, a copying machine, or the like.

[0016] As shown in FIG. 1, the image forming apparatus 10 constitutes an image forming system 100 together with a sheet feed device 11, a drying device 12, a discharge device 13, and a sheet conveying device 8. In other words, the image forming system 100 according to the present embodiment includes the image forming apparatus 10, the sheet feed device 11, the drying device 12, the discharge device 13, the sheet conveying device 8, and the like. Herein, the image forming apparatus 10, the sheet feed device 11, the drying device 12, the discharge device 13, and the sheet conveying device 8 are connected in the stated order of the sheet feed device 11, the image forming apparatus 10, the sheet conveying device 8, the drying device 12, and the discharge device 13 from an upstream side with respect to a conveying direction of the sheet Sh1. Thus, the image forming system 100 can continuously perform a series of processing performed by each of the sheet feed device 11, the image forming apparatus 10, the drying device 12, and the discharge device 13 on the sheet Sh1. In addition, each device of the image forming system 100 is collectively managed by a control device 7 of the image forming apparatus 10. However, the present disclosure is not limited to this configuration, and a control device that collectively controls each device may be provided separately from the control device 7.

[0017] The sheet feed device 11 is capable of storing a plurality of sheets Sh1. The sheet feed device 11 supplies the sheets Sh1 one by one to the image forming apparatus 10. The image forming apparatus 10 ejects ink from the recording head 51 onto the sheet Sh1 supplied from the sheet feed device 11, to form an image (ink image) by the inkjet method. The image forming apparatus 10 sends the sheet Sh1 on which the image has been formed to the subsequent drying device 12.

[0018] The image forming apparatus 10 includes a first conveying unit 4 and ejects ink from the recording head 51 onto the surface of the sheet Sh1 conveyed by the first conveying unit 4, to thus form an image (ink image) on the sheet Sh1 by the inkjet method. The first conveying unit 4 conveys the sheets Sh1 supplied from the sheet feed device 11 one by one and discharges the sheets Sh1 on each of which the image has been formed one by one.

[0019] The sheet conveying device 8 is arranged between the image forming apparatus 10 and the drying device 12. The sheet conveying device 8 conveys the sheet Sh1 from the image forming apparatus 10 to the drying device 12. In other words, the sheet conveying device 8 is positioned on a downstream side of the image forming apparatus 10 in the conveying direction of the sheet Sh1, receives the sheet Sh1 discharged from the image forming apparatus 10 and on which the ink image has been formed, and further hands over the sheet Sh1 to the drying device 12 positioned on the downstream side.

[0020] The drying device 12 dries the ink image on the sheet Sh1. The drying device 12 includes a drying chamber therein, and includes a heater, a heat pump type heating unit, or the like in the drying chamber. The drying device 12 heats the surface of the sheet Sh1 conveyed from the image forming apparatus 10 into the drying chamber via the sheet conveying device 8, to dry the ink image formed on the sheet Sh1. The drying device 12 includes an exhaust fan that exhausts (discharges) moisture from the drying chamber. The drying device 12 sends the sheet Sh1 that has been subjected to drying processing to the subsequent discharge device 13. Thus, the sheet Sh1 on which the image has been formed by the inkjet method in the image forming apparatus 10 is discharged to the discharge device 13.

[0021] The drying device 12 also includes a second conveying unit 14 (see FIG. 4) and heats the surface of the sheet Sh1 conveyed by the second conveying unit 14 to dry the ink image. The second conveying unit 14 conveys the sheets Sh1 received from the sheet conveying device 8 one by one, and discharges the sheets Sh1, the ink images of which have been dried, one by one to the discharge device 13. That is, the sheet Sh1 is conveyed from the sheet feed device 11 to the discharge device 13 while by passing through the first conveying unit 4 of the image forming apparatus 10, the sheet conveying device 8, and the second conveying unit 14 of the drying device 12 in the stated order.

[0022] The discharge device 13 stores the sheet Sh1 conveyed from the drying device 12. Further, for example, the discharge device 13 may have a post-processing function such as a stapling function, a folding function, an inserter function, or a punching function. That is, the discharge device 13 may be a post-processing device that executes post-processing on the sheet Sh1 conveyed from the drying device 12. In this case, it is possible to perform appropriate post-processing on the sheet Sh1 on which an image has been formed in the discharge device 13. Furthermore, while, in single-sided printing in which an image is formed only on one side of the sheet Sh1, the sheet Sh1 that has been subjected to the drying processing in the drying device 12 is sent to the discharge device 13, in double-sided printing in which images are formed on both sides of the sheet Sh1, the sheet Sh1 is returned to the image forming apparatus 10 after being subjected to the drying processing in the drying device 12. Then, an image is formed on a back surface in the image forming apparatus 10, and the sheet Sh1 is sent to the discharge device 13 after being subjected to the drying processing in the drying device 12.

[0023] Further, as shown in FIG. 1 and FIG. 2, the image forming apparatus 10 includes an image forming portion 5, an ink supply portion 6, the control device 7, and the like in addition to the first conveying unit 4. The image forming portion 5 includes a plurality of recording heads 51. The first conveying unit 4, the image forming portion 5, the ink supply portion 6, the control device 7, and the like are housed in a housing 21 that constitutes an outer shell of the image forming apparatus 10.

[0024] The first conveying unit 4 conveys the sheets Sh1 supplied from the sheet feed device 11 one by one through a conveying path 40. Thus, the sheet Sh1 taken into the housing 21 of the image forming apparatus 10 from the sheet feed device 11 is conveyed below the image forming portion 5 in the conveying direction D1 through the conveying path 40 and discharged to the drying device 12. The conveying path 40 is a path for conveying the sheet Sh1 inside the housing 21, and includes a preceding conveying path 401 on the upstream side with respect to the image forming portion 5 and a subsequent conveying path 402 on the downstream side. The first conveying unit 4 conveys the sheet Sh1 supplied from the sheet feed device 11 to the image forming portion 5 through the preceding conveying path 401, and discharges the sheet Sh1 from the image forming portion 5 to the drying device 12 through the subsequent conveying path 402.

[0025] The first conveying unit 4 includes a sheet delivery portion 41, one or more preceding conveying roller pairs 42, a main conveying unit 43, a separation mechanism 44, and the like. The sheet delivery portion 41 delivers the sheets Sh1 supplied from the sheet feed device 11 one by one to the preceding conveying path 401. The plurality of preceding conveying roller pairs 42 take over the conveyance of the sheet Sh1 from the sheet delivery portion 41 and convey the sheet Sh1 toward the main conveying unit 43.

[0026] The main conveying unit 43 is arranged below the image forming portion 5. The preceding conveying path 401 is a path that leads from the sheet feed device 11 to below the image forming portion 5 (above the main conveying unit 43). The main conveying unit 43 conveys the sheet Sh1 while causing a first surface (front surface) of the sheet Sh1 to oppose the image forming portion 5. The first surface of the sheet Sh1 is a surface on which an ink image is to be formed. The main conveying unit 43 includes a plurality of tension rollers 431 and a main conveying belt 432, and causes the main conveying belt 432 to rotate while supporting the main conveying belt 432 by the plurality of tension rollers 431. Thus, the main conveying unit 43 conveys the sheet Sh1 toward the separation mechanism 44 while the sheet Sh1 is placed on the main conveying belt 432.

[0027] The separation mechanism 44 is positioned on the downstream side of the main conveying unit 43 in the conveying direction, and separates the sheet Sh1 conveyed by the main conveying unit 43 from the main conveying belt 432 and sends it to the subsequent conveying path 402. In the present embodiment, the separation mechanism 44 is arranged above the downstream side of the main conveying belt 432, and separates the sheet Sh1 from the main conveying belt 432 by blowing air (airflow) onto the main conveying belt 432. In other words, the sheet Sh1 is separated from the main conveying belt 432 by air being blown against the sheet Sh1 on the main conveying belt 432.

[0028] The main conveying unit 43 discharges the sheet Sh1 on which the ink image has ben formed, that has been separated from the main conveying belt 432 by the separation mechanism 44, to the drying device 12 through the subsequent conveying path 402. The subsequent conveying path 402 is a path that leads from below the image forming portion 5 (above the main conveying unit 43) to the drying device 12.

[0029] The first conveying unit 4 may include a discharge roller pair or the like in addition to or in place of the separation mechanism 44.

[0030] The image forming portion 5 is positioned above the main conveying unit 43. The image forming portion 5 ejects ink of a plurality of colors toward the sheet Sh1 conveyed by the main conveying unit 43 of the first conveying unit 4, to thus form an ink image on the first surface of the sheet Sh1.

[0031] The image forming portion 5 includes the plurality of recording heads 51 and a head frame 52 that supports the plurality of recording heads 51. The plurality of recording heads 51 eject ink of the plurality of colors toward the sheet Sh1 conveyed by the main conveying unit 43, to form an image on the sheet Sh1.

[0032] In the example shown in FIG. 1, the plurality of recording heads 51 are respectively sectioned into four line heads 50 respectively corresponding to the ink of the respective colors of black, cyan, magenta, and yellow. The ink supply portion 6 supplies the ink of the respective colors (K, C, M, Y) to the recording heads 51 of the corresponding line heads 50. The four line heads 50 are arranged side by side in a sub-scanning direction D12 and are fixed in a predetermined positional relationship (see FIG. 3). The number of line heads 50 provided in the image forming portion 5 is not limited to four, and may be, for example, two, three, or five or more. The sub-scanning direction D12 is the same as the conveying direction D1 of the sheet Sh1 on the main conveying belt 432.

[0033] The plurality of recording heads 51 are arranged at positions where a gap of about 1 millimeter is formed between an ink ejection surface provided on a lower surface of each of the recording heads 51 and an upper surface of the sheet Sh1 on the main conveying belt 432. As shown in FIG. 3, the plurality of recording heads 51 are arranged in a state where longitudinal directions thereof are aligned along a main scanning direction D11. In the present embodiment, as an example, the line head 50 of each color includes three recording heads 51. The ink ejection surface of each of the recording heads 51 is formed with a plurality of ink nozzles 53 that eject ink onto the sheet Sh1 conveyed along the conveying path 40. Each of the recording heads 51 includes a plurality of piezoelectric elements corresponding to the plurality of ink nozzles 53. Each of the piezoelectric elements vibrates when a drive signal is supplied from the control device 7, thereby pressurizing the ink to cause the ink to be ejected (spouted) from the ink nozzle 53.

[0034] The control device 7 collectively controls the image forming apparatus 10. The control device 7 is mainly constituted of a computer system including one or more processors and one or more nonvolatile memories. In the image forming apparatus 10, the functions of the control device 7 are realized by the one or more processors executing a program. The program may be recorded in advance in a memory (storage portion), may be provided through a telecommunication line such as the Internet, or may be provided by being recorded on a non-transitory recording medium that can be read by a computer system, such as a memory card or an optical disk. The one or more processors are constituted of one or more electronic circuits including a semiconductor integrated circuit. Furthermore, the computer system used herein includes a microcontroller including one or more processors and one or more memories.

[0035] The control device 7 controls the first conveying unit 4, the image forming portion 5, the ink supply portion 6, and the like included in the image forming apparatus 10. In the present embodiment, the control device 7 controls not only the image forming apparatus 10 but also the sheet conveying device 8 and the like. In other words, the control device 7 is electrically connected to the respective portions of the image forming apparatus 10, the sheet conveying device 8, and the like, and is capable of, for example, controlling the image forming portion 5 to form a desired image on the sheet Sh1, controlling the sheet conveying device 8 to convey the sheet Sh1 from the image forming apparatus 10 to the drying device 12, and the like. In other words, the control device 7 executes an image forming program recorded in the memory to execute an image forming method for controlling the respective portions of the image forming system 100.

[0036] The image forming apparatus 10 further includes a head cooling device, a maintenance unit, a cap unit, an operation display portion, and the like. The head cooling device cools the recording head 51. The maintenance unit performs a wiping operation to wipe the ink ejection surface (the lower surface of the recording head 51) and clean the ink ejection surface. The cap unit covers the ink ejection surface of the recording head 51 to protect it from drying. The operation display portion is a user interface in the inkjet recording apparatus. The operation display portion includes a display portion such as a liquid crystal display that displays various types of information in response to control instructions from the control device 7 and an operation portion such as a switch or a touch panel that is used to input various types of information to the control device according to user operations.

[2] Details of Sheet Conveying Device

[0037] Next, the sheet conveying device 8 of the image forming system 100 according to the present embodiment will be described in more detail with reference to FIG. 4 and FIG. 5.

[0038] As described above, the sheet conveying device 8 conveys the sheet Sh1 from the image forming apparatus 10 which forms an ink image on the sheet Sh1 by ejecting ink onto the surface of the sheet Sh1 to the drying device 12 which dries the ink image on the sheet Sh1. In other words, the sheet conveying device 8 is arranged between the image forming apparatus 10 and the drying device 12 and hands over the sheet Sh1 on which the ink image has been formed from the image forming apparatus 10 to the drying device 12.

[0039] Specifically, as shown in FIG. 4, the sheet conveying device 8 receives the sheet Sh1 conveyed by the first conveying unit 4 of the image forming apparatus 10, conveys the sheet Sh1 in the conveying direction D1, and hands over the sheet Sh1 to the second conveying unit 14 of the drying device 12. In other words, the first conveying unit 4, the sheet conveying device 8, and the second conveying unit 14 are arranged in the stated order from the upstream side of the conveying direction D1 and cooperate to convey the sheet Sh1 toward the downstream side of the conveying direction D1.

[0040] Incidentally, as the related art, there is known an image forming system (inkjet recording apparatus) including an image forming apparatus (image recording portion) which records an image on a surface of a sheet (paper) by an inkjet method and a drying device (ink drying processing portion) which performs drying processing on the sheet on which the image has been recorded by the image forming apparatus. In the image forming system according to the related art, the sheet is handed over to the drying device by a conveying drum of the image forming apparatus.

[0041] However, with the configuration of the related art described above, the sheet is delivered between the image forming apparatus and the drying device only by the sheet conveying guide. Therefore, for example, a downstream side end portion of the sheet (an end portion on the downstream side of the conveying direction) may float by the wind from the separation mechanism or the like for separating the sheet by the blow of air from the image forming apparatus.

[0042] In contrast, in the present embodiment, by a configuration described below, it is possible to realize the sheet conveying device 8 and the image forming system 100 in which the floating of the sheet Sh1 is suppressed with ease.

[0043] Specifically, the sheet conveying device 8 according to the present embodiment includes a suction conveying portion 81 and an auxiliary suction portion 82. The suction conveying portion 81 conveys the sheet Sh1 along a guide surface 800 while sucking the sheet Sh1 onto the guide surface 800. The auxiliary suction portion 82 is arranged on the downstream side of the conveying direction D1 as viewed from the suction conveying portion 81 on the guide surface 800, and sucks the sheet Sh1 onto the guide surface 800.

[0044] In short, since the sheet conveying device 8 includes the suction conveying portion 81 that conveys the sheet Sh1 in the conveying direction D1 while sucking the sheet Sh1 onto the guide surface 800, floating of the sheet Sh1 (from the guide surface 800) between the image forming apparatus 10 and the drying device 12 can be suppressed. Furthermore, since the sheet conveying device 8 includes the auxiliary suction portion 82 on the downstream side (drying device 12 side) of the suction conveying portion 81 in the conveying direction D1, floating of the downstream side end portion (end portion on the downstream side of the conveying direction D1) of the sheet Sh1 by the wind from the separation mechanism 44 acting on the sheet Sh1 can also be suppressed, for example. Therefore, it is possible to realize the sheet conveying device 8 and the image forming system 100 in which floating of the sheet Sh1 is suppressed with ease. As a result, it becomes easy to maintain stable image quality as the image forming system 100.

[0045] In particular, the sheet conveying device 8 according to the present embodiment further includes an optical sensor 83 for detecting passage of the sheet Sh1 on the downstream side (drying device 12 side) of the conveying direction D1 as viewed from the suction conveying portion 81. Since it is difficult to arrange the suction conveying portion 81 which has a relatively complicated configuration within a detection range of the optical sensor 83, floating of the sheet Sh1 at a portion where the floating of the sheet Sh1 is apt to occur, that is, this portion within the detection range of the optical sensor 83 can be suppressed by the auxiliary suction portion 82 in the present embodiment.

[0046] Herein, the sheet conveying device 8 according to the present embodiment includes a plurality of suction conveying portions 81F, 81R arranged in a front-rear direction (depth direction) which is the main scanning direction D11. Furthermore, also for the auxiliary suction portion 82, the sheet conveying device 8 includes a plurality of auxiliary suction portions 82F, 82R arranged in the front-rear direction (depth direction) which is the main scanning direction D11. In other words, the sheet conveying device 8 includes the plurality of suction conveying portions 81F, 81R and the plurality of auxiliary suction portions 82F, 82R.

[0047] Of the plurality of suction conveying portions 81F, 81R, the suction conveying portion 81F is positioned on a front F side of the front-rear direction which is the main scanning direction D11, and the suction conveying portion 81R is positioned on a rear R side of the front-rear direction which is the main scanning direction D11. Similarly, of the plurality of auxiliary suction portions 82F, 82R, the auxiliary suction portion 82F is positioned on the front F side of the front-rear direction which is the main scanning direction D11, and the auxiliary suction portion 82R is positioned on the rear R side of the front-rear direction which is the main scanning direction D11. Therefore, the auxiliary suction portion 82F is positioned on the downstream side of the suction conveying portion 81F in the conveying direction D1, and the auxiliary suction portion 82R is positioned on the downstream side of the suction conveying portion 81R in the conveying direction D1.

[0048] Since the plurality of suction conveying portions 81F, 81R have a common configuration, descriptions below will be given on the configuration of one of the suction conveying portions 81 unless stated otherwise. Similarly, since the plurality of auxiliary suction portions 82F, 82R have a common configuration, descriptions below will be given on the configuration of one of the auxiliary suction portions 82 unless stated otherwise.

[0049] In the present embodiment, the suction conveying portion 81 includes a case 80, a suction portion 811, and conveying rollers 812. The case 80 includes the guide surface 800. The suction portion 811 sucks the sheet Sh1 onto the guide surface 800. The conveying rollers 812 convey the sheet Sh1 sucked onto the guide surface 800 along the guide surface 800.

[0050] More specifically, an upper surface of the case 80 is the guide surface 800. An end portion of the guide surface 800 on the upstream side of the conveying direction D1 (image forming apparatus 10 side) is a tilted surface that is tilted downwardly in an oblique direction, and this makes it easy to lead a tip end of the sheet Sh1 delivered from the image forming apparatus 10 onto the guide surface 800. The case 80 constitutes a suction box in which an internal space thereof is set to a negative pressure by, for example, a fan or the like.

[0051] The suction portion 811 includes an opening formed on the upper surface (guide surface 800) of the case 80. Since the internal space of the case 80 is set to a negative pressure, the suction portion 811 sucks in air from the opening so as to generate sucking power for sucking the sheet Sh1 toward the guide surface 800 side (downwardly).

[0052] One or a plurality of (three in the present embodiment) conveying rollers 812 are provided and is/are configured to be exposed on the guide surface 800 from the opening of the suction portion 811 while being housed in the case 80. Thus, by the rotation of the conveying rollers 812, the sheet Sh1 on the guide surface 800 can be conveyed in the conveying direction D1.

[0053] With this configuration, the suction conveying portion 81 can convey the sheet Sh1 along the guide surface 800 of the case 80 by the conveying rollers 812 while sucking the sheet Sh1 by the suction portion 811. Therefore, when the sheet Sh1 is conveyed by the conveying rollers 812, the sheet Sh1 is less likely to float from the guide surface 800.

[0054] The auxiliary suction portion 82 includes a plurality of suction holes 821 formed on the upper surface (guide surface 800) of the case 80. Since the internal space of the case 80 is set to a negative pressure, the auxiliary suction portion 82 sucks in air through the plurality of suction holes 821 to generate sucking power for sucking the sheet Sh1 toward the guide surface 800 side (downwardly).

[0055] Further, the suction portion 811 is not limited to the configuration described above and may alternatively be configured to suck the sheet Sh1 by a negative pressure for sucking in air through a plurality of small holes formed on the surface of the conveying rollers 812, for example. Furthermore, the suction portion 811 is not limited to the suction by a negative pressure and may alternatively be configured to suck the sheet Sh1 by an electrostatic force or the like. Similarly, the auxiliary suction portion 82 is also not limited to the suction by a negative pressure and may alternatively be configured to suck the sheet Sh1 by an electrostatic force or the like.

[0056] Furthermore, as described above, the sheet conveying device 8 according to the present embodiment includes the optical sensor 83 that detects the sheet Sh1. Herein, the guide surface 800 includes an extension portion 801 formed with the auxiliary suction portion 82 on the downstream side of the conveying direction D1 as viewed from the suction conveying portion 81. The extension portion 801 includes a transmissive portion 802 through which light from the optical sensor 83 passes.

[0057] In short, the case 80 has a shape that overhangs toward the downstream side of the conveying direction D1 (drying device 12 side), and an upper surface of this overhanging portion constitutes the extension portion 801. The extension portion 801 is formed with the plurality of suction holes 821 that are in communication with the internal space of the case 80, thereby constituting the auxiliary suction portion 82. In addition, the extension portion 801 is formed with the transmissive portion 802 for causing light from the optical sensor 83 to pass therethrough.

[0058] In the present embodiment, as shown in FIG. 4, the optical sensor 83 is arranged above a center portion in the main scanning direction D11 on the downstream side of the conveying direction D1 as viewed from the suction conveying portion 81. The optical sensor 83 is a reflective sensor, and a mirror is arranged below the optical sensor 83 at a position opposing the optical sensor 83. When there is no obstruction (sheet Sh1), the optical sensor 83 receives light from below which is light obtained by reflecting a light beam that has been emitted downwardly by the mirror. Therefore, it is possible to determine that the sheet Sh1 as an obstruction is passing below the optical sensor 83 at a timing when the optical sensor 83 does not receive light from below.

[0059] The transmissive portion 802 is formed at a center portion of the portion of the case 80 overhanging toward the downstream side of the conveying direction D1 in the main scanning direction D11, and has a notched shape that is recessed toward the upstream side of the conveying direction D1. In other words, since the transmissive portion 802 is positioned between the optical sensor 83 and the mirror, it is possible to avoid a situation where the light from the optical sensor 83 is blocked by the case 80. The extension portion 801 is divided into two in the main scanning direction D11 with the transmissive portion 802 in between.

[0060] With this configuration, even when the extension portion 801 is positioned at a position where the extension portion 801 interferes with the optical sensor 83, it is possible to avoid the situation where the light of the optical sensor 83 is blocked and detect the passage of the sheet Sh1. Therefore, the degree of freedom in arranging the optical sensor 83 becomes higher than that of a case where the extension portion 801 is not provided.

[0061] Further, as described above, in the sheet conveying device 8 according to the present embodiment, the guide surface 800 is provided with the plurality of auxiliary suction portions 82. The sucking power of the plurality of auxiliary suction portions 82F, 82R can be adjusted individually. In other words, the sucking power of the auxiliary suction portion 82F positioned on the front F side of the front-rear direction, which is the main scanning direction D11, and the sucking power of the auxiliary suction portion 82R positioned on the rear R side of the front-rear direction, which is the main scanning direction D11, can be adjusted individually. The adjustment of the sucking power is realized, for example, by a shutter that is provided for each of the auxiliary suction portions 82F, 82R and adjusts an opening degree of the plurality of suction holes 821. In other words, for example, by narrowing (reducing) the opening degree of the plurality of suction holes 821 only for the auxiliary suction portion 82R by the shutter, the sucking power of the auxiliary suction portion 82R can be suppressed to be small.

[0062] With this configuration, the plurality of auxiliary suction portions 82F, 82R can individually adjust the sucking power in accordance with a passage position of the sheet Sh1 in the main scanning direction D11, so that the floating of the sheet Sh1 can be suppressed with appropriate sucking power. As an example, when the sheet Sh1 is biased toward the rear R side of the front-rear direction, which is the main scanning direction D11, the sucking power of the auxiliary suction portion 82F is set to become relatively smaller than that of the auxiliary suction portion 82R to avoid an action of sucking power larger than necessary.

[3] Modified Example

[0063] The plurality of constituent elements included in the image forming apparatus 10 may be provided dispersedly in a plurality of housings. For example, the image forming portion 5 and the ink supply portion 6 may be provided in separate housings.

[0064] Conversely, in Embodiment 1, at least one of the constituent elements provided separately from the image forming apparatus 10 may be provided in the image forming apparatus 10 as the constituent element of the image forming apparatus 10. For example, at least one of the sheet feed device 11, the drying device 12, and the discharge device 13 may be provided integrally with the image forming apparatus 10 by being provided in the housing 21, or the like.

[0065] Further, the image forming target on which an image is to be formed by the image forming apparatus 10 is not limited to the sheet Sh1 such as paper or a resin film, and may be, for example, a roll of fabric such as non-woven fabric or cloth. In this case, the image forming apparatus 10 is a textile printing machine (textile printer) which ejects ink onto the fabric and dyes fibers of the fabric with the ink, to record an image on the fabric.

[0066] Furthermore, the recording element is not limited to the ink nozzle 53, and may be, for example, the recording head 51 or the line head 50. Moreover, when the image forming apparatus 10 uses a recording method other than the inkjet method, the recording element is changed as appropriate according to the method used in the image forming apparatus 10, and the like.

[0067] Further, the optical sensor 83 is not limited to the reflective sensor and may be, for example, a transmissive sensor in which a light-emitting portion and a light-receiving portion are arranged opposed to each other.

[0068] Furthermore, it is not essential for the sucking power of the plurality of auxiliary suction portions 82F, 82R to be adjustable individually, and the sucking power of the plurality of auxiliary suction portions 82F, 82R may be adjusted collectively.

[0069] Moreover, it is not essential for the sheet conveying device 8 to include the plurality of suction conveying portions 81, and only one suction conveying portion 81 may be provided. Similarly, it is not essential for the sheet conveying device 8 to include the plurality of auxiliary suction portions 82, and only one auxiliary suction portion 82 may be provided.

[Notes of Disclosure]

[0070] Hereinafter, a general outline of the disclosure extracted from the embodiment described above will be noted. It is noted that the respective configurations and processing functions described in the notes below can be sorted and arbitrarily combined as appropriate.

<Note 1>

[0071] A sheet conveying device which conveys a sheet from an image forming apparatus which forms an ink image on the sheet by ejecting ink onto a surface of the sheet to a drying device which dries the ink image on the sheet, the sheet conveying device including: [0072] a suction conveying portion which conveys the sheet along a guide surface while sucking the sheet onto the guide surface; and [0073] an auxiliary suction portion which is arranged on a downstream side of a conveying direction as viewed from the suction conveying portion on the guide surface, and sucks the sheet onto the guide surface.

<Note 2>

[0074] The sheet conveying device according to note 1, in which [0075] the suction conveying portion includes [0076] a case including the guide surface, [0077] a suction portion which sucks the sheet onto the guide surface, and [0078] a conveying roller which conveys the sheet that has been sucked onto the guide surface along the guide surface.

<Note 3>

[0079] The sheet conveying device according to note 1 or 2, further including: [0080] an optical sensor which detects the sheet, in which [0081] the guide surface includes an extension portion formed with the auxiliary suction portion on the downstream side of the conveying direction as viewed from the suction conveying portion, and [0082] the extension portion includes a transmissive portion through which light of the optical sensor passes.

<Note 4>

[0083] The sheet conveying device according to any one of notes 1 to 3, in which [0084] a plurality of the auxiliary suction portions are provided on the guide surface, and [0085] sucking power of the plurality of auxiliary suction portions can be adjusted individually.

<Note 5>

[0086] An image forming system, including: [0087] the sheet conveying device according to any one of notes 1 to 4; [0088] the image forming apparatus; and [0089] the drying device.

[0090] It is to be understood that the embodiments herein are illustrative and not restrictive, since the scope of the disclosure is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims.